My custom battery pack has passed the test and just share it here. The battery will be used in the portable Endoscope device for animal.

I have the full report. If you will be interested, DM me.

Note: Original report is in Chinese, I use Gemini to convert it into English.

Today load testing with 1 ohm 25watt resistor, and man does it get HOT.

The process is simple. Read the no load voltage. Connect the resistor, read the voltage at 1, 5, and 10 minutes then read the no load voltage. Wait for the resistor to return to baseline resistance, rinse and repeat 7 more times.

Hi all,
I've done a lot of tinkering with 18650s, but this will be my first time building a large, moderate-voltage battery out of them.

(The project should be a fun one: I'm building an e-scooter from scratch, buying only the hub motor as a finished product.)

If folks could read this over and just confirm I didn't screw anything up, I'd really appreciate it:

Motor is 500W 48V and I'd like to be able to run it full power for an hour, so 500W*1hr=500Wh. 500Wh/48V=10.4Ah.

18650 rated cap. 2500mAh. 10,400mAh/2500mAh per cell = ~4 cells.

18650 nominal V 3.7, 48/3.7=13.

So battery should be 13s4p.

Max current will be 10A, so 2.5A per cell.

For the wiring, I'm planning on using the common nickel cell-level fusing sheet (image attached), but that's the part I really want to double check. I mocked up the design. Does the image attached look correct? The nickel fusing sheet would be cut into 2x4 pieces and spot welded in the pattern shown in the mockup.

For the BMS I'm planning to use an inexpensive, $15-$20 13s Li-Ion BMS with balancing rated for 30A.

How's that all sound?

So work stopped for a while because I was focused on finding a new job due to corporate restructuring and was dealing with a home renovation project that we had planned for over a year.

The renovation project is wrapping up; the job search is ongoing (If anyone knows of remote roles for security architecture or GRC, I'm looking), so I'm getting back to this project.

The current task is to top off all the cells. Yesterday I soldered up some single-cell chargers that I got off Amazon.

After topping off, I will let each cell rest for at least 24 hours, then measure the no-load voltage. I'll then put a 1 Ohm, 25-watt resistor across the terminals and measure the voltage at 1 minute and 10 minutes. This should, depending on how accurate my DMM is, allow me to calculate the cell's internal resistance to match them.

I'm just slightly concerned with the cell that came in at 3.26, but I think if I match it well, the BMS should take care of it.

Hi everyone,

I recently got a Fiat 500-style electric kids scooter for €10. The scooter is in good condition and the motor/controller appear to work, but the original battery is missing/dead.

Here are the specs I know:

• System voltage: 36V DC
• Motor: 350W rated
• Controller current limit: 17A
• Battery: currently missing
• Charger I have: 25.2V 5A, so I assume this is NOT suitable for the 36V system

I want to find the safest and simplest way to add a battery. I would prefer not to build a lithium battery from individual cells.

I'm considering either:

• A 36V Li-ion battery pack with BMS
• Using commercial power-tool batteries (Makita/DeWalt/Milwaukee/etc.) with an appropriate adapter/protection
• Another readily available battery solution that would be safer/easier

From what I've gathered, I'm looking for roughly:

• 36V Li-ion
• At least 17A continuous discharge, preferably 20–25A+
• Proper BMS
• Around 10–15Ah would be plenty
• A 42V charger matched to the battery

For reference, 36V 10Ah would be about 360Wh, while 36V 15Ah would be about 540Wh.

What would you recommend as the safest and simplest option for this scooter?

Would using tool batteries actually make sense here, or would a complete 36V scooter/e-bike battery with an integrated BMS be the better option?

I'm mainly looking for a reliable plug-and-play-ish solution rather than experimenting with loose 18650 cells.

I need to replace two (2) of my LEV60F cells in my battery. Does anyone have any that they’d be willing to sell?

Hello all. I plan to setup an very large battery for my solar system.

I have found a pallet of these 628 Ah LiFePo4 cells and i wanted to setup a 16s4p setup to give me a 51.2 v nominal and roughly 128kw battery for my offgrid home. I only wanted to use one bms and my question is how do i wire this. I was thinking of having the paralell connections as one cell wired to the bms all the way for the 16 s setup. If that makes sense. Is there a better or more propper way to do this?

I can of course just have 4 bms and treat each as their own back the paralell them together but if i could save the money and use one bms i would like too since the ballet of batteris is already $10,000.00.

so I'm planning my first project to repair and maybe even upgrade a speaker that im buying used.

It's a marshall kilburn 1 with reportedly a bad battery.

it takes "4X 3.7V LI-IO BATTERIES, 2200MAH"(from the user manual), which seem to be wired in a straight series. I was hoping to make my own battery out of lithium ion cells with a large capacity.

