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Old 07-19-2015, 02:54 PM   #7 (permalink)
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Originally Posted by oldtamiyaphile View Post
Thanks for the input. I think 4400lbs is about right for a typical loaded van with the expected added weight of the conversion factored in. I have a 1000lbs trailer that I tow quite often, but I plan on building a lighter 6-700lbs version soon. I could fit a generator to the trailer for occasional last resort use. The EV calculator predicted range doesn't change as much as I expected when I play with the curb weight. From 3800 to 5000lbs reduces range by 14 miles, which typically won't be the end of the world.
Using a generator to extend range is a good idea. There are implementation issues. Normally you have an interlock to disable the controller and ensure that the car does not move when you are still plugged into the charger. Many chargers have been ripped off garage walls, and cord ends have been wrecked if this is not implemented. Charging while rolling presents an issue to this interlock. Starting and stopping the generator while driving is another issue that can be avoided by doing the once-in-a-while start while stationary on the side of the road.

What's the most popular way to run the A/C?
Sorry about that. I was talking about running an Alternating Current or AC motor, instead of a DC motor, for driving the van.

I think running it off the drive motor is out as I spend too much time stationary. I definitely like the idea of cooling off the interior before I get in it. Has the Prius A/C compressor been cracked?
There are Air conditioning compressors available. I don't run Air myself, so I don't have experience.

It's front wheel drive, so I'll have to put a lot of batteries under the hood or it will just be forever spinning it's wheels (the rest will go under the floor as far forward as possible). It already has wheelspin issues I think an electric motor will be easier to modulate than a TDi in this regard. When I fitted a tuning box to add 50Nm it made it peaky and quite unpleasant in first and second.
Depending on the motor you choose, you may not have to put as many batteries in the front as you may think. A UQM Powerphase 100 brushless DC motor is about 110 lbs and the controller is another 60 lbs. That's on the low side of the weights and the controller is liquid-cooled. A Siemens 1PV5135-4WS14 AC Induction Motor is about 200 lbs (without cables) plus the adapter plate - another 30 lbs or so (I can't locate that info at the moment) and the DMOC645 (a compactible controller) is about 60 lbs. That's the heaviest single-motor solution I've seen The motors and controller are both liquid cooled so you need to keep the radiator/fan/pump.

I'm surprised there isn't an established formula for converting fuel use to electron use. It would surely be more effective than using vehicle weight as the only input, ignoring aero drag and required speed.
I think that's how the EV calculators work. There is a HP requirement based on rolling resistance (friction) of tires on the road that has to do with weight plus the wheel bearings and transmission losses, that is not dependant on aerodynamics, then there is an acceleration portion that has a lot ot do with weight, and finally there is the aerodynamics portion. The last one, as you know, rises exponentially with speed.

If a heater wasn't a legal requirement, I would probably not bother fitting one.
I expect to need mine mostly to keep the windows clear when it's raining. It's not rolling as yet, so I guess we'll see.

Is it more common to run DCC converters or to retain separate 12V batteries? I'm thinking my 12V battery would be grid charged and sized to match my EV range, my 12V usage wouldn't affect my range that way. The roof has space for ~500W of solar panels which would probably be enough for my 12V requirements.
The DC/DC converter is one of the things in an electric car that appears to have problems. I think it's the part that I've heard replaced the most. Most times you need a small 12V battery anyway, to close the contactors on the large pack. So if it's there anyway, making it a bit bigger is not an issue. If you are intending to use the generator on the trailer, you will run out of 12V battery while you are charging your main pack if you have no way of charging the 12V. Lots of stuff uses 12V and you may have some challenges sizing a stand-alone 12V battery. That said, all of my testing is done with a stand-alone 12V system. I use a DC/DC in my car with a 10A 12V lithium 'starting battery' and the DC/DC supplies 30 amps (which is very low). I guess I'll adjust the size/output of the DC/DC if it causes me trouble.
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oldtamiyaphile (07-19-2015)