High Mileage Battery Health

[1pk]

Hi All,

My I-MIEV has 117k km on the odometer and I have been paying closer attention the the battery voltages lately because I'm wondering when my range is going to start dropping. I became more vigilant recently after I replaced the tires with new Enasaves and noticed a significant change in my RR. I never would have thought that the tread depth of a tire would make a noticeable difference in range, but now I know it to be true.

Anyway, I'm wondering if anyone can comment on my delta V in this pic. The battery is at 9%. Cells 18 and 19 are worrying me.

thanks

Pete

 

[1pk]

So I'm trying to use dropbox to host the file and It doesn't want to work. I'll just post the link here for anyone who wants to have a look

https://www.dropbox.com/s/lx3hjpa10hdumcb/Volt%409.jpg?dl=0

 

[siai47]

How do the cell voltages look after a full charge and balancing? They should all be very close in voltage somewhere around 4.105 with very little difference. If you can run the CANION while driving, are the low voltage static cells also the ones that drop the most under load? If so (and balancing doesn't correct this) you might have some failing cells. Have you ever driven it lately to the turtle and looked at the cell voltages along with what kind of range you are actually getting?

 

[kiev]

i agree you need to look at it when it's fully charged, you have several clusters of low cells across the pack giving a ragged appearance. The 0.125V difference between high and lowest cell should get much lower at full charge. When you have a bad cell this difference will cause a reduction in range and the car will no longer charge back up to the full 16 bars level on the "fuel" gauge.

The filename of your image has the "@" symbol in the name--that may be causing it to not load properly. change the name and remove that symbol, maybe it will work.

 

[JoeS]

9%SoC (1-2 bars) is very low (I never go there), but it does highlight possible individual cell inadequacies. tpk, I second siai47's comment about first fully fully charging the car - letting it charge all the way to the end and turn itself off, and only then seeing what the cell voltage readings are. Might want to do that a few times if you haven't fully charged the pack lately to let the (slow) balancing process do its thing. I would expect to see all the bars to be within 10mv (preferably 0-5mv) of each other when fully charged.

If you have installed the latest version of CaniOn, what is your pack's capacity (Ah)?