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Discussion Starter #1
I'm on about my 10th IMA battery charging/discharging/charging and the two that I just completed had voltage readings of 179v and 180v. I'm using hybridautomotive grid chargers which I love. The strange thing about the IMA battery that grid charged to 180v was that the mA reading was at appx 250mA near the end of the charge. It's always at appx 350 mA with Jeff's chargers. In any event, I've never seen such high readings on my other IMA batteries I've grid charged. Is there any correlation between the ending voltage and the quality of the battery? Suspecting these may be weak which I don't want in any car I sell. Anyone grid charge their IMA and get a reading of 179-180v and the battery was a strong battery? Or do I have this reversed and these batteries will end up being very strong? Or is there no correlation?
Thanks
Gerald
 

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Yes, lower resting voltage = healthier battery.
 

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Discussion Starter #3 (Edited)
So the new IMA batteries are grid charging closer to 170v than 180v?
Is it that simple that the lower the voltage of a fully charged battery the healthier it is? Did life just go from complex to simple on me? I'm a skeptic.
Gerald
 

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What was the temp where these were charged ? You'll see higher final voltages in colder weather... but in general, higher voltage is an indicator of a weaker pack. Most like to see 174v or thereabouts...

When I charged my pack in situ I was up to 178.2v in around freezing weather (nighttime low). In the basement when @ 60 something degrees it only charged up to 174v... but I had replaced 2 bad sticks at that point too...
 

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HA grid chargers are set for 180V open circuit, so if you hit 180, or very nearly, current flow will slow below 350mA.

The general rule is that a higher voltage is the result of higher internal resistance, which is bad, but this is not absolute.

Per GM's statement, you'll also get higher voltages with lower temps.

If you have two batteries charged in identical conditions, and one peaks several volts higher than the other, it MAY be less healthy.

Additionally, my experience with several packs has show that batteries subjected to reconditioning via cycling or especially deep discharge will have higher peak voltages than before.

Steve
 

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I think I posted a similar question a while back as to how to interpret the 12 post cycle data readings. Was no clear answer but it seemed more important to concentrate on the discharge times, milli-Amp-Hours charged, Watt-Hours charged, Charge and Topping Times. The more the better. What is considered good, weak or poor wasn't addressed. Maybe a message to Mike D would clear it up better.
 

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I've only did deep discharge and balancing on my battery twice, but mine has also ended up at 180v and 250mAH, it was about ~35*F out.

I have never driven any other hybrid or another Insight so I really don't have much to compare with as far as my battery condition goes, but I'm fairly confident that it's getting up there in it's life span. I've gotten a p1449 after the car sat for 2 weeks. As far as I know this is still the original pack.
 

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I think I posted a similar question a while back as to how to interpret the 12 post cycle data readings. Was no clear answer but it seemed more important to concentrate on the discharge times, milli-Amp-Hours charged, Watt-Hours charged, Charge and Topping Times. The more the better. What is considered good, weak or poor wasn't addressed. Maybe a message to Mike D would clear it up better.
12 post cycle data readings? What is that?

There's been lots of discussion about acceptance criteria. Only Eli has a scientifically/rigorously derived set of criteria (61 or so?), and he's understandably mum about it.

Peter has published:
1) 5.4V @ 100A for 10 seconds
2) >4000mAh capacity
3) <1000mAh self-discharge over 7 days.

Mike D's site references good self-discharge at 5-10% over 7 days. He is pretty flexible, but seems to draw a line a 4000mAh for capacity. No discussion of high-current testing.
 

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12 post cycle data readings? What is that?
I'm referring to the Genesis 1 charger readings

Discharge time DCT
Start discharge voltage SDV
Discharge stop reason DisR
End discharge voltage EDV
% Amp-Hours capacity charged PAH
Start Charge Voltage SCV
Charge Stop Reason ChSR
End Charge Voltage ECV
milli-Amp-Hours charged mAH
Watt-Hours charged WtH
Charge Time ChT
Topping Time TpT
 

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Discussion Starter #10
What was the temp where these were charged ?
My garage was about 60 degrees inside. I'm probably going to stick one of these in my daily ride and see how this performs.
Gerald
 

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I'm referring to the Genesis 1 charger readings

Discharge time DCT
Start discharge voltage SDV
Discharge stop reason DisR
End discharge voltage EDV
% Amp-Hours capacity charged PAH
Start Charge Voltage SCV
Charge Stop Reason ChSR
End Charge Voltage ECV
milli-Amp-Hours charged mAH
Watt-Hours charged WtH
Charge Time ChT
Topping Time TpT
Thanks... I had sticks on the brain... No idea about the Genesis 1...
 

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It took me a little while before I learned to correlate grid charging results with the ambient temperature. However, my overall experience with these batteries is that when they had high ending voltages they were not as good.

My 0.02 worth,
Tim
 

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I think cold ambient temp and degraded cells are the main things influencing grid charge end voltages in the many reports we see here. But I don't think internal resistance is the cause of higher readings; at low grid charge currents internal resistance per se shouldn't make much difference. There's something else going on...

With some of the cell-level work I've done, I've noticed something like a 0.05V higher voltage for cells that, on subsequent tests, turn out to be 'degraded'... Not sure how prevalent/consistent this +0.05V thing is, as it's not like I've done a buttload of tests on a buttload of cells - yet I've seen it for at least a 'handful' of cells... 0.05V X 120 cells=6V; a 'normal' termination voltage of around 174V + this 6V puts us at 180V... Might be something to this...

In general, I think it has to do with capacity, the way the cells are degraded, something to do with the reactions happening at end of charge that cause voltage to rise more than it should - like reduced capacity on the negative electrode, or maybe running out of electrolyte, et al... But I don't think it's high internal resistance in itself...

btw, Here's a table I made not too long ago with calculations showing the voltage differences you might expect given different ambient temps, based on some data in a Panasonic chart. The summary is in the far right column: expect about +0.360 volts per degree Celsius ambient temperature decrease within the range of 19 degrees C to 0 degrees C; and expect about +0.312 volts per degree Celsius decrease in the range of 39 degrees C to 20 degrees C. For example, if you charge a pack that normally peaks at 174V at say ambient temp=19C, yet you charge it in 9 degree C ambient temps, then you should expect the voltage to peak at 174V + (10 X 0.360V)=177.6V... Pretty sure the table calculations are right...
 

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Your garage temp is warm enough. For comparison purposes, plug in an obdiic&c and check voltage compared to what the grid charger read out. (as soon as possible after stopping the grid charge). If you see a similar reading, then it's likely that pack is not as 'healthy' as others' you've charged up.

I saw higher end voltages on the ailing pack I used to have in my cvt. (178 and +).
 
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