Community Forums

Sagamore · 09-15-2016, 04:16 PM

I bought a new coach battery and it started going dead even after being on the road for hours. Had the coach battery retested and it's good. Connections are not corroded. Help?

TeJay · 09-15-2016, 06:56 PM

Always, always start with a measurement at the coach battery with the engine running to determine the voltage coming from the converter to charge the coach batteries.

Your engine alternator is going to go through the converter to re-charge the coach batteries. The voltage should be 13.6 Volts or slightly higher. If you are not reading that voltage or reading 12-volts or lower your converter is not working to re-charge your coach batteries.

While checking also check the engine battery to determine the charge voltage to that battery as well. It should also be 13.6 volts or slightly higher.

grtharris · 09-15-2016, 08:16 PM

TeJay Voltage only comes from the converter when the coach is connected to 120VAC either shore power or generator.
Sagamore, When the engine in running the alternator charges the coach batteries through the Chassis/Coach Battery Isolation Relay (Aux Battery Relay). The relay closes when the engine is running and opens when the engine is off.
The contacts in the relay will get pitted and not pass current with age.

vsheetz · 09-15-2016, 09:15 PM

Check voltage at the battery with and without charging active for each charging source. The voltage should be about one volt higher with charging active. If no voltage change, that charging source is not working.

twinboat · 09-16-2016, 02:08 AM

Some Class C MHs is a basic system to connect the engine battery to the coach battery.

The moment you turn on the key, a solenoid engages between them. On mine, I can hear the " clunk " of it, under the hood.

Although it clunks, the contacts inside do not make contact, so no charging of the coach battery.

Find the solenoid and with engine running, check voltage on each big terminal. If it's not the same, it is not working.

If it clunks, the solenoid is bad. If it don't clunk, there should be a fuse for it. The fuse for mine is under the hood, I'm a harness, on the left side. The solenoid is on the right side, above the master cylinder. It looks like this.