SuperTruck: Drive-Train planning diagram

by Ben N on January 21, 2013

I’ve talked a bit about the powertrain, but so far, haven’t been very good at visualizing it, other than with chicken-scratchings and bad pencil-sketches.So, I took an outline image of the truck, and started drawing in where the Hybrid components will go. It’s still rough (and not quite to scale) but gives an idea of what can go where.As a recap, the basic idea of the drivetrain is: diesel engine > manual transmission > electric motor > shortened driveshaft > differential > rear wheels.In giving it some thought, the existing fuel tank on the vehicle is larger than needed. On the short bed truck, it’s 16 gallons, and it’s 20 on the long bed. If I remove the fuel tank, it could provide some more space under the bed for batteries, and possibly the motor controller and charger.I haven’t carried a spare tire on my original truck in a long time. They always get rusty hanging under the back of the truck, and not carrying one saves weight (which improves fuel economy.) Seems like the space that the spare tire would normally go could be a good space for a block of batteries.I was wondering about the safety of batteries there (due to possibility of getting rear-ended) but that’s exactly where the fuel tank on the 2-door S10 Blazer is! A friend of mine converted an El-Camino to electric, and he had batteries in that same location (and under the bed AND under the hood!)

If I did replace the original gas tank with batteries/controller/charger, then I could put a small fuel tank in the bed of the truck. It would only be ten gallons (which makes fuel-economy math REAL easy) and not take up too much space in the bed. Since diesel pumps have a different size nozzle anyways, this would prevent me from having to modify the existing filler port. I would just fill right through the top of the small tank in the bed. “Fuel Cell” tanks usually have something like a 3″ filler cap on top. I’d keep that on the driver’s side, as the existing tank is, so that I don’t have to get too crazy in rerouting and extending fuel lines.

I’d also like to keep that tank small as I don’t want to loose too much cargo space in the bed. Part of the point of this project is to have a truly USABLE vehicle. One that can tow, haul, carry firewood, and move refridgerators. Eating into the cargo space starts to negate that. I might even be able to get (or make!?!?) a fuel tank that fits in the space between the tire hump and the front of the bed. That’s pretty much wasted space most of the time anyways.

The only other thing that I’m not so sure about is getting at anything mounted under the bed. If I have a tilt-bed (like two of my friends with EV Pickup trucks have done) I can still get at the batteries and whatever else is down there. If I have a fuel tank in the bed, it would be much harder to access the under-bed items.

If you look at the diagram, you might also notice that some of the exhaust system components may have to move. That shouldn’t be a big deal, as the truck doesn’t have the exhaust components in place right now anyways. It’s mostly pipes and a muffler, which can be put almost anywhere. They just need to be away from the batteries and fuel.

You might also look at the diagram and ask “Hey, where do you sit!? Isn’t that motor in your way!?” And in a two-dimensional world, you’d be right. I’d also like to point out that this diagram shows the outline from an extended-cab truck. My truck is just the plain-jane regular cab. That means that the motor is not going to be sticking under the cab too far, but YES it WILL be intruding on the cab. And since the motor is a larger diameter than the output end of transmission, I most likely will need to get out the Sawzall and modify the cab.

Since the truck has a bench seat, this isn’t looking good. However, I believe that if I swap out the bench for buckets, I’ll have just the right amount of room down the middle for a “motor hump”. Rather than welding in a sheet metal cover, if I hinge the motor hump, I’ll also have a motor inspection hatch and an easy way to inspect and change the brushes. I’ll just need to make sure to add some sound-deadening-material over the top.

So, take a look at the diagram? Does this look like a workable configuration for a DIY Plug-In Hybrid Pickup Truck? How else might you mount all the components? What are the advantages and disadvantages of this setup vs. others?

Let me know! All thoughts welcome!

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