What size 12 volt batteries in Thor 31W?

[Steveku]

The Thor 31 foot coaches are supposed to be able to fit four 12 volt batteries in them, if true, what size batteries can these be? Group 24, Group 27, or Group 31? How well do the biggest(capacity-wise) 4 batteries fit in these coaches?

[SuperD]

The batteries in our 29M are group 24, I'm thinking group 27 might fit but it would be tight.

[Steveku]

Originally Posted by SuperD

The batteries in our 29M are group 24, I'm thinking group 27 might fit but it would be tight.

Thanks SuperD, I'm not familiar with the 29M, do you have four 12 volt batteries in that, or are you talking about height-wise?

[SuperD]

We only have two batteries but group 24 is usually what is installed. Our batteries sit sideways, it's not the height but the length, a group 27 will be a very tight fit through the battery door.

Group 24 is 10.3 inches long, a 27 is 12.1 inches.

[Steveku]

Originally Posted by SuperD

but group 24 is usually what is installed. Our batteries sit sideways, it's not the height but the length, a group 27 will be a very tight fit through the battery door.

Group 24 is 10.3 inches long, a 27 is 12.1 inches.

OK, makes sense. I'm trying to figure out all this little kind of stuff before we purchase a motorhome.

[DenverTransplant]

My ACE 30.1 came with 2 size 27 Harris batteries that lasted about 6 months. You will find lots of people who have had premature failures in the Harris batteries. Harris basically denies warranty claims and point to the WFCO converters that Thor provides as the cause (they have a point, but I don't think their batteries make the situation any better).

If you are looking at battery replacement I would recommend going with 2 to 4 6 volt golf cart batteries. The two Interstate GC2-XHD 6V batteries I replaced the Harris with have more capacity (240 AH vs. somewhere around 160 for the 2 Harris 27's). In my battery compartment, there is room for a second pair of 6V batteries, but I have to first remove a steel baffle strip in order to fit them in. I'm considering building/buying a battery tray and leaving the strip in place. Next year project though. I also changed out the WFCO converter with a Progressive Dynamics 4 stage converter when I changed the batteries.

Costco sells an Interstate 6V battery, but the one they stock have less capacity 210 AH, vs 240 AH you get directly from Interstate. But the Costco ones are cheaper - $84 vs $150, but they also don't appear to be the same overall quality as the ones Interstate sells direct.

[Gary A]

I put 2 Costco/Interstate 27's in my C Class under the steps. Tight fit but they went in. One year old this month and when I unplug the coach from the 110 at the house they read 12.7V. I think a good value at $90 each.

[Steveku]

Originally Posted by DenverTransplant

My ACE 30.1 came with 2 size 27 Harris batteries that lasted about 6 months. You will find lots of people who have had premature failures in the Harris batteries. Harris basically denies warranty claims and point to the WFCO converters that Thor provides as the cause (they have a point, but I don't think their batteries make the situation any better).

We just looked at a 2018 Thor Four Winds 31W, it has 2 Group 27 batteries installed. I did see that it had a WFCO Model # 8955PEC converter - which I guess includes the AC & DC distribution box. It appears it is a 3 stage charger, 55A, so is it any good because it is multi-stage and 55A?