Li-Po Series connection issues


I know theres probably someone who already had the same issue as me…

Im trying to connect 4 6s 4500mAh Lipos in series and paralell, and im having issues connecting them up. The Lipos are balanced and charged to the same voltage but as soon as i connect them up my connectors burn out. I already redid the wiring for the balance leads and the xt60 connectors that im using, my setup works fine with just two Li-Po`s in series. Maybe someone has a idea what i could be doing wrong.

My Setup: 170Kv Motor 40A Contactor with constant current source in paralell to precharge the Caps of my VESC and keep my contacts from dying 12S BMS 40A Fuse

Also sorry for any spelling errors i dont do english posts very often c:

upload some pictures and a diagram how you wired everyting up. will help us to solve your problem.

and i didn´t understood what exactly burn out when you connect your packs in parallel. you wrote your connecots burn out. you mean the xt60 connectors?

Im not home atm, ill upload a picture when i can.

Im getting a spark when im connecting up my Lipos, i dont know why they are balanced and at the same voltage level, ive charred two connectors already and i have no ideay why.

you need an antispark first of all. wouldn’t be using a precharger separate

If they’re actually at the same voltages then you’re definitely wiring something up wrong. You don’t need an antispark between the backs, assuming that you’ll be using a BMS.

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I had one but it died on me, i guess i had cheap knockoff fets on it…

Im currently building my own im just using the contactor while im doing that

First thing coming to my mind, is that maybe you are connecting parallel cells plus to minus, the same way as series. Or two series and one parallel between them. Just remember, parallel is plus to plus, series is plus to minus.

@J0ker3366 wheres the lipo king? You’re up.

let @Tachun upload his diagramms and pictures and than our lipo king can manage everything… at the moment it´s just guessing


I don’t know what you got going on without pics. But my setup is 12s lipos but I charge 6s parallel x2.

To charge I need to disconnect both plus and minus main power cables with two loop keys. Or that shit shorts out the balance wires. I have forgot a few times to un plug the two loop keys and it’s a bad seen. It vaporizers the pins in the balance plug. :scream:

Hes asleep anyway.

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ok than let´s tag @J0ker3366 here once more that he will not pass it in the morning… :sweat_smile:

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I dont know if theres anything wrong with it…

also this looks like it was made with ms paint…

Is it sparking when you connect the parallel packs together, or when you connect the series ones?

Does it spark if you leave the balance wires completely disconnected from each other?

it sparks when i connect the series packs, the balance wires are fine

I found about this hard way also…

u cannot connect both series and parallel at the same time… otherwise it shorts the battery / connectors as @lrdesigns pointed out…

U need to install manually operated switch, to switch between 6s charging and 12s discharge…

If 12s discharge is on loop key, then u can either add one more loop key for opposite polarity wire and charge when both keys are removed

Otherwise u need 4 port balance charger (or 4 chargers) and charge seperately through balance wires only

That’s no bueno… are the vesc’s connected when you connect them? Is the BMS connected when you connect them?

He is using a BMS, he can charge all of them at once with a 12S charger

Yeah bruv, pictures of your current wirring set up would be great.

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Surely this can’t be right. Why would there be a a pin after pin 12 that goes to the battery positive when pin 12 is already connected to the battery’s main positive? Assuming that this is in fact a 12s bms. 15%20PM