Best BMS for my project - Page 1
Forum section: electronics / beginners

author: 3dgeo
author_rank: Frequent Contributor
timestamp: December 07, 2017, 10:34:00 pm
content: Hi,In my project I will be using 4 18650 batteries (https://www.ebay.com/itm/112480009597) in series, what BMS I should get?I already have bunch of TP4056(https://www.aliexpress.com/item/5PCS-Micro-USB-5V-1A-18650-Lithium-Battery-Charger-Board-With-Protection-Module/32666559864.html)This one incoming as well:https://www.aliexpress.com/item/4S-30A-14-8V-Li-ion-Lithium-18650-Battery-BMS-Packs-PCB-Protection-Board-Balance-Integrated/32791371632.htmltho I don't know anything about it.I don't know where to start, I'm practically noob what comes to batteries and charging them.EDIT: what will happen if I charge with 4 TP4056 in series (TP4056 output also in series) with 20V PSU and use my project at the same time? (it can handle 8.2V-28V)Thanks for Your time and help.

author: Awesome14
author_rank: Regular Contributor
timestamp: December 08, 2017, 06:19:14 am
content: To make a lithium battery charger for batteries in series requires that the batteries be monitored for resistance and voltage. One battery can use a linear charger. It's only with more than one that you require intelligent monitoring.The items you linked to are for charging 1 lithium battery You can't put them in series, because they all have their own controllers. It would be chaos, if it even worked at all.Have a look at this:https://www.ebay.com/itm/10-100A-BMS-Charger-Protection-Board-3-4-5-6S-18650-Li-ion-lithium-Battery-Cell/302279806036?hash=item466147cc54:m:mRnKiFMrUn8HN_2roEiagTQ

author: paulca
author_rank: Super Contributor
timestamp: December 08, 2017, 10:13:45 am
content: Quote from: 3dgeo on December 07, 2017, 10:34:00 pmFire, brimstone and possibly death or at least lots of lovely blue/white smoke. You'll feel fine though as lithium is a anti-depressant, though I'm not sure if that applies to the smoke.I HIGHLY RECOMMEND:https://www.amazon.co.uk/YoCoo-Fireproof-Explosionproof-Battery-185x75x60mm/dp/B01F5CH8S4/... alternatively an old metal army ammo case.

author: 3dgeo
author_rank: Frequent Contributor
timestamp: December 08, 2017, 10:30:50 am
content: Quote from: Awesome14 on December 08, 2017, 06:19:14 amThanks for Your reply, link You gave – I already ordered 4S 30A 14.8V equivalent from aliexpress (as mentioned above), so its incoming. As far as I know this 4S 30A 14.8V does not charge them with constant current and voltage (need special power supply for that?). TP4056 does charge with with constant current and voltage and has all other features to protect battery, though I notices that there can be some problems connecting them in series, I'll do some digging...

author: paulca
author_rank: Super Contributor
timestamp: December 08, 2017, 10:52:49 am
content: Do you have a link to the charger you purchased?30A is a hell of a charge current for a hell of a battery. Given few batteries will take more than 2C or 4C at a push for fast charge, 30A will be for charging a 7.5Ah to 15Ah battery.Unless the charger comes with it's own AC/DC supply, finding a 30A 15V DC supply is difficult expensive.

author: 3dgeo
author_rank: Frequent Contributor
timestamp: December 08, 2017, 11:30:03 am
content: Quote from: paulca on December 08, 2017, 10:52:49 amAs I said, I'm noob, but I thought 30A means that I can plug something to battery pack that takes up to 30A of current, not charge them at 30A.... I'm looking for BMS that charges properly (constant current and voltage), if possible I would like to avoid purchasing special charger.If 4S 30A 14.8V BMS still require special charger - it does not fit my need (does it charges at constant current/voltage?).I'm thinking using 4 TP4056, but to avoid magic smoke I will add multi latch button so that when I plug charger and I push charging button at the same time it disconnects each TP4056 from serial connection and from my project. Will this work?

author: paulca
author_rank: Super Contributor
timestamp: December 08, 2017, 02:58:54 pm
content: I'm afraid I don't have answer for you, I'm not that familiar with BMSes, how they work and if you can trust the Chinese 50 pence boards with a Lithium Ion.I also gather that advice on Lithium charging and tinkering tends to be quite light in here. I am wondering if that is more to do with the safety aspects around them, which are very often over stated and people not wanting to give advise in case the person explodes a LiPo on themselves and the person giving advice might feel responsible.On BMS stuff, I'm curious to know more about them. I know quite a bit about LiPos and their charging etc, but not for hardware based electronics projects. I would be more interested in building a balancing LiPo charger than buying a BMS. But that's just nerd-ish-ness.If you can find a few BMSes from a reputable brand which have datasheets and study them you might answer your questions.

author: 3dgeo
author_rank: Frequent Contributor
timestamp: December 08, 2017, 10:55:46 pm
content: Quote from: paulca on December 08, 2017, 02:58:54 pmI might be noob, but I'm not stupid, I can use multimeter and my brain to keep me safeAs far as I know TP4056 works pretty good at BMSing 1 cell, tho one disadvantage of it is that it keeps reconnecting battery to its drain when undervoltage is triggered (voltage will raise after disconecting), I dont know if its very bad thing, but I don't like this. TP4056 charges with constant voltage and current with no special charger (you can charge it from USB), I didn't came across any other board that do this.