Rejuvenating batteries - Page 1
Forum section: electronics / repair

author: msknight
author_rank: Regular Contributor
timestamp: January 06, 2018, 08:32:12 am
content: Hi Folks,I'm a beginner with electronics and repair, but I'm attempting a project, one aspect of which is above my abilities.The subject at hand is a portable cassette deck. Actually, at the beginning of December I didn't have any and now I've got four. It's a long story... they usually are with me.But... they need gumstick batteries which are sealed lead acids. Presumably gel. I've read about restoration techniques for car batteries -https://www.elektormagazine.com/magazine/elektor-200109/17100- de-sulphation they call the process ... something about feeding a 300hz pulse to reverse the chemical changes that have happened. Someone described the process as, "sketchy at best," but I've got to try.However, like I said, I'm a beginner and I don't know how to construct a circuit that would do the job. And even then, I'll be doing it outside with some neutralisation agent to hand !!! Just in case, you know.Can anyone lend a hand please?

author: soubitos
author_rank: Frequent Contributor
timestamp: January 06, 2018, 09:09:23 am
content: If THESE batteries are dead, have very low or no voltage and dont charge forget about them... anything you might try to "save"them is not only potentially VERY dangerous but to the best of my knowledge a waste of time.....If you need to restore the decks and bring them to life in their original vintage state, ebay and the like might be your only chance (http://www.ebay.co.uk/itm/NOS-Aiwa-Sealed-Lead-Acid-Battery-PB-3-2V-470mAh-/371202098329one of the first to pop out)Otherwise, you can also replace them with lithium batteries (you will need a board like myTP4056FLEXADV)

author: tautech
author_rank: Super Contributor
timestamp: January 06, 2018, 09:17:50 am
content: Like soubitos says, the age of these batteries would most likely make them a waste of time to attempt to rejuvenate them. I've done a good amount of LA battery desulphation and you need to pick your battles to get much success.Instead I'd be looking hard at alternative power sources for your cassette deck. How many batteries does it need to run ? How much physical space have we got to shoehorn another battery system into ?

author: soubitos
author_rank: Frequent Contributor
timestamp: January 06, 2018, 10:04:09 am
content: Quote from: tautech onTodayat 11:17:50 AM66.04mm x 17.78mm x 5.08mmLithium batteries should work fine if they fit... 18650 are 65mmx18mmx18mm, they might snug in but they would protrude a lot... doing some searching, i found this onehttp://www.all-battery.com/polymerli-ionbattery37v300mah461540-1.aspxwhich is not expensive considering and i think would both fit perfectly and would offer a great lightweight alternative>All you need besides the battery is a proper charger and you are set..

author: soubitos
author_rank: Frequent Contributor
timestamp: January 06, 2018, 10:15:35 am
content: There are (??) also NiMH alternatives like this onehttps://picclick.com/New-Battery-Replacement-for-Aiwa-AM-HX50-AM-HX55-AM-HX70-160565746342.html

author: msknight
author_rank: Regular Contributor
timestamp: January 06, 2018, 10:23:22 am
content: Thanks for the ideas folks.These have all come from Ebay, but not NOS. I'll give Lighthouse USA a line, see if they do replacements for the 3, and I also need to rejuvenate some 4 as well. All 2v.The other option is to remove the insides and use the cases to house other cells.I'd at least like to try and get these running, though. If I can find one or two among the 8 that I've got, then they should be worth trying to resurrect, surely.

author: tautech
author_rank: Super Contributor
timestamp: January 06, 2018, 10:40:54 am
content: I'm guessing you need 3 for a nominal 6V supply, right ?For desulphating 2 V cells you'd need to start from scratch and design a 2 V desulphator, no real hardship if you have the gear and time. Essentially they just zap the pates with several times the nominal voltage and a few amps.Some make them as standalone and powered from another source but ones I made were powered from the battery itself and typically ran @ 1KHz.But if you want this player to give any decent service I'd be changing the batteries to something readily available using one of the lithium technologies that will give better power density and lower weight.

author: msknight
author_rank: Regular Contributor
timestamp: January 06, 2018, 11:15:16 am
content: Actually, it only needs one. I got extras from ebay because I knew the chances were low of finding one that worked, but there was at least a chance.I wouldn't know where to start in designing something of this nature, that's why I'm here.I also found Lighthouse USA on Ebay and dropped them a note with what I need help with. I'm not sure they'll be able to help, but if you don't ask....

author: PA4TIM
author_rank: Super Contributor
timestamp: January 06, 2018, 11:23:36 am
content: I have build a desulfator (they are for lead accid batteries) and had it connected it about a year 24/7 to a battery in my lab. After a year it was still as dead as a Dodo.It can work but only under certain conditions to increase the life of a battery. But once the battery is desulfated to much it is over. my experiments:http://www.pa4tim.nl/?p=3538Batteries are very complex because it is chemical and electrical and there are many types.I had some "succes" on nimh and nicd by zapping it with a high current. see:http://www.pa4tim.nl/?p=5749Sometimes a few seconds with reversed polarirty to a lab supply works. But they are often just short time solutions and battery performance is not great.It has to do with crystal grow/size.http://batteryuniversity.com/this is a very good site with very reliable information.

