# Newbie controller question



## ultbug (Sep 4, 2009)

I have a controller that is rated for 72 volt 350 amp. Is it necessary to put 72 volts to the controller in order for it to work properly?

I read somewhere (not on this site) that it is necessary to have the proper number of volts put to a controller that it is rated for. For example 24 V system for a 24 volt controller or 36 V system for 36 V controller. 

So in the end I plan on running a 48 Volt system with my 72 volt controller. Is this possible?


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## Guest (Sep 15, 2009)

Usually you can run less than the rated voltage. To power the controller you will need either 12 or 24 volts. My Synkro requires 12 and my Golftech requires 24. That is just to power the controller computer. The controller should actually run fine with 24 volts running to the motor. 

I am sure some controllers are voltage specific but many will run less. So your 72 voltage controller should power up with 12 or 24 volts and should run fine pumping 24 volts through it. My Kelly is like that too. 12 to powerup and 24 to 72 volts to the motor. 

Pete


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## major (Apr 4, 2008)

ultbug said:


> I have a controller that is rated for 72 volt 350 amp. Is it necessary to put 72 volts to the controller in order for it to work properly?
> 
> I read somewhere (not on this site) that it is necessary to have the proper number of volts put to a controller that it is rated for. For example 24 V system for a 24 volt controller or 36 V system for 36 V controller.
> 
> So in the end I plan on running a 48 Volt system with my 72 volt controller. Is this possible?


Hi ult,

Read the manual. 

It depends on the particular controller you have. A lot of controllers work over a wide enough range to cover 2 nominal battery voltages. Like the old Curtis 1204s. I have which covers 24 and 36 volt systems and another good for 36 and 48. But the 36/48 volt controller will not work on 24.

Some of the newer types I used are actually programmable for a specific voltage over a range. But you need a programmer or PC pack for those.

Off hand, I'd say a controller made for 72 volts is not going to work at 48. But it probably wouldn't hurt to try. Going lower in voltage is unlikely to blow anything up (going higher in voltage probably will), and it could work, but give you nuisance trips when your battery sags down in voltage under load.

Regards,

major


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## Guest (Sep 15, 2009)

My Zapi requires a programmer to use different voltages. Ugg! My Synkro does not. My Kelly does not. I have used my 72 volt Kelly with 24 volts and 30 volts without having to program the controller. My Golftech was only used with 72 volts but I suspect I could use 24, 36, 48, and 72. I just need the proper 24 volts to power the controller functions. Not programmable. Yes, some are rated with like two different voltages and you need to use those voltages, none lower or higher. Lots of different types. Ask the manufacturer what the voltage ratings are for a particular controller you are interested in buying. 

Pete


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## kek_63 (Apr 20, 2008)

The Alltrax progamable controller AXE7245 will work down to 24v. What controller are you using?

Keith


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## ultbug (Sep 4, 2009)

I originally set out for an electric car project but I have move to and electric motorcycle project. I have two Gem Cars that I am trying to use for parts and the controller I am using is a *GE IC3645SH7R353T2. *I would like to run a 48 volt system for the time. An yes for the time I will be using the motor out of the Gem Car. Only 3.5 HP but I am looking for a very inexpensive project to gain some electric car experience before I tackle something a little more difficult.


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## major (Apr 4, 2008)

ultbug said:


> I originally set out for an electric car project but I have move to and electric motorcycle project. I have two Gem Cars that I am trying to use for parts and the controller I am using is a *GE IC3645SH7R353T2. *I would like to run a 48 volt system for the time. An yes for the time I will be using the motor out of the Gem Car. Only 3.5 HP but I am looking for a very inexpensive project to gain some electric car experience before I tackle something a little more difficult.


Hey ult,

Your best bet would be to run 72 volts. Batteries come in all sizes. So instead of 4-12V 20 pound batteries, use 6-12 V 13 pound batteries. You'd get about the same energy (range) and likely cost you about the same (dollars). 

I'm not sure about this GE controller, or the GE motor either. Might be series, could be SepEx. But from my experience with GE products, I imagine these are custom designed for the Gem application. And you'll never get any help trying to alter parameters. Don't get me wrong, GE makes some excellent products. But in their motor/controller business sector, they are not user friendly, by a long shot.

Regards,

major


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