Analyzing, refurbishing/repairing a dead hybrid battery pack (2000 Honda Insight)

[MetroMPG]

Looks like I've found one stick that's a bit of a dud:

5402 mAh - stick #5's max. discharge capacity

Compare with:

6566 mAh - average max. discharge capacity of the sticks prior to that one

The testing continues!

MetroMPG's battery pack analysis - 2000 Honda Insight (Google Docs spreadsheet)

[Formula413]

Perhaps that stick has one bad cell and five good ones? The capacity is almost exactly 5/6 of the average. Of course that's irrelevant unless you have a way to disassemble sticks and re-weld them together.

[IamIan]

Originally Posted by MetroMPG

Looks like I've found one stick that's a bit of a dud:

5402 mAh - stick #5's max. discharge capacity

Compare with:

6566 mAh - average max. discharge capacity of the sticks prior to that one

The testing continues!

If that is the largest difference you find in discharge capacity ... that is a ~17% effective capacity loss compared to the ~40% you had from the differences in SoC... even without replacing it ... just a balanced SoC will give you effectively about double the initial usable discharge capacity for the whole pack.

It is also interesting that the subpack with this lowest so far discharge capacity ... initially had the 3rd highest SoC with 1,159 mAh ... while the so far highest discharge capacity subpack with 6,714mAh , was initially one of the lowest SoC with only 17mAh.

good stuff

[IamIan]

Originally Posted by Formula413

Perhaps that stick has one bad cell and five good ones? The capacity is almost exactly 5/6 of the average. Of course that's irrelevant unless you have a way to disassemble sticks and re-weld them together.

I doubt it would be worth the trouble ... but ...

After you tested each of the 6 cells in a subpack stick to quantify them ... if it turned out that it was just one cell ... you would need to carefully take the welded 6 cell subpack apart... something like the way Mike D did it ... shown Here.

Then in order to weld the pack back together you need a good capacitive discharge spot welder ... you could buy one for more than a new battery pack costs ... or you could build cheaper if you that the know how ... one like Mike D did ... Here.

To be safe you retest... but that is a lot of work / effort... I wouldn't recommend it ... doing the 20 subpacks is enough work already.

[johnsn]

Good thread.
I have a 2001 Insight that the battery pack has low capacity.
I need to do what you are doing. The only thing that is stopping me is I don't know what to do to be able to drive my Insight without the battery pack.
How did you do it?
Thanks.
john

[RobertSmalls]

Originally Posted by Formula413

Perhaps that stick has one bad cell and five good ones? The capacity is almost exactly 5/6 of the average. Of course that's irrelevant unless you have a way to disassemble sticks and re-weld them together.

That is likely. The performance of a stick will be determined by the weakest cell in the stick, just as the performance of the whole pack can be limited by a single underperforming cell. However, the fact that the weakest cell appears to have 5/6ths the capacity of the rest is coincidence.

[RobertSmalls]

Originally Posted by MetroMPG

But the hybrid stuff is way cool

I'm glad to see I'm not the only one who thinks so.

It looks like you're going about it the right way. One thing that I've learned since my first battery refurb, though: when you put it all back together, evenly torque down the bolts that hold the battery sticks to the end plates. I pulled my pack a while after refurbishing it to investigate performance issues, and I found that one of those bolts had worked its way loose.

[RobertSmalls]

Originally Posted by Old Mechanic

Is anyone aware of a source for sticks in case you find one that won't wake up? It seems from yours and other efforts that they seem to wake up nicely.

*raises a hand*

I haven't been spending much time on the forums, but I do have some sticks for sale. So does Hybrid-Battery-Repair.com. You could try a WTB thread here or on InsightCentral, because I'm sure I'm not the only one parting out a pack.

[Artric]

Originally Posted by johnsn

Good thread.
I have a 2001 Insight that the battery pack has low capacity.
I need to do what you are doing. The only thing that is stopping me is I don't know what to do to be able to drive my Insight without the battery pack.
How did you do it?
Thanks.
john

Disconnect the junction board from the battery and replace it in the battery box, connecting everything as if the battery were there. Works fine, but keep the 12v battery charging so you don't ruin it!

On a side note, I've built a lot of simple 350mah chargers for a lot of Insight owners, and all have been happy with the results so far, in regards to bringing packs back to life. Just mentioning for those that might not see a pack disassembly in your future.

[MetroMPG]

Originally Posted by RobertSmalls

evenly torque down the bolts that hold the battery sticks to the end plates. I pulled my pack a while after refurbishing it to investigate performance issues, and I found that one of those bolts had worked its way loose.

Good point.

I learned the importance of that already with the ForkenSwift (electric Metro). A loose battery terminal can wreak havoc for sure in a high current pack! (Stuff will melt - though I didn't get to that point.)