Ballanced?
 

I have allways charged my saddle lipos as single cells, two fully charged saddles must be ballanced? However I have been recently informed that this not the case, and must be charged as pair through a ballance board toproperly ballance them. Am I right or wrong?

They should be charged together as a pair as then they are paired against each other.

My guess is that charging them as single cells would not actually be balancing them as your charger might finish each cell is on a slighty different voltage.

You would need to plug them at the same time so your charger can 'see' both cells, using a balancing board.

What charger is it, then maybe someone who has the same one could help?

I'm not sure this is the case my charger raises the voltage at fixed current up to a maximum voltage then finishes charging with constant voltage (and lowers the current as it approaches fully charged). All Lipos would reach the same limited maximum voltage.

This isn't how NiMH/NiCd are charged where packs (cells) are charged at constant current throughout the charge and might peak at different voltages.

Does balancing ensure putting the same charge/energy into each cell? If so, charging them seperately won't do this.

I use a quad charger (4charger outlets)

I start th charge the two single at the same time and they finish charging at the same time give or take a few seconds. They finish at the same voltage with almost identical capacity being put into them.

So surley this is the same as the ballance software bring the cells upto there's maximum voltage/ capacity?

I'm confused!

If you had a bucket which when filled weighed 2kg and another bucket which when filled weighed 2.1kg, each with the same size hole in the bottom.

After five minuits the larger bucket would have let more out (higher pressure)

If you were the to fill them to an equal weight the the next combined total discharge would be lower.

Is ballanced better, or both fully charged.

As long as your charger is charging them both to the same voltage when fully charged then they're balanced......

I'm naturally inclined to say you're wrong, but I can't think of a good reason why...

All balance charging does is charge each half of the saddle to 4.2V, so if you charge each half on a separate port to 4.2V then you are doing the exact same thing.

G

they need to be charged as a pair so they balance, ie same millamps and same vaultage,most saddles are made up of 2-3 cells per side, so 4 to 6 in total, the chance of them all reaching the same millamps and voltage if you charge them seperatley is small, im not saying do it everytime , but if the features there use it

how do you know the charger is putting exactly the same voltage in the cells? the only way to know for sure is to charge them together on a balance charger and if it finishs the cells quickly then the way you are doing them is okay if it takes an hour or so to balance them then there not

No they don't.
You are charging them till they are full, this is not the same as old cells where you emptied them and because they were (hopefully) matched they all filled up at the same time.

Yes each saddle is made up of a number of individual cells in parallel, but you don't have a physical connection to them all, so you just have to hope that the cells in each half of the saddle are close enough matched so they are all full at the same time.

Lipo chargers charge different, they charge at a constant voltage and ramp down the current until the cell is full. If both halves are charged on their own until full, then that is no different to charging them together and balancing them. All balancing does is only charge one cell if the other is full.

Because it is a constant voltage charge process...... simples.

G

It always cracks me up how people pipe up and give their opinion and i stress it is usually opinion regarding charging lipo's. Quite often it is wrong as this thread shows. There are a couple of responses that atleast show some of you understand the princible and execution of balancing.

There are several ways to balance a serial string of cells but for the purpose of how the rc community use their cells we will be top balancing the cells to 4.2v each. What this means is that regardless of what voltage they are at when at anything less than 100% charged then as long as each individual cell is at 4.2v when fully charged then they are balanced. This is regardless of how many ma have gone into the cell or how long it takes the cell to finish charging.

If you charge as individual cells as per the OP then as long as the same charger was used to make sure there are no disrepencies between chargers then the cells will be balanced. This can actually be a more accurate way of balancing because there can be desrepencies between the individual balance ports on chargers.

In summary if you charge your cells individually they will be balanced.

+1, both methods should give the same results

so why do you balance stick packs?

The only downside I can see by charging them as single cells is your doubling the time it takes to charge them as opposed to as a pair.
If you,ve got the time and patience to do that and keep an eye on them while they charge then carry on.

Stick packs are still 2 cells, just in a single hardcase rather than 2.

His charger will do them at the same time, so no problem.

so if you charge one pack to 8.40 volts and it takes 3200mah to charge and the other pack takes 8.40 volts and 2600 mah thats balanced and charged ok, if so ill stick to charging them all together were they all get the same mah thanks

If that happens Lion-O then one half of your saddles is knackered :lol:

You are thinking about it the wrong way, you are thinking of filling them from empty like we did with NimH cells etc.

If you had your pair of saddles as above and they were that far out of balance before you put them on charge on a normal balance charger, all it would do is put 2600mah into one saddle and 3200mah into the other - it does it for you without seeing. The end outcome is the same, both are FULLY charged at the end of charge ;)