Balance Charging 1s LiPO

[Chequered Flag Racing]

quote from another thread

Originally Posted by mark christopher

you can not balance a 1s cell?

looks like you can with this one

so how many cells are in a 1s lipo?

[metalmickey0]

Err one? Thats why its a 1 cell lipo. Perhaps that isnt a 1 cell as not seen one with that capacity

[neallewis]

Originally Posted by Chequered Flag Racing

so how many cells are in a 1s lipo?

I'm just guessing here, but maybe its a 1S2P pack. So to get the capacity they have paralleled two 1 (3.7v 2300mAh) Cells, hence the need for a balance charge lead. I'd expect it to be printed on the label though, so you can set your charger correctly?

[Chequered Flag Racing]

if it's one cell then why have a balance port

1s Lipo's from Nosram/LRP are at 6700mah, but that's another story
http://www.nosram.com/en/products/ba...c-37v/details/

[sosidge]

The balance lead only has two wires... it has no balance function.

Perhaps it is there for the very small market of people who use trickle chargers that connect via a balance connector. More likely is that it is there because the supplier builds the packs with a balance lead and hadn't bothered to remove it from the design.

More importantly, does it really matter?

[mark christopher]

Originally Posted by sosidge

The balance lead only has two wires... it has no balance function.

Perhaps it is there for the very small market of people who use trickle chargers that connect via a balance connector. More likely is that it is there because the supplier builds the packs with a balance lead and hadn't bothered to remove it from the design.

More importantly, does it really matter?

Ditto

[Chequered Flag Racing]

thanks all

a club member was asking on FB and I didn't have a clue

[smarkham]

Its so you can use a cheapo charger some only charge through the ballance leads think the bottom line orion lipo chargers like the Orion Advantage IQ240 use ballance leads only.

[adon30]

The extra leads are just for an external measurement. Which would be a more precise measurement than using the charge leads only. So in effect giving you a 4 wire measurement. May also be for chargers that don't have an inbuilt meter (which is rare nowadays).

[SlowOne]

Our 1S cells are all 1S2P. There are two cells in there connected in parallel. When charging any set of cells from a single connection there is the chance that they will become unbalanced. That connection could easily be for balance charging.

My experience is that it isn't necessary. All the cells I have replaced have been just tired after a lot of use. Cells bought at the same time and used the same amount (I usually buy two and use them by rotation for each race) have become tired at the same time, suggesting to me they are just tired, and not out of balance.

Adon sounds like he knows the real answer though...

[adon30]

Originally Posted by SlowOne

Adon sounds like he knows the real answer though...

or a good guess!! Lol

I never even balance charge my 2s cells. Waste of time in my opinion. All it does is stresses the batteries more trying to get them equal. I haven't done this on a pack of cells for 4 months now and when I plugged them in to check if they were still matched there was 0.003v difference!! So still perfectly balanced.
I also don't 100% charge them as nowadays the capacity is so large i can still run for 12+ minutes from 95% and they still read 3.6v when they come off. This stops further stresses and overheating on the batteries.
Apologies if I strayed off topic

[mark christopher]

Originally Posted by adon30

The extra leads are just for an external measurement. Which would be a more precise measurement than using the charge leads only. So in effect giving you a 4 wire measurement. May also be for chargers that don't have an inbuilt meter (which is rare nowadays).

i doubt it very much, each wire will go to the same place on the cell,no matter where you take a reading from on those conectors you will get the same reading, my guess is its for this sort of charger

http://www.vapextech.co.uk/cgi-bin/s...html%23a14#a14 bottom of page, though it wont balance the pack on 2 wires

[adon30]

Originally Posted by mark christopher

i doubt it very much, each wire will go to the same place on the cell,no matter where you take a reading from on those conectors you will get the same reading, my guess is its for this sort of charger

That is the whole point of a 4 wire measurement. To have both measure and sense wires as close to the point requiring measurement as possible. This is what we use for high accuracy tests of aerospace products. I'm not categorically saying that this is the exact purpose the extra lead was added for but this is the principle of the measurement technique.

[RudolfXC]

Originally Posted by adon30

That is the whole point of a 4 wire measurement. To have both measure and sense wires as close to the point requiring measurement as possible. This is what we use for high accuracy tests of aerospace products. I'm not categorically saying that this is the exact purpose the extra lead was added for but this is the principle of the measurement technique.

Yes, it will be to reduce voltage drop errors in the cable which shouldn't be too great when charging but would if you cycled them.

[ianjoyner]

I think Adon is right, although you can't use it to balance, it's a measurement point which avoids voltage drop on the main leads and is also a common charge connector on low rate chargers.

You can't balance a 1s LiPo, even if it's 2p, there's no way to access the cells individually, by definition they are connected in parallel. You would have to disconnect the cells, but since they are always connected, they will also always be in balance, so there would be no reason to.

I've also found with cells in series they never to drift apart in normal usage. The only time I've had cells go unbalanced is with a fault in the balance lead! I now check the balance with a meter regularly, but never balance charge, because if there's a problem with the lead/charger this could put them out of balance. The balance is just fine when left well alone.

[adon30]

Originally Posted by ianjoyner

I've also found with cells in series they never to drift apart in normal usage. The only time I've had cells go unbalanced is with a fault in the balance lead! I now check the balance with a meter regularly, but never balance charge, because if there's a problem with the lead/charger this could put them out of balance. The balance is just fine when left well alone.

I actually found it out from a top F1 driver who regularly makes national A finals Although I would like to take credit for it myself I can at least share the knowledge with others and save you from damaging you £60+ packs of lipos uneccessarily.

[mpg200]

Adon is correct on this.

It is whats known in power electronics as a 'Kelvin' connection. basically its a voltage sense point that isnt carrying current so it is free from the voltage drop of the main cables. Used frequently in large power supplies in industry and anywhere that requires acurate voltage measuments with large currents flowing.