battery warning comes off and on

I am currently on the road with my family in our 05 conversion and started to experience a battery/charging indicator coming off and on. N tneds to stay off for the 1st 20 minutes to the drive bfore coming on sometimes for seconds other times for an hour. I have used a multiemeter to determine that when the light is on the positive terminal on the alternator is not producing voltage as reading is that of the battery. Is it normal for an alternator to work then not work before failing. At the moment I am in the middle of no where. I do have solar which have kept house batteries up but things are starting to lag on charge a bit. Any helpful. Would be great before I send a mechanic fishing. Thanks

Kavy
If your vehicle has done lots of miles it probably has worn brushes in the alternator. You can get a bit more life out of the brushes by bending the lugs that the wires are bonded to. To do this you will have to strip the unit, an easy job if you have the tools. Eric.

Intermittent charging could also be a sign of a loose connection somewhere... including the engine to vehicle frame ground strap.

--dick