New House and Engine Batteries- all now dead??

mything2

Member
I had posted an earlier thread in December 2013 about a 12 volt problem and I thought that just replacing both batteries had solved the problem BUT now I have 2 dead batteries. Here's what I have so far:

-what appears to be a bad alternator -meter is supposed to show a 1 volt increase to the 12.4V fully charged engine battery when the engine is running which indicates that the alternator is good.....no increase at all so MAYBE the alternator is bad?

-when plugged into shore power, the Parallax controller should allow the house battery to charge but no charging is taking place.

-the switch that allows u to isolate the 12 volt system doesn't work consistently....I have to toggle it several times and then I can -sometimes- get it to go on (use).

Is it possible that I'm looking at a fried charging system? Any and all replies are greatly appreciated.

Dan
 

glas1700

Member
A fully charged chassis battery should measure 12.65V, not 12.4V. A battery that measures 12.4V is at about an 80% charge state. A good alternator should supply up to 14.4V when charging your chassis battery.

If this was my motorhome, I'd go buy a good battery charger and charge each battery separately up to a full charge. At that point, I'd start the engine and measure the alternator output and make sure that the coach battery is also receiving a charge. If you don't measure over 14V, then you may have a failed alternator or if you have a V6 chassis, it could be the cable that connects the alternator, starter and battery.

Parallax converters have what I consider to be a unacceptable failure rate, but if you measure 13.6 to 13.8V at the converter output, then it's okay. You can check the converter output with your voltmeter by probing the terminal above the two 30A fuses and any convenient ground point, such as the ground lug on the fuse board.
 

beachbum57

2003 LTV Free Spirit
I would also check the toggle switch that isolates the 12 volt system. I had a bad disconnect switch once... which drained my house battery. Maybe...
 

mything2

Member
I would also check the toggle switch that isolates the 12 volt system. I had a bad disconnect switch once... which drained my house battery. Maybe...
What's the best way to check the battery disconnect switch? I know it sometimes requires me to toggle it several times before it lights so this may be the root cause if the Parallax converter isn't bad - I check it tomorrow. Thanks
 

beachbum57

2003 LTV Free Spirit
I would check the wires going to the back of the switch to make sure the wire terminals have good contact with the switch contacts. I would use a voltmeter on the switch terminals and toggle the switch to see if it is connecting and disconnecting the power. If it is, then the problem is elsewhere, however, you have already indicated that it does not work properly without you having to toggle it several times. If it's not a loose wire, I would just replace the switch.

Hope it turns out to be something simple and cheap!
 
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