Questions tagged [bms]

A battery management system (BMS) is any electronic system that manages a rechargeable battery (cell or battery pack)

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BMS for 12V Lead Acid Batteries (48V)

I'm thinking about creating a BMS for my Battery Bank. The bank consists of 12 VRLA Batteries connected in 4 series and 3 parallel configuration to get a 48V system. For this bank I wanted to monitor ...
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41 views

Problems with LiPo Volt buck boost for a LED

I need a little bit of help in understanding buck-boost converter. I have 4 LiPo 18650 batteries in series an BMS to charge and discharge the batteries properly. After that I added the buck-boost ...
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29 views

Building a 1S Li-ion battery pack with all the cells in parallel and using a DC to DC converter to get higher voltage

I want to build a 12 V battery for my Mac Mini and possibly a 36 V battery pack for a electric scooter I plan to make later using some old 18650 cells. I have read that a lot of battery management ...
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29 views

If I connect three different capacity lithium batteries in series with a 3S BMS board, When the BMS will stop giving output?

If three different capacity batteries are connected in series with a 3S BMS board, when the lowest capacity battery runs out and under voltage occurs of the battery then will the BMS continue giving ...
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39 views

What does 2.5-3.0V mean on BMS specs?

I'm looking at buying a cheap eBay BMS to prevent overdischarge of a Li-Ion battery, but I'm confused about the specs. Basically every BMS I can see lists the overdischarge cutoff voltage as "2.5-...
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36 views

In BMS if I connect li ion batteries of different capacities, how much mA will it provide in the output?

If I connect one 1200mah, one 2600 mah and one 800mah li ion battery with a 3S BMS board. How much mA will it provide at the output? And when the BMS will stop giving output? Thanks in advance for ...
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How to Design BMS in simulink?

I have designed a battery pack of li-ion batteries. At the initial stage I have given 0 at both constant blocks. This indicates there is no charging or discharging In the second fig I have applied ...
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34 views

Is a buck converter necessary for a 18V drill conversion? (NiCad to Li-Ion)

Im currently planning out my (first) conversion of an old 18V drill with dead NiCad cells to 18650 Li-Ion. I have enough cells that should support the high discharge rates and I'm putting them into a ...
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51 views

Multiple CC/CV charge controllers in parallel?

Can multiple cc/cv charge controllers (TS1052 for example, which is rated for 100mA drain current) in parallel configuration to achieve a higher drain current? (input signals also connected in ...
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49 views

How to supply limited power to a hungry BMS for li-ion charging

I am building a li-ion battery pack in a 7-series (3.6V) cell configuration. That gives 25.2V nominal voltage and 29.4V charging voltage. I have a BMS with balancing charging capabilities. This BMS ...
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Solution to prevent load from drawing the current from battery while it is charging and draw it from charger instead

I have the following problem: I have a 12.8V LiFePO4 Battery that powers the circuit and a lead acid charger with Intelligent MCU Control of 12V and 1.5 A to charge the battery. When the battery is ...
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Connecting 36V LiIon packs in series to get ~120VDC to run lawn mower

I'm converting my electric plugin lawnmower to battery power. I was able to get 3 used e-bike identical model 36V 5Ah packs (obviously not matched with respect to lifetime usage). Each pack has its ...
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48 views

How to go about testing which pins to short to turn on Daly BMS?

I have a 7S DALY BMS, but I forgot to buy the 'SOC (state of charge) display board', which has LEDs that display the state of charge, and crucially, a switch to turn on the battery itself. The board ...
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18 views

Charging 2 x 14S6P battery packs

I built 2 14S6P battery packs which each have a BMS with a separate port for charging. I am wondering if I should wire a separate charger to each battery or can I create a parallel charging cable ...
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43 views

Tesla Model S BMS Solar

I have six 2012-2018 TESLA MODEL S MODULES I have been using two in series for a 48 volt inverter with no BMS (set the low voltage and high voltage limits accordingly). Now that my energy needs are ...
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18650 Li Ion Questions

Good morning All, I'm obviously a complete novice as far as 18650 and Li-Ion or LiPo batteries is concerned although I do have a reasonable amount of knowledge as far as Electronics design goes, ...
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34 views

Could I get a second pair of eyes to check if this BMS can be used for charging?

