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Discussion Starter · #1 ·
Hello all! I want to make a stab at an EV, or at least see if its feasible.
I recently received a 70's CJ7 Jeep as payment for doing some work on a guys car. ive always been interested in EV's and i am going to look into converting this one this summer
i am experienced enough working on cars and i also think my fabricating skills are up to snuff for a project like this. I also work at napa now and at cost car batteries are at my disposal. I did do some reading in the getting started thread, there is some great information in there!

all of that being said, i want to hear from some veteran EV enthusiasts:D


ideal goal = 40 mile range with a top speed of 45-50mph
im looking for suggestions on motors, controllers, and voltage. or conversion "recipes" if you will.

-The jeep should weigh just under 3,000 lbs after gasoline equipment is removed
-it is a manual
-it has the suspension to withstand some weight, being a 4x4 (part time)


MY QUESTIONS
-what are some adequate drive train suggestions (specific motors, controller, batteries, voltage to use)
-What is the cost for something like this approx?

none of this is set in stone, i just want to hear from some experienced people. thanks in advance!:D
 

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Figuring about 3500 lbs finished weight, / 10 Wh/mile/lb (a rough guess that seems to work) x 40 miles /0.8 (because you don't want to take your battery below 80% depth of discharge), that's about 17.5 kWh- a little more than one Chevy Volt battery pack, or about 2/3 of a Leaf pack.

Forget about lead-acid, especially car batteries. Lead is dead. The rest will cost you enough that toying with lead is a waste of money. Used EV batteries are the way to go.

There are basically three options: used DC forklift motor and kit-built controller (lots of work but cheap), AC or DC motor and bought controller (about the same cost, but AC is more reliable/lower maintenance and DC is higher power/more torque for the buck), or transplant an entire crashed but driveable Leaf into your Jeep- that's hardest, but might be cheapest in terms of features per dollar spent. The Saab Sonnet build is trying that right now. There are also some "any OEM EV motor" ideas floating ar

Parts cost can be determined from the vendors who advertise here, and a few who don't (like CanEV). Packs can be bought on carpart.com, and partial packs from some vendors you can find here and on E-Bay.
 

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Looks like a fun project! Seems like you've got the right attitude about specs. Anything can be done if you want to throw enough money at it, but your numbers seem pretty reasonable. Keeping the top speed low should help if you can keep the gearing low to get more torque out an AC motor, and/or not have to sacrifice low end torque on a DC motor to deal with the rpm limits. I'd start looking at the torque output and rpm ranges of various motors, and seeing how that lines up with the gear combinations you have available and/or can reasonably acquire. I'd expect on an old Jeep you probably have lots of gearing options. I guess you'll also have to consider whether to keep the transfer case or go straight RWD to reduce drivetrain losses.

IMHO one of the most overlooked but most important factors is the starting condition of your rolling chassis. If what you really want to be doing is building an EV, tackling what could amount to a full restoration on top of that can really stretch out the project and increase cost.

Best of luck!
Rob
 

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Discussion Starter · #4 ·
Thanks for both the replies! I hadn't considered using current ev batteries. nor had I put any thought into an AC setup, from the information i was gathering it seemed as though a DC setup would be easier, but thats why im posting here.

glad to hear you think my goal is reasonable. If i had to guess, id say the jeep will go 50mph in 5th gear (it has an over drive transmission) at aprox 2,000 rpm.
 

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Discussion Starter · #5 ·
another BURNING question I have is lets say (Hypothetically speaking) I got a 48v forklift motor, a 36-48v golf cart controller that was 400amp, and lets say 4 to 8 deep cycle 12v marine batteries. I know im leaving some components out but for the sake of the question they arent necessary.

with a total weight of 3,500lbs using this jeep, what kind results do you think a setup like this would yield? top speed, mileage, etc.
 

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I'd say maybe... 45 mph assuming your gears are short enough.

Adding 8 100ah 4s2p, 8-10 miles assuming you want to use the pack more than 5 times.

Sam
 

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Someone can probably give you a better answer, but here's my gut feel. You can also play with the evcalc linked above if you want to look at DC motors and lead batteries. Range estimates will be reasonable in that case. ADC L91 is a 6.7" forklift motor, good up to 120V. ADC XP1263 is an 8" forklift motor good up to 144V. ADC FB-4001 is a 9" forklift motor good up to 144V. Warp 9 is a 9 inch forklift motor specifically modified for EV use. The AC and Li options in there don't really seem to work, and aren't representative of current options.

- 8-9" forklift motor is probably fine. Particularly if you advance the timing and run up the voltage. There's a good sticky thread in the motor forum about how to pick a good one. 6.7" probably not. With a 5sp, a 6.7" 96V lead system with a blower was working hard in my 2200lb low drag sports car.

- 36-48V 400A controller isn't going to cut it. That's at best 14-19kW (~20hp) before electrical and mechanical losses. Using the evcalc preset for a ford ranger and adjusting finished weight to 3500 lbs, estimated power to cruise at 50mph is ~17hp. With a 5% incline (or 1 mph/s acceleration) that goes to 43hp. You might be able to maintain 50mph on a flat with no wind, but you won't be able to accelerate up to 50mph. I'd say a 120V / 500A controller is probably about a minimum.

- Deep Cycle Lead Acid probably isn't going to cut it. It will end up being almost as expensive as Li from a Leaf or Volt, and 40 mile range will be a stretch. The same evcalc setup as above (Ranger, Warp 9 motor, Curtis 1231C Controller, 3500lb finished weight) yields a ~22 mile range at 50mph with 10 Trojan 12V 115Ah batteries (120V) at a cost of $1500 and 600lbs. So you might get up to 40 miles with 2 strings, at a cost of $3000 and 1200lbs, but you'll also likely have to replace the lead batteries every few years.

This is based on a calculated ~300Wh/mi at 50mph, so you'd need 12-15kWh of Li to do the equivalent job. 30 Nissan Leaf modules configured as 15 series / 2 parallel would give you ~114V and about 13.7kWh capacity. At $120-130ea, that's about $3600 to $3900. Probably less if you buy a whole battery and sell off the modules you don't need. And it will weigh 250 lbs. That would be ~45 miles at 50mph, again flat no wind and at 100% depth of discharge. If you average 40mph that would push out to ~60 miles giving you a bit more margin to protect the batteries and deal with temperature effects and additional electrical loads, hills, accelerating, etc.
 
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