Dead House Batteries

[mikemc53]

Bear with me - this post might run long as I try to give some background.

Bought the coach (2004 HR Vacationer with V-10) last summer and the house batteries were fairly new, having been replaced the year prior (2017). They are 2 deep cycle 6V and have worked well in the short time I have owned the coach.

Drove from Michigan to Florida in November/December time frame and parked the coach in storage with no shore power. I have started the coach and generator every few weeks and always let them run for a while along with some appliances, particularly the AC. For the first few months everything was fine.

About two weeks ago I started the coach and after letting it run for 20 minutes or so I went to start the generator and it reacted as if the batteries were low/dead - started to turn over then nothing. I started the coach back up and tried the generator again, which worked. After the gen started I shut the coach off and ran gen with the AC for a good half hour. I checked the house batteries at the inside console (which I do every time I run the gen) and they were charging at 14.4 V. I will admit that I didn?t check them while the generator was not running.

Today I went over to the coach and started the engine right up and let it run. The generator, though, only turned over one time and then nothing ? even when I had the coach running. I tried turning on some small DC lights and ? nothing. I then checked the voltage of the house batteries at the console and it show 3.5V. I was shocked that they could be that low (basically dead) and I tried to think of what may have been left on in the past two weeks since the only thing I ever really turned on earlier was the AC. Since I always shut it off at the console there should not have been anything drawing excess current. I know there are always small things running in the background but I have left the coach sit for this amount of time in the past and had no issues.

I need help with a couple of things: First I want to start the generator so that I can at least try to get the batteries up some ? though I?m sure that will take quite a while if it can even happen at all with them so low. What can I do to try and start it, knowing that I am not near shore power at this time? Can I jump the house batteries with a portable jump starter, or maybe jump the generator?

Also, obviously, I need to find out what caused the drain of the batteries but I will likely need to get things going (generator) so that I can ring out some things.

I guess I could pull the batteries out and take them home (not too far away) to charge and then bring them back.

I am open to any suggestions.
Thanks, gang.

 

[Gizmo100]

I will get the ball rolling..

I would remove the batteries and charge them at home. Check the water before charging...BUT Just enough water to cover the plates.

Your 6 volt batteries most likely has been damaged with such a low reading. But you may be able to get some life out of them.

A disconnected battery will lose a small amount of power over a period of time. Add to that the phantom power loss of a RV and in 2 weeks you can see a fairly good loss. So your dead battery may be due to insufficient charging time from the generators.

How long and often do you normally recharge the house batteries?

 

[Larry N.]

Does your coach have an AUX POWER switch? Or it might have another name, AUX START, AUX, etc.. It's a momentary on switch that connects the two sets of batteries for just such situations as you describe.

 

[John From Detroit]

Starting batteries are designed to both derliver and accept a lot of current for a very hort time.  Total discharge should not be much more than 10% of capacity and that can be restored fairly quickly.

DEEP CYCLE are designed to deliver much slower.  Also to be charged slower (Relative to total capacity)  Your starting battery is likely less than 100 Amp Hours. but the six volt's are over 200 amp hours (So Starting current is not as great compared to total but re-charge time.. Six hours is what it takes if your converter is big enough. Shorter damages the batteries. Smaller converter may take a bit longer as the first stage of recharge takes longer.. I'd run the Genny for at least six hours and then use a hydrometer to test batterierd.  Also check the fluid level and top off to about 1/4 to 1/2 inch below the bottom of the filler tube BEFORE charging.

 

[Gary RV_Wizard]

A few additional thoughts:

3.5v is extremely dead, not "almost". Anything below about 10.5 is considered totally dead.

The Aux start switch may not do anything useful if the house batteries are that low. The house batteries will simply drain the chassis battery, and probably very quickly. Have the engine running if you try it, so that the alternator can help.  If Aux doesn't seem to engage, try old fashioned jumper cables from chassis to house.

I would have thought that the generator in an '04 would start off the chassis battery rather than house, but that was around the year when RVIA changed their recommended source for gen start.

As I recall, back in '04 Monaco/HR electrical systems did NOT charge the chassis battery from shore power or genset. Maybe another owner could verify or disprove that?

 

[skydivemark]

I had a similar issue with my first motorhome (when I was much less informed). After I drove it for 1/2 hour or so the house battery had enough to start the gen. I found that running the gen once every few weeks didn't seem to completely charge the house batt, so every time I ran the gen - after I shut it down - I would run an extension cord from the house and hook a battery charger or just plug in the main cord over night. Seemed to solve my problem.
I know this is much less feasible when parking in a storage lot so maybe you could bring it home for the weekend every few weeks or so and plug it in.

 

[mikemc53]

Well I did the battery boost and got the generator started. It was charging the house batteries properly at 14.1/14.3 V. I ran it for a while and then disconnected the batteries, pulled them out and took them back to my place to put on the charger. Not expecting miracles since they were quite dead but we'll see if I get anywhere with the charge. If not - new batteries.

Thanks, gang.

BTW, I had forgotten to hit the battery shut-off the last time I was at the coach which likely contributed to the drained batteries.

 

[Gizmo100]

Well I did the battery boost and got the generator started. It was charging the house batteries properly at 14.1/14.3 V. I ran it for a while and then disconnected the batteries, pulled them out and took them back to my place to put on the charger. Not expecting miracles since they were quite dead but we'll see if I get anywhere with the charge. If not - new batteries.

Thanks, gang.

BTW, I had forgotten to hit the battery shut-off the last time I was at the coach which likely contributed to the drained batteries.

Don't give up on the batteries ...Just keep an eye on your water level and make sure they have water...But be careful not overfill. Then let them charge

The battery shut off may have played a part in killing the batteries but some items may still have power with the battery shut engaged and you still have normal battery loss. So IMHO lack of charging time was likely the key problem