author: msknight
author_rank: Regular Contributor
timestamp: January 06, 2018, 11:33:50 am
content: Thanks very much for this information. All good stuff.My problem with this particular walkman unit, is that there is an external battery compartment for AAA batteries, but it is hard to source... and the external transformer connects through that external compartment... so without that compartment, I'm totally reliant on getting these cells to work.So I've got nothing to loose except maybe a minor explosion....

author: soubitos
author_rank: Frequent Contributor
timestamp: January 06, 2018, 11:41:37 am
content: Quote from: msknight onTodayat 01:33:50 PM

author: coromonadalix
author_rank: Super Contributor
timestamp: January 06, 2018, 11:59:09 am
content: well if you have a battery to spare, dismantle it slowly and securely, remove the insides and try to solder 2 flexible wires and power up you unit that way to test it, i remember theses batteries ....Bad souvenirs, the secret was to always maintain them charged ... pb1 pb3 pb5 proprietary cells, but Aiwa made incredible Walkman at the time ... always hated any companies who used special cells, i totally avoid them if possible ...There's a few on Ebay not sure if they are good, its an old technology ...good luck

author: msknight
author_rank: Regular Contributor
timestamp: January 06, 2018, 12:35:51 pm
content: The PB-3 sits inside the unit. The AAA module is built to screw on the outside. I believe there is circuitry inside the AAA module to drop the current to 2V before it reaches the PCB, but I don't know as the walkman on the right is a P505 and the units don't cross over.

author: jolshefsky
author_rank: Regular Contributor
timestamp: January 06, 2018, 02:30:56 pm
content: Another option would be to 3D print a replacement enclosure then put a rechargeable lithium pack and a voltage-matching circuit inside. I'm assuming you should be able to charge it from the unit, but a microUSB at one end of the stick and an off-the-shelf charger would probably be easier.

author: msknight
author_rank: Regular Contributor
timestamp: January 06, 2018, 02:34:35 pm
content: I don't have a 3D printer, nor the knowledge on how to design/use them. Good suggestion though. If I can get a suitable lithium pack that would fit, that would be a start. Where can I source one from please?

author: msknight
author_rank: Regular Contributor
timestamp: January 06, 2018, 02:56:02 pm
content: Looks like once you get it out of the metal surround, that the battery itself has a nice case with a plastic film cover. Might just be the ideal holder for a new battery itself :-) - All I need to do is work out how to neutralise whatever's in there and dispose of properly.Internal dimensions appear to be 58,, x 14mm x 6mm

author: soubitos
author_rank: Frequent Contributor
timestamp: January 06, 2018, 03:19:36 pm
content: Quote from: msknight onTodayat 04:34:35 PM

author: msknight
author_rank: Regular Contributor
timestamp: January 06, 2018, 04:08:47 pm
content: One of the other things I could do, in order to do bench testing, is install a USB input that would drop 5v to 2v. The question is, doing it safely in that kind of space. Nothing on Google comes up with 2v step down, however.I'll keep searching.

author: soubitos
author_rank: Frequent Contributor
timestamp: January 06, 2018, 04:22:38 pm
content: You can use anything from the clasic LM317 up to MC34063, there are literally hundreds of voltage regulators for the task....

author: Armadillo
author_rank: Super Contributor
timestamp: January 06, 2018, 04:37:40 pm
content: Such old technology operate down to 2V??? Cannot be!Use a 2 cells lithium, the voltage will be just nice, don't need to step down or anything.There is a external cradle for the battery, you can modify it to suit the 2 cells lithium.

author: msknight
author_rank: Regular Contributor
timestamp: January 06, 2018, 04:44:38 pm
content: "2 cells lithium" sounds like military terminology! "These, Private, are not Drawers, cellular, pairs one!"So where do I get these 2 cells lithium please? - Bear in mind that I'm still trying to find a course in basic electronics!

author: Armadillo
author_rank: Super Contributor
timestamp: January 06, 2018, 04:57:47 pm
content: Quote from: msknight on January 06, 2018, 04:44:38 pmOr use 2 nano tech wired in series to form 2S.If you fly heli or drones, you will know all the batteries.Size 50.8 x 13 x 8mm

author: msknight
author_rank: Regular Contributor
timestamp: January 06, 2018, 05:32:50 pm
content: Hmmm... 2 mill too high... so very nearly... but I'm going to contact Nano tech though. Thanks for the heads up!

author: Armadillo
author_rank: Super Contributor
timestamp: January 06, 2018, 05:42:22 pm
content: Don't just simply trust anything you read on the web.Normally teased the logical side of the mind and sounded "too" promising and waste human lifetime.So here is the Lead Acid Battery Rejuvenator I built long time ago. Promise to break down sulfate that adhered to the electrodes.There are Burst Rings of high voltage you can see on the oscilloscope. First ring burst as high as 70Vdc.But after 1 day of rejuvenating, the battery is "SAME".So, if you put your "dead" battery onto adjustable lab voltage power supply, slowly increase from 2 volts up up up while observing any appreciable increase in charging current flow until you reach 50vdc stop. If no appreciable increase in current flow or no current flow at all, the battery is "DEAD" "DEAD" and don't waste your time as others have pointed up already. Otherwise "maybe" still can be saved.Now the rejuvenator just sit there taking up my storage space.

