Any harm in disconnecting alternator and driving on?

[DJJ]

Alternator started putting out almost 17 volts. I was only about 15 miles from home after our summer travels so I figured the batteries could take it for that short amount of time. I will take it to be rebuilt.

But I started thinking, what if I had needed to drive a long way. Is their any reason I don't know of why the alternator can't be disconnected electrically while driving. Other then the oblivious, batteries are not being charged.

FL XC chassis, Cat 3126B.

Jeff

[C.Martin]

If you are measuring 17v at the battery...I would see if there is an voltage regulator adjustment on the Alternator to dial it back in, check the connection for the sense Lead...or replace it if it is not functioning properly.

Depending on how your bi-directional relay reacts...you may or may not wind up loosing the chassis battery...and all the control that it gives you for the engine and drive train. I personally wouldn’t recommend that course of action...unless told by a chassis engineer that it would be safe and for how long.

[arcaguy]

I guess it all depends upon how long you disconnect it. Some of the modern electronics in vehicles are real persnickety about voltage. That said, I'm thinking that you could limp along by disconnecting the battery (negative terminal), run for a half hour or so and then reconnect it for 10-15 minutes to recharge the battery, rinse and repeat. Probably the worst thing overcharging the battery would do is boil off some water which is better than sitting on the side of the road. It will be interesting to see what other folks have to say.

[Podivin]

Wouldn't running the generator, and therefore powering the converter, make up for the lack of an alternator?

[garry1p]

I had a problem where the alternator stopped charging. I ran the generator for better than 70 miles with no problems.


I don't know how far I drove before I figured I had a problem, I just noticed voltmeter showing around 12.0V pulled over and checked alternator output. Cranked up gen set and kept going.

[dennis45]

Originally Posted by garry1p

I had a problem where the alternator stopped charging. I ran the generator for better than 70 miles with no problems.

The alternator died on our old dutchstar between Alaska and the Yukon. Ran all the way to Kamloops, BC before I could source a new replacement. Plugging in every night and running the generator on the long travel days. No problem....
Just a matter of keeping the battery voltage up.

[twinboat]

Originally Posted by arcaguy

I guess it all depends upon how long you disconnect it. Some of the modern electronics in vehicles are real persnickety about voltage. That said, I'm thinking that you could limp along by disconnecting the battery (negative terminal), run for a half hour or so and then reconnect it for 10-15 minutes to recharge the battery, rinse and repeat. Probably the worst thing overcharging the battery would do is boil off some water which is better than sitting on the side of the road. It will be interesting to see what other folks have to say.

No, no, no, don't disconnect the battery and run just on the alternator.

The alternator will run at extremely high voltage, without a battery, and start burning up electronics.

Disable the alternator and start the generator. If you have bi-directional charging, you'll be fine, the house charger will support the chassis battery, otherwise jam the boost switch in boost mode to do the same thing.

[DJJ]

I used my scan gauge D to determine the voltage. The red battery light and for some reason the abs light came on also. When I got off the interstate and came to a red light, while at idle, the lights would go out and the voltage would come down and lights would go out. This cycle repeated all the to backing the RV in the carport. I'm sure it's the voltage regulator in the alternator.

Gary1p, 6 years ago, I had to do the same thing the last few days of a trip. Alternator quit charging all together. Just connected the shore power at night to recharge batteries. And ran the generator for a couple hours in the middle of the day while driving.

To my way of thinking if the alternator does not put out voltage to charge the batteries and I could drive several days like that by charging the batteries at night. In an over charge situation was their a reason I could not disconnect the Alternator?

The coach is a Newmar Dutch Star 2003 and does have the bi-directional charging.

And this is all academic. If in the future my lack of luck with alternators continues.

[Randy125]

Not a problem just run generator and converter and monitor voltage, also disconnect alternator sensing wire.

[ladagobago]

Originally Posted by twinboat

No, no, no, don't disconnect the battery and run just on the alternator.

The alternator will run at extremely high voltage, without a battery, and start burning up electronics.

Disable the alternator and start the generator. If you have bi-directional charging, you'll be fine, the house charger will support the chassis battery, otherwise jam the boost switch in boost mode to do the same thing.

listen to TwinBoat. alternately, you could hot wire the relay. Once I had an alternator trouble and used a my HF charger plugged into my block heater outlet to charge the chassis batteries and ran the generator to power that and my house batteries. The FL didn't know the difference. I keep that HF charger there to charge my chassis Deepcycle AGM batteries when we are parked at home. ,

[arcaguy]

My bad, I should have said disconnect the alternator and run on the battery, but even then the coach would still be getting 17 volts when the alternator was hooked back up. I'll go stand in the corner for 10 minutes.

[Milford 47]

Originally Posted by DJJ

Alternator started putting out almost 17 volts. I was only about 15 miles from home after our summer travels so I figured the batteries could take it for that short amount of time. I will take it to be rebuilt.

But I started thinking, what if I had needed to drive a long way. Is their any reason I don't know of why the alternator can't be disconnected electrically while driving. Other then the oblivious, batteries are not being charged.

FL XC chassis, Cat 3126B.

Jeff

Let us know what the problem was, regulator or whatever

[DJJ]

Originally Posted by Milford 47

Let us know what the problem was, regulator or whatever

Will do.

[DJJ]

Milford47,
Regulator was bad, $89 part. Back and running.
Jeff