Question on a balancing board

[mappo]

Just got my first paralleling board today and was hoping to get some clarifications on para. charging.
I use a Hyperion Duo 610, and is hoping to get some answers on a few questions..first when charging 3 - 2 cell lipo batteries, 6000, 5200, and 2200 mah the charger is asking what size battery i am charging. there is no instructions on my para. board that addresses these issues. what should my input on battery size. i do know my amps output is. 6+5.2+2.2=13.4 amps. what shud i program for batt size?
will like all inputs. Thanks all

[Basstronics]

Add up the total mah

[mappo]

Hi Bass does that mean that i will have 1 13.400 mah batt charged at 1c will be 13.4 amps?

[BHChieftain]

Yes, but... while theoretically you should be able to balance packs with different MAH, you probably want to keep the differences to a minimum, and you also want to keep everything else as close as possible-- when you hook up all these cells in //, it looks like 1 large mah battery pack so you want the C-rating, IR, ideally the same.

If one pack is 6000 and the other is 2000 I'd be concerned that these pack might be "too different" on other parameters to safely charge them in //. This is my own personal paranoia vs. a claim based on research, and I take this position because I've read so many differing claims about what is safe to do when charging this way.

After sifting through tons of "information" on the topic, my personal practice is to only // charge batteries by the same manufacturer and C-rating, and I keep the mah delta to a min (ie, I will charge 5000 and 5500 packs together but that is about it). I also keep the discharge levels close as well-- meaning, if I run one pack but only partially run another pack, I don't try to // charge those packs together.

In any case, the odds of a problem happening go way up when you // charge, so be sure to charge them under constant supervision in a safe place-- you don't want to risk burning your house down.

That being said, I usually always charge my lipos in //-- I use a hyperion duo charger with // squid cables and // balance taps and charge 8 packs at time at 1C (4 on each port). I spot check the individual cell balances every now and then and they have always been perfect.

I'd love to hear other people's perspective on this.

Chief

[ray schrauwen]

FYI, I bought some parallel balancing boards from China through Ebay and they are now in the garbage. Horrible soldering, horrible quality so I'm making my own now instead with just wires...

They gave me errors and didn't charge evenly with identical packs that are used together in each boat.

Just giving you a heads up that there are some crap quality balance boards out there in case you have some odd problems.

[785boats]

Have a good read of this. It should ease your mind about parallel charging.

https://sites.google.com/site/tjinguytech/charging-how-tos/parallel-charging

I've been doing it for years & have never had a problem.

But ALWAYS connect the main leads together FIRST & allow the packs to equalise before connecting the balance leads together.

Different types, capacities, C rating, voltage level, etc doesn't matter, as long as they are all the SAME CELL COUNT.

Each pack & each individual group of cells will take on the exact same voltage & its full capacity.

[BHChieftain]

Have a good read of this. It should ease your mind about parallel charging.

https://sites.google.com/site/tjinguytech/charging-how-tos/parallel-charging

I've been doing it for years & have never had a problem.

But ALWAYS connect the main leads together FIRST & allow the packs to equalise before connecting the balance leads together.

Different types, capacities, C rating, voltage level, etc doesn't matter, as long as they are all the SAME CELL COUNT.

Each pack & each individual group of cells will take on the exact same voltage & its full capacity.

Good info, thanks! Can you elaborate on why differing C-rating is ok however? I've been confused on that point. If you can't discharge packs with different c-ratings tied together, why is it ok to charge them together?

Chief

[785boats]

I'll try to elaborate the best I can Chief.
Basically different C ratings are just different cell resistances. Higher C rating - Lower resistance.
The old Ohms law insists that when resistances are paralleled the total resistance is less. So the Charger sees a lower resistance than either one of the original ones.
For example... If A 4s pack has an Ir of 2.8 mohms/cell and another 4s pack has an IR of 2.8 mohms /cell and they are connected in parallell, the charger would see about 1.4 mohms/cell.
It actually makes it easier for the charger to balance the packs because it has less resistance to push the last couple of hundred milliamps in.
If there are say 4 cells on each branch of the charger,(say 4 x 3s packs), the varying resistances will average out & the total will possibly end up being closer to the total resistances of the other branches, than if the packs were being charged individually.
Each cell in a branch will fill up to the same level at the same rate. And the charger will balance each branch as per normal but with less effort because of the reduced resistance that it sees.

I know what I'm trying to say, but I don't know if I'm making sense.

Have a look at the pic. I borrowed it from a thread at R/C Groups. Explains it perfectly
Consider each vertical pipe as a different capacity and/or C rating pack. The parallel connection is the horizontal tube at the bottom.
Note that all tubes even though they are different shapes, sizes, & volumes, they are all filled to the same level. Parallel charging of packs of different capacities & C ratings is the same principal.
Does that help at all? Or have I made it worse?
Paul.

[BHChieftain]

Thanks Paul! That helps.
Chief

[mappo]

Hi guys, great wealth of info. and a great link too.. thanks very much

Have a good read of this. It should ease your mind about parallel charging.

https://sites.google.com/site/tjinguytech/charging-how-tos/parallel-charging

I've been doing it for years & have never had a problem.

But ALWAYS connect the main leads together FIRST & allow the packs to equalise before connecting the balance leads together.

Different types, capacities, C rating, voltage level, etc doesn't matter, as long as they are all the SAME CELL COUNT.

Each pack & each individual group of cells will take on the exact same voltage & its full capacity.

[Brushless55]

Have a good read of this. It should ease your mind about parallel charging.

https://sites.google.com/site/tjinguytech/charging-how-tos/parallel-charging

I've been doing it for years & have never had a problem.

But ALWAYS connect the main leads together FIRST & allow the packs to equalise before connecting the balance leads together.

Different types, capacities, C rating, voltage level, etc doesn't matter, as long as they are all the SAME CELL COUNT.

Each pack & each individual group of cells will take on the exact same voltage & its full capacity.

I have two of these 6 port balance boards and love them!!
so cool to plug in my 6s packs to my Blade 500 (2650mah-3300mah) and my Trex 600 (5000mah) packs all at the same time and charge them up as one BIG 6s pack
and on race day I can charge my 4s packs all with different levels from racing to charge at the same time...

[785boats]

Makes life so simple doesn't it Brushless.

[longballlumber]

In theory, I am not a fan of Parallel charging... How do you identify if you've got a bad cell or a weak cell in one of the packs?

Later,
Mike

[Brushless55]

Makes life so simple doesn't it Brushless.

man, I cannot tell you how much time these boards save me...
and so simple to boot!

[785boats]

In theory, I am not a fan of Parallel charging... How do you identify if you've got a bad cell or a weak cell in one of the packs?

Later,
Mike

The same way you know when you charge them individually. With a cell checker before you hook them up to the charger.
I use one of these both immediately after a run & immediately before charging.

http://www.offshoreelectrics.com/proddetail.php?prod=emp-eos07sentry2

If a cell has a voltage & remaining capacity that is way different, usually lower, than the other cells in the pack after a run, then there is a problem & it is not put in parallel with other packs. It is charged & monitored separately.
While I'm checking the packs before charging (usually 12 or more packs) I put them in pairs with the closest possible voltages. Although not entirely necessary, It just makes it easier on things.
While the charger is charging I also monitor the individual cell voltages & Internal resistance lines. But I've never had a problem during a parallel charge. If a faulty cell is put on charge then there will be some issues.

Mappo.
If you go through the titles in the menu box on the top left of that link, you will find a wealth of info on many different things. It is all worth a read.
Cheers.
Paul.