I was wondering what 36volt bilge pump float switch people liked. My boat was origionally using 12-32v standard float switches but I just killed two of them so I need to find a 36v one.
The voltage should not be the problem. Look at the motor rated current draw. It is very likely that the bilge pump motor current is significantly greater than the switch rating.
The problem could be that the bilge pump motor is having issues. Could be something wrapped around the impeller shaft or windings that are shorting.
It could also be that you are not using a switch with the required current rating.
Thanks for your response. This is for a very old diaphragm bilge pump, and I'm not sure what it is rated for. The pump is working fine if I switch it to automatic mode and bypass the float switch. Talking to West Marine and searching online I can't seem to find many alternative float switches that might allow for a higher draw. I'm going to try the below one (unless anyone has another suggestion).
Your float switches might be being damaged by contact bounce. diaphragm pumps tend to cause a rippling in the bilge between strokes triggering the float switch. this will cause contact arcing. 32VDC is much more susceptible to this than 12VDC.
A couple of possible solutions. First I would suggest putting an arc suppressor across the float switch contacts. This will prevent an arc from occurring when the switch opens.
Another solution for switch bounce is to use an off delay timer. This would allow the bilge pump to run for a selectable amount of time after low level is reached. It also makes the float switch as only a sensor device and not a current carrying device.
These are not expensive items and will likely resolve all of your issues.