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Someone correct me if I'm wrong, but you might be able to keep the LS in addition to the electric motors? ...
that's a serial hybrid setup, if the engine isn't connected to the wheels...
Yes, that's a pure series hybrid, and compared to a conventional mechanical transmission system it is heavy and it transmits the engine's power inefficiently. There are advantages to hybrids, but whether they are worthwhile or not, this just isn't an EV. I don't think it addresses the desired characteristics of the project.
 

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As explained above, that means that the module thickness is constrained, with the other dimensions being relatively flexible, although to avoid every customer getting a custom product there would need to be some standard sizes.
That's right. We'll have standard offerings that I think will suit most people. The first standard one I'm working on will be about 100Ah and 14S. That should be a pretty good size for a lot of projects I think...a 700V performacne system would be about 71kWh and a 350kWh system would be 35kWh. Other sizes to follow, plus the opportunity for custom versions.

I think it would be nice to have the option of fewer than 12 cell groups in series, to allow for more modules (for the same total capacity and pack voltage) for more flexibility in packaging without making every module uniquely shaped to fit its mounting location.
Exactly. The most recent project we did was 6S, and we've done others as well. Only real downside is that it's not as efficient at utilizing the embedded BMS boards so you need extra slaves. I'm also actually working on a design for a 1MWh string in which the individual modules will just be 1S (Obviously you don't embed BMS at that point). I guess in a way that's just a "prismatic" albeit with cylindricals inside...
 

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Discussion Starter #23
Would like to thank Hollie Maea for taking the time to answer my questions over email, even for this prospective customer who is months away from being at a purchase point. Great pre-sales support from EV Drive gives confidence in there being quality support after the purchase.
 

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We built a Power Trailer for a 1500-mile road rally in our EV. I also used it on a 1000-mile road trip to the Amelia Island Concours. It's not a perfect solution, but it got the

yours might be the only functional gas generator trailer I've ever seen on here

what's the GVWR?
what's the tongue weight?
can it fully supplement your watt hours per mile usage? As in, you never need to charge, just run the generator while driving?
how is it wired relative to the batteries and motor and inverter? Like, is it wired parallel to the motor as like a "Second battery?" Or is it wired into the charge controller and its like a charger that's continuously plugged in?
 

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yours might be the only functional gas generator trailer I've ever seen on here

what's the GVWR?
what's the tongue weight?
can it fully supplement your watt hours per mile usage? As in, you never need to charge, just run the generator while driving?
how is it wired relative to the batteries and motor and inverter? Like, is it wired parallel to the motor as like a "Second battery?" Or is it wired into the charge controller and its like a charger that's continuously plugged in?
Generator and trailer weigh about 600 pounds. Tongue weight is negligible, I balanced it on the trailer pretty well. It's not particularly noticeable when driving, but I've got a lot of regen programmed in so my braking is very good. I also have a lot of relatively heavy i3 batteries in it now for long road rallies, so it's a bit porky.

It's wired into an eMotorWerks 12kw charger, which is the real limiter in the system, and we run it while driving. The output of the charger is parallel to the traction pack. Up to about 50 MPH you can run off the generator, and above that it pulls from the traction pack and the charger. For long trips we tell Google Maps to avoid highways and we can go for hundreds of miles without stopping. Even if it gets a little low, with 12kw charging we just stop for a bite to eat and it charges it back up pretty quickly. When I went to Amelia Island for the Concours (about 500 miles), I easily made it 380 miles solo on day one and the charge never got very low; I just stopped because I was tired and wanted to get to bed early.
 

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We built a Power Trailer for a 1500-mile road rally in our EV.
Tell us more!

What wattage is the generator?
How many watt-hours per mile does your car typically consume at 50mph?
How many watt-hours per mile did you car consume at 50mph when towing the trailer?
How big was the gas tank?
How long at highway speeds did the gas tank last?
 

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Generator is good for 15kw continuous. It's this one: Generac Power Systems - 15000 watt GP Series Portable Generator with Electric Start - 5734

It holds 16 gallons of gas and uses close to 3gph at 12kw.

It's been a while since I did the math on energy usage and trailer towing, but As I recall you use about 5kw to tow a trailer like that, maybe less. What we observed was that if you kept it under 50mph, then you could pretty much go all day. Even that varied, traffic and a few stop signs/lights would extend that while continuous steady-state speed could cause a slow drain on the pack. If I went 70mph on the Interstate, then I could get a couple of hundred miles before stopping for a few hours to charge up a really run-down pack. I basically tried to keep it slow, go 100-200 miles, take a short break and top it off, and then do it again. On a good day I could do 2-3 stints like that.
 

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Yeah, I tried mounting some smaller generators in the car with mixed results, but having a big running generator in the car with you is pretty much unbearable.
 

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if you guys want to upgrade that generator at some point, the chevy volt's engine has a built in generator transaxle thing and it claims to deliver 55kw continuous electrical, that'd keep that car topped off at all speeds no problem. You can pick up Volt engines from wreckers for like a grand all-in, not bad

of course then the problem is making a charger which can accept those kinds of KWs constantly

or wiring the system to take power from both the generator and the batteries in parallel while the car is in motion, maybe have it cut off when you're driving slower than 40mph

this is something i've been thinking about for a while, but i don't have the electrical engineering knowledge to really pursue it. It could make most any diy EV absolutely feasible as a year-round all-purpose car
 

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Bingo, without the budget to design/build a DC charging system, the charger is the limitation. I'm a little surprised at how well the eMotorWerks charger has held up to the abuse.
 

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is wiring the generator in parallel with the batteries onto the motor not feasible?
so the motor pulls from the generator when it's available, but from the batteries when it isn't
again i'm not sure if this a thing which can work. But it must, since i think that's what the chevy volt does?
 
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