# What happens when u connect cells like this

If u have ten cells for example all in series but one cell switched facing the wrong way.

With a competed circuit to the Esc

1 Like

Probably would kill the BMS

Ummâ€¦Kaboom?

Effective voltage on esc =8s. As you have 9s in series in the positive direction minus the voltage of the upside down cell. Donâ€™t think it will be good at all for bms or balance of charging or discharging. So unless you have a reason, donâ€™t.

Nothing happens as long as you donÂ´t close a circuit somhow with balancer cables or somehow.

If youÂ´re facing the last cell upside down for example, you neither have a seriell nor a parallel connection somehow. Only two plus or two minus poles together. So nothing happens

1 Like

This is only true if you donâ€™t complete the circut. If you complete the circut the other 9 batteries will begin pushing current through the 10th battey backwards at 37.8 volts. Then they will begin charging the 10th battery until it overcharges and lights on fire.

If you have a circuit closed you have to substract the cell voltage from the others. But not sure about what happens inside of that one battery. http://resources.schoolscience.co.uk/britishenergy/11-14/circh1pg2.html

if the circuit isnâ€™t compete pretty sure nothing will happen but if complete it would force current the wrong way through the backwards cell. If it will charge and blow up I wonder and according to what that last link seems to be saying its no big deal and just wonâ€™t add the voltage.

maybe some battery guy like @PXSS can join and tell us about this beside the facts on paper?

That link leaves it sounding like itâ€™s doable and would just add or subtract without any other consequences. Iâ€™ve a feeling running big current through the wrong way would be big bad news

1 Like

@Hummie

We both know that overcharge is very bad for lithium ionâ€¦

Think of it like a tug of war with 10 people. The way the rope goes would represent current. There are 9 people on one side pulling and 1 person on the other. Obviously the 9 people would win and current would flow. Because current would be going backwards in the 10th battery it would chargeâ€¦ This is how regular charging works, you push current through the battery backwards.

Please donâ€™t complete the circuit if it is backwards you will destroy the cell and probably start a fire

1 Like

put 4 cells in parallel last night but one was backwards. This is a different scenario from above but definitely wasnâ€™t good. The one cell got pretty warm and the other 3 got a bit warm and I broke it up and realized quickly. So was I speed charging the one while discharging the 3 into it? I didnâ€™t check the voltage immediately to see what had happened but now that iâ€™ve put them all in parallel theyâ€™re all the same voltage.

Hoping I didnâ€™t damage more than possilbly the one but Iâ€™m sure Iâ€™ve asked this before and Iâ€™m not satisfied with the answer: at what voltage is it ok to throw cells together in parallel? If ever a cell were exposed to an extreme discharge or charge this seems the scenario.

@Hummie Thatâ€™s a good question. and is up to interpretation. I personally have stayed on the safer side of things and only connected cells in parallel after they have been balanced to the same voltageâ€¦ Iâ€™ve also never worked with Liion. Only Lipo. If I had to guess Iâ€™d say stay within 0.1 Voltsâ€¦ but thatâ€™s me just throwing random numbers around.