# Can I put too many volts to an AC controller



## stealthE (Jan 31, 2016)

Ill be using an AC51 and the curtis controller rated for 144 volts. I assume that means my pack should have a max voltage of 144v...not a nominal voltage of 144 right?

What happens if I had - say 165 volts?


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## major (Apr 4, 2008)

stealthE said:


> Ill be using an AC51 and the curtis controller rated for 144 volts. I assume that means my pack should have a max voltage of 144v...not a nominal voltage of 144 right?
> 
> What happens if I had - say 165 volts?


I bet that information is in the manual.


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## Vanquizor (Nov 17, 2009)

Max voltage and nominal voltage are 2 separate specifications. As Major said read the manual, I'm pretty sure 144 is your nominal spec.

Exceeding max voltage at best causes the controller to shut down protecting itself and at worst results in smoke and fire... I wouldn't do it unless you know what you are getting into.


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## Caps18 (Jun 8, 2008)

Yes, yes you can. For the 96V one, it is safe to put in 120V, but 130V or more will fry it from what I've been told. The 144V one has similar limits. Ask HPEVS about it, I'm not sure the manual comes out and says it plainly though.


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## galderdi (Nov 17, 2015)

The Curtis manual confirms the nominal voltage is 144V but does not mention an upper limit. This is probably an effort by Curtis to manage liability. I did get a response from Curtis saying my 155v source (when fully charged) would not be a problem.


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## major (Apr 4, 2008)

galderdi said:


> The Curtis manual confirms the nominal voltage is 144V but does not mention an upper limit. This is probably an effort by Curtis to manage liability. I did get a response from Curtis saying my 155v source (when fully charged) would not be a problem.


Can you supply a link to the manual you used? Thanks.


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## galderdi (Nov 17, 2015)

This is the one I used for my controller. I am not certain if we are talking about the same controller.

http://www.google.com.au/url?sa=t&r...yN__LyaiATkiHm698YQExQ&bvm=bv.115339255,d.dGo


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## galderdi (Nov 17, 2015)

Also here is the response I received from the vendor (These are NOT my words):

All Curtis controllers are rated to take nominal battery pack voltages which run about 10% higher than stated voltage. So, the 144V battery pack is expected to have a fully charged peak voltage of about 10% greater than the stated pack voltage so you’re in the clear using the 144V battery pack.

The controller design also has an overvoltage protection circuit which is 20% higher than the rated battery pack voltage. If you try to operate the controller with too high a voltage, the controller won’t function till the battery voltage is brought within operating range.


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## tomofreno (Mar 3, 2009)

Max is 170V:

http://www.diyelectriccar.com/forums/showpost.php?p=308903&postcount=18


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## major (Apr 4, 2008)

tomofreno said:


> Max is 170V:
> 
> http://www.diyelectriccar.com/forums/showpost.php?p=308903&postcount=18


Yes tom, I saw that on the data sheet. 



> MODEL CHART
> SYSTEM ACCESSORIES
> Model Nominal Voltage (V) Max Voltage (V) Min Voltage (V) Peak Current S2–60 min Current
> Power Logic Power Logic Power Logic (Arms) (Arms)
> ...


I was looking for the manual which does not appear to be available on-line.

major


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## major (Apr 4, 2008)

stealthE said:


> Ill be using an AC51 and the curtis controller rated for 144 volts. I assume that means my pack should have a max voltage of 144v...not a nominal voltage of 144 right?
> 
> What happens if I had - say 165 volts?


Yes, the manual for your controller will have this information. I have used a number of DC and AC controllers, both EV and industrial, and all the manuals have this information. Unfortunately I cannot find the manual for the Curtis 1239 on-line. The manual for the 1238 is and I have it. It does cover the subject, but the 1238 is not rated at 144V. I suspect much of the other info is common between the 1238 and 1239, but I have not actually used the 1239, so just a guess. You can locate and view a data sheet by Curtis for the 1239 which states the maximum voltage is 170.

To answer the title of this thread: Of course you can put too many volts to an AC controller. You may damage it. In most cases, if the applied voltage is higher than the upper limit of the controller, the controller will not turn on and register an over voltage (OV) fault. Since it may not turn on, you may not be able to view the fault code until the next time. It is likely that a voltage could be high enough to damage the controller even though it attempts to protect itself by faulting, but I suspect such a voltage is quite high, although a spike can do the damage.

Often there will be settable parameters where the user can set the OV and UV trip points within the limits of the firmware of that particular controller. This can customize the system to a certain battery or other limiting feature.

major


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