Opinions wanted - Odd battery results

[Hybrid-Battery-Repair]

I've got a weird one, and I wanted to solicit opinions about the cause before talking to the customer.

I'm reconditioning a pack from a 2004 HCH. I clipped on a fan and I'm cycling the sticks at 10amps. This is the most screwed up pack I've ever seen. I'm getting 4th cycle charge numbers ranging from 5600 down to 2100 and everywhere in between. The average capacity appears to be about 3400 Mah. I've finished the bottom 2 rows, and I don't see any pattern with respect to heat, even with the 45 degree angle positioning of the battery in a HCH. Additionally, I'm seeing more than a 5% improvement between each cycle, which is my criteria to keep running cycles (but even after 12 cycles, I've got one stick that's only up to 2700 Mah).

His error was a P1449 and he lives in Alabama. Does anyone have any theories about why his pack would be so messed up? I'm going to wind up sending it back to him with a capacity of only about 4500Mah (usable, but weakened),

Bad battery fan in the car? Heat & humidity?

[retepsnikrep]

Ron

Have you double checked with a different charger? Results consistent?

You should get closer and closer results from each cycle as the number of cycles builds up unless the cells are so bad they are overheating even in this mild use.

Have you pulled all the cells out? This might be an occasion where you need to to check localised heating.

Peter

[Hybrid-Battery-Repair]

Originally Posted by retepsnikrep

Ron

Have you double checked with a different charger? Results consistent?

You should get closer and closer results from each cycle as the number of cycles builds up unless the cells are so bad they are overheating even in this mild use.

Have you pulled all the cells out? This might be an occasion where you need to to check localised heating.

Peter

I tried three chargers and I get similar results. The pack is showing a PTC gain of 10 ohms charging two sticks as opposed to the normal 2, but that seems to be within normal parameters.

The problem is that they are SO different. I'll try to post some #s later.

[JimIsbell]

Maybe you could try bringing up the low ones individually till they were closer to the high ones???

[3-Wheeler]

You mentioned that he lives in Alabama. Does he ever drive in the mountains in that area?

I remember Insightful Trekker mentioning that his battery pack was taking a large hit due to his location in that area. Eventually his pack failed before the 150k mile warranty ran out for him, and Honda replaced it.

I was always curious if the combination of heat and high current use from hard assist and regen in the mountains might have been a large contributor to his pack demise.

Jim.

[uhtrinity]

Originally Posted by ogregev

I've got a weird one, and I wanted to solicit opinions about the cause before talking to the customer.

I'm reconditioning a pack from a 2004 HCH. I clipped on a fan and I'm cycling the sticks at 10amps. This is the most screwed up pack I've ever seen. I'm getting 4th cycle charge numbers ranging from 5600 down to 2100 and everywhere in between. The average capacity appears to be about 3400 Mah. I've finished the bottom 2 rows, and I don't see any pattern with respect to heat, even with the 45 degree angle positioning of the battery in a HCH. Additionally, I'm seeing more than a 5% improvement between each cycle, which is my criteria to keep running cycles (but even after 12 cycles, I've got one stick that's only up to 2700 Mah).

His error was a P1449 and he lives in Alabama. Does anyone have any theories about why his pack would be so messed up? I'm going to wind up sending it back to him with a capacity of only about 4500Mah (usable, but weakened),

Bad battery fan in the car? Heat & humidity?

I'm thinking that pack has just gotten too hot too many times. Was the car ever garaged or was it always in the sun? I wouldn't think a Civic would cycle the pack to heavily, so maybe it could be the environment. I know the Insight won;t throw a fault until the pack as a whole hits 140 - 150 degrees, maybe the Civic is the same.

[Hybrid-Battery-Repair]

Originally Posted by JimIsbell

Maybe you could try bringing up the low ones individually till they were closer to the high ones???

I'm trying, but they range from 5600 to 1200. They're not going up that fast.

[Hybrid-Battery-Repair]

Originally Posted by uhtrinity

I'm thinking that pack has just gotten too hot too many times. Was the car ever garaged or was it always in the sun? I wouldn't think a Civic would cycle the pack to heavily, so maybe it could be the environment. I know the Insight won;t throw a fault until the pack as a whole hits 140 - 150 degrees, maybe the Civic is the same.

That may be the case. I didn't think of ambient heat. It's definitely not heat damage from a stick going critical, because there would be a pattern of lower corner to upper corner due to the 45 degree location in the back seat. The pack was throwing a P1449.

Would ambient heat randomly affect the cells? Here are the final 4th (or 8th or 12th) cycle discharge capacities:

Bottom row 1st cell in string (let's call it "front") to "back"
4460, 3851, 2111, 4706, 3354, 5629, 4620 (lower corner)

Middle row from "back" to "front"
5885 (above lower corner), 2880, 4711, 2788, 2599, 2924, 1866 (below upper corner)

Top row "front" to "back" (end of string)
5580 (upper corner), 1620, 4851, in progress, N/A, N/A

Normally, I don't allow more than a 5% variation between sticks. Here I have 300%.

I think I'm going to have to scrap all but 2 (go with 5500 - excellent) or maybe 6 (go with 4400 - low normal) sticks. Note that these numbers are from a 10amp charge and therefore read a little low due to wire losses (heat loss in the cables). It really only matters in how they compare to each other, not the overall numbers. I typically see a max of 6200 at these charging rates.

Some of the cells show notable improvement from the 3rd to the 4th cycle, so I will give them some more cycles to see how they end up. Others, most notably the 1st stick show a DECREASE. The 1st stick numbers were:

D1 2487 C1 4862 (started with half a charge - 2487)
D2 4789 C2 5789
D3 4975 C3 5941
D4 4460 C4 5777 (you'd expect the 5777 to be lower than the 5941 because the battery isn't as empty with the 4460 as it was with the 4975)

Note that D4 was down from D3. There was a 20 minute rest between cycles, so heat should have no bearing. I'm taking them down to 0.9V and using a 5Mv delta-V.

Another example of this is #14

D1 0404 C1 2804
D2 1862 C2 2906
D3 2023 C3 3228
D4 1866 C4 3068



I'm going to put a more advanced charger on the pack tomorrow and see if it can improve some of those numbers.

Maybe his fan (in the trunk) is blocked or failed?

[Hybrid-Battery-Repair]

Originally Posted by 3-Wheeler

You mentioned that he lives in Alabama. Does he ever drive in the mountains in that area?

I remember Insightful Trekker mentioning that his battery pack was taking a large hit due to his location in that area. Eventually his pack failed before the 150k mile warranty ran out for him, and Honda replaced it.

I was always curious if the combination of heat and high current use from hard assist and regen in the mountains might have been a large contributor to his pack demise.

Jim.

Not from looking at Google Maps (terrain). He's just outside of Birmingham by his zip code (35173).

[JimIsbell]

Will the battery be affected negatively by heat when its NOT CONDUCTING CURRENT....IOW, sitting in a hot parking lot all day?