Hi everyone, im starting my first EV conversion

That's awesome! I LOVE my electric. One thing to consider though, and I don't know ALL the pros/cons but if you'll use 12V batteries and jack up the pack voltage, there are benefits to that. I do recall someone who used 12V batteries in a car like yours with tight space and got pretty good range from it.

Higher voltage = less amperage. Less amperage = smaller wire. It also means the pack will be able to provide more power since it is delivering less amperage. Read about Peukert effect which you likely already know about. Going from 6V to 12V you double the watts (power) delivered for a given current flow (amps). So from 8 to 12 you'll get 50% more power per amp. Formulas are below to calculate this.

You will benefit from two electrical formulas if you will understand them well. Watts = Volts X Amps. So you can see higher volts will deliver more watts for a given amp. 12V at 1A = 12W. [email protected]=6W. And all that means less Peukert loses.

The other formula is Volts = Amps X Resistance. So if you know the Voltage and Amps you can divide it to find the resistance. For voltage loses in wire, you can calculate it Vloss = Amps X wire length X ohms of resistance per foot.

Good luck and I reiterate, go with as high a voltage as you can while not exceeding the device requirements (controller, DC-DC etc). I think you'll be pleased with the results.

Another tip. Reduce weight wherever you can. I figured on my S10, each pound requires about .1watt to move. So every 10 lbs you can eliminate will reduce a watt per mile. Use Allow wheels and narrow tires, aluminum battery racks if you can, if you can learn to do carbon fiber, it's a lot like doing fiberglass but much stronger. Aluminum bolts will help in non critical fastening situations. Get a CF hood or other body parts. Use aluminum wire, it weighs a boatload less than copper but go a size larger than you would with copper. Got to go but I may add more later.

Thanks for your help!! i wrote down those formulas u gave me in a book, and i understand what you're saying by using the 12v batteries, i looked up the peukert effect. I would be saving money on batteries too! but then again i would probably be paying a lot more in higher voltage equipment

I have a few newbie questions, for my power steering would i be able to just leave that in the car and drain the fluid or something and use it as manual steering without having any problems or buying anything?

for dc-dc converters i understand from reading the book that i wouldn't need an accessory battery, but i read on descriptions and the forum that people use them with a battery, how do i know which one to get where i wouldn't need to use a battery?

Are power brakes mandatory? lol

what the difference between a 0-5K pot or 0-5V pot box lol? and a sw200 main contactor is what i would need? im not exactly sure how to pick all these parts

Here is the cheapest setup i can find on the internet that i have settled for please tell me if this combination will work.

AMDx91-4001 motor 1,111$ tax and shipping included apparently 72-144v.
Kelly kdh14300a 24-156v series/pm controller with 0-5k potbox 790$ tax n shipped included. Together thats 1,901$ buckaroos i searched all day long and its the best deal i can find! these will be the basis for everything else i need.

However i read somewhere that its a bad idea for the x91-4001 to do 144v so i was thinking of doing 132v with 11 x 12v trojan scs200 batteries or something similar with this setup. My curb weight is 2730 ice stock. the ice itself weighs 380 pounds. The 11 batteries would weigh 660 pounds. I'm wondering what kind of range i could expect from this setup and if its worth it.

Well this is what i have come up with thus far, can anyone tell me if this plan is a good or bad idea? i want your inputs before i purchase anything, i don't feel knowledgeable enough yet to spend all this money if i haven't a clue what i'm doing

However i read somewhere that its a bad idea for the x91-4001 to do 144v so i was thinking of doing 132v with 11 x 12v trojan scs200 batteries

Click to expand...

I think there is no problem with using the ADC motor at 144V, so 12 12V batteries. I haven't heard of the Trojan scs200 batteries. Ensure you are using deep cycle batteries made for traction applications such as golf cart batteries, or they will only last a year or two, cheap ones even less. The Trojan T-1275 12V, 150Ah, battery is one 12V example.

If you roughly estimate about 300 Wh/mile for your car at 50 mph, then 50 miles range requires about 50*300 = 15 kWh, and a pack of about 50*300*1.3 = 19.5 kWh (The extra 30% is so the pack is only discharged about 70% of its total capacity for longer battery life). Lead acid batteries have a significant Peukert effect which lowers their useful capacity at higher discharge currents (due to power dissipation internal to the battery). At 50 mph it takes 6/5 minute or 0.02 hr to go 1 mile. Assuming 300 Wh/mile and dividing by 0.02 hr gives a required 15 kW power to move the car at that speed. If you use a 144V pack of T-1275 batteries, that means you draw about 15,000/144 = 104A (neglecting voltage sag). The capacity of the T-1275 is about 90Ah at 100A to 120A discharge current (Peukert exponent 1.192). So with 12 of them you have about 144V*90Ah*0.7 = 9 kWh of energy available, but you require 15 kWh for your desired 50 mile range. It is just a rough estimate, so you might do a bit better, but not close to your goal. Fifty miles at 50 mph is going to be very difficult to achieve with lead acid batteries. People that get range in this ball park with lead acid usually convert a small pickup truck, and load it up with 24 T-145 6V 260Ah (Peukert 1.159) or T-125 6V 240Ah (Peukert 1.176) batteries. These weigh 72 and 66 lb each respectively, so a lot of weight for your car, not to mention space. If you could handle 16 T-145 batteries for 96V, you would require about 156A current and have around 175Ah useful capacity, so 96*175*0.7 = 11.7 kWh, so about 50*11.7/15 = 39 mile range (96V would be ok if you don't require fast acceleration to 50 mph, and don't need to go faster). Getting closer. If you only use 250 Wh/mile, or 0.83x as much energy/mile, you would only require 0.83*15 kWh = 12.45 kWh, so you would be at about 94% of your goal for range with the 96V pack.

I'm just trying to set realistic expectations for range, and show you some sample calculations. If you can do with less range, or fit more higher Ah batteries like the T-145's your conversion will work for you. If not, you will likely be disappointed. Some others here who are using lead acid batteries may give some real data on their range to give you some calibration (I use LiFePO4). Be careful with ranges given in the evalbum. Many of those are just wags - wild ass guesses - people made before actually using the vehicle. Look for posts with actual measured data. Also check out the "EV Performance" forum for data on range at highway speeds.

You are off to a very good start reading Bob Brant's book and searching the garage and suppliers. Keep it up, and keep asking questions!

I am not familiar with the motor you mention, but I expect that at 2500 lbs it would require around 10 to 12 HP to cruise at 50 mph. It will require much more power to accelerate to that speed. What is the peak power of the motor? Sounds like you might be pushing that little motor. A pack comprised of 30 60Ah LiFePO4 cells is 5760 Wh, and one comprised of 90Ah cells is half again that or 8640 Wh. If your vehicle uses 250 Wh/mile at 50 mph, you need 12.5 kWh for 50 mile range. You won't get that using 70% of either of these pack's capacity (the Peukert exponent for LiFePO4 is very close to 1 so you don't need to worry about that). You need about a 18 kWh pack for 12.5kW useful energy. You could discharge to 20% SOC rather than 30%, but I wouldn't recommend it. You could use, for example, 35 160Ah cells for a 112V and 17.9kWh pack, with 12.5kWh useful energy. These are just rough numbers since I don't know exactly what Wh/mile your vehicle will use. Again, check the "garage" here and www.evalbum.com for vehicles similar to yours (similar weight, drag coeff, and cross sectional area) to see what range and/or Wh/mile they get to calibrate yourself.