17.1 kWh @ 20,000 miles

[campfamily]

My car is about to turn over 20,000 miles this week, so I decided to run a battery run-down test once I returned home from work last night. I am showing 17.1 kWh capacity. How does that compare with what other people are seeing at this point?

No problems with the car, just two recalls (software update and modem replacement) and three tire rotations. Averaging right around 247 Wh/mi in mostly highway driving.

Keith

[triangles]

I'm at 2 years and just under 10K miles and I get about 18kWh - 18.5kWh. With winter I'm in the upper 300's of Wh/mi. What average freeway speeds are you getting just under 247Wh/mi??? I know you said "mostly" so you have some slow driving bringing the number down. With average freeway speeds near 70MPH around here it would be hard to match your numbers doing mostly freeway.

[jmueller065]

Yeah I used to get closer to 275 Wh/mile with freeway driving (and 300+ in winter).

[fbitz777]

I was still getting 20kwh a few months ago at 12,000 miles
Now I am only getting 19Kwh or less at 16000miles. NOTE: if I only get 17Kwh or so at 20,000 then I will be upset.

I know it's colder but I think the fact that I kept depleting it all the time adversely affected the capacity!

Unfortunately I am always running close the limit of the range in my trips...I kind of stopped using the car in the cold as I would run short by a few miles

time to move to the '17 FFE

[michael]

My car is about to turn over 20,000 miles this week, so I decided to run a battery run-down test once I returned home from work last night. I am showing 17.1 kWh capacity. How does that compare with what other people are seeing at this point?

No problems with the car, just two recalls (software update and modem replacement) and three tire rotations. Averaging right around 247 Wh/mi in mostly highway driving.

Keith

That's right in line with my experience.

[cpwl]

Ok, Yes I should know this after 18 months plus with Montgomery but what screen displays the battery capacity and what is the “buttonology” to get there? I’ve looked through the readily accessible screens several times and have yet to find this information. Obviously I’m missing something quite “simple” and I suppose I really should know my current battery capacity and monitor it even though it "seems" to be giving me the original range and charging performance.

Thanks and Cheers
Carl

[campfamily]

Ok, Yes I should know this after 18 months plus with Montgomery but what screen displays the battery capacity and what is the “buttonology” to get there? I’ve looked through the readily accessible screens several times and have yet to find this information. Obviously I’m missing something quite “simple” and I suppose I really should know my current battery capacity and monitor it even though it "seems" to be giving me the original range and charging performance.

Thanks and Cheers
Carl

Carl - here's what I did. I reset one of my trip odometers (I do this every Monday anyway, after recording the data from the previous week). Then, I drove to work and back. I still had about 15 miles range remaining. So, I parked the car in the garage, rolled the windows down, and turned the heater up to full blast. I left the car "running" in the garage while I had dinner in the house. When I was done, the car showed 1 mile remaining. At 0 miles remaining, I noticed the heater stopped blowing hot, and the energy useage screen showed that the Climate control was no longer using power. The car showed that it had consumed 17.1 kWh. So, I figured this was the max capacity that the battery had (maybe an extra tenth or two remaining, but not worth it to me to go any further).

For average consumption, I track my electrical consumption on a weekly basis using the trip odometers.

Keith

[michael]

You might (or might not, I'm not sure) get a slightly different answer if you used the heater to do the entire rundown (from fully charged). The reason it might be different is that this approach uses a constant load, about 6 kW. Driving adds the variable of changing power loads and regeneration.

For laughs, you might try it once with a pure heater drawdown, compare the result.

[WattsUp]

Driving adds the variable of changing power loads and regeneration.

True, but the energy measured by the trip meter will indeed "run backwards" due to regeneration (or charging), so the net result should still reflect total energy used. In theory, the "extra variables" should not matter.

I do agree, though, simply running the entire battery down via the heater is a more "constant" approach. But, I don't think anybody has any idea whether it produces a more accurate answer than just driving around to deplete the battery.

Probably any two "run-down" tests are more affected by ambient temperature than anything else. Possibly driving around will also affect internal and (clearly) external temperatures.

The best bet is to do a few run-down tests under similar circumstances and average them.

[michael]

Agreed... I said that it wasn't clear there would be a significant difference.

However, the run forward-run backward is not symmetrical. Each round trip energy is lost to heat, it's not zero sum. For example, if you regen 1 kWh, the battery will not gain that full 1 kWh but rather something less. Unless, of course, the trip meter has a fudge factor to adjust for this. Does it? Who knows?

Enough to notice? I don't know...that's why I said "maybe" and why I suggested a test. And, as you pointed out, temperature is important. Ideally this should be done with battery at or near 98 F