23 Jan 2015
I scored two free "dead" battery packs from Daryl at Wellington Electric Bikes this week.
They are 36V 12 Amphour packs with MNKE IMR-26650 4.2V Lithium Manganese Dioxide (Li-Mn02) batteries.
One pack had two cell groups dead and the other had three dead cell groups.
The individual batteries are arranged in groups of 4 cells (wired in parallel) and there are ten groups wired in series for a maximum voltage of 42 volts when fully charged.
Battery: MNKE IMR-26650
Type: Li-Mn (High Drain)
Chemistry: Lithium manganese Dioxide (Li-Mn02)
Rated Capacity: 3500mAh
Nominal Voltage: 3.7V
Peak Voltage: 4.2V
Maximum Continuous Discharging Current: 20 A
Maximum Pulse Discharging Current: 60 A
Maximum Continuous Charging Current: 6.5 A
So - I've hack-sawed out the bad groups from one pack and replaced them with good groups from the other battery.
I'm currently charging it and we'll see how it goes. I suspect it would benefit from balance charging and discharging a few times too.
If it works out OK I'll test it on the go-kart.
I may be able to use the left overs to build a new battery pack for my cheap 14V power drill.
It looks like the BMS controller was bad - after getting it going great in the go-cart... I came back one day to find all the cells at 0 volts. Bummer.
Note to self: don't re-use that BMS controller.
Next battery pack using old laptop batteries.