author: kalel
author_rank: Frequent Contributor
timestamp: January 06, 2018, 07:29:19 pm
content: I'm not sure how I would go about the same thing (I have already learned some terms here - but I am still a complete beginner), but if you have a higher voltage source, and want to step it down to e.g. 2v, you don't necessarily need to build any circuit. You could buy a cheap circuit from eBay.Just search for adjustable step down module (they are also known as buck - voltage step up would be known as boost). These types of modules should allow you to set any output voltage desired with a screwdriver (for the miniature ones).Charging is another matter. If you have a battery pack with a plug, say those made for RC planes/copters as recommended above you could possibly solder a compatible plug (same as the charger would have) to the input of a step down (and the output would be connected to the device battery input). Then when the battery is empty, take the battery out, plug it into the charger to charge... and plug it back into the module once full (in case the buck output voltage depends on the input/battery voltage, I would also configure the output voltage on the step down module when the battery is completely full, so that it couldn't output too high voltage at any point).I am not sure how to reuse the battery case. I would check some YouTube videos of the disassembly process first to see what to expect, but it's surely easier and safer (while maybe less aesthetically pleasing) to avoid using the original case if at all possible.

author: Gyro
author_rank: Super Contributor
timestamp: January 07, 2018, 10:38:59 am
content: I suspect that these Rejuvenators have some level of success in flooded wet cells (car batteries), where the Lead Sulphate can be dislodged from the plates and can float away.In a gell cell, everything is tightly sandwiched with minimal electrolyte, so there is nowhere for the Sulphate to go. There is no way to chemically break it down either in a sealed cell.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 06:54:17 am
content: OK - so I now turn my attention to 3.7v LiPoly batteries.If I can get one to fit in the case, I'm presumably going to need a small circuit to knock it down to 2v and also allow charging when in the walkman.Where do I start with this please?

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 07:01:56 am
content: Ok - I'm going to run with Armadillo's suggestion of these -https://hobbyking.com/en_us/turnigy-nano-tech-200mah-1s-35-70c-lipoly-battery-5pcs.html?___store=en_usI'm presuming that there is some circuitry within the cap, which I should be able to remove to gain the 2mm I need to make this fit. Whether that is a charging circuit, who knows. I'll find out when they get here.At 50.8mm long, that leaves me only 7mm to somehow drop this to 2v and make up for whatever isn't in the cap.So... no pressure then.

author: james_s
author_rank: Super Contributor
timestamp: January 08, 2018, 07:19:26 am
content: I've never had any luck at all rejuvenating any kind of gelled lead acid battery, especially something that old.Be careful with high current LiPos like the ones pictured for RC aircraft, they can deliver very high currents, lack any kind of internal protection and have been known to catch fire if abused. I would suggest looking at small prismatic lithium ion cells like the kind used in cell phones and music players, ideally something with internal protection circuits.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 07:31:55 am
content: Good points. Any suggestions on where I start looking/who I should be talking with please?

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 07:32:10 am
content: Quote from: msknight on January 08, 2018, 06:54:17 amWhy do you need to knock it down to 2V? I don't think the motor will even turn at 2V. Yesteryear semiconductor don't operate at 2V.You can temporary wire a 2V into the circuit board to see if it will operate.As someone has said, 3 batteries are connected together in series to form at least 6V to operate this player.As for the lipo, 2 in series will form over 7V, so may be a diode IN4001 in series will drop the volt to 6V region but I am sure it will work fine for your player.So you should check and confirm the voltage the player is designed to operate, definitely not 2V.Edit: If you ever dismantle any of those GPS/Car camera etc.. you will find these bare unprotected small capacity lipo in it. Because the VA is low, you don't exactly need to be overly concerned or worried about it.

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2018, 07:54:45 am
content: Quote from: msknight on January 08, 2018, 06:54:17 amBased on what you said here:Quote from: msknight on January 06, 2018, 11:15:16 amAnd what we'd expect in the circuit design....there's likely a boost converter to bump a single cell 2V supply to 6V, but this need be checked, So we need some good pics of where the 2V supplies the PCB inside the Walkman and the general area. Some clues will be the voltage rating of the electrolytic caps that must have some voltage headroom over the main PCB voltage. There even may be some test points and makings on the PCB indicating voltages present.In all likelihood the boost converter can handle a higher supply than 2V but to be sure some of the experienced guys and gals need a peep at the guts please.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 08:25:36 am
content: I had the unit apart two days ago and took some pictures. I might be able to get them from another post, for you.Most of the caps are 100uf 2v and 220uf 2v, with some 220uf 4v and two 470uf 6.something near the power in.I'll hunt the pictures down.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 08:28:25 am
content: Here you go. The cutaway in the board is where the gumstick battery sits. There is a separate input at the top right.... that is where the external battery pack comes in.The external battery pack contains two AAA batteries, and also is pass-thru for the external Aiwa transformer, which is 2V at 350mA.And yes, the board is a bit of a mess. I've got replacement caps on order.

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2018, 08:45:30 am
content: No sign of a boost converter.Do you remember if there was componentry on the other side of the PCB ?

