Why do laptop batteries disconnect their output? - Page 1
Forum section: electronics / beginners

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: January 04, 2016, 06:51:06 am
content: So I now have two laptop batteries that have discharged below their normal level.As a result, the internal protection circuit disconnects the output terminals from the cells, no worries...The problem is, the laptops will then no longer charge them, and even by charging the cells with an external changer (opening the battery up) the protection circuit still refuses to connect them to the output terminals.Why is it so?!?

author: Simon
author_rank: Unknown
timestamp: January 04, 2016, 06:52:29 am
content: Are the batteries maintaining a charge. It could be that the protection circuits lock out permanently and need resetting.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 04, 2016, 06:57:10 am
content: Two genuine batteries, or two aftermarket third party batteries?

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: January 04, 2016, 06:59:12 am
content: Genuine.One had a cell at under 2 volts.The other I don't remember as I found it to not be working a few months ago now.One I've only just gotten today, so not sure if it holds charge.The other one does.

author: peter.mitchell
author_rank: Super Contributor
timestamp: January 04, 2016, 07:03:13 am
content: this is pretty common, when you over discharge the cells, the controller permanently disconnects them, because if you start charging/discharging a damaged cell there could be some serious trouble.

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: January 04, 2016, 07:36:06 am
content: So how does one get the controller to reconnect them?

author: SeanB
author_rank: Super Contributor
timestamp: January 04, 2016, 07:40:27 am
content: Replace the bad cells, replace the safety fuse and reset the controller. Or buy a new battery and get a dozen of those cheap power bank cases to use the good cells in. must look on eBay next time and order a few more, they are kind of handy, especially at 99c incl shipping.Edit, just ordered 10 at the expensive price of 99c CAD each.... Incl free shipping from Shenzen. Different prices per colour, so of course chose the cheapest, as that likely is the one they have the most of.

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: January 04, 2016, 07:46:33 am
content: how does one reset the controller?

author: SeanB
author_rank: Super Contributor
timestamp: January 04, 2016, 07:52:07 am
content: There are methods, but you need to find the model of the charge controller and see how it does failed battery detection. Then you either have t replace the safety fuse it blew to disconnect the pack, or how to reprogram it using I2C or JTAG to reconnect the pack. If you are lucky and it is just locked out try disconnecting all connections from the cells and then reconnecting them, so the BMS powers up and it might then work.

author: Kjelt
author_rank: Super Contributor
timestamp: January 04, 2016, 11:22:20 am
content: Quote from: peter.mitchell on January 04, 2016, 07:03:13 amWeird that the controller would allow to over-discharge the cells, it should protect the cells from over discharging.

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: January 04, 2016, 11:38:22 am
content: Quote from: Kjelt on January 04, 2016, 11:22:20 amIt most likely happens if the battery is left flat, then the cells self discharge slightly, enough for the protection to then disconnect them.

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: January 04, 2016, 11:46:32 am
content: This is someone elses picture, but my battery has the same two bigger ICs.

author: wraper
author_rank: Unknown
timestamp: January 04, 2016, 12:14:50 pm
content: Controller can be reset but not with free tools. Controller is password protected. Software will cost like a few batteries so repairing less than a handful of batteries is financially prohibiting.http://be2works.com/Home.aspxYou would need to pay $200 to be able to reset BQ8030.

author: Kjelt
author_rank: Super Contributor
timestamp: January 04, 2016, 01:39:41 pm
content: So if you have such a 3yr old battery and want to preventively replace the cells will it block asap you remove the old cells?

author: mikerj
author_rank: Super Contributor
timestamp: January 04, 2016, 02:17:47 pm
content: Quote from: Kjelt on January 04, 2016, 01:39:41 pmIt's quite likely. I have replaced cells on older laptop batteries without the safety fuse blowing, but that was probably more luck than judgement.I have also salvaged a a few over-discharged packs without needing to reset the controller, but you need to be very careful with the charge regime. The cells should be trickle charged until the voltage is about 3.3v and then charge at a low-ish rate under supervision (I use 0.5amps), and in an area that won't matter if something bad happens (i.e. not in your bedroom).

