Speeding up the process: watching initial subpack charging for "false peaks"
(The following was explained to me by a remote control airplane flyer who has quite a bit of experience with NiMH batteries.)
So now we know that the charger is watching for voltage to peak and then drop slightly to determine when the sticks are full.
But NiMH cells which have not been regularly used (like a hybrid pack that has been sitting unused for some time following the setting of error codes) may also give "false peaks". That means voltage irregularities trigger the charger to stop when there is actually more capacity available to continue charging the battery.
Quote:
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Packs that sit for extended periods of time may false peak when they are first used again. This is normal and will happen with all NiMH cells. You can re-peak the pack and use it. The pack will be back to normal after 2-3 charge cycles.
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Source:
Chargers
So we can potentially speed up our pack analysis knowing it's likely that subpacks which have been sitting for weeks/months may trigger the charger to shut off too soon during the initial charge cycles.
It's easy to test for "false peaking": wait 30 seconds after the charger stops. Then re-initiate charging. If the charger stops again in short order, it was a "real" peak. If it keeps charging, then you've just passed a "false peak" and may be able to add a significant amount of charge.
So far, I've detected false peaks in 3 of 5 sticks. In those 3 cases, I was able to add ~28-42% in mAh to the sticks:
Initial charge capacity:
- Stick #2, 4247 mAh: 3001 + 1246 (42% added after "false peak")
- Stick #4, 5159 mAh: 4129 + 1030 (25% added)
- Stick #11, 4505 mAh: 3523 + 982 (28% added)
Watching for false peaks
could potentially speed up analysis (that's the theory, anyway - comments??),
if it reduces the total number of cycles needed for each stick's capacity to stabilize.
Even reducing the analysis by 10 cycles would save ~20 hours.
Or I could have just bought another charger and run two, then sold one afterward.