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 09:09:35 am
content: Nothing. Only traces.

author: SMdude
author_rank: Frequent Contributor
timestamp: January 08, 2018, 09:23:02 am
content: What an obscure bit of gear!Given that the supply voltage from the AC adaptor is 2v and looking at the caps, I think it is very likely this is a special 2v system! How bazzar!If going with li-po, or li-ion, make sure you use a pcm(protection circuit module) between the batteries and power supply, so the batteries get disconnected before they are totally drained.https://www.ebay.com.au/itm/1S-2-5A-3-7V-Lithium-Batterry-Protection-Board-Polymer-BMS-PCM-PCB-Li-ion-Module/252826406992?epid=700767788&hash=item3adda0d050:g:6GoAAOSwsW9Y02HF.For the charger, use a tp5100 board (ebay) they run from 12v, just don't reverse it!Now, to step down the voltage, probably the best way to do it is to just use some general purpose 2 or 3A diodes in series. Start with 4 or 5 in series and reduce them back until you have just over 2v with the fully charged lipo(4.2v approx). It will need to be connected up to the load to test the voltage, if there is no load you will still read 4.2~v after the series diodes.Going the route of diodes is good in that you don't need to worry about turning off a power supply that lives between your battery and walkman.

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2018, 09:41:15 am
content: For a electronics novice SMdude's solution will be the simplest, just silicon diodes in series each of which offers 0.6-0.7V forward voltage drop. All you need is a voltmeter to confirm how many you need while the battery is under load. They can be added to the negative or positive rail wherever you can shoehorn them into the circuit and case.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 10:11:39 am
content: Yes, it is obsolete :-) - It is a tape deck - the Aiwa HS PX-303 -http://walkman-archive.com/gadgets/walkman_aiwa_04_px303_eng_v3.htmThe story behind this is long... nearly 30 years long :-)My target is still the LiPo as mentioned a few posts earlier. It stands the best chance of fitting. The question is... I want to put this back in the gumstick and seal it back up... so how would I charge it once I have the diodes fitted? Or would I have to connect the charger between the diodes and the battery?

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 10:17:39 am
content: The TP5100 I'm finding are listed at 4.2V to 8.4V - and these LiPo's will be 3.7 -https://www.ebay.co.uk/itm/TP5100-2Cells-Single-Lithium-Lion-Battery-Charger-Module-18650-4-2V-8-4V-BS2/322917861077- Can I realistically still use these?

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2018, 10:22:08 am
content: Quote from: msknight on January 08, 2018, 10:11:39 amFit the diodes into the Walkman case (Cut a PCB trace if necessary)and the LiPo into the gumstick.Arrange a charging system that charges the LiPo in the gumstick maybe with small "charging only" jack point and include the 1S 2.5A 3.7V Lithium Batterry Protection Board on the outlet pins to the Walkman.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 10:32:41 am
content: The walkman charges through the extended battery adapter. That adaptor has circuitry in it to drop the two AAA cells to 2V as well.I think I'll be safer to work on charging the battery outside the walkman. I'll have to build a charger that matches the pins. So... in this case... do I still need to attach the charger behind the diodes, or can I still connect it at the front, assuming the case is sealed? - I'd rather not attach the diodes inside the unit if possible. There may be the ability to fit a socket to the front, or rear, of the case itself. I'll have to look at that option first.But if it doesn't matter that the diodes are in there, it will enable me to use the external points.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 10:53:31 am
content: OK ... I'm speed reading all this in gaps at work, so this is how I read this so far....I can use the 3.7v LiPo cell, with some 0.6-0.7v diodes on the +ve side to drop the voltage to 2v.To charge, I'll need to do this externally, using a TP5100 board (even though the board is putting out 4.2v and the battery is rated at 3.7v) but I will have to do this behind the diodes, so I'll need to fit a small charging port in the gumstick.Because of this, I won't need the protection circuit module, but I won't be able to charge via the walkman itself.Some questions remain...*) What mAh must the external transformer be to power the TP5100(the unit appears to run from a range of voltages... and I'm wondering that if I power via 5V from USB, would that handle it?)*) I presume from reading the rather sketchy e-bay description, that the TP5100 has protection to avoid over charging.*) What would happen if I were to forget about the gumstick being in the unit, and hook up the external 2V supply via the battery bay?*) I'm actually wondering how the original charged the Lead Acid, because there is no apparent circuitry inside the battery... maybe there is voltage protection already on the board?

author: soubitos
author_rank: Frequent Contributor
timestamp: January 08, 2018, 11:06:21 am
content: The lipo you will need is very small, you dont need a TP5100 rated 2A to charge a 300-350mAh pouch, you dont even need a stock TP4056 rated 1A to charge such a small battery... if you want to keep it safe your max charge current should be 0.5C max 1C .... this means 300-350mA charge current... this is one of the reasons i made and one of the issues solved with myTP4056FLEXADVboard unless you want to desolder the 1.2K stock smd resistor (can be 0805-0603 or even 0402 in some pcbs) and replace it with a 2.4K to set charge current somewhere between 0.5-1C of a said 300-350mAh lipo (250mA)

author: SMdude
author_rank: Frequent Contributor
timestamp: January 08, 2018, 11:19:16 am
content: I would still use the pcm, it is very small and it saves the battery from discharging below its critical limit. Overdischarging a li-po (li-ion) kills them.3.7v is the nominal voltage. Fully charged they are 4.2v.I would pack the cell and diodes back into the original battery packaging if at all possible. I would even include the charger board with a 2.1mm dc socket to the outside for charging. How big is this battery?There are many different size/shape lipo's, try and see how much room is taken up by the diodes etc, then see what battery space you have left. You can use 2 or 3 cells in parallel depending on what you can find.And yes the charger needs to connect in directly to the battery or output of pcm if you have one.Allow about 1A for the 12v input to the charger.If you hook up the 2v supply with the battery in, nothing will happen to the battery.The 2v supply is probably a bit over 2v and that is most likely how it charged the original battery. They never made nice chargers like we have today for li-po!And you probably don't need the tp5100, I just like them as they are a very handy cheap lipo charger. To adjust the charge current you can just remove one of the 0.1r resistors, and or replace the other one to .2r and it will charge at max current of 500ma~ But something else may suite better depending on the battery capacity.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 12:39:24 pm
content: This is the internals of the battery case. It is covered by a metal surround which fits tightly. The internal is 58mm x 14mm x 6mm.I'm not going to get the pcm in there with the battery. If I can get the plastic header off the lipo, I think it will just fit, with 7mm of room at the top for the diodes.

