Chargers lipo parallel charging question

[studio398]

i'm trying to understand this better. i have made some assumptions and want to know if my assumptions are correct.

theoretically, let's say you have a 1000w, 30A charger, and a 1150w power supply at 24V. let's say you have 10 batteries, all 3s. 6 of them are 2200 mah, and 4 are 3000 mah. hook them all up to the charger using 2 para boards. set the charger to 30 A out.

1. if i'm understanding this correctly, you would have 12.7V * 30A(i realize it's 12.6, but the charger may bump it up 0.1 to charge faster)= 381 watts. between the PSU and the charger, the efficiency might be 80%. so, the psu will be consuming 381 / 0.8 = 476 watts.

2. my other assumption or question is, are all ten batteries receiving equal amp flow? IOW, set charger to 30A, 30A / 10 batteries = 3A per battery being received? to take this one step further, is the charging rate different for these different capacity batteries? for 2200 mah, 3A / 2.2 = 1.36 C. and for 3000 mah, 3A / 3 = 1.0 C

are these assumptions correct?

thank you,

pat

 

[Lee]

You want to charge all these batteries together.
First they must all be very close to the same voltage.
Add up all the Mah. Thats 25,200 in your case, which is 25.2 Amps
So if you want to charge the batteries at 1C charge rating (recommended), set the charger to 25.2 Amps
The power supply has more than enough power to run the charger.
In parallel, each battery will be seen as one cell, even though they are 3 cell batteries.
The charger will adjust the current to each battery as they fill up, to balance out all the batteries as they rise towards 4.2V

Hope this helps

 

[studio398]

so, no matter what you set the amps to on the charger, these batteries will all charge at the same C rate, even though they are different capacities? is this what you are saying?

thanks

 

[Lee]

Yes. Its the total Amps of all the batteries not the individual.

 

[Tony]

You will add up all of the mah of every battery. Think of it this way, when you plug all of the batteries in together to parallel charge, all of the cell 1's will combine, all of the cell 2's will combine and so on. So pumping in 30 amps when you have 25,000mah worth of batteries is going to be fine, even if you have a 5000mah pack with a 5c charge rate as well as a 700mah pack with a 2c charge rate, it's all going to even out so that you can charge at a higher amp since it's not pumping it all into one battery. It's spreading it out among all of the batteries. Hope this makes sense.

 

[Tony]

If you have not done so yet, check out my Parallel charging video. I have everything from a 250 mah pack up to a 1900mah pack charging all at the same time. Can't remember what I charged at though. But it was pretty high.

 

[studio398]

Tony, i took your advice from the other thread. i pulled the trigger tonight on an icharger 306b. thanks for steering me in the right direction.

pat

 

[Tony]

It's my pleasure pat. You are going to love that charger.

 

[studio398]

so i watched the vid on parallel charging. and it was said the batts should be close in voltage before hooking them up to prevent a huge surge of current between them. it was said the voltages should be within 5 %.

soooooo, before connecting them in parallel, 1 cell or 3.8 v batts should be within 0.2 v from lowest to highest, and 3 cell should be about 0.5 v. do i have this correct?

thanks

pat

 

[Tony]

That is correct. Batteries are made to discharge fast and if you hook it up to a battery with less voltage, it will equalize the batteries and far exceeding the charge rate of the lower battery.