Battery Capacity

[rob6894]

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

Thanks,
Rob

 

[jmueller065]

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.

 

[michael]

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.

 

[brogult]

How are you reading the final SOC at 8%?

 

[WattsUp]

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?

 

[brogult]

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]

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.

 

[GladeStorm]

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/viewtopic.php?f=7&t=2178

 

[michael]

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)

 

[brogult]

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.

 

[michael]

286 Volts at termination. Final battery temperature was 87F


Here are some of my logged values (sorry, didn't collect everything, but did my best....)

Dash % Battemp SOC kWh used ETE Volts

100 95 89.8 0 18.4 --

83 -- 76 2.3 15.0 --

43 -- 43 10.3 7.6 326

29 87 31.8 12.9 4.85 318

14 -- -- 15.6 2.25 306

4 -- -- 16.9 0.6 294

1 -- 8.9 17.2 0.1 288


0 -- 8.4 17.3 0 286

(sorry, web site messed up my formatting)


ETE is "energy to empty" as shown on the OBD, while kWh used is the dash display. You might expect that used + ETE would always equal the starting ETE, but you can see this is not the case. So the initial ETE seems to be an estimate only.

This device shows total battery voltage, not individual cells.

And yes I agree, best estimate is about a 5% degradation which is pretty much in line with Tesla reported values at this mileage. So a long range extrapolation is 100K miles at 15% degradation. This is in a moderate Socal environment.

 

[michael]

Here is a plot of Tesla experience with battery degradation

http://chargedevs.com/wp-content/uploads/2015/02/Tesla-Model-S-max-range.png


It seems to show about 95% of original capacity at 50,000 km, not materially different than what I think I saw.

 

[KrazyEd]

I have various OBDII scanners, and, they don't seem to give me much information
on the FFE. I get lots of information on my Civic Hybrid, and, got a pretty good
amount of information on my Volt, but, the FFE doesn't really give me anything.
I talked Progressive into giving me a Snapshot devise. All the lights lit up, it showed
that the vehicle was in use, but, didn't transfer any information to them. They sent
me a second device, same deal. I have tried both the FFE OBDII port, and, the left
over ICE OBDII port, without much success. Is there something that I am missing?

 

[sefs]

Standard OBDII readers are not going to work. Just a side note, both OBDII ports on the car have identical pinouts and work the same. It is suggested in the service manual to use the one behind the door and not the one up under the dash.

 

[GladeStorm]

OBD Scan Port: http://www.myfocuselectric.com/forum/viewtopic.php?f=7&t=2178&p=13488#p13488