General EV Questions and Answers. (noobs, come here first please)

I will be adding to this as we get more posts on the site, but for now its bookmarked. If anyone has anything to add to it, post in here and I’ll update it to the question and answer list on here.

Q:What is an EV?

A: An Electric Vehicle, typically run off of big batteries almost like an RC car but bigger.

Q:What is easier to start off with, a Manual transmission car or an Automatic Transmission?

A: Manual Transmission because you dont have to worry about programing for shift points or excess weight that you would normally have to deal with.

Q: What are the goals for an EV to be able to remain practical?

A: Light weight, proper power to weight ratio, decent range, reasonable recharge time, and realistic cost.

1 Like

what kind of electrical requirements are there for your home . I haven’t seen alot of discussion about this . i.e. does it matter how many amp supply your home has ? i know more is better of course but is there a limit ?
can you charge with a 110-120 outlet or you need 220-240 ?
I forget what the line going to my garage is but I think it’s rated @ 25 amps thats probably not going to work is it ?
thanks
DD

My ZENN EV plugs into a 110 volt, 30 amp circuit in my garage. Haven’t had a single problem with it - although I did dedicate this circuit for use ONLY for recharging. I could foresee a blown circuit breaker if too many applications were using this same circuit. This way, a potential problem was avoided.

I’ll try not to make this too lengthy

My dad and I are trying to convert my car from a combustion engine to an electric motor.
We are using a 36v fork lift motor. And we plained on using three series of three 12v batteries in parallel.
Sorry that last sentence was kind of confusing

                                                       ---[=]--[=]--[=]---
                                                   --!---[=]--[=]--[=]---!---   (like this)
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But anyway I’m using a controller that needs 400 AH. The 12v batteries that we where going to use put out 85 AH each. I got to thinking and I think that three batteries in series will still put out 85 AH. If thats the case then with the AH of the 3 series will total 245 AH which will mean that we are 155 AH short.

If we do come up short i don’t know what that will affect. The three possibilities that i can think of are that it ether
Wont work at all
Work until the starting juice drops bellow 400 AH
Work but not obtain its maximum rpm

Please help
and Thanks for your time

All of my equations and coefficients came from the book
"Build Your Own Electric Vehicle" by Bob Brant (If you wanted to know)

I’m trying to calculate the amp draw for a hypothetical scenario for
a car that should weigh about 2,000 lbs
can make it to 75 mph
run for 25 miles
and use a 72v system

I decided to calculate how many watts it would take to maintain 75 mph

To maintain 75 mph the motor needs to run just enough to counteract wind resistance and the drag from the weals

Fr = CrWcos@ (pretend that “@” is theta or phi, whichever you prefer)
Fr is the rolling resistance force W is the weight
@ is the angle of your tires which will be 0 (we are not turning)
and Cr is the Rolling resistance factor (which the book stated was 0.018)
so i got
Fr = (0.018)*(2,000)*cos(0) = 36 lbs

Fd = (CrAV^2) / 391 (that is "(CrAVV) / 391")
Fd = aerodynamic drag V = speed
A = area of the front of the car (which i measured to be 17.5 ft^2)
Cd = coefficient of drag (which was given to be .42)
so i got
Fd = ((.42)
(17.5)*(75^2)) / 391 = 105.7 lbs

Total force = 141.7 lbs

HP = F*V / 375
so i got
HP = (141.7 lbs) * (75 mph) /375 = 28.34

W (“W” now means watts) = HP*745.7
so i got
W = (28.34) * (745.7) = 21133

A = W/V (V is volts)
so i got
A = (21133 ) / (72) = 293.5 amps

I don’t know if all of this equations are accurate or not. If you have a better way to calculate this or any other comments; they are welcome.

And if my math is right; can i run a 72v motor with six 12v batteries. That are rated at 125 AH each. I guess my question is, will six batteries with 125 AH each put in series run a motor that takes 294 amps.