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 01:49:23 pm
content: Try this and complete with pcm.https://www.ebay.com/itm/3-7V-500-mAh-Li-polymer-Rechargeable-Battery-501646-for-Recording-Reading-pen/262500045648?epid=1375129230&hash=item3d1e38d350:g:s1wAAOSwukdXcOsEOnly 4.5mm thick

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 01:59:00 pm
content: Wow. Stunning :-)I would charge this with the same TP5100, yes?

author: soubitos
author_rank: Frequent Contributor
timestamp: January 08, 2018, 02:03:06 pm
content: Quote from: msknight onTodayat 03:59:00 PM

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 02:06:45 pm
content: Quote from: soubitos on January 08, 2018, 02:03:06 pmApologies... I'm at work, speed reading between tasks to keep the conversation running. Otherwise, it would wait until I got home to be able to respond to people. That would slow everyone down.The one two posts above which is 500mah.To be honest, everything coming out here is opening my eyes. I didn't even know that half the things here existed, let alone how to start searching for them.

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 02:07:58 pm
content: Quote from: msknight on January 08, 2018, 01:59:00 pm

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 02:10:50 pm
content: Quote from: soubitos on January 08, 2018, 02:03:06 pmSo you're saying that if I hook this 3.7v 500mAh LiPo up to the TP5100 ... then I'll have a recreation of the New Year fireworks on my workbench. Yes?

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 02:16:44 pm
content: This fit neatly;52mm X 14mm X 6mmhttps://www.ebay.com/itm/3-7V-450-mAh-Li-polymer-rechangeable-Battery-Li-Po-061452-bluetooth-mp3-mp4-/261285922057?hash=item3cd5dac509

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 02:33:35 pm
content: What soubitos is saying sort of makes sense to my beginner brain."unless you want to desolder the 1.2K stock smd resistor (can be 0805-0603 or even 0402 in some pcbs) and replace it with a 2.4K"I think this is worth doing. What do people think?

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 02:57:30 pm
content: You can also go for this 80 cents charger if you are too worried.This is a small VA battery, in reality it will very quickly switch from constant current to constant voltage mode where the current will be freewheeling reduced down accordingly.Anyone using intelligent charger will knows this, example setting the charger to 10A doesn't mean it will be charging at 10A continuously.AFAIK, You begin to be more concerned if your battery will cost you above $100. [those Hi-capacity battery for speed racing or heli].Don't need to reinvent the grains when commercially there is already simple charger for it.If in doubt, ask the seller of the battery for the recommended charger.https://www.ebay.com/itm/5V-1A-1S-3-7V-Li-ion-18650-Lithium-Lipo-Battery-Charging-Module-Charger-Board/322366742192?hash=item4b0e8e1eb0:g:xooAAOSwUchaNIn8Below is the E-Flite charger. Small nice heli Blade MCPX I had.https://www.ebay.com/itm/E-Flite-EFLC1006-Celectra-1S-3-7-Variable-Rate-LiPo-Charger-Blade-Nano-QX-FPV-SR-/253340725347AFAIK, don't need to spend that kind of money.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 03:14:44 pm
content: A big part of my problem is that I've got a task that I need to do, which is way above the little knowledge that I've got.I've already managed to upset someone because I'm speed reading... and there's a lot to take in here.I'll be home in a few hours, and then I can sit and read through all this carefully.I'd like to take a moment to thank everyone for their patience with me on this. I'm still trying to find myself a suitable electronics course. There is a penny about electronics that isn't dropping in my head, and none of the YT videos I've watch yet, have flipped the light switch in my head.

author: soubitos
author_rank: Frequent Contributor
timestamp: January 08, 2018, 04:28:02 pm
content: Quote from: msknight onTodayat 04:10:50 PM

author: james_s
author_rank: Super Contributor
timestamp: January 08, 2018, 04:41:52 pm
content: Quote from: Armadillo on January 08, 2018, 07:32:10 amIf there is no protection circuit attached to the cell then it is built into the electronics of the device it is in. Even a small low current Li-ion pouch will catch fire if sufficiently overcharged and will be damaged by excessive discharge. Some form of protection is mandatory.

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 05:04:09 pm
content: Quote from: james_s on January 08, 2018, 04:41:52 pmAny batteries may also catch into fire if it is sufficiently overcharged and any batteries will also be damaged if it excessively discharged.Mandatory as in "must", "necessary" in your terms or by act of LAW?I have alot of lipos that don't meet the mandatory. Infact alot of helis, drones flyer will be facing the same situation in the US, in the UK in the world.Above 1000mA batteries short circuit test;I am not against batteries with pcm. By all means, have it.IMHO those <500mA ones, you can rethink about it.

author: Gyro
author_rank: Super Contributor
timestamp: January 08, 2018, 05:13:25 pm
content: As you're in the UK, have a chat with Mjolinor about cell protection boards. He's up to his ears in the things - they're really tiny and work well....https://www.eevblog.com/forum/buysellwanted/fs-single-cell-liion-battery-management/Even with protected cells, there's no harm in having an additional protection board in-line, just a tiny increase in quiescent current.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 05:44:33 pm
content: OK, I'm going to ask a stupid question here....Both those units, the 5v mini usb and the TP5100 ... they both have full LED's. So... do they not stop charging?Or is the issue that once they've fully charged, they drop down a little and start charging again, and cycle like that?Or that they are being charged too fast?

