18650 Lithium battery help - Page 1
Forum section: electronics / beginners

author: moderategamer
author_rank: Contributor
timestamp: May 14, 2016, 04:12:51 am
content: Hi there I'm trying to make a simple battery pack for a portable Gamecube I'm in the process of making. My issue is that I don't know how to charge/protect the batteries I was hoping to use these charger boards that do just that but not sure if it is possible to do what I want with them. I've drawn a crude mock up of the battery pack wiring without the charge and protection boards involved to give you an idea of the sort of thing I'm looking to achieve. Basically what I want from these boards is the ability to charge all of the batteries off a single lead and have the batteries be protected so that I can't over drain them. From my limited understanding of these boards I can see a couple of problems with what I'm trying to do but I'm not sure, I think that if there is a way to wire these up to protect the batteries it's likely that one of the batteries would drop to the cut of Voltage before the rest turning the circuit off and the batteries would not stay married if that makes any sense. Another problem I see is that my pack will contain 3 sets of two batteries in series to get a higher voltage then wired in series to get a higher capacity so would the board on the second battery wired in series not receive 7.4V causing the circuit to not work.I'm not to worried about the ability to charge the batteries off of the one lead as I can always charge the batteries with an external charger I'm more worried about protecting the cells form over discharge the charging thing would be nice though. If this is not possible then any suggestions on alternative means would be much appreciated. I may just be using 4 cells that's why there are two battery pack in the image. Thanks in advance for any help given(battery charging circuit)http://www.ebay.co.uk/itm/5pcs-TP4056-with-Battery-protection-LIPO-Charger-Module-Board-Micro-USB-TE420-/301905672102?hash=item464afaf7a6:g:kn4AAOSwxp9W8TXs

author: VK5RC
author_rank: Unknown
timestamp: May 14, 2016, 07:01:50 am
content: I thought the good 18650s eg Panasonic often had built in cut off circuits.

author: moderategamer
author_rank: Contributor
timestamp: May 14, 2016, 11:27:02 am
content: nope they're just the bare cells 18650s are the round ones the same ones they use in the tesla battery packs.

author: Habropoda
author_rank: Regular Contributor
timestamp: May 14, 2016, 05:33:35 pm
content: I don't want to get into a whole battery tutorial. I just wanted to say:Gah!!! Please don't hook up your batteries as shown in your drawings. They are in a big loop and the batteries/wires will get hot or burn! See the attached diagram I googled, for the correct connections. You could also do 2S3P in the same way.There are nice 2S2P 18650 battery holders on ebay that include protection.Those charger modules will not work in series because they will share the same ground. You can find 2S charger modules on ebay.18650 batteries can be purchase by hobbyists both with and without individual protection on the battery.edit: 2S2P means 2 serial 2 parallelI'm sure I have not answered all you questions. Perhaps others will chime in.

author: Audioguru
author_rank: Super Contributor
timestamp: May 14, 2016, 06:35:50 pm
content: Why would anybody buy the cheap Chinese protection/charger circuit when the manufacturer or seller cannot say what it does in proper English?It is for only one battery cell. Then each battery cell must be disconnected from the others and connected to its own protection/charger board.Why not buy a "balanced charger" from a hobby store for your set of battery cells instead? Then design and build a low voltage detection and disconnect circuit for the battery.

author: Rick Law
author_rank: Super Contributor
timestamp: May 14, 2016, 08:08:46 pm
content: Quote from: Audioguru on May 14, 2016, 06:35:50 pmWhy would you expect Chinese manufacturers to say what it does in proper English? They areChinesemanufacturer(s), selling to other Chinese manufacturer(s) to make protected batteries.That we want to tap into those outlets and save a buck or two doesn't even mean the manufacturer themselves are interested in serving this low volume hobbyist market. In fact, may be they don't even want to sell to anyone but other manufacturers.Try to get some Sony lithium cell datasheet as an end user and you will get no where. They are not interested in selling to average end users. In short, in Sony's mind, you don't matter and they rather you stay away from their stuff (for liability reasons, I suppose). If you are interested in it, it is up to you to dig up those info.

author: moderategamer
author_rank: Contributor
timestamp: May 14, 2016, 11:00:23 pm
content: Quote from: Habropoda on May 14, 2016, 05:33:35 pmThanks for the help/correction.

