Best way to add regenerative braking to a Jeep?
 

I have a 1998 Jeep Cherokee 4x4 that I am trying to both modernize and make as efficient as possible. It's never going to be a prius but I know it can get better MPG than what the factory built.

With that said, I'm converting most of the accessories to electric power - cooling fans, water pump, air conditioning, power steering. Basically I'm going to eliminate everything on the belt system. The "alternator" will be a bank of rechargeable batteries so as not to add extra load to that. I will plug it in to recharge when it's parked. I'm going to set it up so I can kill the engine and coast as much as possible, also during stops instead of idling.

I'd really, really love to have some kind of regenerative braking on this thing. The fewer batteries I can have, the better, obviously.

Does anybody have any good ideas as to where I can add some sort of generator that would be activated with the brakes? I could add one to the engine pulley and use it like compression braking, but, the engine will still be wasting some of the power if I do that. It would need to be in gear while coasting.

Is there a (relatively) easy way to add some kind of generator to the driveshaft? Something that would activate with the brakes and start generating power? It could go on either the front or rear driveshaft. Or maybe something that would attach to the transfer case? I know I've heard of hot rodders using an axle mounted alternator to clean up the engine bay, but I'm not sure how they attach it.

Just looking for some input before I try and re-invent the wheel.

Thanks for any info.

Is your Cherokee an automatic? Most automatics can't handle engine-off coasting.

I want to do what you're suggesting on my Civic. I drive with the alternator belt off in the daytime and I'd love to get some charging down big hills. With a 4WD Jeep, you have a lot more places to drive an alternator. I'm guessing an axle-mounted alternator would be driven by a pulley sandwiched between the axle and driveshaft. Some trucks have a PTO output on the transmission and/or transfercase. That would be a really clever way of doing it if your drivetrain has a PTO output.

I suggest leaving your alternator on the engine, but having a kill switch for it so you can turn it on when going down hills to capture some of that kinetic energy. I've been known to use the air conditioner like this too, since it's effectively free.

A free-spinning alternator not generating power has very little resistance and you'd probably not see any difference at the tank level vs taking the belt off. The advantage here would be that you would also be able to flip it on if you need to drive greater distances than the batteries can sustain. If you wanted to use some of that electricity for propulsion you could, I suppose, put another small motor on the belt system running off of the same 12v, but be aware that the net effect of the system will be near-negligible.

Even on my Insight, where the car only weights ~1900lbs and the batteries can provide 100amps @ ~165v (16,500 watts), the energy captured by regenerative braking is relatively small, and though you can definitely feel the assist in propulsion, it saves relatively little gas overall; it's more a drivability aid for an undersized engine running lean, which is what really saves gas. With a 12v system you're not going to be capturing 1/50 of that, in a vehicle with more than twice as much mass.

Is the purpose to recharge your 12v on-board battery? or to capture power to put back to the drive wheels when you take off?

Wow, off-the-shelf differential mounted alternators! (of course overpriced)

https://www.summitracing.com/parts/p...eZORoCUeHw_wcB

http://www.speedwaymotors.com/9-Inch...tem,27898.html

http://www.ebay.com/itm/Powermaster-...-/330828187386

I've long wanted to do this with an AC drive motor such as the following to not only get significant boost, regen, and mpg, but also allow slow maneuvers without the engine running. Of course that is after the power steering goes electric.
AC 2X Kits

How will you convert the air conditioning to 12v electric?

Only like 3 people on here besided my self have even been able to go electric on power steering.

I have an electronic water pump and I actually do not recommend them unless part of a coolant prewarming circulation setup.

Unless you have some pretty incredible instrument controls and elecrtical knowledge, fabrication and design skills along with the tools to do make a regeneration hybrid it's not going to happen with out more money than it would take to buy a new hybrid SUV.

Why is that? Yes, it is an automatic, and yes, I coast downhill with the engine off all the time. Put it in neutral and kill the engine. My biggest concern is the extra work on the starter, but, it's easy to replace and I'm going to make sure it has extra large cables to keep the cranking voltage as high as possible.


I'd like to get rid of the belt system entirely. I know the alternator doesn't use a lot, but completely eliminating the belt would sure help eliminate a lot of energy waste. Also, using it to re-capture energy going downhill through the engine is very inefficient...the compression braking from turning the engine crankshaft would eat up more energy than the alternator.

I'm not attempting to do any electric driving of the wheels, just every accessory. Also keep in mind my Jeep only weighs about 3,000lbs - only slightly more than a small economy car. Of course, more batteries means more weight, but more regenerative braking means less batteries.

That's cool, I didn't know they made kits like that. I doubt they make one that fits a Jeep, but, definitely something that could be copied. With something like that I would still have the option to flip a switch and generate electricity even while driving with gas, if the batteries are getting low.

There are a number of 12v A/C compressors available these days, but more likely, I would use a standard 120v A/C compressor running from an inverter, which I plan to install anyway.

