I think I have "Googled" myself into confusion! I have a 2000 Four Winds Infinity (35') that I bought used in 2009. I had one of my three 12V coach batteries to go bad (boiled, gurgled, leaked, smelled). I am planning on replacing all 3. The three batteries are all Interstate Workaholic 31-MHD's, which I do not think are Deep Cycle Batteries, and not sure they are the proper type batteries for coach use. The chassis battery is a deep cycle--which confuses me also. All the batteries are the ones that were installed when I purchased the RV. I was going to replace the Interstates with similar replacements; however, if they are not deep cycle, I do not know that is a good idea. I have also considered the AGM, but I have read some posts where the AGM's could create a problem with the RV's converter. Right now, I am just interested in replacing the coach batteries with the proper type, without having to worry about doing anything with the converter. Any comments and/or suggestions to alleviate my present confusion is greatly appreciated!

Almost all batteries come from 3 or 4 factories in US. Therefore look for the lowest cost. For coach you should have deep cycle batteries. O'Rielly's Auto Parts usually has best price in Phx area. Chasis battery should be started auto starting battery.

The chassis batteries should be your typical starter battery, not deep cycle. On my inverter/converter there is a set up process where you tell the unit what type of battery is installed for the house so that it handles it properly. Deep cycle is preferred for the house. You need to make sure that your inverter is a 3 stage type unit so it doesn't boil out the battery again (or you need to make sure that the water is topped off on a regular basis)

I keep it simple. Kirland signature from Costco. Great no-hassle warranty, and great batts.

If you have 3 GP31 batteries, it's possible you can fit 4 GC2 in there (I did). You will see a significant increase in performance and life if you can.

31 MHD's are CHASSIS batteries and are NOT designed for the COACH system. You need Coach batteries that are deep cycle type batteries, that are designed for slow discharge and quick recharge. AGM's are way more expensive and if you have a standard CONVERTER may have a problem with recharge correctly. Inverter/Chargers usually have a way to set the charge for all the various battery types. Doug

Coach Battery Replacement Help | Good Sam Community

11 Replies

Wannabrving
Explorer
Jan 06, 2014
I'm thinking I've been rather lucky the last 4 years, having non-deep cycle batteries and having never filled them (they appeared to be maintenance free, but I have since read where they look that way, but actually need to be checked and filled). I'm seriously considering getting the AGM's from Sam's--just hoping I don't have any converter issues. I'll probably be waiting another week or so before I make a final decision--waiting on this polar express to retreat back to the North Pole!:)

I greatly appreciate all the responses thus far--it definitely helps. I do not have much experience with the battery/electrical system since this is my first big issue with it. I have learned that if your carbon monoxide detector goes off and you can't understand why the RV reeks of a sewage-type smell, it may just be a battery issue! :B
SCVJeff
Explorer
Jan 06, 2014
wa8yxm wrote:
3 Group 31's that's an impressive amount of power (390 amps)

I recommend true deep cycle batteries over Marine/Deep cycle, and I do know the 31 comes in a true Deep Cycle model.. IF you wish to stick with 12 volt check out GOLF CAR stores and the batteries used in some golf cars (I think it is EZ-GO but it may be CLUB CAR, one uses six volt, the other 12s)

Or if you want to save money take measurements (I will do a bit of that for you)

Interstate battery info

I think you can only fit a single pair of GC-2 in that tray, (Depending on how the 31's are mounted) that would give you 230 Amp hours. If you can fit in 2 pair though (I do not know how tight the fit is) you would get 460 amp hours (An improvement) and likely about the same cost. Or less.
Like you said, he needs to take measurements. I had 3 GP31's and replaced them with 4 GC2's, and had close to 4" of leftover space to fill
full_mosey
Explorer
Jan 06, 2014
Wannabrving wrote:
I think I have "Googled" myself into confusion! I have a 2000 Four Winds Infinity (35') that I bought used in 2009. I had one of my three 12V coach batteries to go bad (boiled, gurgled, leaked, smelled). I am planning on replacing all 3. The three batteries are all Interstate Workaholic 31-MHD's, which I do not think are Deep Cycle Batteries, and not sure they are the proper type batteries for coach use. The chassis battery is a deep cycle--which confuses me also. All the batteries are the ones that were installed when I purchased the RV. I was going to replace the Interstates with similar replacements; however, if they are not deep cycle, I do not know that is a good idea. I have also considered the AGM, but I have read some posts where the AGM's could create a problem with the RV's converter. Right now, I am just interested in replacing the coach batteries with the proper type, without having to worry about doing anything with the converter. Any comments and/or suggestions to alleviate my present confusion is greatly appreciated!

