# Curtis 1231C modification question - Add more batteries



## CPLTECH (Sep 14, 2007)

Curtis 1231C modification question 
I was thinking (dangerous, I know) that to increase batt pack voltage from 120 to 144, it would require an upgraded controller at almost $2K, but it would improve motor performance. However, this electronic mind of mine was looking for a solution that did not require the $2K. What IF we just added the additional batts between terminal* B+ *of the controller and *A1 *of the motor? Would it work? Has this been tried before? To me, it appears that only the motor would see the voltage and not the controller. There may be a slight(?) jerk (time to use the clutch) when controller is told (by potbox) to energize and the additional batts are out of the circuit until then. Am I overlooking something?
Unable to insert a schematic diagram.


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## Greenflight (Sep 13, 2007)

Hmmm... The batteries would still be in series with the controller. It would still have to switch the entire power of the pack. Don't know what effect it would have on noise though.


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## Twilly (Jan 22, 2008)

The controller is converting DC to a pulsating 15K hz to control the speed of the motor... I think the batteries in series would act as caps and smooth the pulsations, and eliminate the speed control, or destroy the batteries in series.

I just bought a curtis 1231 for $1400 ( i know, still alot o money ) But I think it might save you in the end... Also, some dist sell a 1231 rebuild kit for $800, might have all the parts to upgrade your controller to 144V?


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## Greenflight (Sep 13, 2007)

Caps in a controller are installed in parallel with the motor. The batteries are in series with the motor so the current through them will be the same as the current through any other batteries in the pack. It should be the same as adding batteries on the other side of the controller.


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