Electric assist for SUV?

[Tony Raine]

Alright, I'm pretty new to all this, so I have been reading through this site for sometimes hours on end. the "electric assist" threads have me particularly intrigued.

my question is about an electric assist, solely for accelerating from a stop light to around 20 mph. I keep reading that a "controller" is one of the most expensive parts of a full EV conversion. since my intended range of speed is very small, and only for a few seconds at a time, is there a way around that expense?

heres the thought that just popped in my head. while my explorer is a 2 wheel drive, the frame has all the brackets to install the 4wd front axle parts. even the spindles have a threaded plug where the axle shafts would go. I could probably get all the 4wd parts (except the transfer case, which wouldn't be needed) for relatively cheap from a junkyard, since this front suspension was used from '95 to '00 in explorers, '95 to '03 in explorer sports, and in the newer rangers. basically an electric motor about where the transfer case would be, hooked to the front axle with a driveshaft, and a "momentary" switch for on/off. i can mount batteries where the spare used to be, under the truck. the cable crank is broken, so the spare is now tied down inside.

since i have an automatic, i can't EOC to a stop light, and of course my worse gas mileage is accelerating from a stop light. my daily commute is around 40-50 miles and i have the potential to hit 28 stop lights in that 40-50 miles. i usually don't hit that many, i can usually time half of them.

So would this be a worthwhile venture? basically i would just let my truck idle while i used the electric motor to get going, then turn off electric and resume normal operation. of course weight would be an issue, so how few of batteries could i get away with? i could charge it at home, so i wouldn't need a charger on board.

one problem i see with this is that the electric motor would still spin even when not in use. there where 2 hub systems used with this 4wd system. one had pulse vacuum operated hubs, and the other was "locked" all the time, with the only disconnect being at the transfer case. the vacuum system was junk, it was only used on 98 and 99 rangers, so i want to stay away from that. that leaves me with a front driveline that turns all the time, but that doesn't seem to make much of a difference in stock 4x4's.



so let me have it. good, bad, whatever. i've got thick skin

[LostCause]

The idea of attaching a motor to the unused differential of a 4x4 has come up a number of times, so a search could probably answer more questions than I can.

The first thing to consider would be losing the SUV. You'll save the most money by selling the SUV and buying a cheaper, more economical car in cash. Otherwise, you'll have paid for an expensive car and an expensive modification just to reach parity with something that can be had cheap to begin with...

Secondly, stop lights can be pretty well dealt with by maintaining momentum. People have been known to pass through over a 100 stop lights on a trip without using the brakes once. It will take effort, but it is free. Technology has shown itself to be a handicap for incompetence (look at the Prii speeding on the freeway).

I'm not the most knowledgeable on electric cars, but I believe DC motors do not technically need controllers. A potentiometer could do. Personally, I would try to calculate the possible savings first through detailed testing and theory.

The constantly spinning motor could be solved through a sprag clutch. It would probably take some unique engineering, though.

Overall, it's feasible but impractical. Why set your sights on Everest if you're a novice mountaineer? Take the cheap, low hanging fruit first. You'll be surprised how much you can save by changing your driving habits and performing a few basic modifications.

- LostCause

[Tony Raine]

yeah, i searched more and found some good topics that are very similar. for some reason, i am only able to log in for a few minutes at a time, then i can't log in for several hours. so most of my searching has been while i was not logged in and couldn't use the search button. of course, i just realized that you can search while not logged in....... all the other forums i'm on don't have that feature. haha, i feel a little dumb now, but oh well. i learn a little more each day.


i plan on keeping this rig for a little while. its paid for and has horrible resale value. its been an amazingly reliable vehicle. besides regular maintenance, the only thing to go wrong was the PCV valve in the last 105,000 miles. with good maintenance, it will last 300,000 or more. i say this because my parents had a '94 explorer that lasted 298,000 miles with semi-decent maintenance. eventually, i want to get a more efficient car. check my intro thread. this rig will end up either being driven by me, or given to my mother to DD.

i figure since its paid for and i can't get jack for it, i might as well have some fun with it and see what i can do. soon, my commute will be cut in half, and i will be carpooling. my wife's car is used for longer trips ('08 pontiac g6).