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 05:58:40 pm
content: Quote from: msknight on January 08, 2018, 05:44:33 pmThese are dedicated intelligent charger, constant current and constant voltage mode.Please see attached datasheet, please self-translate it.For the TP5100, need to set to single cells and you can alter the charging current. Read it.TP5100 is designed for double section 8.4V / single section 4.2VLithium-ion battery design and switching of large current chargerChip, the use of power transistors inside the chip into the batteryLine Trickle, constant current and constant voltage charge. Charge current can be usedExternal resistor programming, the maximum sustained charge current up2A, do not need additional anti-reflux diode. TP5100 includedTwo open-drain output status indication output, chargingStatus indicator CHRG and battery full status indication inputSTDBY out. The chip's internal power management circuitry is atChip junction temperature exceeds 145 ? automatically reduce the chargeFlow, this feature allows users to maximize the use of the coreChip power handling capabilities, do not have to worry about the chip overheating and lossBad chip or external components.When the input voltage is greater than the chip start-up threshold voltage andThe chip enable input is tied high (VREG) or left floatingWhen the TP5100 starts charging the battery, the CHRG pinOutput low, indicating that charging is in progress. If double sectionLithium-ion battery voltage is lower than 5.8V (single-cell lithium batteryLower than 2.9V), the battery charger with a small currentTrickle precharge (precharge current through external resistor can beTune). Constant current charging current from VS pin and VBAT tubeThe resistance between the feet is fixed. When the double lithium-ion battery voltageClose to 8.4V (single lithium-ion battery close to 4.2V)The charge cut-off voltage is about 50mV (depending on the electricityRoad connection resistance and battery resistance voltage is different), charging electricityFlow is gradually reduced, TP5100 into constant voltage charging mode. whenCharging current reduced to cut-off current, the charge cycle junctionBunch, CHRG end output high impedance state, STDBY end loseLow out.When the battery voltage drops to the recharge threshold (two lithium-ionSub-battery 8.1V / single lithium-ion battery 4.05V), sinceStart a new charging cycle. High-precision chip internalVoltage reference, error amplifier and resistor divider network indeedBattery-side cut-off voltage accuracy of + -1% or less, to meetLithium-ion battery charging requirements. When the input voltage is powered downOr the input voltage is lower than the battery voltage, the charger goes lowPower down mode, without external anti-back-diode,Battery leakage from the chip close to 1uA.The choice of cut-off voltage. When CS is connected to high potentialVREG, 8.4V dual-cell lithium-ion battery charging standardQuasi, cut-off voltage 8.4V. When CS end vacant, as a singleLithium-ion battery battery charging standard, cut-off voltage 4.2V.When CS is tied low GND, the charger stopsCharge.TP5100's CS-side composite design, you can passThe external control determines that the TP5100 is in charge mode and downtimeMode switch.When the CS side vacant, said TP5100 for a single lithium fromSub-battery charge.8.4V dual lithium-ion battery charging status and downtimeMode switch. Shown in Figure 4, through an open drain inputThe output port is connected with the CS terminal if the gate of the NMOS transistor is inputLow, N1 end, this time CS termination highCharge cut-off voltage of 8.4V, TP5100 for the two-cell lithium fromSub-battery charge. When the NMOS transistor gate input high,N1 turns on, at this moment CS end is pulled down to GND, TP5100For the stop mode. VREG pin can output 5mA drive powerFlow, pull-up resistor optional 1k-100k.

author: james_s
author_rank: Super Contributor
timestamp: January 08, 2018, 06:00:17 pm
content: Mandatory as in necessary, to build a cell with no protection into a consumer device with no protection is something I would consider gross negligence, I don't know what law(s) may apply. My RC airplanes and multirotors all have a low voltage cutout, not something intended to be used regularly but it is there to prevent damage to the cells if for some reason one flies too long. The packs are not charged in the craft, but removed and connected to a purpose designed charger which itself contains the protection and monitoring circuitry to prevent the cells from being overcharged. This is something one has to consider when thinking of retrofitting Li-ion batteries into a device not originally designed to use them.Most batteries will only charge up to a certain point and are then self limiting, if you keep pushing energy into the cell it will dissipate that energy as heat but it will not just keep charging. Li-ion chemistries are different in that if there is a point where they will self limit, it's beyond the point at which they catch fire. If you keep charging a Li-ion battery the voltage will keep rising, and at some point it *will* burn.LiPos are particularly dangerous as far as batteries go. I have personally witnessed a large electric RC helicopter go down in flames, and I know several guys who have had LiPo packs catch fire while charging, mostly due to using old/improperly configured chargers. At least a few guys on the RC forum lost their houses, sheds or cars to battery fires. It's common enough to warrant taking precautions.

