Paralleling Batteries.

[SteveW]

My MH has a 100ah OE battery. I also have 110ah deep cycle battery (AC Delco HCM31SMF). Both batteries are of similar age - less than a year old and have been maintained in a charged state.

Can they be paralleled?

[T1 Terry]

Yes, will it be sucessful.... ummmm..... I'm guessing one is a start battery and the other a house battery, start batteries can supply big current for a short time, deep cycle batteries a much smaller current for a long time, just the way they are made. It might work fine, but it doesn't mean you will have an extra 110Ah. The start battery will have an RC value, (reserve current,) if you multiple half that number (50%) by 25 (amps) and then divide it by 60, (minutes into hrs) that's how many Ah it could supply and still deliver 12v when it was new and fully charged.

[BruceS]

Steve I presume OE means Original Equipment as in 'came in the vehicle'?
I also presume it's a simple lead/acid with 6 caps on top to check the acid level?
...... I personally wouldn't parallel them if that's the case.
Maybe a Redarc unit or does it already have one?
http://www.redarc.com.au/products/produ ... _12v_100a/
With one of those you can drain from both batteries until your start battery gets down to a safe level & then it'll auto disconnect.
Maybe a bit more detail on what you're after may help some give better advice?

[SteveW]

Both batteries are maintenance free, deep cycle batteries. The OE is some sort of Generic battery installed by Jayco - the same as the battery that was in my Jayco caravan and which was still strong strong at 5 years. Th Ac Delco is a heavy duty marine deep cycle (in the brochure). The vehicle is fitted with the Redarc unit between the alternator and the house battery. 240v house battery charging is via the 35A 5 stage Setec.

[SteveW]

Further info. My purpose is simply to use the second deep cycle in the MH which mostly does nothing at home. I use it occasionally to run an Engel but it is under utilized.

[BruceS]

I read your last post over & over & I'm afraid I don't really understand it.
Maybe you're thinking like me?
I've got terrific solar panels hooked up to two good deep cycle batteries & have a reasonably sized inverter. (in the motorhome) I've often thought how stupid I am to have these sitting for weeks at a time outside my house while I'm inside using expensive bought electricity. I've considered have a dedicated SEPERATE circuit wired into the house to run TV's, computers & maybe the fridge/freezer on the (I consider) free power that I'm not utilizing at present.
Solar grid connected is out now at the rates they are now offering.

[SteveW]

Further info. My purpose is simply to use the second deep cycle in the MH which mostly does nothing at home. I use it occasionally to run an Engel but it is under utilized.

Perhaps I can reword the post to make it clearer - it's the battery that is mostly doing nothing, not the motorhome. The intent is to increase the battery capacity in the motorhome.

As an aside, I have just one 120w solar panel at the moment.

[BruceS]

Yep, I'd be using them both hooked together. Probably throw another panel on the roof or maybe have a portable that you can put out in the sun & follow it.
I recently added an extra two cells & can't believe the difference. I found 150% to 200% more solar than AHrs.
eg. 220AHr batteries you should aim for 350 - 440watt cells. (mine is 24V)