i love it when people in yaris', civics, camry's etc..., pass me on the highway or floor it at stoplights. i laugh because i'm getting the same mpg as them, without new car payments. and theres no way i am buying a used civic that some punk beat the crap out of, cut the springs, and put a gigantic exhaust tip on (thats the way they end up around here).

i can't really do the more extreme driving tips. i would seriously get plowed over by a big rig or a crack-addict in an 80's chevy caprice. i have read the tips on this website, and i am implementing as many of them as i can.




i guess what i am saying is that i don't really need to do it, i just want to see if i can. i'm in no rush, so waiting for the right part to come along is no problem.

i'm fairly mechanically inclined, so the driveline stuff is no problem. part of my current job is rebuilding electric motors, but on a smaller scale. i've just never put the 2 together.

[MetroMPG]

Originally Posted by Tony Raine

i guess what i am saying is that i don't really need to do it, i just want to see if i can.

If pure interest is your motivation, then go for it. If saving money is the goal, I predict you'd decide it's not worth pursuing if you properly costed it out (including scheduled battery replacement).

To answer your controller question: no, you don't strictly need one for a DC motor. You can do what was done in the days before pulse width modulation controllers: use a series/parallel switching "contactor controller". EG: if you have a 72v pack, you design a 3-speed circuit that lets you use all the batteries wired for 12v for "creeping", 36v for low power, and 72v for full power.

That said, used 72v controllers are going on eBay these days for a couple hundred bucks.

[meemooer]

I've been thinking of the same idea, except my ranger is four wheel drive. Live axles suck. I'm getting about the same mileage as you, and i have a 3in body lift and 33in mud tires. So driving habits help alot. I'm assuming you have the 4.0SOHC, the only thing to worry about with those would be the timing tensioner. I have 99K and they are shot. Doesn't help that i sucked water in last year, overheated, and now i burn oil faster then gas.
With the pulse vacuum hubs on the older front diff's there is a conversion to make them manual locking hubs. so with welded gears and only one half shaft that part is do able

[Tony Raine]

thanks for the responses! i think a "contact controller" is what the "GEM" electric carts we have at work use. they have a "low" and "high" switch. when you press on the accelerator, there is a very loud click, and it takes off to top speed fairly rapidly.

in my truck, when starting from a stop and rolling downhill, the transmission shifts into second at around 20-25 mph. so i figured having an electric motor take the load off the engine during 1st gear driving would help out at least somewhat.

of course, this is not going to be the first thing i do. right now i am working on replacing the egr valve, the o2 sensors, and getting the transmission serviced. i predict a noticable jump in MPG after this. i'm also trying to figure out if i can replace the 4 catalytic converters with one "universal" cat without throwing codes.

meemooer, i used to have a 98 ranger with the same tire/lift setup as you, except 3.0/stick shift. the AVM manual hub conversions came out after i traded it off. too bad, the hub design was one of the reasons i got rid of it.

[mikeross]

What the best indication that there's a problem with a vehicle's transfer case electrical switch? I have an SUV too and as soon as the clutch starts to grab a little I start to hear a weird grinding noise from the center of the car(prob X-case??), The grinding usually occurs for some reason when the car is put in gear to move foward.

[ron]

tony Im interested in an ev assisted kicker also whats going on lately

[Cobb]

Ive had that idea for my sidekick ljx. I got a 48 volt 4 kilowatt pack from my engine phev kit for my honda I was going to use to power a motor. Of course I can always find some 0 gauge welding wire, a starter solonoid and a starter battery for a simple click bang method of speed control and a crude test.

Yeah, the speed controller is rather expensive and even more so if you want regen capabilities.

I saw the hybrid va tech made and displayed at the state fair in VA a few years ago. It was basically front wheel drive ford escape using a turbo charged diesel power plant the rear was electric powered and the batterys/guts was in the rear behind the rear seats. I dont think the mpg was that impressive, but it worked.

My sidekick loves to coast, so if I can FAS it and use a few hp to extend the coating once up to speed I am sure my mpg could easily hit 40 from its current 30mpg.