Water Pump and Electrical Gremlin

[BattChief]

First, a little background. Last fall, I installed lithium batteries and solar panels, and a lithium battery isolator. A couple weeks later, my water pump failed, (leaking water) and I replaced it with an AES 3.5 gpm pump. As we were leaving Mini Hoots, my chassis batteries were dead. The result was flashing lights in my a/v cabinet and stairwell. I made it home, load tested the batteries, and they were bad. I got 4 1/2 years out of them, and figured it was just a coincidence.

Fast forward to now, and we're in Arizona at another rally. The water pump was acting up, and the lights in the a/v cabinet were flashing again. The water pump quit working, so I thought it was a charging issue while being parked. I got another charger and separately charged the chassis batteries, went through everything I could find and tightened all the battery connections I could find, and all of a sudden the pump worked better than it ever had! We had flow in the shower like we have at home, and life was good! Then we moved to another spot, and it was back like it was.

It seems like the water pump is getting power from the chassis batteries, which makes no sense at all. The fuse is in the bathroom in a fuse panel powered by the house batteries. When the gremlins occur, I can press the battery boost switch on the dash, and everything works as it should. The flashing lights quit, and the water pump works, until the boost disconnects. I even purchased a cheap water pump here to have as a spare, and turning it on causes the same problems as the other pump, so the pump isn't the issue. I replaced the controller, problem still exists.

It's difficult to trace out the wires from the controller to determine where power and ground is sourced because they are behind the bay panel. It seems like a bad ground, but that wouldn't explain why it seems the power comes from the chassis batteries.

Any ideas are appreciated!

[BattChief]

I've resolved the problem, though I still don't understand how things interfaced together. It's possible it was all a common ground.

I thought it may have been the water pump, but an inexpensive pump acted the same. I finally ran a temporary power and ground directly to the batteries, and the pump ran fine. I then removed the temporary power wire and reconnected the original, leaving the temporary ground, and the pump ran fine. I removed the temporary ground and tried multiple ground locations without any luck. I tried tying into a couple other ground wires found behind the water bay panel, and none of them worked. I finally found a 10 gauge ground wire behind the cord reel with a bullet connector on the end, only crimped on the wire side. I ran a 14 gauge wire to that wire, and voila! Problem solved!

I still don't know where the original ground goes for the water pump, but I do know I saw multiple grounds tied together with crimped unions or scotchlok connectors, and any of these could be weak. A bad ground could have been the demise of my previous pump, and a common ground could be how it affected other circuits. The pump may have drawn more voltage than the ground could support, being the root cause of all this. We'll see how it works from here!

[Jon_C]

I get rid of every scotch lock I come across, if it hasn’t failed It will shortly.