Check your battery cable

[firetrucker]

Well, it certainly took me long enough to find this problem, especially with all the topics about batteries, but take a minute to check the size of the cables connecting your second battery to the first. I was checking the water in the batteries before our next trip and noticed that the cable from the first battery to the rig was 6 guage, but the cable the dealer used to connect the second battery was 12 guage.

That's ok when you're not drawing much current, but it unbalances the batteries when you're opening or closing slides or charging at a fairly high rate. I don't think it will cause a problem in the short term, but the general principle should be to use the same size cable for both batteries.

Bob

[Cat320]

Good point. I'm in the process of putting a new 40 amp charger in my boat...that has two 4 D batteries that crank out about 200 amps...each.

[Parrothead]

Bob
That was what we discovered when we had our little accident last spring. Evidently the dealer installed the second battery in our unit (he never mentioned it to us) and used 10 gauge. When we were fixing the problem we couldn't find ten and so used 6. Later I read where what we did was good!
Happy trails..................

[Steve and Brenda]

Yep, cable size is important for good current flow. Those darned electrons like open spaces

Something to make better current flow and to reduce corrosion is to solder the lugs to the cables themselves instead of crimping them. After the solder use heat shrink to weatherize the cables. Any propane plumbing brazing torch can solder the lugs, well worth the extra steps to ensure you get every amp you deserve.