House Batteries Dead

[akadeadeye]

Well, will this first-year learning curve ever end?

We got back from a long weekend trip over the 4th of July and took our MH in for a couple of minor service items. The dealership was running behind so it has been there for 12 days now. I awoke in the middle of the night last night remembering I had not turned off our Norcold 12v/110v refrigerator/freezer unit we have in a basement compartment. So, it has been running on 12v house batteries all this time and the MH was not plugged in.

I went out to the dealership this morning and checked on it. No power in the coach at all. No lights, no radio light, nothing. I turned off the frig unit but it did not have a power light on anyway. Nothing but beverages in there. I assume the batteries were drained all the way down.

I added this to the "minor" repair list.

Is there any way they can be completely recharged, or did I ruin them? There are 4 deep cycle 12v batteries.

If they are ruined, what batteries should I replace them with?

Don

[wolfe10]

Don,

There is no way your question can be answered WITHOUT fully charging them and THEN testing them. Said another way, there is no way to prove a fully discharged battery as good or bad.

So, plug it in to shore power so your converter or inverter/charger can bring them to full state of charge (or start generator and charge from it until it can be moved to a site with shore power). It will take at least overnight to get them fully charged.

If wet cell batteries, most reliable indicator is Specific Gravity which you check with a battery hydrometer (around $5 at any auto parts store).

THEN determine if their life was just shortened or terminated.

Brett

[akadeadeye]

Thanks, Brett.

I will charge them and check with a newly purchased hydrometer.

Don

[kevinpvb]

Hi Brett:

This is a timely thread. I have a 2007 Discovery that I bought new. I'm having issues with my House batteries too. I have 4 Trojan 6 volt flooded cell batteries. I can leave the coach connected to 50 amp shore power for several days and my Magnum Energy panel shows that the batteries are sitting at 13.1 volts and "float charging". I also have a solar trickle charger attached to the power grid.

But, within one hour of disconnecting power, there is not enough stored power to start my generator. But, if I start my engine and let it run for about five minutes, I am able to start the generator. But, nothing seems to charge the House batteries enough to allow me to start the generator without additional input such as engine alternator or shore power.

When I checked the batteries with my hygrometer, one battery showed two dead cells while the other three showed a 75% charge. I changed the battery with the dead cells.

My RV service shop wanted $55 per battery to do a load test, $169 for each battery and $55 to replace each battery. That's a lot of money to see if I need to replace the batteries.

Do you have any suggestions that I could follow before forking out the cash?

Don,

There is no way your question can be answered WITHOUT fully charging them and THEN testing them. Said another way, there is no way to prove a fully discharged battery as good or bad.

So, plug it in to shore power so your converter or inverter/charger can bring them to full state of charge (or start generator and charge from it until it can be moved to a site with shore power). It will take at least overnight to get them fully charged.

If wet cell batteries, most reliable indicator is Specific Gravity which you check with a battery hydrometer (around $5 at any auto parts store).

THEN determine if their life was just shortened or terminated.

Brett

[travelerbob]

OPPS senior moment. That's Trojan not Trogan Yesterday I couldn't even spell comparuter now I are a IT specialist!!

[juanclem1@msn.com]

I had a similar problem with my '04 Monaco Cayman, but I sure don't know if this will help - only Brett will know for sure. My new house batteries (4) Interstate, kept going dead even while plugged into shore power. We discovered my inverter was not charging the batteries. We checked the 300 amp fuse that is between the inverter and the batteries was blown. We replaced the fuse ($54.22) and wa la, we had charging power and the house batteries stayed charged. Be extremely careful though, 300 amps packed a lot of wallup.

[wolfe10]

Hi Brett:

My RV service shop wanted $55 per battery to do a load test, $169 for each battery and $55 to replace each battery. That's a lot of money to see if I need to replace the batteries.

Do you have any suggestions that I could follow before forking out the cash?

Boy, that is a tough one. Without knowing whether you have the time, inclination and ability to do this yourself, I really can't tell you which way to go. I will tell you what would be involved if you want to do this yourself-- look it over and then decide if you want to do part or all of this yourself.

First step is to check the water level in the batteries. Make sure they are filled to just below the ring in each cell. Then you need to fully charge the batteries (plug into shore power overnight and verify that the converter, charger or inverter/charger is working). A digital voltmeter will verify that they are being charged-- voltage should be 13.2-14.2 VDC at the batteries once batteries are no longer deeply discharged and depending on what converter or charger you have.

Next, decide if you want to remove the batteries yourself for testing or take the coach to someone to do it. Either way, take a digital photo of how they are wired to make reassembly easier.

Take the coach (or batteries if you remove them) by most any auto parts house that sells batteries and have them load test them-- generally for FREE.

You might choose the store by what brand/size battery you want to replace them with if they do test bad. If going with pairs of 6 VDC deep cycle batteries (in series to make 12 VDC) be sure to check with local golf cart shops.

Brett

[dbelanger]

This may be of interest to all: Recently installed an inverter and one thing I did was use the same ground connection, to the RV frame, that the house batteries use. Everything worked fine on the day of install. After parking the coach for about a month with the battery disconnect operated we fired everything up and went on a trip. After parking for a week at a RV park we disconnected from shore power and had no 12 volt power to the house. Voltmeter would drop to zero as soon as anything was turned on. Dead batteries, right? Wrong. Somehow that ground connection had an impedance of infinity. Removed ground, applied sandpaper and a couple of star lock washers to bite into the metal all is again OK.

[akadeadeye]

OK. I think my batteries are OK, but have probably had their life shortened a bit. First, I was mistaken about having 12v batteries. I have four 6v deep cycle Interstate batteries. RC@75 amp 122. And 20 amp hour rating 232.

I charged them up until I got a float charging message on the monitoring panel, then disconnected them overnight so I could test them this morning. They tested by digital voltmeter as follows;

6.65

6.68

6.65

6.68

Then I tested for specific gravity using a hydrometer. The results, by cell, were as follows.

1.225

1.225

1.225

1.225

1.225

1.225

1.225

1.225

1.225

1.200

1.225

1.225

These results would indicate the State of Charge is about 75% while the digital voltmeter results indicate 100%. Any explanations are welcome. (Brett?)

Don

[wolfe10]

Don,

Since these are wet cell batteries, if your charger or inverter charger has an equalization mode I would run that.

I like to see the house disconnected while equalizing, as voltage can rise to over 15 VDC. Yes, on some coaches, your charger will not work with the battery disconnect switch in the OFF position. Doing this isolates all the PC boards on the coach from high voltage. The other option is to pull the fuses on the refrigerator, furnace(s) , water heater, etc.

Equalize them and quite equalization when the SG stops rising.

Re-test the batteries.

Brett