christopheraburns
New member
- Joined
- Oct 3, 2017
- Messages
- 3
I just picked up an EV-Peak CQ3 400w charger (http://www.ev-peak.com/CQ3.html). This project will be on the road with me soon and I really need the ability to charge multiple batteries at once, it was the only way to justify the cost.
I have two batteries complete. Both are 2P3S with 18650s taken from relatively new laptop battery packs.
One battery is 12v 4.4A, (2200mAh cells)the second battery is 12v 4A (2000mAh cells).
When I plugged them into the charger I was surprised to see an error message [CELL LOW VOL] from what I can make out from the rather lean instructions -it means one of the cells voltage is too far off from some acceptable variance to continue.
Using a cell logger the two battery packs have the following voltages in their respective cells:
Batt 1:
4.19
4.14
4.17
Batt 2:
3.71
3.66
3.70
This is a bit of a surprise to me, when I measured each cell prior to assembly they were relatively close. Maybe .01 -.02 variance.
I assembled them with 100% nickel strips and used a spot welder (not hand soldered).
I want to use these particular batteries at around 3.9V - one battery i tried to discharge but received the error message, the other battery I wanted to charge and received the same error.
Is there an "industry" standard for acceptable variance in a series of cells?
Anyone have any ideas why the variance increased after assembly?
Anyone have any ideas how I can drain or charge the appropriate cells to get these balanced without disassembling?
Sorry for so many questions in one thread and thanks in advance!
I have two batteries complete. Both are 2P3S with 18650s taken from relatively new laptop battery packs.
One battery is 12v 4.4A, (2200mAh cells)the second battery is 12v 4A (2000mAh cells).
When I plugged them into the charger I was surprised to see an error message [CELL LOW VOL] from what I can make out from the rather lean instructions -it means one of the cells voltage is too far off from some acceptable variance to continue.
Using a cell logger the two battery packs have the following voltages in their respective cells:
Batt 1:
4.19
4.14
4.17
Batt 2:
3.71
3.66
3.70
This is a bit of a surprise to me, when I measured each cell prior to assembly they were relatively close. Maybe .01 -.02 variance.
I assembled them with 100% nickel strips and used a spot welder (not hand soldered).
I want to use these particular batteries at around 3.9V - one battery i tried to discharge but received the error message, the other battery I wanted to charge and received the same error.
Is there an "industry" standard for acceptable variance in a series of cells?
Anyone have any ideas why the variance increased after assembly?
Anyone have any ideas how I can drain or charge the appropriate cells to get these balanced without disassembling?
Sorry for so many questions in one thread and thanks in advance!