8 amp charger for a 34 aH battery?

[Deus]

I have been supplied a 8 amp charger with my 34 aH battery should i change it for a 5 amp one ? and charge slower and put less stress on the cells or is 8 amps ok ?

 

[Nealh]

How many cells in parallel ?
What cell brand, type ?
I would think at least 10 so likely each cell will only see 0.8a charge rate.

 

[Deus]

98 x Panasonic Tesla 21700 cells. 14s7P 52v Battery (58.8)

 

[vfr400]

As a general guideline, you should charge at 0.2c, which would be 7A, so 8A should be fine. If you don't discharge it too far, 5A would be OK too, but would take 7 hours to charge from empty.

 

[Deus]

As a general guideline, you should charge at 0.2c, which would be 7A, so 8A should be fine. If you don't discharge it too far, 5A would be OK too, but would take 7 hours to charge from empty.

How do you work out the C rate for a charger?

 

[sjpt]

How do you work out the C rate for a charger?

C rate is for the cells; part of the specs if you look in detail.

 

[vfr400]

C is a factor for expressing the current flow rate for a battery based on its capacity:
For a 10Ah battery 1C = 1 x 10 =10A
For a 20Ah battery 1C = 1 x 20 = 20A
For a 5Ah battery 2C = 2 x 5 =10A
For a 34Ah battery 0.2C = 0.2 x 34 = 6.8A.

 

[Nealh]

Individual C rate for a cell is 1 x it's mah rating.
Example #1.
Samsung 25R 2500mah & 20a max rated, 8c capable . 1c is 2500mah, 8 x 25 = 20a.

Example #2.
Samsung 29E 2900mah & 8.7a max rated, 3c capable. 1c is 2900mah, 3 x 29 = 8.7a.

The C rating is different for each cell so the manufacturers specs need checking for max charge and discharge rate. The lower C rate overall used for a cell group in parallel the longer the life span might be, life span is also dependant on discharge rate and how deep one goes beyond 3.2/3.3v per cell.

The more cells in parallel means each cells C rating is divided so one can use a slightly higher charge rated.