The battery builders club

thisguyhere · July 20, 2019, 5:15pm

yelnats8j · July 20, 2019, 5:28pm

Thats what I was looking for thank you so much.

yelnats8j · July 21, 2019, 3:07pm

I messured the voltage

Seems like a dead cell in P1

legend27 · July 21, 2019, 3:42pm

what bms are you using?

0.2V difference is quite big. Maybe bad bms?

Or B1 could be draining the other cells?

yelnats8j · July 21, 2019, 3:46pm

D140 BMS

So not a bad bms

I think its the cells

legend27 · July 21, 2019, 3:48pm

Where did you get the cells?

Have they been reused?

yelnats8j · July 21, 2019, 3:50pm

There the P26a cells, could have been no clue got them from IMR

Flasher · July 21, 2019, 4:19pm

You like to play with fire dude

yelnats8j · July 21, 2019, 4:21pm

Yeah, Im planning on ordering new cells today, just dont know which ones I want yet.

30q? 20700b? What else is there

yelnats8j · July 21, 2019, 4:24pm

Ive been practicing my fire bending so im good

2jebXI0k0HLFK

Crashmaster · July 21, 2019, 4:38pm

Funny you mentioned this. I was just doing this last night for the new pack I’m building.

Songsta · July 21, 2019, 4:53pm

I’ve realise that I might be missing something.

Refer to the diagram I posted:

The switch I’m getting is from @Kug3lis (https://shop.3dservisas.eu/products/fatboy-mini-sparky-switch-50a-200a-100v-pre-charged-anti-spark-switch-with-push-to-start) and my assumption is that this is fine to protect the VESCs when turning on the board. However, what about when I want to charge? I was thinking that I can mount a XT90 anti-spark port to the boosted enclosure and that should suffice, but it’s gonna be really tricky and not very slick. I would prefer a barrel charging port, but those aren’t anti-spark, are they? If I wanted to use a barrel charging port how could I make it anti-spark? Do I even need an anti-spark port for charging?

ZachTetra · July 21, 2019, 5:01pm

What’s the best place in the US to get a dozen Samsung 40T cells at a sexy price? Preferably with some nickel too

Edit: or something similar (4000mah and 30A)

M.Hboards · July 21, 2019, 6:58pm

I like useing liion wholesale but there prices Aren’t the greatest and there currently our of stock on the 40t.

thisguyhere · July 21, 2019, 7:23pm

ordered 72 40t cells from imrbatteries for $6.62 a cell shipped. that’s volume discount tho, a dozen will be $7 per cell plus shipping.

rich · July 21, 2019, 8:48pm

It’s all good , you don’t need an anti spark for charging if you turn the charger on before plugging it into the charging port. Only if the charger is unpowered then it will spark.

Zach · July 21, 2019, 9:05pm

Just had an awesome idea for those who use battery pcb’s. I’ll try to mock it up soon and share it with y’all!

JeffDJ · July 21, 2019, 11:02pm

This is awesome! Editorial comment: When talking about form factor I think you mean cylindrical when you say spherical.

Flasher · July 22, 2019, 2:07am

@rich You’re shitting me right? God fucking dammit…I wasted so much time soldering xt90s to my chargers

deucesdown · July 22, 2019, 5:07am

Generally, it’s charging the capacitors that causes the spark. As rich said, if your charger is unpowered, there’s a difference in voltage (~40v on pack side, 0v on charger side). If the charger has some capacitors on its output, there may be a spark.

So, you don’t need an antispark, but depending on the charger, it’s better to power on the charger before connecting.

(BTW I fried 2 smart BMS this way, saved a 3rd one with a charge port fuse)