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Question(s)

(1) - Comparing a 3,250lbs and 5,500lbs (1,250lbs difference) vehicles. How much extra Wh/km (or Wh/mile) would there be between the two vehicles? (In city driving)

(2) - What affordable electric motors + controllers should I be looking for?

(3) - Using AC instead of DC a valid option to look at?


The lowdown of my idea.


Buying a Jeep Cherokee or Chevy/GMC Tahoe/Yukon - Leaving the i.c.e. intact to be able to drive on gas when I wish, and adding an additional electric motor somewhere in the drivetrain to help with MPG.


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The Long Story - The Ideas!
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I do not know if the term MILD HYBRID is correct or not, not much on Youtube and I really can't find much overall on the web.

My general idea was to keep the i.c.e. drivetrain intact and figure out a way to complement the driving force with electric. My original thought was to have a machinist make a differential yoke with a gear on it, that the drive shaft connects to on the axle. Then have some heavy duty chain from yoke to an electric motor. I have had that idea for a year or two now. The problem I foresee here is the movement of the axle going over bumps, so the electric motor would have to be mounted on the top of the axle pumpkin and the floor of the cab modified if it needs extra room.

Upon further looking into my generalized idea, I see some setups have an electric motor attached to the output of the transmission on one side, the other side would connect to the drive shaft in some way. So a shorter drive shaft would be in order, securing the electric motor and figuring out a way to connect the shaft of the electric motor to the output of the transmission or transfercase, and the drive shaft.

I wanted to do it on a Jeep Cherokee Inline 6 which gets 16city 19highway MPG. There is the Sidekick/Tracker which is great on gas, 20 and 24, but is too small and parts arent widely available, even the 4 door models are cramped spacewise.. Fullsize SUV Sub/Yukon/Tahoe gets 12 and 15mpg.

Weight is like like 2750lbs and 3350lbs for the Jeep. Then once I step into the full size arena, Yukon/Tahoe/Suburban we are talking 4500lbs 2 door, and 5500lbs 4 door. So there is a dramatic weight jump.

Now, I think I can come up with a solution here.

I do like the Jeep Cherokee's over the Sidekick/Tracker, for the simple reason that parts availability for the Jeeps are everywhere, same too with the Yukon/Tahoe/Suburban. For a daily driver the gas guzzling of full size I think would be too much, but the offroad ability would be amazing! And the other major downside is the weight of the vehicle. 5500lbs vs 3250lbs.

I want the best of both worlds.

4 door Jeep Cherokee 3350lbs - Inline 6
4 door Chev/GM Yukon/Tahoe/Suburban 5500lbs - V8

Me being well over 6' tall, I keep gravitating towards the full size, because I can fold the back seats flat, push the front seats forward and can sleep in the back stretched out when I am in the bush.

The Jeep Cherokee on the other hand I have owned, and tried sleeping in the back and it doesnt work, I have to bend my legs. I could fabricate up a new rear door that would give me an extra bit of space.

But thats where it stands.
 

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What you're describing is a parallel hybrid - the engine and electric motor are in parallel (either one can drive without the other). Many production hybrids have been parallel designs.

A "mild hybrid" has an electric system of very low capacity - it can't drive at all without the engine, has very little energy storage, and usually runs on only 42 or 48 volts (nominal).
 

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Do-It-Yourself projects are great learning experiences, but if all you really want is a hybrid SUV, and a Yukon or Tahoe is suitable, perhaps you can just buy a used one... the 2008-2013 Tahoe/Yukon hybrid used the most advanced hybrid transmission produced so far.
 

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... I see some setups have an electric motor attached to the output of the transmission on one side, the other side would connect to the drive shaft in some way. So a shorter drive shaft would be in order, securing the electric motor and figuring out a way to connect the shaft of the electric motor to the output of the transmission or transfercase, and the drive shaft.
This was the approach used in the Balance Hybrid Electric system by Azure Dynamics (for commercial vehicles and small buses) based on the Ford E-450 chassis:

(this illustration shows the traction motor, the Ford engine and transmission ahead of it and the axle behind it are not shown)

Any motor mounted inline with the driveshaft this way, without any gearing, is forced to run at relatively low speed. The suitability of this depends on the motor.
 

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Leaving the i.c.e. intact to be able to drive on gas when I wish, and adding an additional electric motor somewhere in the drivetrain to help with MPG.
Just to be clear, what are you expecting...
  1. To help with miles per gallon of gas by using electrical energy stored in a battery (charged at home or other charging station) instead of using gas?
  2. To help the efficiency of the gas engine by leveling out load, by avoiding idling, and by recovering energy by regenerative braking?
How you expect this to work determines the capabilities required of the hybrid system, including energy storage capacity, regenerative braking ability, and control of the gas engine.
 

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My 82 2wd c-code Diesel Suburban with a 5 speed shift and 2.8 rear gears would get almost 30mpg at 55mph

Perhaps something easier would get you your goal?
 

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Do-It-Yourself projects are great learning experiences, but if all you really want is a hybrid SUV, and a Yukon or Tahoe is suitable, perhaps you can just buy a used one... the 2008-2013 Tahoe/Yukon hybrid used the most advanced hybrid transmission produced so far.
Matt
Brian, once again nails it. If you want to experiment and enjoy the learning hands on experience this could be a great project. If your ultimate goal is the vehicle than looking at existing ones is very viable.
 
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