12 volt overcharge?

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New member
May 29, 2010
I have a 2010 Mountaineer. I have installed 3 solar panels 110W each. The charge controller is a Solar Boost 2000E by Blue Sky Energy. The batteries are Trojan Golf Cart. Trojan says the charge controller should be set at 14.8 volts to sufficiently charge the batteries. This last winter the system worked great. I was preparing to head out this year and have discovered that the water pump is damaged. The pump runs non stop, pressure switch does not seem to work, and the pump was covered with a very fine black powder. The fact sheet that came with the pump (Shurflo 4008) says that the proper voltage with the pump operating can be + or - 10%. This would make a window of 10.8 to 13.2 volts. My question is Would the pump be damaged if operated during the period the batteries are at full charge ie 14.8volts? Is it possible to get a voltage regulator? Any help or ideas would be greatly appreciated.

John From Detroit

Well-known member
Apr 12, 2005
Davison Michigan
13.6 +/- 10 percent,, It's never 12 volts.

And no, the pump would not be damaged by a slight over voltage,  In fact I do not thing 18 volts would damage it.. 30 might, but I doubt it.

If the pressure switch is not openeing then either it is stuck or there is another issue with the system.  But if the pump is running it was not damaged by overboltage.


Well-known member
Jun 25, 2006
Jonesboro Arkansas
Take switch apart , more than likely spring has lost tension or corroded an switch may just be Bad. Was pump winterized? mostly when a pump freezes it gets end pump where the switch is most likely to break, even though pump will still run bypass switch and see, their a rotary pump an pretty simple desine an will run very long time no water, but voltage nota problem unless AC power went throuh it !  Good Luck hope this helps somewhat,,,,, Rodney ,,, ;)

Gary RV_Wizard

Site Team
Feb 2, 2005
At our Silver Springs FL home
A "12v" pump will be designed for normal 12v system use, which means that voltage can range from 10.5v to at least 14.0v. I doubt if voltage is/was your problem. And if it was, the pump motor would almost surely have burned out and it wouldn't run at all.

A common reason for the pump not shutting off is that a valve which allows water to flow from the city inlet to the fresh tank has been left open. The pump is taking water out of the tank and pumping it right back in.  Other possible reasons are a leak somewhere in the system, a clogged pump inlet screen, or a failed pressure switch in the pump head.


Well-known member
Feb 20, 2008
NAS Pensacola, FL
In addition to what has been listed above, running a pump with a loss of suction (no water) could cause the pump to wear.  If this occurred, the pump may not build up sufficient pressure to trip the pressure switch.  Does the pump put out adequate water flow when it is pumping?  JM2?...

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