The battery builders club

I’ve counted 20s20p. :smiley:

Thats what I saw as well, very cool 6kWh

Yea its 20S20P. Not P42A though its a DLG cell, actually not that highly spec’d (60Ah, and only 120A continuous max)

1 Like

DLG INR18650-320?

Its predecessor, the 3000mah one

1 Like

This was a fun little build.



12s2p P42A NESE pack done. Will build a similar 12s3p pack once I get another balance harness.

8 Likes

Happy new year Battery Builders Club. :tada: You survived another year. :mask:

Making baby steps here. I build some solder pools on tabs before soldering. Are the solder pools big enough? Planning to use 3x12AWG.

3 Likes

Personally I would use a touch more, but looking good :call_me_hand:

Make sure you tin the wires too!

2 Likes

You don’t need to rough up the solder surface. Thats just a feel good thing, not actually useful. :slight_smile: The solder sticks anyway, rough or not.

It might just be me being sus but I feel like it actually sticks better to nickel that hasn’t been roughed up

i check mine every time i charge! :crazy_face:

i feel it’s like glue

more surfsce area to grab

i do some crosshatching with an exacto :face_with_hand_over_mouth:
but not too heavy just a couple strokes each way and then get that bitch tinned

I’ve done tests, and they’re roughly the same as far as adhesion. Nickel that’s been roughed up very coarsely seemed to have slightly better adhesion, and took a bit more effort to rip off.

I’ve found that a small scratch pattern helps to localize the solder pool, and makes applying it without it spreading a bit easier.

This was using Kester 60/40 with a T12 station at 375C and rosin paste flux. That’s what I usually use, so that’s all I can offer.

4 Likes

Need some advice here:

Replacing bms for a local dude, the white silicon is all over the balance connector plug. I’m afraid to heat it too much and melt the wire coating. Chop stick is trying its best but I’m also afraid to get too stabby with it.

My current mental plan is to cut the balance leads like below and splice in the new bms balance header staggering joints so they don’t overlap or rub.

I’ll be cutting the leads one at a time and soldering the header on as I go so no 2 exposed leads should be hanging out… I imagine if 2 exposed balance leads touch it makes a pop.

Safety questions:

  1. Is there any order in which I need to cut the wires since the bms is still connected to the battery?

  2. The cut leads coming from the old, still wired in BMS (left of cut lines in photo)… Are those leads capable of shorting out anything?

1 Like

Hello friends,
I’d like to hear your opinion before repairing this 10s4p, Samsung 30Q battery i purchased (New) 1 year ago.

  • B- wire is 48cm long. 18 AWG.
  • C- wire is 21cm long. 18AWG.
  • Charging wire is 18AWG with 16A fuse according to seller but i can’t confirm it (no info about its voltage)
  • BMS is 12s. It’s flashed to 10s (maybe the seller didn’t have a 10s in stock?). BMS is wired for charge only.
    Now the issues i am facing :
  • Voltage of 1st serie and 10th serie cells are always drifting. They can drift up to 0.25 Volt lower than the other series after charging and discharging. I asked the help of the seller but he gave me useless advices. (Luckily, James from LLT told me how to charge each serie with JST connectors and a 5V USB charger).
  • Silicone of B- kinda melted near the 1st serie
  • i need to make more than 3 attempts to connect to the Xiaoxia Android app via Bluetooth . Sometimes it takes up to 7 attempts. Very annoying.
  • there’s a 0.01 voltage difference between the multimeter reading and the BMS. BMS reads all the series 0.01V lower.

So before unwrapping the battery, I’d like to know what do you think of this build?
Should i unwrap the battery and replace the wires AND the BMS?
Or should i replace B- and C- wires ONLY?

Any help would be greatly appreciated!!




P. S I didn’t react earlier because i am not a regular rider and the field of batteries and BMS was totally foreign to me. I thought BMS would balance the cells again but it didn’t happen.

1 Like

lol I would have put that first on the list. Did it happen during aforementioned

No. I used a phone charger. 5V/ 1A
Maybe it’s the board charger? I have a 42v. 5A charger.
Do you think i should cut & solder the b- wire? Or remove it completely?.. I’m lost

1 Like

if the wire did not melt during the 5v usb charging method then was it during riding?

5A charging should be fine over an 18awg wire. I’m guessing that wire was abraded and not melted?

I would just replace the wire by soldering a new one in from the BMS to the pack. Then make sure it’s routed in a way that it won’t rub on the enclosure. You can pickup that blue heat shrink wrap on eBay for fairly cheap. It would give you a chance to inspect the rest of the battery’s build quality and make changes if needed.

1 Like

I bypassed the bms during the 5v charge. I plugged the 1mm jst connector directly in the grd/b+ of the white connector.