author: sleemanj
author_rank: Super Contributor
timestamp: May 15, 2016, 12:05:56 am
content: What are the current demands of your project? If it's not that much, say 500mA or less, then put your cells in parallel (depending on your run time desires), use a single charger/protection (TP4056 + DW01 + FS8205) module available for a couple dollars from the usual places, and hang a small boost converter off it to get your 7.4v.Save yourself lots of headaches that way and you get built in charge ability too.Just make sure the cells are close in their voltages before you parallel them.

author: moderategamer
author_rank: Contributor
timestamp: May 15, 2016, 01:55:51 am
content: I would think much more than 500mA the TFT I'm using wont stay powered on a 450mA 12V DC power supply Plus I've got to power the gamecubes GPU and CPU I don't know much about how to calculate how many amps things draw but my uneducated guess would be no. I think the gamecube draws about 1700mA. `

author: moderategamer
author_rank: Contributor
timestamp: May 15, 2016, 03:00:28 am
content: Quote from: Habropoda on May 14, 2016, 05:33:35 pmI know you said you don't want to get in to a whole battery tutorial but I would greatly appreciate your help. I took your advice and found a 2s battery protection circuit linked below and I was wondering if you could help me with the wiring (get ready for another crude drawing) would this work and what are the BM battery connection points? also would this allow me to charge of of a single cable from what I can gather by the images of the board is that the charging input and the battery output are on the same solder pads if that is correct and my wiring diagram is correct that should mean I can charge bath packs at the same time as they are already bridged no?http://www.ebay.co.uk/itm/2S-Li-ion-Lithium-Battery-18650-Charger-Protection-Board-Module-3A-7-4V-8-4V-New-/272109713078?hash=item3f5b00b6b6:g:zaMAAOSwpRRWngZp

author: Habropoda
author_rank: Regular Contributor
timestamp: May 15, 2016, 04:40:39 am
content: I don't think your circuit would work properly and I doubt you can parallel two boards. You should only use one board and, using my original diagram, you would connect the red wire to B+, the black wire to B- and the grey wires in the middle of the batteries to BM (battery middle, I guess). P+ and P- would be for the output and for charging - the same cable for charging and output.In your first post you talked about using six batteries. You would be better off using those for your cube in a 3S2P configuration since it will give you about 12 volts. You would need a 3S protection board. Those boards also seem to be better matched to your power requirements. Look at the attached diagram for the layout.Good resources for battery pack information are vaper forums, hobby forums and flashlight forums.http://benheck.com/forums/has lots of talk about portablizing game systems. The 2000 section has lots of Gamecube posts. You would do well to post there to see if your ideas have merit.A tip: charge the batteries fully on the same charger before connecting them in parallel. They need to be very close to the same voltage.

author: sleemanj
author_rank: Super Contributor
timestamp: May 15, 2016, 04:54:40 am
content: Quote from: moderategamer on May 15, 2016, 01:55:51 amOk then. Next easiest solution, is to use protected 18650 cells, or add protection boards to each of the unprotected cells to make them protected cells.A protected 18650 is just an 18650 which has a little circuit board hidden on the negative end, upside down so that the bottom of the circuit board becomes a stand-in for the negative end of the cell, the board has a wire (flat strap really) running down to the positive end to power the protection circuit. A protected cell is treated just like any other cell in terms of how you use it, series or parallel.This page shows you how the protection modules are fitted to an unprotected cell to make them protected cells (this is exactly what you get if you buy a protected cell - well a protected cell that isn't fake and not protected at all, which is not unheard of):http://www.lygte-info.dk/info/battery%20protection%20UK.htmlIf your cells are unprotected, you can buy the 18mm diameter protection boards for less than a dollar a piece from Aliexpress etc, usually in lots of 10, but of course attaching the wire/tabs may be tricky without a spot welder. Here'san example which looks like it uses the venerable DW01 and 8205A combination, no affiliation just a random one from my search, you can see that you connect your cell to the B+ and B-, then the back side of the protection circuit is what you use for the negative terminal of your cell. Heatshrink tube around the whole assembly and you wouldn't know the protection board was there.Note that a protected cell is more like 67-70mm long so some cell holders may not fit, the holders with spring terminals are usually better in this regard (rather than the bent-metal terminal types).