I believe you are correct that the 3 31-MHD's are starting batteries. The specs in the link do not list AHs at all.

If you are considering AGMs because you don't want any more acid spills, you might consider GRP-31 from Sears Platinum or Sam's Club AGMs. The Sam's Club near me (73132) has them for $180 which is $28 more that the replacement $152s. You may not need a newer converter.

Be sure and have the expert flooded folks around here explain the special procedures and charging equipment you might need if you switch to pure deep cycle batteries.

The AGMs are dual purpose and will also be fine as a drop in chassis battery.

HTH;
John
wa8yxm
Explorer III
Jan 06, 2014
3 Group 31's that's an impressive amount of power (390 amps)

I recommend true deep cycle batteries over Marine/Deep cycle, and I do know the 31 comes in a true Deep Cycle model.. IF you wish to stick with 12 volt check out GOLF CAR stores and the batteries used in some golf cars (I think it is EZ-GO but it may be CLUB CAR, one uses six volt, the other 12s)

Or if you want to save money take measurements (I will do a bit of that for you)

Interstate battery info

I think you can only fit a single pair of GC-2 in that tray, (Depending on how the 31's are mounted) that would give you 230 Amp hours. If you can fit in 2 pair though (I do not know how tight the fit is) you would get 460 amp hours (An improvement) and likely about the same cost. Or less.
bull1
Explorer
Jan 06, 2014
I just replaced the batteries in our unit. After much checking of proces I determined that O'Riellys had the best prices and warrenty. In our case the Starting battery is a regular 12 battery and the Deep Cycle batteries are 6 volt golf cart batteries. Our original batteries were interstate batteries and they changed the batteries a bit. I found the Interstate to be about a 1/2 inch longer and an inch and a half taller than the originals. The O'Rielles replacemnts were 1/4 inch bigger on the foot print and fit very tightly and were about 1 and 1/2 inch taller than the original which made for a difficult pacement but it worked.
full_mosey
Explorer
Jan 06, 2014
Wannabrving wrote:

...
I was going to replace the Interstates with similar replacements; however, if they are not deep cycle, I do not know that is a good idea. I have also considered the AGM, but I have read some posts where the AGM's could create a problem with the RV's converter. ...

I have used AGMs that I bought new since Jan 2009. I can assure you that that is no reason they will be incompatible with or harm your converter.

I have charged my AGMs by converter/charger, portable charger, alternator, and two solar controllers without incident.

I don't care what reasoning you use to choose your new batttery type, I am simply saying do it with facts.

HTH;
John
dougrainer
Nomad
Jan 06, 2014
31 MHD's are CHASSIS batteries and are NOT designed for the COACH system. You need Coach batteries that are deep cycle type batteries, that are designed for slow discharge and quick recharge. AGM's are way more expensive and if you have a standard CONVERTER may have a problem with recharge correctly. Inverter/Chargers usually have a way to set the charge for all the various battery types. Doug
SCVJeff
Explorer
Jan 06, 2014
If you have 3 GP31 batteries, it's possible you can fit 4 GC2 in there (I did). You will see a significant increase in performance and life if you can.
crasster
Explorer II
Jan 06, 2014
I keep it simple. Kirland signature from Costco. Great no-hassle warranty, and great batts.
JohnInAz
Explorer
Jan 06, 2014
The chassis batteries should be your typical starter battery, not deep cycle. On my inverter/converter there is a set up process where you tell the unit what type of battery is installed for the house so that it handles it properly. Deep cycle is preferred for the house. You need to make sure that your inverter is a 3 stage type unit so it doesn't boil out the battery again (or you need to make sure that the water is topped off on a regular basis)