ditchner
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Was on the Final Bar but consumption was only 15.8 kwh

Mon Jun 06, 2011 11:47 am

Last Saturday I drove the 17.5 miles to the golf course in my fully charged leaf and I drove it like I drive my Audi TT (faster than I should). Upon arriving it was raining harder than I expected and the place was deserted. I decided to drive home which involves a significant hilly section where elevation goes from sea level to about 500 feet. But then it appeared the rain would break so I turned around and went back to the course. At this point I started being more speed conscious and kept my highway speed at about 60 and used eco mode for slowing and stopping. On my ride home from the course the dash indicated I had about 35 miles left for my 17.5 mile drive and by the time I reached home I was on the final bar with 8 miles of range left according to the dash.

I'm still using the 110 trickle cable until I can sort out the politics of PG&E, electrical contractors, and the EV Project. I plugged it in and it took about 21 hours to charge which seemed about right since the battery was nearly depleted. Today I was able to see the Carwings report for Saturday and here's what it said:

Distance Traveled: 59.2 miles
Electricity Consumption: 15.8 kwh
Average Energy Economy: 3.7 miles/kwh

This makes no sense to me. If my battery was nearly depleted why was my consumption only 15.8 kwh? Anybody?

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davewill
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Re: Was on the Final Bar but consumption was only 15.8 kwh

Mon Jun 06, 2011 11:53 am

ditchner wrote:Today I was able to see the Carwings report for Saturday and here's what it said:

Distance Traveled: 59.2 miles
Electricity Consumption: 15.8 kwh
Average Energy Economy: 3.7 miles/kwh

This makes no sense to me. If my battery was nearly depleted why was my consumption only 15.8 kwh? Anybody?
Carwings sucks. Seriously. It's been talked about a lot. Between fictional numbers and taking two days to show trip info, NOBODY is going to pay for this when the free subscription is up.
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garygid
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Re: Was on the Final Bar but consumption was only 15.8 kwh

Mon Jun 06, 2011 11:59 am

Yes, simple: Carwings lies!
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planet4ever
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Re: Was on the Final Bar but consumption was only 15.8 kwh

Mon Jun 06, 2011 10:38 pm

Yeah, what they said about CARWINGS. And, two more things:
  1. The only way to see what you really used is to measure it at the wall. Since you are (at least currently) using 120v charging you could measure that using a Kill-A-Watt meter. You can pick one up a number of places, including Home Depot, for under $30. They are very useful to see what other electricity hogs you have around the house.
  2. It sounds like you got your car recently, so it probably has the April firmware update. That redefined what the bars mean, and now you have maybe 15 miles of reserve after the last bar is gone.
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Re: Was on the Final Bar but consumption was only 15.8 kwh

Mon Jun 06, 2011 10:50 pm

Some libraries will let you borrow a Kill-a-Watt for a month for free. :mrgreen:
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gudy
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Re: Was on the Final Bar but consumption was only 15.8 kwh

Mon Jun 06, 2011 11:25 pm

You can't measure electricity used by looking at how much you put back in the pack. If you drive aggressively, you're also discharging the battery at higher currents, which reduces its effective capacity. So you could very well empty your battery by getting only 16kWh out of it, and you'll still need to charge it for 24kWh. You lost the rest in heat...
Going at 80mph uphill, you'll easily be pulling 40kW, and you'll be at 80kW for a while to get to that speed... That's almost 2C and 4C discharge rates, fairly high for the battery.
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davewill
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Re: Was on the Final Bar but consumption was only 15.8 kwh

Tue Jun 07, 2011 7:53 am

gudy wrote:You can't measure electricity used by looking at how much you put back in the pack. If you drive aggressively, you're also discharging the battery at higher currents, which reduces its effective capacity. So you could very well empty your battery by getting only 16kWh out of it, and you'll still need to charge it for 24kWh. You lost the rest in heat...
Does it matter whether you're losing it it in heat? I think you want to know how much you're having to put into the car to go x miles, not some abstracted amount that was actually consumed by the motor.
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DaveinOlyWA
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Re: Was on the Final Bar but consumption was only 15.8 kwh

Tue Jun 07, 2011 8:04 am

Essentially it does not matter but neither does your budget in that regard. U still have to pay for it.

Unless u r tracking charge from the wall u cannot state what it took to recharge as the OP has done.

A kill a watt costs $20 or to put it anomaly her way... the same a a weeks savings from not buying gas
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gudy
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Re: Was on the Final Bar but consumption was only 15.8 kwh

Tue Jun 07, 2011 9:11 am

My point was mostly that you can perfectly use less kWh that you need to recharge. Driving in eco with lower speeds and slow acceleration will likely result in the "used" kWh to match closer the amount you put back in the pack.
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wsbca
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Re: Was on the Final Bar but consumption was only 15.8 kwh

Tue Jun 07, 2011 9:17 am

For reference, the L1 charger pulls about 1270 watts (until it slows down to taper off the end of a 100% charge - an 80% charge goes full bore until the end). If your charger was really active for 21 hours, it would have sucked down ~26.7 kWh, less any taper as it approached full. I suspect L1 tapers less aggressively than L2/L3 - there's some data on that buried in the forum somewhere...it's also less efficient (than L2). You probably pulled on the order of 24-25kWh from the wall. As noted, you can measure this with a Kill-a-watt device. Given the terrain and driving style for the first part of your drive, you probably got around 2.5 miles per kWh wall to wheels. A comparison point would be the typical 3.2 miles per kWh reported by people driving relatively conservatively (but not hypermiling per se.)
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