author: moderategamer
author_rank: Contributor
timestamp: May 15, 2016, 08:41:31 pm
content: Quote from: moderategamer on May 15, 2016, 08:37:55 pmThanks I'll have a read through these link they look very helpful

author: Habropoda
author_rank: Regular Contributor
timestamp: May 15, 2016, 10:10:17 pm
content: Yes, you can use that board in a 2S3P configuration. The only thing I would be concerned with is the 3A limit which might be too low. I don't know the exact power requirements for your system. You could just try it.Yes, you connect the red + in my circuit to the B+ on the board and the black - to the B- on the board. The BM connects to the bridge between the two parallel sets. The board monitors each parallel set of battery voltages separately and if either set goes outside the voltage limits the whole pack gets shut down. The board does not check for balance.You seem to be getting the general idea. The batteries that are in parallel will self balance so you don't need to worry about them as long as they were very close to the same voltage when first connected together and as long as they are from the same brand and batch. All batteries in a parallel set will always be the same voltage. When a parallel set is connected in series with another parallel set, one parallel set can get out of balance (a different voltage) with the other set. With good well-matched batteries this happens slowly so you can just check the voltages once in a while and pull the batteries out and charge them to get them re-balanced.Another option is to add a balance charge connector and use a hobby charger as suggested by aguru. Go on a website like rcgroups.com for suggestions and recommendations. RC hobbyists have been doing this stuff for longer than anyone I think.Though often overlooked by beginners, power supply is a major part of any electronics project. Batteries are a complicated part of that and different projects will require very different solutions depending on their requirements. Lithium batteries are great but they are very powerful not as forgiving of mistakes as some other chemistries. Take your time and do lots of research and you will be fine.

author: moderategamer
author_rank: Contributor
timestamp: May 15, 2016, 10:58:19 pm
content: Quote from: Audioguru on May 14, 2016, 06:35:50 pmSorry I never saw your post till just now I would do that it's just If I did I would have to use battery holders which would add quite a bit of bulk to the unit and space is very limited in my case plus I want to try to avoid having to open the case up to much.

author: moderategamer
author_rank: Contributor
timestamp: May 15, 2016, 11:14:26 pm
content: Quote from: Habropoda on May 15, 2016, 10:10:17 pmYeah I think I'll try my luck with the board as I think 3A should be sufficient with the Gamecube drawing somewhere near 1700mA and I shouldn't think my little 7" TFT wouldn't even draw a Amp should be plenty of headroom.Thanks very much for all of your help much appreciated it helped me out a lot.

author: moderategamer
author_rank: Contributor
timestamp: May 16, 2016, 02:01:02 am
content: Quote from: moderategamer on May 15, 2016, 08:37:55 pmSomehow I managed to quote the wrong person when trying to quote you basically what I said was thanks for all the info and links and that I'm looking through them and they are very helpful.

author: ECEdesign
author_rank: Regular Contributor
timestamp: May 16, 2016, 03:19:43 am
content: You might also want to look into Li-polymer cells. You can get them 7.4V and of various capacities. Most will have an additional wiring harness to provide cell balancing which makes sure that once cell is not much more charged than another which could cause problems you could also implement a cell balancer in your 18650 setup if you wanted too.

author: moderategamer
author_rank: Contributor
timestamp: May 16, 2016, 03:28:50 am
content: Quote from: ECEdesign on May 16, 2016, 03:19:43 amThanks I'll have a look in to that I did see some nice 5000mAH LI-po's which would be good as they are flat and have a much higher capacity than 18650 cells I'm not sure if it had the balancing lead I'll need to check.

author: sjd.aliyan
author_rank: Contributor
timestamp: May 16, 2016, 05:56:04 am
content: Quote from: ECEdesign on May 16, 2016, 03:19:43 amHe's projects doesn't need too much current so Li-pos are not good for him.Li-Pos are Expensive and have lower density in compare of a Li-Ion with the same size.

author: moderategamer
author_rank: Contributor
timestamp: May 21, 2016, 12:19:56 am
content: Quote from: Habropoda on May 15, 2016, 10:10:17 pmSorry to keep hounding you here last questions.If I wanted to charge each cell with 1A on a 2s3p pack would I need to supply 6A or 3A I don't know how having batteries in series would affect charging.And is it safe to draw current from the batteries while charging them at the same time or would this cause problems.

author: Rick Law
author_rank: Super Contributor
timestamp: May 21, 2016, 06:30:16 pm
content: Quote from: moderategamer on May 21, 2016, 12:19:56 amMr. Moderategamer,I hope you don't take offense for my being direct. Judging from your line of questions, you may benefit from more prep-ing and learning prior to tackling this project. Some projects are more dangerous than others. Charging lithium happens to be one of them. Mishaps with a "real time clock with coin batteries" project will just make you a bit late. Mishaps with charging lithium could cause you a burn-down house or worst.Re: "charge each cell with 1A on a 2s3p pack"To increase your probability of success and safety with such a project, draw 2s3p batteries out on a piece of paper with lines as wire, follow Kirchhoff's current law at each junction, you should arrive at the answer readily.A pack of 6x18650 lithium has quite a bit of power and should be treated with due respect. Search for some "battery fire" video. It is certainly not something to toy with.Perhaps I am just over cautious, but some more knowledge and some more reservations regarding the potential danger certainly would not hurt your project.Rick