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 06:03:52 pm
content: I read the post... but the PDF is mandarin.I have also been reading about the chip on the 5V USB -http://cds.linear.com/docs/en/datasheet/405642f.pdfThey seem to cut off when they detect a full charge.I've got the feeling I'm missing something obvious.

author: soubitos
author_rank: Frequent Contributor
timestamp: January 08, 2018, 06:13:46 pm
content: Quote from: msknight onTodayat 08:03:52 PMhttp://cds.linear.com/docs/en/datasheet/405642f.pdfThey seem to cut off when they detect a full charge.I've got the feeling I'm missing something obvious.

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 06:18:55 pm
content: Quote from: msknight on January 08, 2018, 06:03:52 pmYou will need to buy one and test for yourself and then you learn something. Make sure you put current meter to see the charge current and so you will be amazed of what you learn. This will form your electronic foundation.They all cut out when fully charged. But it will be in constant voltage mode not constant current. To explain to you the 2 modes, too lengthy. I try.When the battery voltage increases when charged, a 4.2 constant voltage impressed across the battery cannot sustain constant current mode anymore, hence goes into constant voltage modes and the current constantly reduce by itself until terminal voltage is reached  and the charging stop.This is not the constant current you made out of LM7805 where it continously charge at constant current. [search LM7805 constant current].

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 06:23:00 pm
content: Quote from: james_s on January 08, 2018, 06:00:17 pmFortunately I checked James_s dictionary.Like I say, I am not against PCM.Cheers !

author: msknight
author_rank: Regular Contributor
timestamp: January 08, 2018, 06:34:05 pm
content: Thank you very much.I have a lot of reading to do.

author: BravoV
author_rank: Super Contributor
timestamp: January 08, 2018, 06:44:20 pm
content: Quote from: james_s on January 08, 2018, 06:00:17 pmAlso discharging ...https://youtu.be/Svyv8jgwq0Y

author: soubitos
author_rank: Frequent Contributor
timestamp: January 08, 2018, 06:51:59 pm
content: Better Safe Thank Sorry...

author: james_s
author_rank: Super Contributor
timestamp: January 08, 2018, 07:46:06 pm
content: You can't make the battery explode by over-discharging directly because at that point there is no energy left in the cell to create the fire. Over-discharge can damage the cell though creating a dangerous situation if it is then recharged. A short circuit or overload on a mostly charged cell can easily result in a fire too. Most fires seem to occur while charging, followed by mishaps with fully or mostly charged cells.

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 08:17:16 pm
content: Looks like the plane burnt because its a nitro plane and the fuel is burning.Engine Overheats, spark etc... the fire triangle likely.AFAIK lipo don't burn like that.Yes, lipo is dangerous!This forum is about discussion so it would always be best to quantify with the merit of sizes  in the discussion, too general makes it too grey.Yes, lipo is dangerous! and practice caution is necessary in handling it.Many people worried that the battery will overcharged to the extent that it will burnt.But OP will be using the charging board that will limit and protect against such overcharging.I think he intends to mount it in, hence inadvertent charging would be unlikely.Yes, put pcm additonal one. Its better to be safe than sorry......................blah blah blah blah...

author: james_s
author_rank: Super Contributor
timestamp: January 08, 2018, 08:21:33 pm
content: No, it's not a nitro plane, it's electric. As I mentioned I've personally seen a large electric heli burn similarly at the field where I fly. If you do a youtube search for "lipo fire" there are hundreds of videos, many of them deliberate tests but some accidents as well. They do indeed produce a large fireball as flammable electrolyte is vented.

author: Armadillo
author_rank: Super Contributor
timestamp: January 08, 2018, 10:09:44 pm
content: It's nice to know a fellow flyer.Generally, AFAIK, if it's a wide flat head, it's a nitro plane. Electric plane only needs narrow head. Also for electric plane, the Lipo will be placed at the CG of the plane near the wing  because of the weight.For nitro, the smaller battery will be placed further back from the head because the engine is heavier.

author: james_s
author_rank: Super Contributor
timestamp: January 08, 2018, 10:37:00 pm
content: Lots of planes these days are available in multiple power options and many guys retrofit older nitro planes with electric power, you can't always tell just by looking at the airframe except for foamies which are universally electric.

author: SMdude
author_rank: Frequent Contributor
timestamp: January 09, 2018, 07:32:20 am
content: Quote from: msknight on January 08, 2018, 12:39:24 pmLOL OK, from the original pics I thought these packs were much larger than that!I must say, it is really impressive that such a small battery was able to do anything.What was the runtime like with the original batteries?(back in its day)Ok, so unless you intend to replace current sense resistors on the tp5100, just forget about it. I thought we could fit at least 1 or 2A lipo in the battery space, but it is much smaller.For simplicity sake, are you sure you really don't want to fit the voltage reducing diodes within the walkman? Then you can charge from the original contacts and keep the battery looking original..

author: Armadillo
author_rank: Super Contributor
timestamp: January 09, 2018, 08:55:13 am
content: Just buy this TP4056 at $0.99centshttps://www.ebay.com/itm/2Pcs-1A-5V-TP4056-Lithium-Battery-Charging-Module-USB-Board-Electronic-Component/302255054546?hash=item465fce1ed2:g:mksAAOSw32lYy3vUChange the Current Programming Resistor as shown according to the schematic and table attached and you are all set.

