Question on a balancing board

[grsboats]

Great link and thanks for sharing.Gill

[Brushless55]

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/pro...p-eos07sentry2


Cheers.
Paul.

That is possibly my most used tool in my tool box!

[785boats]

That is possibly my most used tool in my tool box!

Yep.
I never hit the lake without it.

[ray schrauwen]

How long does equalization take???

I'm making my own parallel adapters.

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.

[785boats]

How long does equalization take???

I'm making my own parallel adapters.

Hi Ray.
Not long at all. Almost immediately if the difference is only, say, 3.75V/cell in one pack & 3.85V/cell in another pack. With that sort of difference I plug the balance leads in straight away & start the charge. With a larger spread (which is very seldom) I just plug the main leads together then use the cell checker on the balance tabs alternately. After about 30sec or so the voltages are within a couple of 100ths, & that's fine to plug the tabs in & start the charge.
But as I said earlier, I match the packs up with the closest voltages/capacities first, & they can always be plugged in straightaway & the charge started.
The only reason the voltages should be as close as possible before the balance tabs are plugged in, is because a high current flow of 3 or 4 amps in the balance leads can blow the traces in the back of the balance boards. The balance leads & pins themselves are only rated to 3 amps I think. The traces in the boards are less than that. Remember they only usually need to deal with milliamps while balancing a pack.
Cheers.
Paul.

[ray schrauwen]

Hi Ray.
Not long at all. Almost immediately if the difference is only, say, 3.75V/cell in one pack & 3.85V/cell in another pack. With that sort of difference I plug the balance leads in straight away & start the charge. With a larger spread (which is very seldom) I just plug the main leads together then use the cell checker on the balance tabs alternately. After about 30sec or so the voltages are within a couple of 100ths, & that's fine to plug the tabs in & start the charge.
But as I said earlier, I match the packs up with the closest voltages/capacities first, & they can always be plugged in straightaway & the charge started.
The only reason the voltages should be as close as possible before the balance tabs are plugged in, is because a high current flow of 3 or 4 amps in the balance leads can blow the traces in the back of the balance boards. The balance leads & pins themselves are only rated to 3 amps I think. The traces in the boards are less than that. Remember they only usually need to deal with milliamps while balancing a pack.
Cheers.
Paul.

...and this is most likely why my balance boards were bad because I always plugged in the balance leads first. I learn a lot from you, thank you!

[longballlumber]

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/pro...p-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.

What about seeing what each cell is doing "under load"? A cell's voltage can look fine in a static state. However when the pack (or cell) is put under a load THAT is when you see if a cell or cell's in a pack are going bad.... Just my 2 pennies worth....

Later
Mike

[785boats]

Thanks Ray.
I'm glad my ramblings are of some help to someone.


Mike.
If you mean while it is on the charger in parallel with another cell, then if you are periodically checking the IR/cell & the Voltage/cell you will see a problem arising. If a cell is developing a high resistance the voltage on that balance line will be less than the others. The other cell in parallel with it will also be of lower voltage as they will always both be the same. The bad cell will basically be holding the other one back. Just stop the charge & check each pack individually to find which pack has the bad cell.
A good cell will almost never go faulty during a charge. Charging at 10C might cause a weaker cell to fail. But who does that. I never charge higher than 2C myself for single packs & only 1C when in parallel. Only because I don't have a big enough power supply to charge 4- 5000mah packs at 2C.
That's the beauty of the cell checker that also gives you the percentage remaining in each cell. When a cell is down say .4 or .5 of a volt compared to the other cells in the pack after a run the percentage remaining will be down a lot.
For example, three cells in a pack may be at 3.8V & 40% but if the fourth cell has say 3.5V the percentage left might be say 12% or less if the IR is high in the cell. The cell will also be hot & probably a bit squishy. That pack should not be paralleled with other packs.
I always check all cells for voltage & capacity remaining after a run. It is more important to me than checking temperatures of motors or ESC's.
Cheers.
Paul.