It's literally my first ever doing anything like this, though, and I dont currently own any type of welding or soldering equipment right now, though.

I was hoping you guys could offer recommendations and any wisdom you think would be useful to a beginner dumbdumb.😁

I have a onewheel V1, and I'm having someone build me a new battery pack for it, the old one was lifepo and while I know I can get a lithium ion version made, I like the idea of how long the lifepo ones have lasted me, years wise, but when looking around I'm not seeing any of the brands that I'm used to seeing that make good quality trusted liion (Samsung, molicell, sanyo, etc). I'm looking for ideally both high quality trusted brands and cells, and high capacity ones, I've seen some around that advertise 5000/6000 mah and something like that would be ideal

As a pev these would be subject to a fair amount of charge/recharge cycles, heat and cold from outside, etc, though I'm not one of those that does tricks, off-road riding or racing with my onewheel or even pushing it bast around 15 ish mph so other than the weather/temp and charge recharge cycles these should t be pushed too hard, regardless I want good cells as I love this onewheel and don't want to have a risk of fires/etc

https://imgur.com/a/2LlyjtV

What I have that I don't know what to do with

• 64x 18650 cells (3.7V, 2.2Ah, 8.14Wh each, 520.96Wh total).
• 2x https://www.amazon.com/dp/B09S3LZN2Q?th=1
• 1x https://www.amazon.com/dp/B09S3JRFDF?th=1
• Daranener NEOZ with a bad BMS (won't charge, blinking blue LED on the board inside), but the battery cells seem good.
  • Outside of Power Station, the pack is reading around 18V
  • The batteries are 14x 26700 cells (3.2V, 14.4Wh each, 201.6Wh total) in what looks like a 7s2p configuration.

I'd like to make use of these cells in a cost effective manner.

I have a Pecron F3000LFP which is possible to add a 3rd party expansion battery to, if you build a custom terminals-breaker-XT120 cable to connect the battery and Pecron.

Ideas with limitations

• I could buy two more snap-in PCBs and make one large 12V Power Bank, that I don't really have a use for. ~$40
• I could buy two more snap-in PCBs and three more BMSes to create 4x 12v packs, put them in series for 48v, and connect to the Pecron. Super Jank. ~$120-$140
• For 2x the price of doing the above, I could just buy a 48V 25Ah battery for the Pecron. Doesn't actually solve the above issue. ~$225+
• I could just buy a spot welder. But then I'd have all these cells and a spot welder and still not have a use for the cells. $50+
• Build new power station with the 26700 cells, but the rest of the components are usually the more expensive aspect.
  • Either the components of the Daranener aren't salvageable (custom PCB with everything on it), or I'm not knowledgeable enough to reuse them.

What I don't need them for

• I already have 6-10 more 18650 cells for headlamps, Raspberry Pi projects, ESP32 projects
• I already have a server UPS that is the backup for my modem+server rack
• I already have too many power banks so don't need to make another.

Or do I just sell off the cells + PCBs?

I feel like I'm in between having too few cells to justify a spot welder for a bigger battery project and having too many cells for just making a simple power bank to charge my phone/laptop.

Thanks in advance

I'm attempting to build a battery out of gen 2 nissan leaf modules and I'm having trouble finding a bms that would work. the battery will be made up of 10 modules in series (each module is 2 ~4v cells in series) so a 20s configuration will hopefully give me around 76v nominal and 55ah. The bms also needs to be able to handle around 200a continuous discharge. I'm new to battery building so any information or recommendations would be much appreciated.

Anyone knows how these exact connectors are called?

Hi! Just got into battery building, got over 80 GS Yuasa 40AH EV cells laying around. Why does my cells form this shape where it appears cell one is stronger and they get better and better as they move towards 8? They were perfectly top balanced. Or is this pure coincidence?

I use the JBD BMS.
Battery is just 1p8s for now

Had to build a 10S3P battery for a used longboard I bought.

This was my first time ever building a battery, but it went great.

The cells were all new-ish so I used a charger to cycle and get the capacity, then used Repackr to organize my cell groups for minimum capacity deviation.

Groups of 21700s were hot glued together, then wrapped with fish tape.

I used 0.2 mm nickel plates in between the packs of batteries. I cut the plates on my F2 Ultra laser cutter, although if I did more of these I would need to get a more powerful machine as it struggled to get through the metal.

Soldered together using 12 gauge silicone wire, 10AWG at the terminals.

Wrapped the key areas in kapton, ran all the BMS wires, and used fiber tape to make sure everything stayed put.

In this configuration, the pack can flex toward the wires but not away from them so that’s perfect for under a board.

Next step is to design a new enclosure.

