Community Forums

andrew55 · 10-16-2010, 01:53 PM

On most RVs, is it necessary to have the house batteries charged to operate the water pump/water heater? I am doing repairs right now on our rig, it's parked and plugged into shore power, but the two house batteries are shot and need to be replaced. The lights on the stove display (for water pump/water heater) are going off and on intermittently, and when they are off, water pump/water heater do not work. Could the lack of batteries, even when hooked up to shore power, be causing me the problems? I have a 1987 Southwind Fleetwood. Thanks for any advice.

DriVer · 10-16-2010, 02:16 PM

Quote:

Originally Posted by andrew55

Could the lack of batteries, even when hooked up to shore power, be causing me the problems? I have a 1987 Southwind Fleetwood. Thanks for any advice.

andrew55, When you are diagnosing or trouble shooting 12 volt problems you need to rule out both batteries and grounds. Having working batteries in a 12 volt circuit is essential even if you are connected to shore power.

Water heaters on RVs require 12 volts to allow the valves to function so that gas will flow to the burners. On my rig I also have a 120v element that will make hot water. A water pump needs good voltage from the batteries or it could overheat the wiring by drawing too many amps. This will also affect the electronics in these devices as well.

Get those new batteries and let us know how your situation has changed.

andrew55 · 10-16-2010, 04:25 PM

DriVer - thank you. I guess I can't put it off any longer - the next step is to get those batteries. Thank you again

TXiceman · 10-16-2010, 06:50 PM

found the best place to get the trailer batteries is Wal-Mart. Get a group 27 Marine or deep cycle battery for normal use. If you plan to boondock, get a pair of 6 volt golf cart batteries....more costly. You can get by with one battery if you never boondock. You also need the battery for the break away sytem to work on the brakes.

ken

andrew55 · 10-24-2010, 12:02 PM

I got the new batteries and still no luck yet. The hot water heater/water pump are still working intermittently. Upon investigating the inverter box (Progressive Dynamics, PD76), I discovered that the fuse connections for the interior 12 volt lights, range lights, and fridge are showing current with the multimeter, but there is no current for the fuses of the water heater, water pump, and battery charger.

The simple fact that there are fuses for the water heater, water pump, and battery charger lead me to think that the inverter should power these, (even without the batteries). I included a pic below. The interior lights, range lights, and fridge are the first 3 fuses going form left to right, then followed by water heater, water pump, and battery charger.

Anyways, after testing with the multimeter and not finding any current in the fuses of the water heater, water pump, and battery charger, I did something that might have not been the smartest thing. I took a spare wire and jumped the fuse connection of the interior lights (working) to the water heater (not working). As I did this, the water heater and the water pump started working. I could hear the pump and see the the lights on the range lights over the stove. The interesting thing is that when I removed the jumper wire, the water heater and water pump continues too work.

Any ideas on where to go from here? Should I get the inverter out and try to bench test it? I doesn't seem this is an issue with short in the wiring elsewhere in the rid. Any suggestions greatly appreciated.

DriVer · 10-24-2010, 12:10 PM

Quote:

Originally Posted by andrew55

Any ideas on where to go from here? Should I get the inverter out and try to bench test it? I doesn't seem this is an issue with short in the wiring elsewhere in the rid. Any suggestions greatly appreciated.

See the wire wire in the bottom of the panel? Completely remove the wire and the lug if you can and clean all those connections. Next see if you can find where the other end of the white wire goes and clean that connection as well. (to the frame or some type of ground)

Last step would be to remove and reinsert all the fuses. This will improve the connection between the fuse and the clips. See if the fuse contacts are gray or corroded in any way.

Good luck.

andrew55 · 10-25-2010, 01:05 PM

As suggested, I checked the ground (white wire) and all the fuses and connections in the inverter panel. All of these seem to be working. Upon checking the positive wire leading to the battery (from the inverter) I discovered there was no current. While following the positive wire from the shore power batteries, I discovered where the current is getting broken. I included a picture of the device which is causing the problems - it looks like some type of relay. This is inside the engine compartment. There are two similar devices (which I don't know what they are). On the one on the right, the big red wire is coming from the shore batteries. The smaller red wire, on the other side of the device, is going to the battery terminal in the inverter. The battery is charged, but this device is stopping the current from flowing to the inverter. I checked the battery disconnect switches inside the rv, but these don't seem to be related to the issue. Any ideas what they devices are? What controls them? Any suggestions for troubleshooting?

STLNLUV · 10-26-2010, 06:30 PM

Andrew55

You are correct, these are power relays, one for the coach 12 Volts DC (pumps, lights, tanks sensors, etc), the other is for the P30 chassis (engine starting, headlights, tail lights). The 2 terminals on the front of these relays are the 12VDC coil (when 12VDC is measured across these terminals the relay is ON). When ON you should read approx 12VDC to chassis ground on each of the side terminals. You should be able to feel or hear them energize. On my old Southwind there was a switch inside the coach that either turned the coach relay ON or OFF by supplying 12VDC to the coil. There was also a push button switch on the dash that would energize the relay so that the coach batteries would be used to help start the engine if the chassis battery was too low.

These relays do go bad. You can check them by removing the coil wires and connecting jumpers from the positive side of your battery to one of the terminals and another jumper from the ground (negative) side of your battery to the other terminal. Measure the voltage to ground on each side of the relay (big wires), they should be equal. If they are not equal or you have no voltage on one side but have it on the other, the relay is bad. You should be able to get these at Napa or any other good parts store.

Let me know how it turns out.