author: msknight
author_rank: Regular Contributor
timestamp: January 09, 2018, 09:48:25 am
content: I can't remember how long it ran back in the day. I used to run the thing most of the night when I was out walking.I've already bought some of these -https://www.ebay.co.uk/itm/3-7V-500-mAh-Li-polymer-Rechargeable-Battery-501646-for-Recording-Reading-pen/262500045648And these to charge with -https://www.ebay.co.uk/itm/2pcs-5V-Mini-USB-1A-TP4056-Lithium-Battery-Charging-Board-Linear-Charger-Module/152070669880I've reached the end of my disposable income for this month... actually slightly overstretched myself.Talked with a friend last night, and I'm starting to understand the current voltage charging thing. .... I think.I believe that the current goes in at a constant level, and the voltage sharply rises to its normal voltage. At the end of charging, the voltage shoots up and the resistive properties of the battery change, so that the current takes a nose dive.

author: SMdude
author_rank: Frequent Contributor
timestamp: January 09, 2018, 10:21:47 am
content: Yeah, that is about right for the charging, it will start in a constant current mode(max charging current) then when the voltage reaches its maximum(4.2v for 1s, 8.4v for 2s), the voltage then remains constant, until the current is about 1/10th of the max current. Then the cell is deemed charged. 1s= 1 cell, 2s= is 2 cells in series.You will also notice that some battery packs will be labled 2p2s. That translates to 2 cells in parallel and 2 series(8.4v), just so you knowIn terms of .5c 1c 2c, what that means(c) is the capacity of the battery or cell, eg 450ma.So a battery that is 450ma capacity, if its max charge rate is 1c, then the max current during charge should be not more than 450ma. If it were 2c, it would be 900ma.Normally for safety sake and battery longevity, I try to limit the charge to .5c or even less. It is just nicer.You can charge a lipo at less than its rated charge current, just not really safe to charge at higher current.

author: msknight
author_rank: Regular Contributor
timestamp: January 09, 2018, 10:44:45 am
content: The long story short is that when I was young, early twenties, I had one of these machines. I was facing a very large decision in my life, one which would ultimately rip me from my family(took years to heal some of the wounds and still healing).... and this unit kept me company on some very late night walks around Sheffield.Anyway... I was burgled. The sod took all my hifi equipment. I managed to get most of it back through some quick thinking(covered in fingerprint dust)but the Aiwa was fenced before the police caught up to him. He denied taking it. Got 100 hours community service and the landlady kicked me out, "for fear of reprisals."You know how you get those ghosts in your life that are with you for years and you just have to lay them to rest? Well, this is one of those things for me. A 25 year-ish ghost that I'm hoping to put to bed.So... I've been trying to find one of these for some time. They are quite rare and people tend to keep hold of them once they've got them. However, everything needs recapping and I'm practising on a HS P505 walkman. Have currently decapped it, isolated a microswitch fault, cleaned off the worst of the capacitor leakage and am about to do a 1 part distilled water to 3 part bicarb paste, to neutralise whatever is left. Then another bath and long dry, before installing the new caps, and run it up on the bench.If I can get the P505 working fine, and my soldering technique sorted (I'm currently practising on SMD training kits) then I'll start work on the 303 units. I'm also expecting microswitch failures, and am wondering how I'm going to get parts.All the caps are here, and I do have an Aiwa 2V PSU, but no battery compartment. I'm sort-of in talks with someone who has one, and a silver PX303... but that's going slowly at the moment.Someone has gifted me two on the proviso that if I get them both working, I send one back to him... and it looks like it might be an IC failure, from what little I've seen so far. That's one reason why I can't put the diodes inside the unit.So... power is a thing.I have also got some of these coming -https://www.ebay.co.uk/itm/AMS1117-1-2-5V-DC-Step-Down-Voltage-Regulator-Adapter-Convertor-Supply-Module-B2/322980775873- in the hope that it will run on 1.8v, and if it does then I can rig an external battery that will run off a USB battery. I'd have to make a custom case, though. Not sure how I'd handle that yet. Basically, I've got a lot of bench testing to do... which will be done through the month, as it will take many weeks for all this to come from China.I did receive news yesterday that someone has made PB-3 cells with a LiPo inside, but given what's been said in this thread, I'd rather be in control of my own build, rather than someone elses.

author: SMdude
author_rank: Frequent Contributor
timestamp: January 09, 2018, 12:25:14 pm
content: Geez, that was a bit rough to get kicked out for being burgled..What is the actual output of the 2v ac adaptor when it is hooked up in circuit with the walkman on? Might be able to run from 2.5v, perhaps with better audio performance(just spectulating).Just bear in mind that you will have to cut power from the regulator board when you are not using it as it will drain the battery quite fast.Good luck getting these going! I hope it all goes wellWith a little bit of patience and lots of thinking, anything is possible, just 1 step at a time.

author: msknight
author_rank: Regular Contributor
timestamp: January 09, 2018, 12:38:14 pm
content: Yes... she just served notice and I had to find somewhere else to live... sharpish. That's how things go, I guess.I can't currently hook up the 2v supply to the 303 without the battery unit. Plus, both PX303's are dead. Suspected IC, but I've got to get the P505 off the bench before I can take a good look. However, although I can hook it up to the 505 ... that one is currently in pieces awaiting a wash and recap :-) ... when I find out, I'll let you know. But it will be a few days.

author: msknight
author_rank: Regular Contributor
timestamp: January 09, 2018, 12:56:28 pm
content: Actually... a jack socket, a few wires and a soldering iron....