Why am i getting dead batteries when plugged into shore power

[WannaFTit]

I plug my Winnebago vectra into shore power when we come back from a trip (it is 30amp service with a 20amp breaker on it). It shows on my energy management system as 30 amp service and I turn off just about everything so I am only drawing 2 or 3 amps. Why, after 3 or 4 days is everything dead and needing to be boosted to start? The panel shows that the charger is in float mode, so why are they not staying charged up?

John and Judy

[Sky_Boss]

I am a little confused on what you said when you talked about getting them to "start". I will assume you mean you can't start your generator.

Here is what I would do to try and trouble shoot this.

1. Find your converter. It will be plugged into an AC outlet. Unplug it and verify you have 110V at the plug. If not...you probably found the problem and need to find out why. You might try to run this test on both shore and generator power just to see if there is any difference.

2. If you have power at the converter's outlet you will want to disconnect your coach from it by either the AUX BAT switch or even disconnecting your coach batteries. Once you do that you will want to disconnect the wires that are the output to your batteries. Then plug the converter back in and measure the voltage output of the terminals you disconnected the wires from. Depending on the model converter, you should show a voltage of somewhere between 13.2V to 14.2V. (You should be able to get specific info on this from your manufacturer). If you have voltage from those terminals, then the converter is working fine. If you followed my suggestion in step 1 to test the AC power outlet on both shore and generator power, there is no reason to do that again.

Here is another twist....

I have had similar problems all summer. Early in the summer I found that one the connectors on my converter was not securely clamped down on the wire. This caused the wire to overheat and insulation was soft and bubbled. I had to trim back about 2" of corroded wire and burnt insulation. I reconnected and all was well for the most part. HOWEVER...The other lead started to suffer a similar fate but the connector will not clamp down on the wire because of some corrosion on the clamping screw threads. The connection block is no longer secure so I have ordered a new converter.

Here is a similarity to your situation. Several times during this summer I was also showing 2-3 amps with everything off. It would then drop to 0 when I unplugged the converter at the AC outlet. With the converter plugged in my EMS didn't show a voltage indicating there was any charging going on. Instead, it would show the current battery voltage level. My 2 stage converter normally shows 13.2V on the voltage display unless the system is calling for a full charge which it will then normally show 14.0V - 14.2V.

Here is a sample trouble shooting chart for my converter. It might be of help in getting a feel for what I am trying to explain.

http://www.parallaxpower.com/7400/Flowchart7400.pdf

If you can wade through these thoughts and the converter checks out OK, then I suggest you go through your wiring from the converter to the batteries. From your description, it just doesn't sound like they are getting a proper charge.

Hope this helps.

[Midniteoyl]

What needs to be boosted to start?

[WannaFTit]

Both sets of batteries end up dead, house and coach. Even when plugged in

[Sky_Boss]

Originally Posted by WannaFTit

Both sets of batteries end up dead, house and coach. Even when plugged in

OK...house and coach batteries have different charging systems. They might be connected if you have a Trickle Start kind of system. Still, unless you had a heck of a coach drain, I would think the converter would be able to handle both a float charge on the house and the draw from a Trickle Start.

Moving on from there...what conditions are you batteries in? Age, condition...

I'm still a bit stymied by both batteries going dead.

[Gary RVRoamer]

It sounds as though your charging system isn't working, which could be the charger itself or perhaps a relay connecting the batteries to it. Yo need to put a voltmeter on the house batteries to see if they are actually getting charged - they should read 13.3v-13.6v while connected to shore power.

You didn't mention the year, but unless your Vectra is a recent model it does NOT charge the engine battery from shore power. The engine start battery may go dead due to use - there are likely things drawing small amounts of power from it even when you think everything is off. It is also possible that the engine battery is cross-connected to the house battery bank somewhere. This happens when somebody installs an accessory improperly or maybe swaps a wire inadvertently. For example, LP detectors are sometimes wired to both house and engine 12v systems, which effectively makes them in parallel.

[Midniteoyl]

Agree with the last - there is most likely a cross-tie between the house and chassis batts. Are there any accessories added?

[Bigd2]

Originally Posted by WannaFTit

I plug my Winnebago vectra into shore power when we come back from a trip (it is 30amp service with a 20amp breaker on it). It shows on my energy management system as 30 amp service and I turn off just about everything so I am only drawing 2 or 3 amps. Why, after 3 or 4 days is everything dead and needing to be boosted to start? The panel shows that the charger is in float mode, so why are they not staying charged up?

John and Judy

You say that you turn just about everything off could one of those
items be the converter?

[YC1]

Find your Inverter/converter/charger and the manual that came with it if possible or download one. Look on the converter for any signs of a tripped breaker. For example on my magnum inverter there are two AC circuit breakers and a small breaker on the face where the battery cables come off that has another breaker that controls the charging circuit. If you have an EMS system check to be sure it hasn't be set to a very low shoreline current setting or a low battery charge setting.

As for both banks of batteries being charged at the same time since they are both going dead it seems they are likely tied together. I sure would expect the top of the line Vectra to have some sort of device to charge all banks when on shoreline power or generator.

In any case, two issues. See if you can get the charging voltage going across the large bank of house batteries and then measure the voltage across the starting batteries. If they are not the same with the house batteries being charged around 13.5 volts a picture of the battery compartment area would be helpful.

[TRELL]

MAYBE a blowed fuse converter. Meter the output on converter when on plugged into
shore power.

[Beabop]

You could have 2 diff problems. You did not say what year your coach is but we have a 2004 and our chassis batteries will go dead if we do not keep a battery minder on them, there are many draws on a deisel (computer etc) that will pull the chassis batteries down. The house batteries maintain the charge from the invertor and if you have one of the Demensions inverters it could be bad or your batteries are bad.

[WannaFTit]

House batteries were just replaced this spring with interstate 12v triples. They have been run down 2 times this summer, I do have the dimensions inverter, ( our unit is an '04 vectra). How do you know if the inverter is bad? We have boondocked a few times this year (and we are VERY new to our RV,) but it seemed to me that the batteries should have lasted more than the one night. We do have an in-motion satellite dish the spends a lot of time searching for bell satellites.

[SarahW]

Sounds like the inverter to me. When our moho was brand new, we had "accidentally" turned our inverter off and got the same result. Well...dead house batteries, but the chassis battery was fine.

[YC1]

Boondocking in a large rv can require running the generator a couple of hours in the morning and a couple in the evening to keep up. The inverter left running all night and a few lights on can be quite a draw in 24-48 hours.

Determining if the converter/charger is running is easy. Just put a voltmeter across the coach batteries and plug in to shoreline or start the generator. You should see a definite rise in voltage upwards of 14 volts if the charger is working. If you do not see that work backwards to the charger itself to bypass any wiring. If the voltage is high at the charger then stuff in between is not delivering. While you are at it start the rv and you should see a similiar rise in voltage above idle speed. This way you can determine the alternator is working and that all batteries are getting charged from it. Finding out what IS working versus what is not is important and you should make notes because you may forget in 6 months. Take pictures of each area as well. The battery compartment wiring in case you disconnect wires or just need to share pictures here. I would love to see a picture of the batteries and charger for reference. Often I will look up the model of the charger for even better advice.