I can pretty much guarantee you there is degradation in 4 years.
A friend of mine just parted out his conversion and I bought his CALB
100Ah cells.
They are 3 years old with only 8000 miles on them.
He did not use a BMS, but they were top balanced when new.
Charge cutoff voltage was kept conservatively low.
I charged each cell individually and then discharged at a constant 30A
to 3.00V.
The amp hours and watt hours were totaled and recorded.
Ah varied from 88 to 96 and Wh varied from 310 to 280.
Internal resistance varied widely as well and there were 3 duds that
were way out of spec.
As Mike said, an RC charger can charge/discharge cells and track Ah.
Discharge rates are usually max of 100W or about 30A for a 3.2V cell
which is fine for a 100Ah cell.
Check Thundersky.com
Al
On 11/4/2015 7:39 PM, Mike Beem via EV wrote:
I have been trying to re-balance my 4 year old 100Ah CALB pack with
mini-BMS, identifying the highest SOC cells by watching for the red LED's
to light up on the mini-BMS boards on the individual cells. I have been
using a 12 volt, 50 watt "A" lamp, leaving it on the cells one at time for
60-90 minutes each, then bringing the full pack up again until I start
seeing red LED's.
I don't have any other suitable DC lamps or other safe (to me) items which
I can guarantee won't damage a cell by my inattention (I set an alarm for
myself every time I connect this load to a cell).
What suggestions do people have for me? How would a 120 volt 500 watt
halogen affect one of these individual nominal 3 volt cell (resting is
actually ~ 3.3v)?
It was my intention 4 years ago when I re-converted the EV Escort to
lithium to see if I could drive an EV for 10 years on a $10,000 layout, not
counting brakes and other expendables. So far, I have seen no loss of
range, and have no indications of degradation.
I set myself up for the current balancing problem by charging individual
cells while the PFC30 was back in Washington for a minor repair, so now I
have high SOC cells turning off the charger before the pack is fully
charged.
Thank you!
Michael B
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