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.

[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.

[SidecarFlip]

You ain't saving them.

[Matt_Colie]

Mike,

Your nice GC2 are hurt.
If you really hope to try to save them, get a small (like 10 amp charger) disconnect the converter/charger. That converter/charger will want to hit them hard and that will make heat that they will not like. They are soooo dead now that they may never recover.

When you get the charger on there, be ready to wait about a day. It may be three or four HOURS until the bank actually starts to charge.

Just future reference, a Lead/Acid battery at 12V is half depleted. (That is actually about 11.8 for good deep cycle, but you get the idea.) As dead as yours are, you are going to have to replace about 250+ Ampere Hours.

I have seen this more than a few times, and I give you about a 50/50 shot and recovering 75% of the capacity.

Good Luck

Matt

[twodownzero]

Sounds to me like you're a good candidate for a solar setup. The worst thing you can do to flooded lead acid batteries is to allow them to remain dead, which solar can prevent. The next worse thing is to let them run low on water, so once you install new batteries and solar, your next step is to make sure you check them once a month or so.

[10forty2]

Another thought.....depending on the type of battery, they may be low on water/acid. But yeah, at 3.5VDC, they basically are toast now, so get some fresh ones and start again.

[MrWizard]

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)

batteries are considered fully discharged (within operational use) at 10.5v
and should not even be allowed to go that low

yours are toast
replace them, then trouble shoot your problem
disconnect the negative cable to chassis, BEFORE leaving the RV in storage
until you are convinced you have found the problem

[chuckftboy]

Mike, from your scenario it seems that you are not running the generator long enough to recharge the house batteries. Running the gen for an hour or so doesn't give the charger enough time to recharge the batteries as it may take several hours to top them off.
You might try starting the engine and then use the battery boost switch to start the gen. You'll probably need to hold the switch for several minutes before trying to start the gen.

[jolooote]

Voltage at the console is 3.5 volts. What is the voltage at the Battery terminals? 1st impression is very bad battery connections somewhere. Not making a very good Ground?

[Lwiddis]

From your description I believe your house batteries are toast. Sorry