author: Audioguru
author_rank: Super Contributor
timestamp: January 04, 2016, 04:38:23 pm
content: A "protection circuit" in a battery is no good if it allows its battery voltage to discharge too low. It is supposed to disconnect the load, not prevent charging. The charger circuit prevents charging a lithium battery that has been discharged too low. A lithium battery that self-discharges too low is also no good.I have the Sanyo Lithium battery from my daughter's first cell phone. It was last used and charged about 19 years ago and it measures 3.68V today with plenty of power. Its self-discharge is almost nothing. It charges perfectly.

author: stmdude
author_rank: Frequent Contributor
timestamp: January 04, 2016, 07:52:19 pm
content: I used to work for one of the largest home-electronics manufacturers, and I dealt quite a bit with the batteries and charging, and I can explain how we reasoned when it came to protection circuitry.1. Once a cell has been discharged beyond a certain point (varies between cells, even within the same chemistry), it's _bad_. The tolerances have been exceeded, and you're working outside of what the cell-manufacturer has tested and what the datasheet says. Ergo, as a manufacturer that takes responsibility, and actually care about our customer (and fears lawsuits), we have to make sure that the cell is not used again, as I could cause (in worst case) fires.Dell, Fujitsu, etc know this all too well...2. Replacing the cells in a pack is _way_ beyond what their intended use is, and to be honest, I wouldn't even do it myself.. Why? Am I chicken/boring/inept? No, because, the likelyhood of me finding the _exact_ same cell to replace the failed ones is close to impossible. No, having the same formfactor and chemistry is not enough. The charge algorithm is tuned _exactly_ for the cell that it shipped with. And the cells that we shipped with were pretty darn good, so sourcing the same from a random internet-site is near impossible. Meaning, if you put a lesser specced cell in there, it will overcharge, over discharge, overheat, depending on how much the cells specs are off.We easily spent a month _per product_, just fine-tuning the parameters. And that's not counting the hundreds of cells that spend a few months verifying the end-result.And, frankly, if you do change the cells in a pack, and get it working, and it burns down your house, your insurance will find out. We did forensics for things like that, as the insurance-companies liked to go after us (usually chargers though, but the occasional batteries as well). As we don't like getting blamed for things we didn't do (both us engineers, as well as our lawyers), it was important for us to figure out. Most of the time it comes down to "this wasn't ours", but we saw "poor repair jobs" as well, for parts that we simply didn't perform repairs on (packs and chargers are both such items, as it's more economical to trash them and send new ones).

author: mikerj
author_rank: Super Contributor
timestamp: January 06, 2016, 01:35:54 pm
content: Quote from: Audioguru on January 04, 2016, 04:38:23 pmWhere do you think a protection circuit draws its power from? How can a protection circuit prevent the natural self discharge of a cell (which can be quite high on aged Li-Ion cells)?Quote from: stmdude on January 04, 2016, 07:52:19 pmThat is simply scaremongering. How many insurance policies prevent the repair of battery packs, either explicitly or implicitly? Unless you deliberately set out to cause a fire with a battery pack then you would be covered (at least in the UK).

author: Simon
author_rank: Unknown
timestamp: January 06, 2016, 05:34:10 pm
content: I'd be curious to know how they find out given how well lithium burns. If you do it yourself and your not qualified technically it may breach your insurance, assume they find out.

author: Audioguru
author_rank: Super Contributor
timestamp: January 06, 2016, 11:19:33 pm
content: Anything that has a name ending with "ium" burns well: magnesium (used in flares), titanium (used in jet engines and it burns if it gets too hot).Brits call out aluminum "aluminium" so maybe British aluminum also burns well but ours doesn't.

author: wraper
author_rank: Unknown
timestamp: January 06, 2016, 11:27:01 pm
content: Quote from: Audioguru on January 06, 2016, 11:19:33 pmIt burns well, actually you can make some explosives with it.

