Low Voltage Alarm Question

CaptainCrab · 01-09-2008, 05:29 PM

OK, Gang, after spending a month with hook ups, I headed to our next location about a 6 hour run. As I was comong down a grade I noticed that the traffic was picking up so I reached over to turn on the engine bake, but hit the Batttery Boot switch by mistake. I didn't notice any thing wrong at the time so I made a fuel stop and headed off again and about 5 miles down the road I get a Check Eng lamp and a Low Voltage Alarm on the control center, I fliped the to see that the Voltage was reading between 11.8 and 12.1 and would not get any higher, but the coach was running fine so I went on to our destanation about 80 more miles. Question, do you think hitting the Booster Sw. did something to the Altantor? If I start the engine now after being pluged in again all is fine? What do you think?

CaptainCrab · 01-09-2008, 05:29 PM

OK, Gang, after spending a month with hook ups, I headed to our next location about a 6 hour run. As I was comong down a grade I noticed that the traffic was picking up so I reached over to turn on the engine bake, but hit the Batttery Boot switch by mistake. I didn't notice any thing wrong at the time so I made a fuel stop and headed off again and about 5 miles down the road I get a Check Eng lamp and a Low Voltage Alarm on the control center, I fliped the to see that the Voltage was reading between 11.8 and 12.1 and would not get any higher, but the coach was running fine so I went on to our destanation about 80 more miles. Question, do you think hitting the Booster Sw. did something to the Altantor? If I start the engine now after being pluged in again all is fine? What do you think?

John_Canfield · 01-10-2008, 02:59 AM

That is an interesting scenario.

Here is how mine is configured - there is a heavy duty solenoid or contactor that bridges both house and chassis battery banks together whenever the engine is running so the alternator charges all five batteries (or however many you have.)

Operating the Battery Boost switch simply operates the same solenoid that is automatically energized when the engine runs.

So what you did was place 12V again to the solenoid coil.

I doubt if you did any harm, but an easy to check is to start the engine and see if both battery banks are being charged at something over 13 volts. And/or you can have somebody operate the boost switch and listen around the electrical bay for a clicking or clunking noise.

Pusherman · 01-10-2008, 05:58 AM

My comment is

but just a note to the diesel owners out there when you find out you have lost an alternator or have a charging problem with your system:

Don't turn off the engine! You might not get it started again. As Mike -N- Sally found out, you can continue your trip with low voltage. Diesel's don't need 12V to run the engine. All the accessory items do need 12V (lights, fan for a/c, radio, etc.) so you can conserve 12V by shutting down all unnecessary electrical items and drive your coach to a repair destination.

Had it happen to me once. I actually drove to my campground with a bad alternator, bought a battery charger from Wally World, charged the engine battery over the weekend and then drove 100 miles home 2 days later conserving 12V along the way..... then had the coach fixed.

Doug Sage · 01-10-2008, 06:06 AM

I was on a diesel tour bus in Alaska that lost its alternator. The driver kept driving until the motor finally died. He found out (the hard way) that the motor needs some small amount of electricity to run. A diesel cannot run forever without electricity.