I would be great full for any comments on this post, Thanks

a comment would be nice

at this point I would settle for “hello”

The Trojan T-1275 deep cycle will give you 150 ah @12v. Many guys are using them for EV. At 82 pounds and about $145 - $175 each, they can’t be beat in lead acid that I’ve seen. They do required a little maintenance - water, cleaning, etc - from time to time but the sealed L.A. batteries are only about half the capcity and about the same price. LiION is about 10x the price for only 1/3 the wieght…
http://www.plymouthbatterycentre.co.uk/battery-products/leisure_battery_and_caravans/t-1275_plus_deep_cycle_battery/

On 75 mph, I’ve never seen an EV do that speed on 36 or 72v systems. Your motor is 36v but you are going to run it at 72v ? I see where you have a 36v motor but then talk about a 72v… everyone I’ve seen going for 75 mph use at least a 144v system. If you are going to buy a new motor - consider the 9.2" Avanced DC motor, and as far as a controller, I like the Zilla Z1K-LV
http://www.evparts.com/prod-CT2510.htm

More important than all this, what vehicle ? They have a great deal of variance in wind resistance. My Jeep Rubicon is about as good a candidate as a 1972 Cadilac - simply too much energy to get it down the road. You will have much better luck with something that already can get 25 - 35 mpg with the ICE. A Saturn, Escort, Fiat 128, Subaru 2 wheel drive, Jetta - these all are light and have fairly low rolling resistance, PLUS both a trunk and engine bay to place your batties. You need to divide them between front and back if you want a stable car at high way speeds.

Oh, one more thing, if you want the best efficiency, look for a donor car with manual steering and a manual trans. Even manual brakes if you can find this - the electric vacuum pumps are hard to get for less than $300 (switch and pump).

I didn’t notice in your calulations a cut for efficencies - like a 10% loss due to various losses. Something to consider.

Thanks that sounds great

I know that the batteries are rated at 150 AH, but do you think that this Trojan battery can put out 300 amp for about 1/3 of a hour.

Well, the 150 ah is for a 20 hour rate, and the fastest they show a spec for is 56 ah for 102 minutes. The thing about higher discharge rates is they generate heat on the plates and reduce the life of your battery pack. If you want 300 amps for half an hour, I’d use double the T-1275, but maybe use a smaller stack… Your vehicle would limit how much lead you can haul. The Ranger EV had the batteries where the trans / drive shaft were - loaded from the bottom. I hope you read about NOT putting the batteries in the passenger compartment for various reasons (collison hazards, hydrogen gas, etc)

Why do you want 300a for half an hour ? That’s a lot of juice !

this car is really for my dad

I’m going to convert my own car soon. But my dad lives in Dallas, and really wants to get on the high way. 25 miles in Dallas by side streets would take a very long time.

To be honest we got a refurbished fork lift motor for free. Its a 36v motor though. We want to crank the voltage as high as we can (but i don’t think will get to more that 72v Max) After i started my calculations, I began to think that we need to at least move on to a 144v system.

Do you think we could get away with using 2 series in parallel. That would be about 150 Amps. I still think thats to much what about you.

Oh and Thanks a ton

If you got 12 of the T-1275, you would have 144v (Actually a tad higher) at 150 ah - that would be a single series stack and give you the speed / range you are looking for. But I don’t think the forklift motor could dissipate the heat even if the commutator didn’t arc.

Is there some reason you want to use the 75 ah batteries rather than the T-1275 ?

no there is no real reason. so to get the speed and range i want i need to go with a 144v. And yes, i think your right we are probably going to have to by a new motor.

I said earlier that I’m using a fork lift motor

the thing is huge. it is 10" in diameter and I want to say that it was 12" long but that does not sound right. I think it’s longer than that. (It’s being refurbished right now or else I would check)

Would anyone know why it would be so big. It’s made for a 36v system so it can’t be to keep it form sparking. It can’t be to save money in production because metal is expensive, and using so much would just be a wast. Since the motor uses magnetism as its power source. It would seem to me that the closer the the coils are to the shaft the better. So long as they are not so close that they are sparking. There has to be some advantage to the design. maybe it’s for ventilation???

the motor is 10" in diameter, and 14.5" in length.

After giving it more thought I can think of only two resons why it would be so big.

It has more winding

and / or needs more cooling room

Any thoughts

I know that you want a light weight vehicle (such as a Chevrolet S10 or compact car) but I live in Canada and I prefer to have 4x4 for icy road conditions. What kind of a loss am I looking at for the transfer case, drive shaft and front differential. I would not be driving it in 4wd all the time, just in severe & hilly conditions.

Here were some original choices of vehicle I was planning on converting. Primary need was 4 doors and lots of storage, secondary need was having a 4x4 for the winter.