I don't know about this board, but electric power steering conversions are becoming more and more popular. LOTS more than 3 people have done it. This is another thing that is common in the hot rod world, they like to remove the belt accessories to make it look pretty under the hood, I like to remove them to save energy.

This is also very common in the hot rod world. No reason it can't be done if it's done right. They cool big block V8s with electric pumps these days. Streetable, too...not just for drag racing. These parts are already available off the shelf.

It really doesn't take a lot of controls for all the things I'm planning, certainly much less than it would take to install a large electric motor for propulsion. Simple thermostats and relays will do most of the work.

I ran an electric cooling pump on my 5L Camaro ,suburban with a 454 and my 6.5L diesel.
I know pretty much all there is to know when it comes to electric cooling pump conversations.

As far as I could tell the electric pump gave no measurable fuel economy important. All it does is use more power and make an alternator delete more difficult.
The main benifit they give is being able to circulate coolant with the engine off.

When I said I know know 3 people who have done electric power steering I was taking about members here.

Cheap power inverters tend to destroy induction motors, a pure sine wave inverter should be used. There are no cheap pure sine wave inverters.

Not all mods have to pay off or make any kind of financial sense though. Sometimes I like to tinker for the sake of tinkering. :p

I don't think regenerative braking is going to happen with bolt-ons, at least not in any meaningful way. Sure, there are hybrid conversions for sale on the market, but they're not remotely cheap and require some fabrication. And, unfortunately, most of the gains from hybridizing a vehicle are not from capturing braking energy, but from being able to use an undersized engine and/or run it lean and/or with the Atkinson cycle, and running that undersized and "detuned" engine as little as possible.

I think the low-hanging fruit is going to be maximizing engine-off time in the Jeep, given how relatively inefficient and large the engine is. However, I'm under the impression that many automatic transmissions require the engine to be running for lubrication and cooling (? never owned an automatic) and that you run a very real risk of detonating it by coasting with the engine off.

Bingo! Part of this is I just like to play with it, and another part is I'm trying to make it more reliable. The engine bay in the Cherokee is quite cramped, and removing the belt system makes changing each of those parts much easier, and even allows me to have multiples installed as a backup just in case.

Well, if I attached an alternator to the driveshaft like posted above, I could generate 300 amps or more every time I hit the brakes. It also would increase the performance of the brakes, and make the brake pads last longer, not that those are very expensive. Heck, if I put an alternator on both axles, I could get 600 amps or more each time I hit the brakes!

I'll have to look into that, though I've been doing it a while now and haven't seen any problems. If I have to, I could add an electric oil pump to the transmission.

Well, there's no question a water pump burns horsepower. I'm not sure how much, but even if it is only 2 or 3hp, it's easy to calculate exactly how much gas 2hp burns per hour and convert that to MPG at a given speed. Without an extensive dyno test, it's pretty hard to accurately see a 1-2mpg difference, there are just too many variables. If you don't delete the alternator or turn it off, then you are just moving the load from the water pump to the alternator.

But yes, I do want to use it to also preheat the engine, and cool the engine while it's off if it ever overheats. (Cherokees are notorious for overheating issues) I'd probably set it on a timer to continue running a minute or two after engine shut down, kind of like a turbo timer. This would prevent the heat soak that happens immediately after shut down.

OP, check to see if your Jeep can be flat towed. If so, the auto trans will be fine doing EOC. If not, you do run the risk of messing it up.

FWIW, I did EOC in my non-flat towable Ford Escort and never had a problem. Granted, I did it sparingly and used neutral coasting and engine off at stops to increase my mpgs.

If you want to talk about something that will actually increase fuel economy a noticeable amount then you need lean burn. When I went lean burn on my 454 I saw between a 10% and 20% increase in fuel economy.
Lean burn works.

The water pump uses hardly any brake horsepower at normal cruise speed.
The coolant pump doesn't use 2 or 3 horsepower it uses more like 1/6th to 1/2 horsepower.
The power the coolant pump uses is actually needed while the engine is running.
They only time the coolant pump uses 2 or 3 horsepower is at 5,000+rpm when pump flow is stalled and the impeller is cavitating like crazy.

Something you don't need running the entire time while rolling down the highway is the power steering pump.
It uses up to 1hp even during normal cruise speeds.

Removing a 1hp load will reduce fuel consumption by about 1 gallon over 12 hours of driving. To quantify to to MPG if you had a vehicle that gets 20MPG at 60mph. You would be burning 18 pounds of fuel per hour or getting 3.33 miles per pound of fuel. Saving 1 horsepower would reduce that to 17.5lb/hr or 3.43 miles per pound. Multiply your miles per pound to your chosen volume, a gallon of gas weighs 6lb.
Before saving one hp you got 3.33 miles per pound, times 6 pounds, for 19.98mpg.
After saving 1hp you got 3.43 miles per pound, 6 pounds per gallon for a total of
20.58MPG.
So removing the power steering load you could notice at the pump.
Removing the 1/2 coolant pump load completely at most you would see a 0.25mpg increase if you started at 20mpg. If the coolant pump load were close to 1/6hp which i belive it is, then it would increase fuel economy by close to 0.1MPG.

