# High Watt Hour Usage



## TheSGC (Nov 15, 2007)

Low Rolling Resistance tires would do you some good, but do you drive in a hilly area? If you do, that would explain the high watts per mile. Changing from 0% incline to 1% nearly doubles the amount of watts needed to travel at a specific speed.


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## helixev (Nov 7, 2007)

I am driving up and down small hills... no more than a 400-500 ft elevation change overall.
I was also thinking I should go and grease the drivetrain... where it needs it.


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## 3dplane (Feb 27, 2008)

Hey Heli! Does your truck roll freely? You could tell when rolling to a stop,if you got a little rocking action or it just stops.That would rule out sticking brakes,draggy drive train(4wd) or misaligned front suspension(excessive toe).If thats good then whats left is probably a combination of terrain,road texture,and maybe driving style.I guess skinnier tires would make a huge difference.Maybe thats all you can expect out of that truck? Hard to tell without a direct comparison with same tipe of vehicle. Barna.


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## CPLTECH (Sep 14, 2007)

My initial thoughts:

*Tires:* Bought a used S10 with wide tires. Truck wouldn’t roll down a hill. When the rubber got thin, put passenger tires on. Got better MPG & would now coast down a hill. Remember the thin “English” bikes vs. the thick “American”. Those 3-sp English bikes would coast great. Wide tires have more rubber to flex.

*Transmission:* Put RedLine MTL synthetic lube oil in tranny. Made a big difference on the S10 5-sp.

*Motor:* Sweet. Since you have twice the design voltage, which means it should require half the amps of a DC motor at the same HP needed at any one time.

*Battery**: *Weak area. I use US Battery #145, 6V (Similar to the Trojan T145) on my 120V S10. It can spit out ~250AH without warping the lead plates inside & is designed for golf carts, EV’s, etc. However, in a system like yours you would need less than half the AH of mine but a lot more than what you have at present. Trojan/US Battery does make the T105 & T125 for those that need less current. Not sure what others use in their 312V systems.
I use 350-390WH per mile on a 28 mile loop (80-90AH @ 120V=watts) with plenty of battery to spare. Less than 50% DOD. (Charge batteries at 1.2 times what you took out)
How fast do you accelerate? How many amps do you pull going up those grades? Yes, I do pull 400A for brief, very brief moments, but to be nice to the batts & motor, I try to keep it under the 250A rating of the batt. I interpret that to mean about 40% for your setup which equals 160A/100A respectfully (if I had your setup in my truck & did not drive like the “leader of the pack”). Hence, I come up that the batts do not have what is needed, plus not rugged enough. Also, batt performance suffers in cold weather.
Not sure if this is correct thinking, but my controller is 550A max, twice the AH of the battery . Since yours is 282A max, does that mean you need a 140 AH battery for similar range?

One more thought to ponder…
DC brush motors have a sweet spot of 3-4K RPM.
I believe an AC motor is twice that.
Driving as if it was an ICE would draw more amps & overheat motor. I never get beyond 3rd gear. You may never get beyond 2nd. Some professional AC conversions locked the trans in 2nd gear. Another reason to put syn lube in tranny.


Only an opinion of a 1 yr EV er.


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## Mastiff (Jan 11, 2008)

I doubt it's the tires.

I'm pretty sure it's the hills you are driving on, I would personally take the vehicle out to a private airstrip or a race track and run the vehicle on a nice flat surface to compare it with your normal driving.

Think about it, you weigh nearly 5000 pounds, gravity will have a HUGE effect on you.

Not to mention the Inertia of your vehicle adds greatly to this.


Other things to test:

You could take an OHM meter and test every wire and connection on your system to make sure that you aren't loosing electricity to resistance anywhere.
You can't have power running though the system though when using an OHM meter or you'll fry it. (or you...)


You could jack up the truck and run the motor with the drive wheels off the ground to see if there's much drive train resistance. (the wheels should be able to spin pretty well freely)


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## ngrimm (Oct 19, 2007)

I noticed the 7000lb Gmc vans on the evalbum are claiming 500w/h. I wonder if it is a combo of the extra drag of the transfer case, larger tires wind resistance due to ride height. Just raising your tire pressure made a 13 percent improvement. As to tire size and tread try pedaling a mountain bike on the highway compared to a bike with smooth narrow tires and you can see a huge difference. I assume you have locking hubs. Are the transfer case and hubs unlocked and not stuck? Norm


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## helixev (Nov 7, 2007)

This morning I greased all the u-joints on the drive shaft and had a chance to push it on a nearly level concrete floor. It definitely rolled... but was not super easy to push and it definitely did that nudge-back thing when the front wheels were locked in 4wd and maybe just a hair when they weren't.
I just drove 11.65 miles round trip to town and back and used 6764wh so that is just about 580Wh per mile.

Experience driving a Ford Escape Hybrid with a mpg meter has shown me that depending on where you drive it can make a big difference in mpg and the hill up to hour house though not real steep is half a mile and gravel and it makes a definite impact.


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## O'Zeeke (Mar 9, 2008)

TheSGC said:


> Low Rolling Resistance tires would do you some good, but do you drive in a hilly area? If you do, that would explain the high watts per mile. Changing from 0% incline to 1% nearly doubles the amount of watts needed to travel at a specific speed.


Hi SGC, do you or anybodys else have any recommendations for LRR tyres?
Thank you


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## TheSGC (Nov 15, 2007)

O'Zeeke said:


> Hi SGC, do you or anybodys else have any recommendations for LRR tyres?
> Thank you


I am not really sure of what is out there. I got lucky and the tires on my donor are Toyo Spectrum Touring Radial tires, model P185/65 R14 85T and claim that they are "Reduced Rolling Resistance Tires".

I would go down to your local tire store and inquire about low rolling resistance tires, like the ones on a Civic HX or a Prius.


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## helixev (Nov 7, 2007)

I got a set of 225/75R15 tires on my truck vs. the 265/80R15 that were on there but it has not made as much difference as I would have thought and my wh/mile is still between 5 and 6 hundred.

One thing that could possibly be contributing is that my flywheel or motor hub is not perfectly balanced and if I rev it up with no load it chatters a bit... this is something I have to fix but requires pulling the transmission and getting the machine shop to check and fix it.

Also I figured getting the breaks tuned and hubs greased to make sure nothing is rubbing or sticky would be a good idea.


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## Funkeydude (Apr 10, 2008)

Hi Helixev,
I think (with my limited knowledge) that your electric car is doing a good job, congratulations. In your previous post you mention around 15kw pack, so what you achieve is imho pretty ok!


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## helixev (Nov 7, 2007)

I have been having this suspicion that my handbrake is to tight or stuck so I jacked up the rear axle and spun the tires... they do not turn easily by hand and when I drive (wheels off the ground) 45mph in 4th gear (1:1) it takes 20amps @ 312v, that's 6kw!!! and then it only takes 6 seconds to coast to a complete stop. I could also hear what sounded like the drums rubbing eachother.
How much energy should I expect to have to use to spin the tires with no load?
How long should it take for them to coast to a stop?


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## ngrimm (Oct 19, 2007)

You may be on to something with the parking brake. You should be able to get a little slack in the cables when released. If not probably the cables are rusty or gummed up. Maybe try to oil them up and work them in and out. Otherwise someone might have adjusted them too tight. Norm


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