author: Galenbo
author_rank: Super Contributor
timestamp: January 07, 2016, 08:21:44 am
content: Quote from: Audioguru on January 06, 2016, 11:19:33 pmIf you ignite Diesel Fuel the way you tried on aluminium, it also doesn't burn.Both burn well in the same way: When pulverized, mixed with air.

author: mikerj
author_rank: Super Contributor
timestamp: January 07, 2016, 09:39:16 am
content: Quote from: Audioguru on January 06, 2016, 11:19:33 pmA basic thermite compound is made from iron oxide and aluminium powder, and that burns extremely well. Perhaps thermite doesn't work in the USA...

author: stmdude
author_rank: Frequent Contributor
timestamp: January 08, 2016, 09:50:44 am
content: Quote from: Simon on January 06, 2016, 05:34:10 pmThey sent it to us, with a note basically saying "your shit (nearly|completely) burned down our clients house. WTF?".Once the engineers get their hands on it, everything is inspected, and compared to a known original from the same production-run. The folds on Lithum-Ion casing are almost always intact. Stamping on the same.The PCB might be burnt to a crisp, but most of the time you can still see the placement and approximate size of the chips that used to be on it. This catches at least 99% of the clone batteries.Analysis of the LiIon casing would most likely reveal any replaced cells.We also did forensic analysis in some extreme cases. Ever tried to dump NAND-flash that has been through a bombing? I have..

author: Nerull
author_rank: Frequent Contributor
timestamp: January 08, 2016, 10:17:54 am
content: Metals in general burn pretty well. Steel wool can be set on fire, and most powdered metals are extremely reactive. Magnesium burns well in strips, but is difficult to light as a solid block - but if you manage it, good luck putting it out again.You may have seen these big white things, strapped to the shuttle:http://www.spd.org/images/blog/Shuttle-Layout-3L.jpgThey burn aluminium as fuel (with ammonium perchlorate as the oxidizer).

author: Simon
author_rank: Unknown
timestamp: January 08, 2016, 06:24:37 pm
content: Quote from: stmdude on January 08, 2016, 09:50:44 amWell if parts survive then yes I can understand that small differences from a genuine product can be noted.

author: Simon
author_rank: Unknown
timestamp: January 08, 2016, 08:24:12 pm
content: On the one hand many people need protecting from themselves. i had to advise my boss that there was a reason his shitty device was being charged off a 4.2V power adapter and no he could not cut the wire off and put a USB plug on it.but then it makes life hard for those that know what they are doing.

author: Zero999
author_rank: Super Contributor
timestamp: January 08, 2016, 08:26:09 pm
content: Quote from: wraper on January 04, 2016, 12:14:50 pmThere's a demo version. Presumably only the paid version can reset the controller.There's bound to be a kegen/crack floating around for said software, somewhere on the interwebs.

author: wraper
author_rank: Unknown
timestamp: January 08, 2016, 08:39:39 pm
content: Quote from: Hero999 on January 08, 2016, 08:26:09 pmThere is no keygen possible. The software do not store any keys locally and communicates the server on every unlock.

author: Sjokolade
author_rank: Regular Contributor
timestamp: January 08, 2016, 10:19:06 pm
content: Also there is UBRT - but homepage is Russian -https://translate.googleusercontent.com/translate_c?act=url&depth=1&hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=auto&tl=en&u=http://ubrt.com.ua/&usg=ALkJrhjNzP8NNJaxfGz_MmqlurXKClN_Ng

author: wraper
author_rank: Unknown
timestamp: January 08, 2016, 10:35:05 pm
content: Quote from: Sjokolade on January 08, 2016, 10:19:06 pmeven more expensive. for BQ8030 need black_label -> $600 per year.

author: Sjokolade
author_rank: Regular Contributor
timestamp: January 08, 2016, 10:50:51 pm
content: Hehe yes it is - I see that the software was updated 2016-01-04 - do you know if BE2Works still is updated ?

