Bad Alternator?

[Dean Johnson]

Hello, I need some help!
I had a 12v FM transmitter plugged in to the 12 volt socket in the dash that got left on and drained the chassis batteries, had to use the battery boost to start the engine. I took a 10 minute drive as we were moving locations and the transmission kept kicking out of gear while trying to back up a driveway. I put a battery charger on for a few hours and all was good, the digital voltmeter showed 12.5 volts on each battery and both combined. We drove for three hours today and the dash voltmeter never got above 11.8 and was at 11.2 for most of the drive. The digital voltmeter now shows 11.75 Is my alternator about to fail?

Thanks
Dean

[Steve Huber Co-Admin]

Dean,
Sure sounds like it. You probably fried the alternator when you fired it up with badly discharged batteries. Best to use the generator to charge the batteries before starting the engine since the alternator doesn't put out enough current to handle 2 badly discharged batteries. There are a number of threads on this in the Tech section of the forum.
One other possibility is that your Echo charger is bad, but it's doubtful based on your description.
Steve

[Joel Ashley]

After a deep discharge, most chassis batteries are never the same.  But if you boost start to get on the road again, you can also stress the alternator, which has to work harder to recover the batteries.  It might have been better to charge all your batteries up first with the generator.  It sounds like your alternator is not about to go... it's likely left the building already.  A voltmeter on the chassis bats with engine running should read 13 - 14 volts, not 11.8.

Joel

[Edward Buker]

It does sound like the alternator is gone, but there is a small chance that the battery isolator is gone instead of the alternator.  With the engine running, check the alternator output terminal with a meter and see if you are getting 14V or so.  If so, check the battery banks and see if either are seeing the 13.5v or so.  The isolator is between the alternator and battery, if they are not.

If you have a continuous duty emergency boost solenoid, I think it is a very good modification to change the momentary rocker switch to an on off type. I did that on my last coach. When the starting battery is that low, you can put it in the on position and leave it. You would start the generator and the inverter/charger now has the ability to charge the chassis batteries at a high rate. The echo charger will not recover a dual set of dead batteries, and using the alternator to do it is a tough job for it.  The only down side is forgetting and leaving the switch on. That one is solvable, and you get to not buy new alternators...

Later Ed

[Keith Moffett]

Dean
I just dealt with a similar situation, for the second time in four years.  If you have the Leese Neville alternator that came standard on many Beavers, there are 6 diodes and not all fail.  For this reason the alternator may put out but not enough (14.2 V).  The first one I replaced cost about $650. new and lasted two years and about 3000 miles.
I took the origional and the replacement to a trusted shop and the manufacturing was very poor causing a short.  Leese Neville promised to look into it and never got back to me.
Regardless, the shop ordered all new guts and rebuilt it to better han new quality for $250.
The moral here is new isnt always better but is more expensive.

Best of luck
Keith

[William Brosam]

the alternator is nothing special on these motors the previous owner of my coach got a new one from auto parts store for under 150$.

now i dont know what part number or model he used.

[Dean Johnson]

All,
Thanks for the replies. I was able to find a mobile repair tech, Bark's Auto Repair in the Palm Springs area, 760-774-1312. They came out same day, diagnosed it, pulled the bad alternator and came back the same day with a new one, installed it for less than $600. That was less than I thought and in less time than I thought. All this only cost us one extra day so we are back on the road but if anyone is ion this area, these guys do a greart job.

Dean