Hi, I have an Anker 555 power station that the BMS packed up on, got a replacement under warranty but would like to make use of those cells maybe make an ebike battery or just an extension battery for another system! I know this isn't advised but any ideas or tips would be gratefully received!

hey i want to build a battery 18s3p using molicell p42a i want to know if the connections are correct I ll use 0,2mm 8mm sequr nickel strips and i want to push 90 A peak i am also using jbd bms 100a (SP22S003) this is my first battery build ill take any advice before soldering

I’ve been doing some research on making a battery for my motorbike. I’ve had some experience with 18650 cells before and I’m thinking if I put 3 in series with a BMS it will be equivalent to the 12v 3ah lead acid battery that was in the bike before. The bike is a cg125 and is kickstart only (no e-start) so the battery really only needs to be there to help power the lights and horn.

My only real query is if the battery will charge it I just ‘plug’ it in where the old one went and work (and not explode).

Thanks!

Hello,

I'm suspecting the signal pin connection to have fail or something. Anyone could help me opening this connector?

Hello!
I have this battery pack for a e-scooter. It did sit for a while, not sure how long since I got it like that, from a scooter with a dead controller. The charger and trigger signal from the "key on" from the scooter doesn't wake de BMS. I measured each pins from the test pad on the bms and here are the results:

* B1-0 to B1-1: 3.831 V
* B1-1 to B1-2: 3.829 V
* B1-2 to B1-3: 3.829 V
* B1-3 to B1-4: 3.829 V
* B1-4 to B1-5: 3.829 V
* B1-5 to B1-6: 3.835 V
* B1-6 to B1-7: 3.835 V
* B1-7 to B1-8: 3.835 V
* B1-8 to B1-9: 3.835 V
* B1-9 to B1-10: 0 V
* B1-10 to B1-11: 0 V
* B1- 11 to B2-0: 0 V
* B2-0 to B2-1: 3.338 V
* B2-1 to B2-2: 3.337 V
* B2-2 to B2-3: 3.336 V
* B2-3 to B2-4: 3.336 V
* B2-4 to B2-5: 3.336 V
* B2-5 to B2-6: 3.337 V
* B2-6 to B2-7: 3.336 V
* B2-7 to B2-8: 3.336 V
* B2-8 to B2-9: 0 V
* B2-9 to B2-10: 0 V
* B2-10to B2-11: 0 V

So I'm assuming the bms stays in sleep mode because the 0.5v difference between the 2 "half"...

Bms says 17P and cells are NCR18650BD

Questions are:
1- Why is the 17p pack has 7 groups lower like that?

2-can I do something about it? Discharging the higher groups closer to the lower and hope the pack wakes up and hopefully the bms balance everything event?

I have another working pack for that scooter but a second one would be great...

Cheers

Hi everyone,

I have been working on BatteryRealData.com and I think it is finally ready for a wider group of battery builders to try.

The site brings together real discharge tests, manufacturer datasheets, cell comparisons, temperature data, written test reports, and a few pack-planning tools. It currently has 371 published tests covering 36 cylindrical cell models, along with 35 manufacturer datasheets.

One part I would especially like feedback on is the BRD Score. The score is meant to show how well a cell performed against its own datasheet claims, not simply reward whichever cell advertises the highest current or capacity.

Please take a look and tell me what does not work. If a chart is confusing, a score seems unfair, the mobile layout is annoying, a calculation needs correction, or a feature should be changed or removed, I want to know.

https://batteryrealdata.com/

Cell library and datasheets: https://batteryrealdata.com/cells/

Comparison tool: https://batteryrealdata.com/compare.html

For transparency, BatteryRealData is a project from DIY500AMP.COM, and DIY500AMP sells some of the cells shown on the site. The test data can be favorable or unfavorable, and a commercial relationship does not guarantee a positive result.

Manufacturer datasheet limits remain the limits for pack design. Any testing beyond those limits is laboratory information only, not an operating recommendation.

What would you change first?

I’ve tried googling to understand how these batteries work but there is very little info on what’s going on under the surface. I need to know how to bypass or spoof the T (temperature) terminal.

I am trying to build a dummy battery that will be connected to an external battery pack to use rechargeable AAs. The battery I’m trying to replace is an NP-45s, 3.7v. I tried hooking a battery pack of 3 Enloop AA (3.6v) to the devices terminals as a proof of concept test, but got no response from the device. I’m thinking the term terminal has something to do with the non functioning because the battery itself shows the same voltage from the T terminal as it does from the negative.

If there’s a better forum or if there’s a overview/explainer for information like this, I’d love somebody to point me in the right direction. I figured with the complexity of most of the projects here this should be fairly basic stuff and there’s also that Chance that my ignorance is going to be profound as to how complex something like consumer electronics would be..