Chassis Battery Charging Problems

[Jerry Parker]

I have a 98 Beaver Patriot. During the winter I have started the engine about once a month and ran it at 1500 RPM until the water temp got to 190. Never had a problem until last week. I went to start the engine and the chassis batteries were dead. (about 8 volts) I suspect the step switch was left on the last time I ran the engine. I hooked up my 15 amp battery charger to the terminals with the large main cables (per Ken at Beaver service), but after 3 days of charging, the batteries are still only showing 10 volts. Does any one have any ideas, or will it just take a long time to charge with only 15 amps going in? I also get an intermittent humming sound somewhere in the coach when it is charging.

[Edward Buker]

You should disconnect the coach + or ground cable from the starting battery bank and try charging for a day and see where the voltage is. If you find it is still quite low (less than 12V) disconnect the jumper that parallels the two starting battery plus leads so that they are independent. Then charge each one and see where the voltage is after a day of charge. If a battery will not charge to 12.6 to 12.8V after being disconnected for awile or one ends up much lower than the other then it is bad. You can replace one or both. If they are 2-3 years or more old you could consider replacing both. Once charged and set reconnect the coach and check the voltage after 8 hours and it should be within a tenth or two with a normal discharge rate due to electronic loads.

As far as the humming, with the voltage that low it could be a stalled motor that was left on or some electronics sounding off due to circuits that are not functioning properly at such a low voltage. If you have a DC ampmeter and can place it in series with the + lead and the battery before you connect it after charge you should see about 2 amps of load. Something much more than that I would  suspect something is left on. My assumption here is that there is no AC connected to the coach while you are hearing the hum.

Later Ed

[Jerry Parker]

Thanks Ed, I will try the things you suggested. I will check everything inside the coach to see if I can find anything on. I did have a buzzing sound and found the step motor or the plastic box the motor wires connect to was where the buzz was coming from, so I disconnected the wires. Maybe something else got left on to. The coach was used as a bedroom for guests in January. Maybe something was left on that I didn't find. I do have the shore power plugged in.

Thanks for the help
Jerry Parker