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mayco · 04-23-2014, 03:25 PM

I need to replace my house batteries in my 310. This is my first motorhome and i am trying to get a handle on how the electrical system all works but i have a long way to go. The old batteries are 7 yrs old and i opened one up today to find it bone dry. So im in the market to replace them both. My coach stays plugged into shore power when not in use and being in central illinois is subject to some pretty severe cold temps in winter. We dont plan on doing a great deal of boondocking while on the road. Could you folks recommend a brand of deep cycle batteries that are moderately priced. I dont think ill be spending the money on the gel type batteries at this point anyway. I believe the batteries that came with the coach are group 35. Thanks for your patience on my learning curve here.

dadstoy · 04-23-2014, 04:11 PM

I'm happy with the Interstate batteries that I put in a few yrs back. I also installed a good multi-stage converter. If you leave the coach plugged in with the old univolt single stage converter, it will simply boil and damage your batteries in short order.

Wayne&Sam · 04-23-2014, 04:18 PM

I just replaced the original Interstate batteries in my 2007 Safari. I went with Interstate again- given I got 7 years out of the last two.

mayco · 04-23-2014, 04:38 PM

So if i were to continue to use the single stage converter, is it better to not leave the coach plugged into shore power while it sits. Im showing my ignorance here, I was under the assumption that by keeping it plugged in to shore power it would keep the batteries, both coach and chassis, charged. If that were the case, would i then want to remove the batteries over the winter and store them inside and keep an i on keeping a charge in them with a trickle charger or a battery minder?

mayco · 04-23-2014, 04:47 PM

Another question out of ignorance on this issue, are the two house batteries 12volt or 6volt?

Wayne&Sam · 04-23-2014, 04:47 PM

When mine is in storage I keep a battery minder charger on the batteries- I leave it that way all winter.

idroba · 04-23-2014, 05:19 PM

The batteries in my '83, 310 (gone now) were a pair of #27 or maybe #31's. I am no longer sure. I had wanted to put a pair of 6 volt golf cart batteries in it, but due to their extra 1 1/2 inch height, they would not fit.

Measure the length of the ones you have and compare in the store. 24's 27's and 31's are all the same width and height. Probably 27's will be fine.

If you are not going to use it much without it being plugged in, just buy a pair from Costco, Sams club, or Wal Mart. They all have decent batteries at reasonable prices.

A better converter/charger would be advisable but I had mine 10 years with the original one. I did not leave it plugged in all the time however. The location of the converter/charger on mine was a bear to get at. It was under the ice maker and behind the fuse panel and would have required a pretty extensive job to get it out and a new one in.

mayco · 04-23-2014, 05:28 PM

Thank you idroba, you hit the nail on the head of what i was trying to get at. My converter is in the exact same place, under the ice maker. I assume i could just buy a battery minder and leave it connected while the unit sits to keep a charge in the batteries.

idroba · 04-23-2014, 05:39 PM

Yes, that probably would work out. Also, the way Airstream wired mine, the Sony dash radio was on the house batteries and the station keeper function and clock on, which constantly drained them. I put a switch on the radio to get rid of that drain. But that was not the only phantom load I located. Mine had a power TV antenna (to raise and lower it, no internal crank). It turned out that even in the OFF position, the damn thing ate power, not a lot but it would deplete the batteries when sitting. So, another switch to turn the power to it off totally.

mayco · 04-23-2014, 05:46 PM

Two good things to check out. Thanks again

dadstoy · 04-23-2014, 07:30 PM

Mine are 6 volt batteries. My dad burned up multiple Trojan 6 volt batteries by leaving the coach plugged in all the time on the univolt converter. With my new multi-stage converter I leave the coach plugged in all the time. I rarely need to add water to the batteries.

I would do exactly what the others have mentioned if I still had the old converter...use a trickle charger. I have a small Sears charger/trickle charger on the engine battery anytime I'm plugged into 110v since the main converter isn't used to charge the engine battery.

mayco · 04-23-2014, 07:44 PM

I guess i am wondering how the original design was supposed to work and be maintained. With the single stage converter, when youre plugged in to shore power for a long period of time. In theory are you using enough 12v power in your daily activities that you wouldnt run the risk of over charging the batteries?

idroba · 04-23-2014, 11:35 PM

More like luck, exactly what voltage your Univolt produced, what condition it is/was in, temperature of where you live/store it and a bunch of stuff like that. Not too much theory in those old beasties, just what was available at the time. I actually didn't have a lot of problems with my old Univolts, but I didn't leave them on all the time. For one thing, I am cheap and they take a lot of energy just sitting there humming. I monitored the use once, and kinda have forgotten the numbers, but something like over 100 watts just sitting there doing nothing. That power didn't go into the batteries, just cooked the Univolt. My new PD convertr/chargers use 8 to 10 watts when the batteries are fully charged.

How electronics have changed in the past 40 years.

mayco · 04-24-2014, 02:41 AM

Ha! Well then.....i think until i have the time and money to install a new converter, i will go ahead and purchase some big box batteries, do my best to keep an i on them, and plan to install a multi stage in the future. I start the genny every month so that would be a good time to check batteries. Definately sound like i was doing more damage than good keeping it plugged in all winter. I was hoping that i would prevent the chance of freezing by keeping the batteties at full charge.

mayco · 04-24-2014, 04:25 AM

After looking at the prices of a new converter i think i better bight the bullet and install a new multistage converter and be done with it. Its only money right?

idroba · 04-24-2014, 05:36 PM

Probably a very good call. Then, if you have power available you don't really need to worry much about your batteries. For most it is the easiest answer.