DIY XJ Cherokee Hybrid

[Zanderanger]

So I have a 1998 XJ Cherokee 4x4 5 speed ax15 manual with a blown 4.0 engine and I've been planning and acquiring parts to do a 1.9 tdi swap for a while. But I had the thought the other day, what if I could do some type of a diy auxiliary electric motor hybrid setup?

I want to have a fully functioning normal 4wd system with the diesel engine, but would it be possible to add in to the existing drivetrain an electric motor, say from a wrecked Leaf or something else, and have it be able to run the existing driveline with the diesel engine off and the tranny in neutral? If it could drive both front and rear driveshafts that would be ideal but even just one or the other would be fine. Would this be possible with some type of clutched chain-drive setup that could freewheel when the diesel is running? Or some other type of setup that I'm not thinking of?

The idea would be to have let's say a 30 mile electric-only range, but then be able to disengage the electric motor and run it off the diesel like normal. And without compromising the existing driveline functionality, just a completely auxiliary electric drive setup. Is this something that could be done or that anyone has done before, or am I crazy?

[Piotrsko]

Yes it's possible, there are several points in the system that accomodate the aux motor and allow 4wd. Suggest looking at DIY electric car forum. Several jeep style conversions

[Logic]

Consider a series hybrid where a small engine, ALWAYS at optimal rpm and load, charges a small battery that handle accelerative loads.
This is ALL about smallest/lightest and cheapest.
Lightest..! F = M x A

Easiest is simply a motor bolted to the stock gearbox.

https://www.youtube.com/watch?v=oYXqEZuLSEU&t=1100s

Then there's:

https://www.youtube.com/watch?v=sfqOh-nQ7wU

Many more videos here.

What most makers want is good range on battery alone so you can charge @ home for shorter trips.
That means BIG expensive engines and batteries!

OK... but where are the weight and cost savings?
And where are the, for constant rpm and load engine optimizations that manufacturers don't bother with when an engine is only at optimal load-rpm for a second, 5 times in the whole Urban Cycle Test..?

(There's more info on that here somewhere. Do a search.
IIRC optimal added ~20% to the 30 or 40% already in modern engines)

[Ecky]

As others have said, 100% possible. There's a whole range of possibilities and a whole range of outcomes, depending on how you choose to do it.

A simple mild hybrid might be a 72v altermotor which sits where the alternator sits, and replaces both alt and starter motor. The batteries might be as cheap as free, from a wrecked hybrid. Mid 2010's Honda are good donors, they had very compact, light, power dense lithium batteries that seem to last forever. I've collected a ton of them just by calling around. You might get 20-40ft-lb extra torque but there wouldn't be much fuel saving. This type of hybrid if mostly a power adder. The fuel savings come from downsizing the engine, and the electric system makes driving it not a dog.

Anything with discrete differentials is pretty easy to make electric-drive, either on the front or rear axle (or both). The sky is the limit with these, both in terms of outcome and cost. Ford has some great battery modules you can get for about $100 each, that might be good for 6-8 miles of pure electric range per. 4-6 gets you enough range for your commute, but you need a much bigger electric motor, and the overall system will take up more space and weight than a mild hybrid. You might find yourself feeling like the gasoline engine is just along for the ride, and makes barely any torque compared with the electric drive.

There's no one right way to do this, and there are lots of off the shelf or salvage parts one can use.

[freebeard]

A simple mild hybrid might be a 72v altermotor which sits where the alternator sits, and replaces both alt and starter motor.

That was my first thought, but it wouldn't allow creeping around in the woods on the quiet; which if I had a Jeep would be the use case.

[Xist]

Originally Posted by Logic

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