Can anyone offer some rules of thumb for making your conversion have good acceleration and speed?
volts = speed
amps = torque
so, the more volts and higher amps the battery pack… the more acceleration and top speed you get.
Basically cram the vehicle with as much power as you can afford, make the vehicle as light as possible, and put a high torque motor in it with a controller to match. In the end, it has more to do with the batteries being able to source enough current and voltage.
Thanks frodus,
usually i only notice the AH ratings on batteries, is there a way to tell what the max amp throughput is, do you have to contact the manufacturer?
For a basic personal commuter vehicle, let’s say 3500lb post-conversion weight, do you know what a good torque would be for a motor? I don’t actually need a racing car, but I want it to keep up with the flow of traffic. Hopefully a happy medium somewhere between my current 4-banger and a V6 would be nice. Top speed would be fine at 65mph.
I have been thinking of 192V pack of 8V golf carts(and Azure AC system, AC24LS/DMOC445). Like many others, I want a decent range too.
[QUOTE=naiche;5336]Thanks frodus,
usually i only notice the AH ratings on batteries, is there a way to tell what the max amp throughput is, do you have to contact the manufacturer?
For a basic personal commuter vehicle, let’s say 3500lb post-conversion weight, do you know what a good torque would be for a motor? I don’t actually need a racing car, but I want it to keep up with the flow of traffic. Hopefully a happy medium somewhere between my current 4-banger and a V6 would be nice. Top speed would be fine at 65mph.
I have been thinking of 192V pack of 8V golf carts(and Azure AC system, AC24LS/DMOC445). Like many others, I want a decent range too.[/QUOTE]
look up the datasheet on the battery you’re buying. There should be some sort of PDF document on the battery.
Not sure what you’d need for that vehicle, too many unknowns. You don’t say what speed, what acceleration… what range.
if you can AFFORD an AC system and 192V, then go for it, it’d be a great match. Thing is, its going to cost you at least 20grand for the AC system… without batteries or donor car.
My donor car is a 1969 Datsun mini-pickup.
If I could have it my way, I would like:
-at least 65mph top speed
-at least 0-60 in 10secs.
-at least 80 miles range
Of course, I understand that sacrifices are inevitable, so a compromise might look like:
-60mph top speed (I don’t do a lot of freeway driving, but when I need to, I should be able to keep up with the flow, at least in the slow lane.)
-0-60 in 14secs (Like I said I want to be able to keep up with traffic, in the city, it can be dangerous to not be able to accelerate at times.)
-70 miles range (I really NEED at least 60miles for my commute, i just want some padding for deterioration of pack over time)
As far as pricing is concerned, on Electro Automotive’s site, they price out the motor at ~$2500 and the controller at ~$3500. So, I was thinking that I might be able to get the entire conversion done for less than 20 grand, hopefully around 15.
US Batteries 8Vs are ~$125 (x24=$3000). I think I can get the rest of the misc parts for about $5000 and then parting out some of the work, such as welding, etc. will be a little more cash.
good prices on the AC stuff…
How much do those 8V weigh? times 24? thats alot of weight… what, 1600lbs?
thats alot of range needed though… and lots of weight for a little pickup… even if you DO remove the engine/gas tank/exhaust… 1500lbs is gonna be sluggish.
You might want to start considering lithium if the weight gets too high… it’l drop the weight by 1/3 and increase the acceleration due to less weight.
Also, I don’t have the calculations needed, but estimate what weight with bats minus engine is, you know gravity constant, you can calculate the accleration needed, and then convert force to torque and see what amps the motor/controller draw at that torque rating to see if its possible. Also, you’ll be able to estimate drag…
go up to 60mph, then put it in neutral and time how long it takes to get to 50mph, 40mph, 30mph 20mph and calculate the drag constant. Then you can estimate what HP is needed.
I’m more worried about weight. Not many people have a 20+kWh pack.
frodus, i have to say thank you, your answers are great and thoughtful.
re: batteries
Yeah, you just about hit it, 63lbs*24=1512lbs.
You can see why I am concerned about acceleration. the estimated curb weight of the truck 2200lbs.
Problem is if I go with 12V, I’m going to lose lots of AHs and thus range. Newer battery technologies are out of my price range, and a little too experimental for me. I have pretty much decided to go with Lead-Acid. It’s going to be my commuter car and I want a reliable situation. Everyone knows what to expect from Lead-Acid. It may be boring, but maybe my second EV will have a diff technology. Or my second battery pack may, if prices drop and technologies get a little more stable.
re: ac system
Here’s a link to the motor/controller page.
If you go to their site, you will notice a larger motor for trucks, which I may have to go with(priced at ~$3500 on electroauto.com, but you can look at the specifications. I am not sure how to tell what 87N-m torque will actually translate to. I have heard that you have to multiply HP by 3 to get the ICE comparable power for an EV. I never heard the explanation for that though. Is it similar for torque? Are electric motor torque and ICE torque proportional by some constant?
re: drag coefficient
unfortunately, the car isn’t running, so i may have to get it running before removing the engine, or see if someone else has figured out the drag on a similar truck.
Projected rough weight estimate:
2200lbs (curb wt.) + 24*63lbs. – 500lbs (ICE components) + 121lbs (E-Motor/Cntrlr, 266lbs. if AC55) = 3333lbs (or w/ AC55 = 3478lbs)
You may find this example interesting, he claims he rode this thing for 85 miles on a single charge, just barely. But talk about a slug.
1990 Toyota XtraCab Pickup
What do you think? Am i dreaming?