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EVDRVR 06-27-2009 05:03 PM

Highway trip with Solectria Force
I took the Force out on the freeway today. This was a little longer trip than usual. Would appreciate it if some one did the mpg conversion for me as I get numbers that don't seem to be the usual.

I fear I'm making some silly math error this morning. Getting a mile per AH or better is pretty common in the Force around town but today I managed it on the freeway.

The Force is 156 Volts nominal
Trip out used 20.09 AHs to cover 22.1 miles
return was 23.30 AHs and 22.4 miles

total 43.39 AHs to cover 44.5 miles

FWIW average speed about 50 mph.


bennelson 06-27-2009 05:25 PM

How are you tracking the AH? Do you have instrumentation in the car listing those numbers, or do you use a Kill-a-Watt or similar device plugged into the car?

I track my amp-hours at the wall with a Kill-a-Watt.

EVDRVR 06-27-2009 06:50 PM

Good question.

AH meter in the car. Shunt type on the main.

Brusa charger also keeps a running charge total but in this case I was just interested in the highway numbers. Just had a 4 wheel alignment and it appears to be worth it from a "mpg" aspect if my math isn't in error. For the past few years I usually see about 1.3 AH per mile on the highway under similar conditions. i could see some tire wear but apparently it was a bigger hurt than I thought. So I know it is better but I was doing the mpg math and I think I was making some sort of input error.

Charger profile is going to input about 5% more than what is reading on the Ah meter. Or what ever I set the profile to. Right now it is set at 5%. Biggest trouble with using the numbers off of the charger is that it also keeps track of the float charge. Which of course is overhead but has very little to do with drive efficiency and more to do with how much it sits around doing nothing. Also my occasional decision as to precool or preheat the interior both of which are registered via the AH meter and the charger. I usually tough it out but my sweet wife likes a proper climate prior to leaving the garage.

102 degrees right now so I might even be inclined to cool it down some myself.

roflwaffle 06-27-2009 07:08 PM

What kind of speeds (hi/lo) were you looking at w/ the 50mph average?

cfg83 06-27-2009 07:30 PM


43.39 AHs * 156 = 6,768.84 watt-hours => 6.76884 KW-Hours

Plugging that into this URL gets me this :

0.18494098360655736 gallon [U.S.] of automotive gasoline

Sooooo, MPG would be 44.5 / 0.18494098360655736 = 240.61 MPG


bennelson 06-27-2009 09:12 PM

I just did some quick number crunching.

You got me beat, but not by so much as to sound completely out of the ballpark.

I am running an overvolted DC forklift motor at 72V on used batteries.
I would imagine that newer batteries in a 156V system would be quite a bit more efficient.

Hey, wait a minute! A Solectria has an AC motor with REGEN! Are you counting that?

I believe that most of the hybrid guys consider Regen to be able to add up to 15% efficiency.

EVDRVR 06-27-2009 10:52 PM


Originally Posted by roflwaffle (Post 112538)
What kind of speeds (hi/lo) were you looking at w/ the 50mph average?

low end 0 high end 65 mph
most of the freeway cruise was at 50 mph and that was about 18 miles each way with the rest mixed city.

Regen was disengaged most of the time as it is less efficient than coasting but I was able to move very efficiently through the lights on the first leg and not so efficiently on the return leg. Also kept a higher speed on the return and accelerated to that 65 mph number once to keep from being a speed bump for a fast moving truck.

The east bound ( first leg) of the trip is also a much smoother pavement than the return leg.

CarloSW2 thanks for the math confirmation.

Alignment was $80 but it seems to be a real positive at higher speeds. In my case the car was driving well but as in skiing you can snow plow straight down a hill just fine. It was off considerably. Had the shop set everything as close as possible to zero on all four wheels. Tire pressure is Solectria recommended 44 psi. Tires are 13 inch, inexpensive and not LRR.

I may have to put my full belly pan back on if Ben is going to whack me 15% for regen;) Spend little time above 45 and couldn't get a real strong positive from it so I left it off when it didn't preform so well in the rain.

Ben- the pack is quite new and still being babied in break in phase. So the voltage is very strong. Both legs were started at 100% SOC. These gel batteries have a 1 hour rate of 70 AHs. I wasn't trying to see how efficiently I could drive nor was I blatantly wasting watts. Mild Hypermiling is pretty much a norm after 4 years with the EV. Just surprised at the positive results of the alignment seemed to have made.

The Solectria as I mentioned can return these numbers all the time at lower speeds and as Ben mentioned when regen is used to advantage in stop and go it helps.

Interesting tidbit is that on the first leg the car had two sheets of 5/8th plywood in the trunk (had the back seat down) so it probably weighted about 60 pounds more than the return. Never did get back that much needed, getting out of the big nasty looking trucks way, power application.

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