Mom Switch Fail

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99WinAdventurer37G

99WinAdventurer37G

Well-known member
Joined
Jun 28, 2012
Posts
1,143
Location
Saginaw, TX (north fort worth area)
On my 1999 Winnebago Adventurer 37G, my MOM switch on the dash does nothing to very little.  Also I think somewhere through the years someone hooked the starting battery in line with the house batteries. 

I recently bought two new AGM group 31 house batteries (204 amp hours each), and one starting battery (850 CCA).  I took a group out to my farm and after using the batteries for just a couple of days, about 70 hours, with about 30 minutes running the furnace) the MH would not start.  The generator started though, and I ran it about one hour.  Then tried again to start it.  No luck, so I tried the MOM switch, I held it down about a minute, then while still holding it down, tried to start it, still nothing, it did seem to have more power, but not enough to start it.  So I got out the battery cables, hooked them up from the house batteries to the starting battery (what I thought the MOM switch was supposed to do) and it started easily. 

I'm thinking that somehow the MH is drawing down the starting battery, and the MOM switch is not hooked up correctly.  I had it in a shop and they told me there was less than 1/2 amp parasitic drain on the starting battery.  Any ideas what's going on here?
 
Where did you find Group 31 batteries with that capacity? They are usually 120 to 130 amp/hr. It does sound like you have a defective battery isolation solenoid. It does sound like your chassis battery is isolated from the house batteries because you could use the jumper cables to start.
 
Sam's club is where I found them.  They're expensive and only have a one year warranty, as they're listed as commercial batteries.  This is the battery;
http://www.samsclub.com/sams/31a-agm-12-mo-free/prod7710329.ip?navAction=push

Thanks all, I'll look for that battery mode solenoid.
 
I don't see an AH rating in  the Sams Club blurb but I seriously doubt if any  Group 31 case can provide 204 AH in the standard 20 hour test. . There simply isn't room enough for the amount of lead plates needed for 204AH @ 20 hours. I suspect that 204 is the RC rating, which is a different measure than AH. An RC (Reserve Capacity) of 204 minutes would be typical for this size deep cycle battery.

I'm not knocking these AGM-31 batteries - I'm planning to buy 4 of these, or the Duracell AGM 31, myself in a couple months. Duracell is another private label brand that Sam's has been carrying.
 
Gary RV Roamer said:
I don't see an AH rating in  the Sams Club blurb but I seriously doubt if any  Group 31 case can provide 204 AH in the standard 20 hour test. ...
Click to expand...
Exactly so Gary.  My premium Group 31 Lifeline AGM's have as far as I know the most amp-hr available in a Group 31 case at 125 AH.  Johnson Controls (JCI) makes the Energizer branded batteries for Sam's club - here's the spec sheet.  Those batteries are rated at 100 AH.
 
I purchased four of the Duracell (also Johnson Controls) Group 31 Deep Cycle AGMs last year at Sam's Club. They are rated at 105AH. The link provided shows the battery with single posts. Mine have the conventional post as well as a screw post. Looks to me like the batteries in the link are AGM Automotive Starting batteries and not Deep Cycle.
 
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