Busbars for top balancing question.

[Danke]

I see batteries and cells use interchangeably here. If I have rack batteries from same manufacture, bought together, do I need to “balance” them individually before I hook up the bank of them in parallel?

 

[John Frum]

Will it cause damage to power supply using original leads or likely just not work?

Current flow will likely be much less than 10 amps so the process will take much longer.

Does this mean it's not a good idea to top balance if I'm unsure on when I can get the system running?

You should top balance just before you assemble the pack with BMS.
The you can draw the battery down to ~50% depth of discharge and leave it like that for monthes.
Leaving cells full for extended periods causes them to lose capacity faster than if the battery were cycling daily.

Also. I read the following in the tutorial manual:

"Before hooking the power supply to the cells, set the power supply to .2C or less of the combined AH of the cells.
This will usually turn out to be the max current setting of the power supply"

Could you please explain this?

0.2c is a way to express charge current as a ratio of battery capacity.
For a 100 amp hour battery 0.2c = 20 amps.
For a 280 amp hour battery 0.2c = 56 amps.

 

[John Frum]

I see batteries and cells use interchangeably here.

Edited my post to refer to cells.

If I have rack batteries from same manufacture, bought together, do I need to “balance” them individually before I hook up the bank of them in parallel?

You should charge each battery full before you parallel them.
That stops excessive current flow between batteries when they are first paralleled and ensures they are at the same state of charge.

 

[withaview2]

Current flow will likely be much less than 10 amps so the process will take much longer.

Ok. But faster balancing individual cells rather than all together?

You should top balance just before you assemble the pack with BMS.
The you can draw the battery down to ~50% depth of discharge and leave it like that for monthes.
Leaving cells full for extended periods causes them to lose capacity faster than if the battery were cycling daily.

Then I will not balance untill about a couple months from now. Should I manage the cells in some way to protect them until full assembly?

0.2c is a way to express charge current as ratio of battery capacity.
For a 100 amp hour battery 0.2c = 20 amps.
For a 280 amp hour battery 0.2c = 56 amps.

I see. So 56 amps regardless number of 280 Ah cells?

 

[John Frum]

Ok. But faster balancing individual cells rather than all together?

My method is for charging individual cells.
That is all that is required for top balance.

Then I will not balance untill about a couple months from now. Should I manage the cells in some way to protect them until full assembly?

Give each cell a number and record its voltage.
You want to make sure you don't have 1 or more cells with excessive self discharge.

I see. So 56 amps regardless number of 280 Ah cells?

My method is for charging individual cells.
With your bench power supply you are limited to 10 amps.

Lets guess that your cells are at 70% DOD
280 amp hours * .7 DOD = 196 amp hours
196 amp hours / 10 amps = 19.6 hours per cell.
If you did the old style parallel top balance it would take 19.6 hours * 8 cells = 156.8 hours.

I have been suggesting that you charge each cell individually at ~20 hours per cell.

Suggest you re-read my posts and the doco that @HRTKD and myself have written.
We have suggested two different alternatives to the classic parallel top balance.
Luckily you have time to get a good understanding of what top balance is and isn't before you proceed.

 

[withaview2]

My method is for charging individual cells.
That is all that is required for top balance.

Give each cell a number and record its voltage.
You want to make sure you don't have 1 or more cells with excessive self discharge.

My method is for charging individual cells.
With your bench power supply you are limited to 10 amps.

Lets guess that your cells are at 70% DOD
280 amp hours * .7 DOD = 196 amp hours
196 amp hours / 10 amps = 19.6 hours per cell.
If you did the old style parallel top balance it would take 19.6 hours * 8 cells = 156.8 hours.

I have been suggesting that you charge each cell individually at ~20 hours per cell.

Suggest you re-read my posts and the doco that @HRTKD and myself have written.
We have suggested two different alternatives to the classic parallel top balance.
Luckily you have time to get a good understanding of what top balance is and isn't before you proceed.

I will do as suggested . Thanks for explaining, it's been very helpful.