I'm new to electric engineering and electronics in general, so as a first project I'm building a battery using 18650 cells (4S4P). I am aware of the risks when buying from Chinese suppliers on ...
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32 views

Connecting six protected 18650 cells 3S2p for close to 12V, suggestions?

I want to make a 12V range battery array with 2P 3S 18650 cells. The cells will be charged in an external charger NOT in the pack. They are removable in holders So I can pluck them out and charge ...
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188 views

Design a BMS (overdischarge protection)

I am tired of BMS that doesn't work the way I want, so I have decided to made my own BMS. Searching on internet I have found the schematic for a 4S BMS and I want to understand how it works before try ...
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42 views

Can LiFePO4 BMSes be connected in parallel without causing charge/discharge issues?

I have two LiFePO4 battery packs in 4S configuration: one with 2x4 cells (4S2P) and one with 3x4 (4S3P) cells. Each pack has a 4S BMS. Are there any potential issues with connecting those two in ...
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43 views

Different chemistry of batteries in operation

I had an idea of using different chemistry of batteries as shown in the schematic figure Is that possible to design a system in that way. According to the design, I am using all the evaluation boards....
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33 views

Why won't my hover board battery charge?

I have a standard hoverboard battery which I bought for my electric skateboard project. The battery has a 10s2p arrangement. 36V and 4.4 AH. Now the battery voltage is 20V. When I plug my charger in ...
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50 views

Did I use Diodes and the Relays correctly in my Circuit Design?

I'm a beginner and recently started a project where I build my own portable bluetooth speakers. I already have a rough layout of the whole thing. I basically want to power a 2x50 Watt Amplifier with ...
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29 views

I have two lithium battery packs with separate BMS, Can I connect the packs in Parallel?

I have two lithium battery packs with separate BMS, Can I connect the packs in parallel, will the BMS get damaged or will something happen? 12v 10ah battery pack, I have three in total and each has it'...
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42 views

Typical voltage range for a LiFePO4 BMS

I'm about to hook up some LiFePO4 (32650) batteries to solar panels. I bought a couple of noname BMS boards ("HX-4S-F30A") for a 4S configuration for the batteries online, and the ...
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44 views

Finding a solution to make a decent batterypack, that I can install and charge/discharge without having to remove it

I have a problem with a power delivery circuit for my bluetooth speaker I am planning to build. I am unable to find a BMS for 4 Cells that would allow me to charge and discharge it through different ...
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103 views

How does a fuse prevent battery overcharging/discharging?

How does a fuse protect a battery? I know that it prevents short circuits, but what about overcharging and over discharging? I asked a previous question here, and the recommendation I got was to get a ...
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76 views

Building 3s 18650 battery pack

I got myself scrap laptop batteries for very cheap, only 2 cells out of 60~70 appear to be damaged (0v) To charge 2 drained batteries, first I used a powerbank circuit that despite being less than a ...
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32 views

Charging Li-ion with BMS but no balancer connector

Is there a safe way of charging a 5S1P Li-ion pack with BMS but no balancer connection? I have a IMAX B6 charger, but it only allows charging Li-ion with balancer connection. Could I use the Pb ...
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58 views

How to control cell balance FET with 5V logic?

I want to control FET to discharge battery cell with 5V logic from microcontroller with common grond with battery as shown. simulate this circuit – Schematic created using CircuitLab What is ...
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77 views

I'd like to know if my own version of a cell balancer will do the job

I have two 3.7v cells in series to make a 7.4v battery. I want to make my own active balancer because I don't have access to buying any cell balancers. I'm using a transformer with 2n turns on the ...
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203 views

Question about an electronic component which could be a fuse

i have an old laptop from which i removed the battery in order to repair it. There were 6 cells in total and 2 of them were bad. One of them was leaking cellfluid when i tried charginging and reviving ...
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244 views

Using 19v laptop charger to charge 4S 18650 battery pack [closed]

I am manually assembling an 18650 4S battery pack for use with an inverter/ups. My goal is to build a portable inverter based on 18650 batteries (around 20AH capacity) which has the provision for ...
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31 views

Laptop's removable battery has 4 18650 3.7v cells in series, can I attach 8 more as external battery pack as 4s2p?

