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martinandanne's avatar
martinandanne
Explorer
Jul 14, 2013

Deep Cycle Starting or just Deep Cycle

I currently have a pair of Interstate SRM-27 Deep Cycle/Starting batteries in our FourWinds Class C MH as the house batteries. The batteries are currently 30 and 18 months old and it looks like I am needed to replace the older battery again.

For the last year we have been taking our MH to only one destination - some land that we acquired. There is currently no shore power at the site, so we rely 100% on the batteries once we get there. (We do have the generator on the RV and we have a stand-alone generator that we also utilize for running the AC during the summer, but we really like the peace and quiet that comes with NOT running the generator!)

I have never had the instance to use the 'emergency switch' to start the coach using the house batteries, so I don't see this as a big need on my part. (Plus I carry one of those emergency jump starter batteries for use with some of the other equipment that we keep on the property.)

I was thinking of making a change to AGM batteries, but I started to look at them, I see them described as being "Deep Cycle" as opposed to the "Deep Cycle/Starting" dual purpose my current Interstate are marketed as.

Given that the only thing that I might ever 'start' would be the on-board generator, do I really need to restrict myself to dual purpose batteries? Or is looking at those just designed as "Deep Cycle" OK?

Thanks in advance!

Martin

7 Replies

  • mena661's avatar
    mena661
    Explorer
    Jul 14, 2013
    RJsfishin wrote:
    Huh ?? Did I say that ??
    I just bookmarked your post in case you deny it later. :B To the OP, if you can afford them, I'd go with some AGMs (Geez, did I say that?). They are lower maintenance and hold a charge longer than flooded batteries when no loads are connected to them. Generally Class C's are space limited for batteries so 6V's in either AGM or flooded may not work. I am slowly liking AGM's due to some unexpected characteristics I've learned recently. Still not sure how you know when they are fully charged though but others (HiTech) are figuring that out. My new preference for batteries are the Fullriver 415Ah 6V AGM's. Very expensive though ($450 each) and large like my L16's.
  • Dr_Quick's avatar
    Dr_Quick
    Explorer II
    Jul 14, 2013
    My question would be what do you do to maintain the batteries when you are not using the motor home? I have single deep cycle/marine battery for my trailer and I am on it's 6th year. I use a trickle charter in the off season, and during the season when not using the trailer, only plug in the trailer about once a month, to keep battery up. If you are connected to power in the off season your converter charger could be "cooking" the batteries, unless you have a multistage charger. Also these batteries require regular water checks too.

    Also I do not do a lot of dry camping, but have gone two days with not problems.
  • RJsfishin's avatar
    RJsfishin
    Explorer
    Jul 14, 2013
    The industry leads us to believe that a deep cycle won't start an engine.
    Its true, they don't have the cold cranking amps that a starting battery does, but they have plenty to start almost any large V-8-10 engine,....except under the most extreme conditions. So, you are much better off going w/ genuine "deep cycle" batteries if you are deep cycling them, as they will last much longer.

    If it were me, (you said you like peace and quiet) I'd save the extra money that AGMs cost, go w/ standard 6 or 12v, and buy a solar panel....or 2.

    Huh ?? Did I say that ??
  • enblethen's avatar
    enblethen
    Nomad
    Jul 14, 2013
    You should be replacing the batteries as a set. The older or weaker battery will draw down the better one.
    I would suggest switching to 6 volt golf cart batteries.
  • midnightsadie's avatar
    midnightsadie
    Explorer II
    Jul 14, 2013
    yes you can buy agm, but there big bucks. I do see a problem in your set up. you should never mix a new battery and a old one. the old one will draw down the new one to its level. I use interstate deep cycle 29,s in my MH , four years no problem. stick with just deep cycle. check the water and charge monthly and you,ll be fine.when not in use put a battery tender on them. about 6 bucks at harbor frth.
  • dougrainer's avatar
    dougrainer
    Nomad
    Jul 14, 2013
    NEVER mix battery ages when they are used together. You need to replace BOTH at the same time and keep the better one for an emergency. Even Interstate replaces all batteries in a battery bank when one fails under warranty. DEEP CYCLE SRM batteries are the STANDARD preferred choice for RV Coach systems. AGM batteries are used when the RV'er does NOT want to check water levels and wants to avoid outgassing and corrosion from wet cell batteries. But, as you found out, you pay a lot more for that convenience. You NEVER install a Deep Cycle SRM type battery on a chassis starting system. You always use a chassis designed battery. Doug
  • harold1946's avatar
    harold1946
    Explorer
    Jul 14, 2013
    Deep cycle/starting batteries are a hybrid, often used for fishing boats where space is limited. They are not the best choice for RV house batteries.
    AGMs are in my opinion an exelent choise, but many feel they are too costly. They do have some advantages over wet cell in maintenance, but it's really a budget decision more than anything.

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