author: moderategamer
author_rank: Contributor
timestamp: May 22, 2016, 01:49:57 am
content: Quote from: Rick Law on May 21, 2016, 06:30:16 pmDanger, Ha I walk on the wild side I laugh in the face of danger... sorry I couldn't help it lion king quote encase you have no idea what I'm taking about.I appreciate what you're saying I'm well aware of how dangerous Lithium cells are I've watched all the videos and I use them all the time for vaping. My usual approach to things is do first think later but I'm aware that's not sensible when working with dangerous cells that's why I'm here to troubleshoot and absorb some wisdom from people who know what they are talking about. The battery pack is fairly simple and I think I have a decent enough grasp on the workings of it now thanks to habropoda.I'm just unsure if for example I supply 1A to two cells in series would the cells in series act as one cell meaning there would be a 1A charge across both cells or if there would be 0.5A across each individual cell which would allow me to supply 2A to get a 1A charge. I Don't want to supply 2A to an individual cell even though they can handle it I'd rather stick to a 1A charge. Basically I want to have 1A across all cells in my battery pack so that I'm not supplying too much that I could damage the batteries but not too little that they will take forever to charge.You may think this is lazy but I don't absorb information by just simply reading things I have to be part of the process for things to stick that's why I came here to ask questions and to have a to and fro conversation to help me better understand. I'm not stupid I've just never learned electronics I did programming at Uni which as you can Imagine isn't exactly the same so I'm just looking to learn. The project that I'm taking on is fairly simple and somewhat well documented but as with most things it's not quite that simple there are gaps in information patches where things don't exist and batteries just so happen to be one of them. So I'm just trying to learn as I go along I'd really appreciate any help that you have to offerEDIT: also no offence taken appreciate the advice and I'll try read up on what you have mentioned.

author: ez24
author_rank: Super Contributor
timestamp: May 22, 2016, 02:16:42 am
content: Sorry if this has been asked and answered.OP do have the ability to remove the batteries so they can be charged outside of your Cube?Seems you would have better choices if you can.

author: moderategamer
author_rank: Contributor
timestamp: May 22, 2016, 03:55:29 am
content: Quote from: ez24 on May 22, 2016, 02:16:42 amI'm trying to avoid it if possible to save space it would really be a much easier route though.

author: Rick Law
author_rank: Super Contributor
timestamp: May 22, 2016, 07:10:39 pm
content: Quote from: moderategamer on May 22, 2016, 01:49:57 amMy Friend,I don't believe anyone here thinks you are lazy.(Judging from how I feel about this...) The discernible lack of response to a simple question isprobablybecauseno one wants to be involved with what would be equivalent to a suicide attempt.Ambition is a great motivator of learning. Then again, trying to learn to fly by jumping out of an airplane usually doesn't work regardless of the level of enthusiasm.Reading up on it first would be a good thing. You need to know Kirchhoff's current law and Kirchhoff's voltage law both, and of course Ohms law. While anyone can easily cut and paste the definitions here, doing so would short circuit your learning path. The knowledge you will gain by the research and then understanding that three laws are the knowledge you need to do projects like this.Prior to attacking the two Kirchhoff's laws, you need to know Ohms law first, and then how to deal with serial-resistors and parallel resistors. Then you are ready to attack Kirchhoff's laws. Lastly, you need to read up on voltage measurement and using shunt resistors to measure current.Once you get these few things under your belt, you would be able to figure out answers for your questions easily - plus, being able to do some debugging of the circuit after you put it together.Best of luck!

author: ez24
author_rank: Super Contributor
timestamp: May 23, 2016, 01:31:11 am
content: You may find something here, only 1268 reply's:http://www.rcgroups.com/forums/showthread.php?t=932319one page uphttp://www.rcgroups.com/batteries-and-chargers-129/page5.htmlI have a bunch of 18650 batteries from dell laptops and I am trying to figure out what to do with them. I have one 4 cell flashlight so far. So this topic is interesting.

author: moderategamer
author_rank: Contributor
timestamp: May 23, 2016, 08:25:34 am
content: Quote from: ez24 on May 23, 2016, 01:31:11 amThanks these links are very helpful. You should make a battery bank for charging mobiles and stuff.