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Old 05-10-2017, 01:12 AM   #1 (permalink)
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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.

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Old 05-10-2017, 07:54 AM   #2 (permalink)
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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.
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Old 05-10-2017, 09:19 AM   #3 (permalink)
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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.
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Old 05-10-2017, 11:43 AM   #4 (permalink)
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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?
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Old 05-10-2017, 02:57 PM   #5 (permalink)
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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
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Old 05-10-2017, 03:17 PM   #6 (permalink)
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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.
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Old 05-10-2017, 05:02 PM   #7 (permalink)
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Quote:
Originally Posted by Gasoline Fumes View Post
Is your Cherokee an automatic? Most automatics can't handle engine-off coasting.
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.


Quote:
Originally Posted by Ecky View Post
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'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.

Quote:
Originally Posted by jray3 View Post
Wow, off-the-shelf differential mounted alternators! (of course overpriced)
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.

Quote:
Originally Posted by oil pan 4 View Post
How will you convert the air conditioning to 12v electric?
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.

Quote:
Originally Posted by oil pan 4 View Post
Only like 3 people on here besided my self have even been able to go electric on power steering.
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.

Quote:
Originally Posted by oil pan 4 View Post
I have an electronic water pump and I actually do not recommend them unless part of a coolant prewarming circulation setup.
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.
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Old 05-10-2017, 05:49 PM   #8 (permalink)
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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.
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Old 05-10-2017, 06:12 PM   #9 (permalink)
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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.

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.
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Old 05-10-2017, 07:00 PM   #10 (permalink)
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Quote:
Originally Posted by Ecky View Post
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.
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.

Quote:
Originally Posted by Ecky View Post
I don't think regenerative braking is going to happen with bolt-ons, at least not in any meaningful way.
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!

Quote:
Originally Posted by Ecky View Post
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.
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.

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