terms:

stick = 6 welded cells
pair or subpack = 2 sticks welded at one end.
cell = D cell (6 per stick, 12 per pair, 132 per battery pack)

Please provide:

1) Charge current and mAh input into "fast discharge" stick.
2) mAh discharged from full to 6V
3) Confirm the rapid drop is happening on which of the discharge phases:

max to 6V
1A to 0.1V
.5A to 0.1V
.2A to 0.1V

Steve

 

Its a 6 cell stick. I charged it at .55 to 8800 mah. Discharged at max to 6v it was 4184 mah lowest of the four sticks. Charged to 8800 then on discharge it is dropping at 0.01 per second all others are still dropping all day and just now below 4v

 

You have a very weak stick. It's the deep discharge that can reclaim some of the lost capacity. It's likely that 1-2 of the cells in that stick are performing poorly or suffering from voltage depression/high internal resistance.

Continue the recommended discharging phases to 0.1V. That stick is probably junk, so you can't make it worse.

What are the discharge to 6V numbers of the other 3 sticks?

Steve

 

The other 3 are 1. 1.89 v 2.4.32. V 3. 4.52v the cell that was running down fast went down fast to 2.5v now its slowed a lot but still going down faster than the others. Yeah absolutely nothing to lose we will see what happens. Thanks

 

Once it goes below 6V, it's random. When a cell drops off, it's abrupt. You were seeing 1-2 weak cells drop off and go into reversal quickly. Now that it's paused, it's bleeding off 2-3 of the strongest cells. Don't worry about it. Just stay the course.

Did you label the sticks to return them to their original locations? Are you logging the data? I recommend a google sheet.

I'm working a HCH1 pack at the moment. I just conducted this on a marginal stick. The capacity went from 4546 to 5657. These are 90, 15 and 10A loads. 100 seconds at 90A and constant 15A & 10A loads to 6V. That's a 24% improvement in capacity in one cycle. Improvement at 90A load was most significant.

Steve

 

A 24% improvement is huge. The stick that's dropped fast has gone to .49 I'm waiting to see if the charger immediately reverses the way I have it set up. Hch1 is the battery in the insight? I have labeled them and am working thru the pack. Keeping the discharge mah for comparison. This is a lot of work. I want to do my own battery when i get this finished.

 

It depends on the quality of your charger. On my IMAX, the 1A and .5A loads will drive the voltage to zero so fast, the load drops to zero and doesn't register the cut-off. At the 0.2A rate, it will catch it and initiate the charging.

HCH1 is Honda Civic Hybrid 2003-2005. The sticks are similar to and interchangeable with the Insight, but the HCH1 sticks are better than the Insight ones were at the time. They had lower internal resistance to accommodate the higher regenerative cycle from the heavier car. I think they replaced the Insight sticks with HCH1 sticks by attrition. Don't quote me on that.

 

It makes sense that Honda would do that. I have a 2011 crz. The salesman told me it had lithium ion battery when I bought it. . . .not so. I want to go thru the pack and exorcise the cells like this before it goes bad. Avoiding future problems.

 

The charger didn't kick over to charge. It could very well be my inexperience with setting it up.

 

It can be a sensitivity thing like I mentioned above. It goes low enough to signal the current should be cut, but after the current cut, the voltage rises above 0.1V so quickly, the charger doesn't signal the switchover. Try discharging to 0.2V @ 0.2A on the last cycle instead of 0.1V

One, I wouldn't touch your CRZ pack until you start to get relatively frequent recalibrations. Two, since you're paying attention to it, I'd get a grid charger and do a topping charge quarterly for maintenance with a deep PACK discharge every other time or as needed.

I've taken entire packs down to 1.8V (Fully charged to 120V with a 500W halogen and 40W tungsten down to 1.8V), and I got a similar ~24% increase in capacity at a 4A load.