Jeep Cherokee = 4600 lbs

Crewcab Sonoma = 5150 lbs

Blazer = 4800 lbs (These are really cheap now, I guess because they always break down)

Grand Cherokee = 5400 lbs ( A little more room, luxerious interior and better styling) I am over 6’ so the Cherokee/Blazer/Sonoma are a little tight for me.)

Suburban = 7300 lbs (The idea I had with this one was, there would be a ton of room to put batteries in, but it is much heavier then even a Jeep XJ or ZJ which knocks it off my list)

I think I am going to be doing a Jeep Cherokee (XJ) conversion. But if I can find a cheap Grand Cherokee (ZJ) then I will do that.

Has anyone every thought about or tried having a seperate battery pack and swapping the packs out if you had to do alot of driving, or even doing a trailer system where you can put batteries in the trailer so you can go even further. The thought came to me while researching EV’s.

Cdn wheeler I live in B.C. up a twisty mountain road and I say this to lots of people. “4x4 is not needed unless you are 4x4ing” if it’s paved or gravel and plowed with good tires you can go anywhere you need. I installed a locking differential on my ranger and it goes amazing places on ice, snow, dirt, gravel…

Just a thought to keep the weight down.

Everyone of the vehicles you listed would be a financial and performance disaster for an EV conversion. If you can’t go with a good candidate (VW Rabbit, S10 Pickup, etc.) you probably should just forget it.

Why do you need 4X4? Doesn’t the highway department keep the roads cleared during the winter months?

[QUOTE=Canadian_Wheeler;4482]I know that you want a light weight vehicle (such as a Chevrolet S10 or compact car) but I live in Canada and I prefer to have 4x4 for icy road conditions. What kind of a loss am I looking at for the transfer case, drive shaft and front differential. I would not be driving it in 4wd all the time, just in severe & hilly conditions.

Here were some original choices of vehicle I was planning on converting. Primary need was 4 doors and lots of storage, secondary need was having a 4x4 for the winter.

Jeep Cherokee = 4600 lbs

Crewcab Sonoma = 5150 lbs

Blazer = 4800 lbs (These are really cheap now, I guess because they always break down)

Grand Cherokee = 5400 lbs ( A little more room, luxerious interior and better styling) I am over 6’ so the Cherokee/Blazer/Sonoma are a little tight for me.)

Suburban = 7300 lbs (The idea I had with this one was, there would be a ton of room to put batteries in, but it is much heavier then even a Jeep XJ or ZJ which knocks it off my list)

I think I am going to be doing a Jeep Cherokee (XJ) conversion. But if I can find a cheap Grand Cherokee (ZJ) then I will do that.

Has anyone every thought about or tried having a seperate battery pack and swapping the packs out if you had to do alot of driving, or even doing a trailer system where you can put batteries in the trailer so you can go even further. The thought came to me while researching EV’s.[/QUOTE]

Weight, Cold and Drivetrain Friction would be a killer for an EV.

If the ICE counterpart vehicle is 5500 pound, four wheel drive high HP engine and poor mileage <15 MPG than you are looking at a poor choice for EV conversion.

Unless you have found some new energy storage method, weight vs power problems on a conversion like this would kill the project.

As for your question about swapping the battery packs after after one is drianed. Well you don’t need to do that; you could wire two series of batteries in perallel to get the same range. No, I take that back. You would get more range becuse the load of the motor would be distributed across two battery strings. So, the two strings won’t heat up as much. Therefore the wire and batteries would have less resistance, and your batteries life would be extended. I can explaine any of this in more detial if you want.

I don’t mean to crush your dream (I do think this can be done). But, EV’s don’t like weight, and EV’s hate the cold. You will also have to acount for the hills.

I think that this can work, but you will have to plan for these conditions. You are going to want a car with as little weight as possible. And if you are using a heavy car. Then you are going to want to strip out as much wheight as you can. And not that I think that any one would do this, but drilling holes in the frame to reduse wheight is not a good Idea. You are going to have to make sure that the car will have a high preformance to acount for the hills. And you cannot let the batteries freeze.

I’ll help you with the calculations and / or resurch if you want me to, but I’m going back to school (I’m still in HS), so after a few days I won’t have as much time, and I might not cheak in as often.

Hope I can help

I was wondering if anyone on this forum posts the hard drawings of their plans. More so to help visualize what is going on. I was hoping to see this to help people like me who are more of a builder. I dont fully understand electricity. Is this a possibility? Can we get a visual diary of some sort?