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: January 08, 2016, 11:55:47 pm
content: Right now, I'm charging a laptop battery that was at about 0.15volts per cell......I'd like to repack it, but there's not much point in doing that only to find that the protection circuit can't be reconnected!

author: Audioguru
author_rank: Super Contributor
timestamp: January 09, 2016, 01:01:24 am
content: Is your dead laptop battery a lithium one? If it is then it is extremely dangerous to charge it with a cheap charger that does not measure the battery voltage to find its very low voltage then begin charging at a very low current while monitoring the temperature of the battery to prevent a lithium fire. That is what a good lithium battery charger IC does. You can read about it atwww.batteryuniversity.com.

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: January 09, 2016, 01:56:26 am
content: Of course its lithium! and of course the charger wouldn't touch it!SO I charged it as a nimh until the voltage was above 6volts, then pretended it was a 2 cell lipo, even though its a 4 cell.All of this being done at the chargers minimum 100ma charge current.

author: amyk
author_rank: Super Contributor
timestamp: January 09, 2016, 02:02:43 am
content: Quote from: blueskull on January 08, 2016, 10:03:16 pmA logic analyser would be enough, even one of those cheap Saleae-ish things. I did the same with some inkjet printer cartridge resetutilityservice.Quote from: Audioguru on January 09, 2016, 01:01:24 amSee this thread for a good discussion of lion cell characteristics, including lots of debunking of "battery university"'s false claims:https://www.eevblog.com/forum/projects/diagnosing-lithium-cells/Quote from: stmdude on January 04, 2016, 07:52:19 pmThat sounds like FUD. Did you by any chance learn from the "battery university" site too? Li-ion is one of the simplest chemistries to work with - just stay within the voltage and current limits. There is no special "charge algorithm".You may find more interesting discussion here:https://en.wikipedia.org/wiki/Talk%3ALithium-ion_battery#.22Battery_University.22one of the most astonishing quotes of which isQuoteFinally, don't forget that the Chinese have managed to release tons of product using bare user-replaceable 18650s (which would probably scare the crap out of you), but it's not like there are suddenly tons of extra fires. There have been some, but not as much as the scaremongers would like to have you believe... and I'd say lipo pouch cells make up the majority of fires since they're so much easier to damage.Note that lithium-ion cells don't actually contain any significant amounts of metallic lithium, and most of the time the fire is the electrolyte burning; primary lithium cells are different, and do contain metallic lithium.

author: stmdude
author_rank: Frequent Contributor
timestamp: January 10, 2016, 03:26:53 pm
content: Quote from: amyk on January 09, 2016, 02:02:43 amNo, professionals dealing with consumer electronics rarely learn from battery university.First off, there is an "algorithm", and it's called "CC/CV", but, yes, it's very simple in ideal conditions.Here's a few questions that you can think of while contemplating how easy it is to charge Lithium batteries:1. Is the cell in your phone/laptop a 4.2,4.25 or 4.3V cell ?2. Would you charge it the same at 0C, 20C, 40C and 60C temperatures?3. At what current do you stop the CV phase of the charging?4. At what point do you re-start charging a battery that's being used ?5. Where does the IR of the battery come into play ?6. Can you charge/discharge an older (as in cycles) battery as aggressive as you can a brand new one?etc.However, I see how you're thinking, and here's what would work..Yes, you could have used any old CC/CV charger (set to the correct cell-voltage) to charge our batteries. You wouldn't get as much capacity out of them as we would (but, close). You would however, _not_ get as many cycles out of it as we did (80% capacity after 1000 cycles, guaranteed), nor would it charge as fast as we did, without danger.The opposite is not true though. Putting a random cell into our device would lead to us charging it incorrectly. For instance, charging a cold battery too fast (bad), charging a room-temped fresh cell too slow (not dangerous), not backing off at at the correct (for the new cell) CV drop after charge-completion, causing excessive crystal buildup on the anode of the cell, etc.Simply put, the charging in your laptop/phone is not a simple CC/CV "algorithm"