This is why removing the belt driven coolant pump isn't even noticed and why I don't recommend an electric swap for improving fuel economy.
Unless it's part of an engine off coolant circulating warm up mod.

Not on an OBDII controlled engine that was not designed to run that way.

I think you're missing the point about the water pump. The intention is to get rid of the belt entirely. Not only does this make the vehicle more reliable, but it gets rid of a lot of random losses from bearings, random idler pulleys, etc. Even the A/C, when the clutch is turned off, still wastes a little bit of power. Removing the belt entirely and everything that is powered by it will most certainly make a noticeable difference at the pump.

Also, having complete on/off control of the water pump helps greatly with warm up and cool down, and works great in combination with electric fans.

The change from V belts to serpentine belts caused an increase in fuel economy, removing the belts entirely gets even more. There is more than one vehicle these days coming with an electric water pump from the factory.

For what it's worth, my car has a serpentine belt and all of its accessories are still attached, and I'm able to get in excess of 100mpg just driving in a straight line at constant speed, no tricks. I've thought about an electric water pump but as-is it's very reliable.

Yeah, but yours was designed for efficiency from the factory. Jeeps, not so much. I'm not saying serpentine belts are unreliable, just that my entire system is getting old and it's going to be more reliable with new electrically driven things.

Also, I don't do a lot of highway driving. I think the improvements would be better with constantly varying speeds. (and more opportunity for regenerative braking)

As the others have pointed out, EOC is like towing...without the engine running, there is no pumping of the ATF to lubricate and cool the transmission. Most owns manuals say not to tow for more than X miles at no more than Y mph. You'd have to check yours to see what it says.

Chances are, you'll be fine for brief periods, but is it worth the risk to save a few pennies in gas each time?

His Jeep is probably fine with flat towing, but not because the transmission can necessarily take it, but because you can just put the transfer case in neutral and be good. So a yes for flat towing isn't a definite green light for EOCing.

Well, I guess you're right, according to the manual the transfer case should be put into neutral for flat towing of a 4WD. For some reason it doesn't say anything about a 2WD with the same transmission. I also see with a cursory google search they sell both driveshaft disconnect kits and electric transmission pumps to solve this problem for RV users. Most of what I can find in google says not to tow with the transmission in neutral for "more than a few miles", but I can't coast more than that anyway.

I'll have to do a little more research on that part. I guess I could just put the transfer case in neutral instead of the transmission. I would really love the equivalent of a clutch pedal that would put it in neutral and let me coast, though the driveshaft disconnects aren't very cheap. Unfortunately I can't drive a manual transmission very well due to some problems I have with my legs, it makes it hard to use a normal clutch.

To be honest, I don't have a chance to coast in neutral very often, just a short hill by my house. Probably not worth the trouble. Engine off during stop/idle would probably save more fuel with the traffic around here...

Putting lean burn an an OBDII vehicle would be a lot easier and give more improvement than trying to create some kind of electro mechanical regeneration brake system from the ground up.

May I suggest using an electric a/c compressor off of a hybrid

Maybe a group 31 deep cycle battery or 2 to supplement the lack of alternator

Maybe a couple of those electric motors made for bicycles to run all the time to charge batteries

And a possible conversion to manual steering off an old 70's jeep

From what I have been abe to find the hybrid AC compressors run at very high voltage.
They run off pack voltage, which depending on the hybrid could be as high as 330v dc.

Hmm, that is probably correct, I didn't research before responding to the thread

I really don't think you're understanding the concept of this thread.

What's the plan to add regeneration braking?
Which I think is cool.

If you're trying to save fuel.
What did I miss?
Since I have done both I'm just letting you know the accessory delete will disappoint and I will leave it at that.

http://ecomodder.com/forum/showthrea...r-35003-2.html

[added verbiage to encourage you to click the link]

Not a single one of your replies has to do with the question asked about regenerative braking. I did not ask you or anyone else how much fuel removing the belt would save, and mostly I do not appreciate your argumentative responses.

As Ecky pointed out so well, I don't need a reason to do what I'm doing, other than I want to.

That works for me.

Now how to do it?

Mostly correct. The most prolific electric compressor (from the Prius) runs on 200VAC. Yes. AC - 3 phase

Would that be single phase or 3 phase?

I [for one] do not appreciate your argumentative response. Especially when it came directly after my contribution and it totally denies that. :mad:

"Best way to add regenerative braking to a Jeep?" seems clear enough.

http://ecomodder.com/forum/showthread.php/controller-mods-build-e-assist-altermotor-35003-2.html

I await your apology.