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Discussion Starter #1 (Edited)
Forgive me if this has been discussed to death...

When I planned my current EV project I decided I'd like to keep the weight down. So I thought I'd go with 12-12v batteries for 144vdc. But now the more I learn and the more I think about it, I'm thinking that compared to 96v, 144v will give me a lot of top end speed but doesn't necessarily contribute to range so much, other than adding a couple more batteries.

So I'm wondering if a 96vdc system with 16x6v would be a better solution for my needs? Voltage has little to do with how well it accelerates, right? That's a function of amps, right?

As I understand it, the more voltage that's applied to the motor, the faster it spins. All I need is 70mph top sustainable speed. So is it unreasonable to think that 16 240Ah 6v batteries would give me the required top end but a whole lot more range than 12 150Ah 12v batteries?

BTW, I'm using a 9" Advance DC motor and a Zilla Z1K controller in a 2000 VW Passat.

Thanks in advance for any info.

-Rick Stewart
 

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Look at the motor specs at http://www.electroauto.com/catalog/dcmotors.shtml
This motor at 144V is rated 28.5HP. Reduce the volts to 96 and it becomes a mild, meek-mannered 20HP. My preference is to use the higher design voltage and the amps are less as a result, too.
Industrial motor experts will tell you lowered voltage causes overheating and higher amp draw. Your home appliances always run cooler when provided with the proper voltage from the utility. No matter what system you use, always watch the amp draw, which means slower speeds on hills, lower the top end.

http://www.austinev.org/evalbum/1317
 

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Discussion Starter #4
This motor at 144V is rated 28.5HP. Reduce the volts to 96 and it becomes a mild, meek-mannered 20HP. My preference is to use the higher design voltage and the amps are less as a result, too
Ahh, I see. Thanks for the clarification.

I see on your AustinEV page that you really would like an upgrade to 144v. Sounds like words of wisdom from someone whose experienced an EV. I'll take your advice.

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156 volt works nice
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That would be one extra battery, not a bad solution. I know my Zilla can handle 156v, but I wonder what 156vdc will do to the motor? It's only rated by the manufacturer up to 144v. Any ideas?
 

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Discussion Starter #7
I made a couple of phone calls and it looks as if the ADC 9" can spin to 7000rpm before it grenades. So it turns out I can use 156v or 168v as long as I set my controller's rev limiter to shut off if I rev it anywhere near grenade speed. I can safely use 168V as long as I keep the rpms in a resonable band. But since HP is based on Torque x RPM, max HP won't be affected, but I'll get a little better range with two extra batteries. I found out too that if we were to use 168vdc straight from the battery pack it would burn up the motor pretty easily. But since we run it through a controller it hacks up the wave and the motor really doesn't see anywhere near 168v.

Thanks for the ideas guys. I like the Saturn, Ohio. Looks good.
 

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That's interesting. 7000RPM = goodbye motor huh?
No one you spoke to mentioned what the safe redline of the ADC 9" motor is did they? I've heard they can handle routine speeds of up to 5600RPM.
 

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Discussion Starter #9
Gavin-

We didn't discuss details, but routine speeds of up to 5600 sounds about right. He did impress on me how important it was to never rev the engine in neutral, especially using a high voltage that could cause the motor to spin past 7000.
 

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After mention of NetGain's WarP9, did brief search. Sounds like it is an improvement over the FB4001A for not much more money. Are these the motors that cause tires to need early replacement???

Grandpa w/FB4001A
 

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I think that one of the best points regarding voltage is actually amps.

Basically, for a given power draw, the more volts the less amps. This minimises I^2r losses and the batteries also have less work to do as you are not sucking current from them so hard.

If fitting in all the batteries is a bit difficult you also have the option of going down a battery size. for example 120V @ 105Ah vs. 156v @ 80Ah are about the same pack sizes but the higher voltage should take you further due to Peukerts losses being less.

Higher voltage is better all round in my opinion but someone feel free to correct me on this though...
 

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Discussion Starter #13 (Edited)
Thanks Nick

I was mulling over the formula Power=Amps*Volts. So it seems like if I have 168V and 140A batteries I'll have 23,520 watts of power. So if I decrease my voltage to, say, 72V I'd have to get batteries with 326Ah to have the same peak power. Does this sound right? I've never seen Pb batteries with 326 amps. So am I on the right track for figuring out my battery pack configuration?

I just ordered an eFUN-D 3000 watt scooter for commuting. So this sort of changes my financial situation a bit.

I have a Zilla controller on order and it's going to run about $3000 total with options. Is there any other controller out there that can handle higher voltages (ie:156-190) that doesn't cost so much? If not, I'll have to get an Alltrax and 72V worth of the biggest Ah batteries I can find. Or get a Curtis and try 96V and use the biggest Ah batteries I can find and have to suffer through that horrible high pitched whining sound that the Curtis makes when you take off.

All constructive comments are welcome.

-Rick
 

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I made a couple of phone calls and it looks as if the ADC 9" can spin to 7000rpm before it grenades.

Hey all

Just had to chime in here on this quote
Please do not run the 9"'s that high as they will blow (I've got lots of examples at my shop!!!) I recommend to keep them to a top end of 5K.
Advance "may" have at one point stated a 7K limit but I believe that has been decreased per my noted 5K, if not it should be. Hope this helps someone from being very upset.
Just my two RPM's worth
Cya
Jim
 

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Hi Jim;
As I have stated before I have 96 Volts on my 1971 Bug, and have limited it to that because of weight, Could I go to 120 volts, which is the top voltage my controller (Curtiss) will take. And not have the Bug Bow in the middle because of the extra weight of the Extra two Batteries, about 80 to 90 pounds each ????? And make the motor more effecient and not so prone to overheat , as stated above, or should I just stick with 96 volts ???? :D
THANK YOU Marty
 

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Hey Marty

I took a quick look through the EV photo album and it looks like most the Bugs are only running 96 volts (did find one at 108 volts). I did run accross Don Cameron's Bug that's running 312 volts here:
http://evalbum.austinev.org/556

Not sure what he might have done to get 26, 12 volts in it, but thought you might like a look.
Hope this helps
Jim Husted
Hi-Torque Electric
http://hitorqueelectric.com/
 

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Hi Jim;
THANK YOU for your swift reply, and all the trouble you went thru, I am happy with the help you have provided THANK YOU VERY MUCH!!! :D :D
Marty
 

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Hey Marty

No problem, I kind of get indoor locked during the Oregon winters (AKA from Halloween to 4th of July :eek:) being I'm an old southern California boy! and I'm on my puter a lot (rather be here than watching TV per example).

I'm kind of a hands on, show me kind of guy, so going to the photo album (for me) is a great place to see what others have done and I was able to scan about 8 to 10 Bugs in a few minutes for a basic rundown of what people are able to cram in them (which in general seems there is an issue in weight or space) I've never owned a Bug though and in general not a big time auto mechanic (makes me cuss to much)(when I bust my knuckles, lol,) but wanted to throw out what info I could.
Cya
Jim Husted
Hi-Torque Electric
http://www.hitorqueelectric.com/
 
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