# I screwed up! Help!



## engineer_Bill (Jun 24, 2008)

Actually 30MPH at 48volts isn't that bad try doubling it and see what you get. How big is the motor DIA? What currnet are you drawing at 48Volts at 30MPH?


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## madderscience (Jun 28, 2008)

3000lbs of battery is about right for such a large vehicle.

yeah, doubling the voltage should get you into the 50mph range. But this is going to mean you will have to upgrade the controller too, and quite possibly things like fuses, breakers, etc. to keep things safe.

Also be cognizant of your motor's RPM limit. 2800rpm is pretty low for a roadgoing EV motor, and over-revving it can lead to a commutator malfunction. (Read: kaboom)

Good luck.


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## electrodave1 (Jun 25, 2009)

Thank you for the suggestions. It is a 12" Dia.


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## electrodave1 (Jun 25, 2009)

Thankyou for the Rev limit alert.


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## FreedomVoltage (Jun 28, 2009)

you can fix it with a good controller and a better battery pack. zilla controllers are top of the line and A123 systems makes a hell of a battery pack, you can probably triple your voltage and come in at around 1000 lbs of battery.. and i'd buy a better motor too.. you can find a good one for about 2000$


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## electrodave1 (Jun 25, 2009)

I would bet when our goals are not met we use the familiar "Its just an experimental" excuse. Thank you for your comments


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## CFreeman54 (Jan 14, 2009)

Dave,

Check Mike's car at: http://www.evalbum.com/1735
It is using a GE 48 V forklift motor too. He is running it at 96 V. He gets 55 mph and is driving 24 miles on about a third of the battery you have (1200 lbs or so). Try increasing your voltage & losing some of that dead (lead) weight and you will be fine. As someone said, you may need a new motor controller to increase voltage, as well as higher rated fuses, main contactor, etc. I know Mike has run his GE motor at well above 2800 rpm and it hasn't blown apart yet. He was running at 144 V for a while but decided to decrease V and parallel the pack to get more range.


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## Guest (Jul 23, 2009)

Keep the motor with in 5200 rpm and you should be fine. The limits on the info tag are for constant use and power. Best power for x rpm at x voltage. Can be run at that speed day in and day out with out ever stopping. You can go up to 120 volts with a timing adjustment and a good controller that will do 120 volts and at least 600 amps. Don't bother with those 400 amp limit controllers at these voltages. Go with a higher one. Looking at specs of those using the under current controllers the top speed is marginal and acceleration is the same. Bump it up a bit and life gets much better. I run only 72 volts but have 550 amps at my disposal and it will do 65 mph. If I had a 400 amp controller I'd be in the 50 mph range. I want the ooomph and I am sure you do too. 

Pete 

If the commutator is clean and the brushes are good and you advance your motor you should do just fine for short bursts with more voltage and amps. You usually only need that for a short time anyway. Also put on a good heat sink to your new controller and put a cooling fan on your motor if it does not have one built in. Use good golf cart batteries. You have loads to choose from.

Time to upgrade. 

Pete


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## electrodave1 (Jun 25, 2009)

Now that gives me some hope. Thanks very much. Dave


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## electrodave1 (Jun 25, 2009)

That gives me some hope. Dave


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