rob6894
Posts: 11
Joined: Sun Mar 29, 2015 1:07 am

Battery Capacity

Wed Apr 29, 2015 12:02 am

He guys have you noticed a reduction in battery capacity like the the Nissan leaf has after a year or two?

Thanks,
Rob

jmueller065
Posts: 2397
Joined: Tue Feb 12, 2013 4:36 am
Location: Southeastern MI
Contact: Website

Re: Battery Capacity

Wed Apr 29, 2015 3:44 am

Nope. Even with the few of us now well over 30,000 miles there still hasn't been any noticeable battery loss.

Myself: I recently surpassed 20,000 miles and with the warmer weather the range is picking back up to where I would expect it to be.
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michael
Posts: 1113
Joined: Sun Sep 22, 2013 9:55 am
Location: Los Angeles, CA

Re: Battery Capacity

Wed Apr 29, 2015 1:34 pm

Actually, I just ran a "rundown with heater" test. It showed 17.5 kWh to SSN at which time the heater shut down. The car would still move (I was in driveway) but I didn't try to find out how much was left. SOC was around 8% at that time

My miles 36,000, battery age is 670 days, battery temp was about 90 F during the test.
2013 FFE Returned after 3 years with 52,000 miles and battery down to 15.2 kWh
2014 Volt returned with 43,000 miles
2014 Volt 26,000 miles
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1962 Corvette 327
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brogult
Posts: 108
Joined: Wed Oct 22, 2014 7:49 pm

Re: Battery Capacity

Wed Apr 29, 2015 9:23 pm

How are you reading the final SOC at 8%?

WattsUp
Posts: 2113
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Location: SF Bay Area, CA

Re: Battery Capacity

Wed Apr 29, 2015 10:04 pm

brogult wrote:How are you reading the final SOC at 8%?
Maybe from the energy screen on the MFT display where it shows the % SOC?

This screen was added in the v3.6 update MFT. Do you have that version?
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brogult
Posts: 108
Joined: Wed Oct 22, 2014 7:49 pm

Re: Battery Capacity

Thu Apr 30, 2015 6:43 am

Yes I have that, but in his scenario the readout on that screen would have been 0%. I'm wondering what he uses (scan tool?) and whether there are other things that can be read, like cell voltage and balance.

WattsUp
Posts: 2113
Joined: Mon Jan 07, 2013 2:58 am
Location: SF Bay Area, CA

Re: Battery Capacity

Thu Apr 30, 2015 10:17 am

brogult wrote:Yes I have that, but in his scenario the readout on that screen would have been 0%. I'm wondering what he uses (scan tool?) and whether there are other things that can be read, like cell voltage and balance.
I just assumed he meant the MFT screen, but maybe michael has some kind of scan tool.
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GladeStorm
Posts: 67
Joined: Thu Nov 21, 2013 9:17 am
Location: TN

Re: Battery Capacity

Fri May 01, 2015 7:14 am

brogult wrote: I'm wondering what he uses (scan tool?) and whether there are other things that can be read, like cell voltage and balance.
Other things:
http://www.myfocuselectric.com/forum/vi ... f=7&t=2178
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michael
Posts: 1113
Joined: Sun Sep 22, 2013 9:55 am
Location: Los Angeles, CA

Re: Battery Capacity

Fri May 01, 2015 10:33 am

I have an OBD scanner. It's a "scangauge" from Linear Logic. It shows battery SOC, battery temp, current, voltage etc. Mine was a beta test version, I don't know whether it went into production.

As the dash display runs from 100 to 0 percent, it shows the SOC changing from about 90% to about 8%

When the dash display hit 0%, I got the SSN message and the heater stopped heating (i.e., the car went into conserve mode)
2013 FFE Returned after 3 years with 52,000 miles and battery down to 15.2 kWh
2014 Volt returned with 43,000 miles
2014 Volt 26,000 miles
1967 Corvette 427
1962 Corvette 327
Awaiting a Bolt

brogult
Posts: 108
Joined: Wed Oct 22, 2014 7:49 pm

Re: Battery Capacity

Fri May 01, 2015 11:58 am

If you ever run that test again, I'd be interested in what your scan tool shows for battery voltage(s). I'd do it myself, but you have the highest mileage FFE I know of--we just hit 5K, so it will be awhile. I would be especially interested in how closely the cell voltages are balanced at the fully discharged point as this is where I've seen other systems run into problems. Your total number of available amp-hours is only that of the weakest cell, and with 88 of them there is plenty of opportunity for trouble.

Assuming your test is somewhat accurate, that is actually very good news on battery degradation--one couldn't reasonably expect better. I figure your test shows roughly 5% capacity loss after 400 equivalent full cycles. On battery packs for computers, equipment, etc, you would expect to see 20-30% capacity loss at that point in real life usage on 2 year old equipment. It will be an interesting to see if the degradation keeps going at a steady pace or tapers off to some stable result.

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