new inverter shutting down my Surfside 29A

[dmx]

I bought a 2006 National RV Surfside 29A last summer. The inverter option was not installed.

Bought a Xantrex Pro 2000. Short thick cables to the battery with an inline fuse (type T 300W). I plug the shore line in the inverter and flip the converter breaker off. Everything works.

With only a few lights on, the 12V side of the rig just dies after 30 minutes. What is powered by the inverter, plugged directly to the battery, keeps being fed.

At first I suspected the batteries: 2 acdelco 6V rated 115min@75amps. Put brand new fully charged 6V Interstate rated at 232Ah.

Same thing happens after about 30 minutes of a couple of lights plus the inverter running, as far as I'm aware of, about 100W max. I should not have used more than a few amps in that time, counting the various detector, water pump and all.

1- What is shutting down the 12V circuitry, and why?

2- Is the converter still pulling amps even if I flipped it's breaker? It does seem to be offline since the generator will quit after a few minutes if I forget to put it back on when getting off the inverter (shutting it off).

[RLKBOB]

What size cable does "short, thick" refer to? 2/0, 2 Ga? The first thing I would check would be battery voltage with a multimeter. See what battery voltage is before turning the inverter on and if possible monitor it every 5 to 10 min while operating and finally see what the voltage is when the inverter shuts off. The most likely cause is low voltage. If the batteries aren't fully charged they could reach the low voltage shutoff point pretty quick, especially with such a big inverter. Even though you said the batteries were fully charged check the starting voltage and monitor it to see if that's what's happening.

[dmx]

Short = 5'
Thick = 2/0

The inverter is pulling about 600 mA by itself even if it is powerful. It is grounded also.

Fully charged at 14.4V until amps fall below 6.2 amps. Resulting voltage is 12.8V measured inside the rv at some far point. 6.52V when measured independently on each battery. Since this is taking me by surprise after sunset, I have not yet started to take measurements as this is happening.

My next step is to test things in daylight when I can take readings. Something is pulling amps when I'm using the shore line even though the converter breaker is flipped (open circuit). The fridge is on gas as is the water heater.

Where are the amps going?

By the way, my rig is a gas Class A MH from National, with a Onan generator. Things work ok until I try to trick the system by plugging the shore line into the inverter, while flipping the converter breaker.

The converter is hard to get at, under the kitchen counter. Not sure I want to try to get at it to install a switch on it just to see if it is the culprit.

[MattC]

DMX,

If I understand correctly, the things powered by the inverter stay running, but the 12V lights and things go off??

That can only be one thing. There is a bad connection between the house bank and the primary distribution point OR a bad ground for the house bank.
Quick check, it does not matter if the inverter is on or not.
Turn on several 12V things.
Feel all the connections from the housebank to ground and from the housebank to the distribution point in the DC fuse panel.
I bet somewhere you feel a warm/hot join. Frequently, electrical joints that are marginal loose connection when the they get hot.
If that doesn't work, use a meter to measure from the house bank positive to the fuse panel. If it shows more than a little tiny number, something is wrong there. Same with the ground side.

Matt

[wa8yxm]

A 2000 watt inverter should be fed with something like 0000ga wire, And it will draw the batteries down a bit (NOTE that 0000 ga also needs to be used to jumper the pair in a six volt pair install such as you have)

However I do not think that is the problem.. I note my inverter (also a Xantrex 2kw but a Prosine) can draw the batteries down much faster than I thought.. I Have never heard of a 12 volt battery protection system. in an RV (Though I have heard fo them elsewhere) it may be a safety low voltage cut out.

Measure voltage AT THE BATTERY TERMINALS when this happens and report.

[dmx]

Thank you guys. My inverter is in fact a Prosine SW.

I might have found the culprit. While moving a battery I probably hit a 150A breaker switch put in a bad place and tripped it. I takes the house batteries at least partially offline. My MH then switches my 12V to the chassis battery without giving any notification.

Then the chassis battery is protected when the voltage drops, gets recharged with the generator while the house battery is still offline and does not.

I did not find any other problems with the wiring, inverter ground and connections and batteries. So I think I solved it and will be sure I have in another 24 to 48 hours.

As for the 2/0 cables from the inverter to the battery: any thicker and they would not bend. They are about an inch thick as it is.

I'll post here for posterity if that was the solution.

[Gary RVRoamer]

Your coach should not be drawing from the chassis batteries if the house system goes low or offline. That is a recipe for a disaster, e.g. getting stranded while boondocking somewhere cause all your batteries end up dead and you can't start engine or generator. You've got something cross-connected between house and chassis so that it is feeding form the chassis batteries. You need to find it and eliminate it.

[rjdelapp]

(By the way, my rig is a gas Class A MH from National, with a Onan generator. Things work ok until I try to trick the system by plugging the shore line into the inverter, while flipping the converter breaker.)

Why do you plug the shore line into the inverter??

[Mr_D]

Is the charging circuit trying to charge the batteries from the batteries themselves? That will draw them down quickly.

[dmx]

Yes Gary, that is wath I was about to bringup. If it is done by design, it is pretty stupid to fall back on the chassis battery with no notification. I have to figure out how this was set up and undo it, if I can. Not familiar with these mixed 12V/120V systems though. I'll get help.

As for the inverter/converter loop, I switch the converter off when switching on the inverter. That is covered. It would indeed deplete the batteries in a hurry if left in the circuit.

After 24 hours, I feel assured that I have pinpointed the problem as described earlier.

Thanks all for the feedback. It helps not having to think out problems alone in the (Sonora) desert.