72 Volt controller max voltage??

[construct]

Hi I have a 72 volt controller from http://www.theebikemotor.com . Its lable says 72V and 35amps +/-1. It came with a 1500 watt hub motor build. I've found the low voltage cut off to be 63.0Volts. I've run it at 18S LiPo which gives 75.6Volts peak and 61 km/hr max on flat level ground. What is the maximum Voltage and if I exceed it will it destroy the controller? I've attempted to contact Sunrise Intl but no response and nothing in the manual. Thanks!

 

[nutnspecial]

Hi, usually those have 100v caps. If you want to confirm you can open it and check the part numbers. 100v caps get sketchy as you get towards 100v, especially pushing amperage too. I'd feel safe with 22s, and some guys use 24s I think.

 

[wesnewell]

My cheap 72V controller came with 100V caps and fets. I've been running it for ~5 years now on 24s charged to 100.8V. ymmv.

 

[dogman dan]

I have heard 90v to be a good upper limit. By that I mean 90v while using it. After all, charge to 100v, and soon enough you will be running in the 90v ballpark.

22s works good for that. I'd call 24s the max.

 

[construct]

Great thanks everyone.

What about the 48V controllers what is their max Voltage? I have 1000W and 1200 W motors, both controllers say 48V but no max. I've run them at 58.8 V peak.

 

[wesnewell]

If you have an lcd display, that usually limits it to 60V. Usually 63V without it.

 

[dfarning]

It is hard to give a good answer to this question because "it depends." The capacitors and FETs (Field Effect Transistors) are usually the limiting components in a controller. Vendors try to put in the least expensive components that will last the expected life of the device. Semi truck engines will last 100,000 hours while a weed wacker will only last 100 hours.

The two critical factors for Capacitor and FET failure are over voltage and heat. All else being equal, higher voltages and higher temperature tend to cause these components to degrade and fail more quickly.