Dead Coach Batteries

[brianwillkan]

I have a 2009 Magna 630 and recently having a very strange problem. For some reason I cannot start my coach without using the boaster switch. The coach batteries on a volt meter shows full 12 volts and plugged into 50 amps shows 13.6 so they are getting a charge. I can run down the road all day and no indication from my drivers panel of any problems as the alternator handles all of the electrical demands and the Silver Leaf shows 12.6 charging but when I stop I cannot start the coach without the booster.

I did a load test on the batteries and they seem fine.

Any ideas??

[mfire1339]

12.6 sounds to me like the alt is not charging batteries. Do chassis batts have water?

Mike

[RV Wizard]

Look for blown fuse or circuit breaker from the chassis battery. Also check to be sure negative side it well grounded to frame.

[wa8yxm]

I have the same problem from time to time... There are two possible issues that I can see (Really more but the rest are 2b, 2c, 2d, et-al)

1: Battery dead.. There are a couple of battery failure modes. one is "High resistance" and when this happens a new battery is the answer. (The other is shorted cell)

2: And was suspects go this is #1,2,3,4, and up to #(n-1) (The battery is #n)

Bad connection... Start by cleaning the battery terminals and the lugs that connect to them.. Even if it is a side terminal (GM type) battery.... I have had to do that 3 times so far on my coach. Battery still passes a load test with flying color (GREEN)

The rest of the "N-1" list is every other connection between battery and starter, both ground and positive side

[brianwillkan]

Problem solved.

Strange as it may seen the problem turned out to be a blown 600 AMP fuse that conducts the power from the coach batteries to the starter. By turning on the booster it trips a relay which sends the power from the house batteries to the starter.

The fuse is a T-Tron JJS 600 AMP and retails through Grainger Supplies for $1,021.

Very strange to see one of these blown but was the cause of my problems.

[mfire1339]

Hope your decimal is in the wrong place!

Mike

[2Divers]

here it is at about $336.00

Bussmann JJS Class T Fuse 1A-800A

[brianwillkan]

That seems to me to be an 800 AMP fuse.

[2Divers]

the link I gave list all the fuses from 1 amp to 800 amp.

The OP's fuse is listed there.

Bill