I have 4 years old HP gaming laptop with removable battery. I never kept the battery in the laptop. Right since the purchase, I stored the battery in a sealed pack in cold place, and charged it to 45% ...
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44 views

Handle simultaneous charge/discharge with a BMS

I am building a series of 13s LiPo battery packs, each with a BMS with B- P- and C-. They are to be charged with a regulated source from a PV array. I know this likely depends on the specific BMS, but ...
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45 views

3S Lithium-Ion power solution for a project

I have a PCB that runs on 12V throughout the day and consumes 2.3A. The power is supplied for 12 hours using a power supply. The other 12 hours it must run on batteries that have charged during the ...
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how to charge 2 Lithium ion 18650 batteries in Series and Parallel

i want to charge my 2 lithium ion batteries in series and parallel. as per my knowledge for single cell Capacity 3350mAh as per datasheet charge voltage: 4.2 V DC Charge current: 0.5C (1700mA) cut-off ...
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81 views

MOSFET instead of a contactor in Battery Management Systems (BMS)

For relatively high current systems (>50 A) with Lithium based batteries, I've seen that usually BMS controls the output with contactors for both main supply and precharge. Why not use a high ...
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67 views

How Charger and Cell Balancer work in BMS?

I'm currently working on BMS for LiIon 4S2P battery pack. Two core components I've choose are BQ77915 balancer and BQ2954 charger from TI. For now, I stick to example schemes from datasheets, but I'm ...
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47 views

Is regenerative braking always suitable for an EV regardless of battery chemistry?

I've been doing a lot of reading on different motion control approaches both for hardwire industrial motion, as well as EV applications. While I've skimmed a few IEEE papers that sought to study the ...
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27 views

How to modifiy DC2259A evaluation board to access Vref2 on LTC6811-1 IC? For the purpose of powering external thermistors

I am using a DC2259A Evaluation Board, to monitor battery cell voltages and am hoping to drive external thermistor circuits for the purpose of measuring battery cell temperatures from Vref2 on the ...
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30 views

How much Amperage can pass through a BMS and DC stepup boost converter?

In my Mini UPS project for my router, I made a little circuit by using a 18650 li-ion battery charger module, a 3.7v /2800mAH li-ion battery, and the DC step-up boost converter. My router requires 9v/...
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56 views

Using discharge protection, BMS and balance charging?

I am building a small high quality headphone amp which needs power supply +/-7V up to +/-17V. According to the manual it uses maximum 200mA. I like to use 2 x 3 16340 rechargeable lithium batteries ...
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31 views

stack/ladder n- mosfets

I need to drive n-mosfets to switch on/off resistors in parallel with Lion cells. Each cell+mosfet is in a series - 50 cells. It looks much like a BMS except it NOT a BMS, but a cell test system. See ...
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71 views

Can a 1S BMS be used for a parallel arrangement of 4 Li-ion batteries?

Currently I am on a Mini UPS for a modem router project. So my router needs a 12V and 0.6A current. I have four 3.7V, 2800mAh Li-ion batteries. So I need to keep the voltage at 3.7V but I need to ...
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271 views

What is wrong with one of the cells in my 4-cell laptop battery? How can I make it better?

History My laptop battery has shown less and less capacity. So I got a new battery (LA04) in Jun 2018, with a warranty of 6 months. After about 8 months, the new battery also showed problems. It went ...
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How can I use a BMS to charge 4 LC18650s in series?

I have a collection of 4 LC18650 batteries. I need to draw at least 12V with a current of at least 1 amp, hence the use of lithium batteries. I know I could use lead acid but environmental impact, ...
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36 views

Does a BMS reduce the quality of the output of batteries?

I plan to build a high quality headphone amplifier. It does not use much power (<1A) so I think about using 18650 batteries as power supply. I am pretty sure these batteries should be a very smooth ...
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42 views

LiFePo4 BMS recommendation

I am trying to design a backup power system around the LTC4015 battery charger. I am looking for a battery balancing circuit to balance the charges in the batteries. 4 Batteries used are with 3.2v ...
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35 views

Choosing A 4s BMS

I am using the panasonic ncr18650pf battery in a 4s pack for my project and I want it incorporate a BMS with balance lead charging. I have already ordered the batteries and holders but I have never ...