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Topic: Alternator charging fluctuation (Read 892 times) previous topic - next topic

Alternator charging fluctuation

Maybe this has been covered but as I am new I have not seen it.
Just lately the gauge on the dash for volts is now upon starting,  fluctuating between just under 12 to about 13.5, back and forth for a few minutes and then stays at 13.5 (or whatever it needs depending on state of batteries). I can drive for hours with no change once it settles down to normal, but then stop engine and start again and we go thru' the same pattern. I am sure someone has ideas on what is happening and what I have to do.
Thanks    John
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Alternator charging fluctuation

Reply #1 –
John, I can tell you with confidence that it is probably a bad ground. I just went through the same scenario. After 3 months of checking things, it was just a dirty battery ground. First step is to clean the starting batteries. If that doesn't fix it then check the chassis grounds before testing the alternator.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: Alternator charging fluctuation

Reply #2 –
Quote
Just lately the gauge on the dash for volts is now upon starting,  fluctuating between just under 12 to about 13.5, back and forth for a few minutes and then stays at 13.5 (or whatever it needs depending on state of batteries).

I had a somewhat similar problem that turned out to be intermittent making/breaking of the 6 amp circuit breaker that sends excitation to the alternator. This breaker is located with many of the other automotive breakers behind the cover in the stairwell.

Re: Alternator charging fluctuation

Reply #3 –
I am going to out on limb and guess something that it might be. I had several Dodge trucks with Cummins diesels over the past several years. When I started them in cold weather the intake heater would come on and off for several minutes until the engine warmed up a bit. Usually just a few minutes. It would cause the volt meter to fluctuate as it would draw amps for the intake heater. I dont know if these engines work similarly. I guess someone will chime in on my guess.

Regards, Mark
The selected media item is not currently available.
Mark and Tanya
Milton , Florida
US Navy Veteran (DV)
1999 U270 Special 40' CAI , 2015 Jeep Wrangler Sahara

Re: Alternator charging fluctuation

Reply #4 –
thanks for these suggestions. I will check each possibility out once I get the coach back from getting new windscreen and a scratch fixed
John
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Alternator charging fluctuation

Reply #5 –
You should have glow plugs on your coach. It s why they say not to use ether in there among other reasons.  It does draw a bit of current.  The M 11 has no Glow screen so they put an ether bottle in line for you. Strong batteries and a good starter and an update to the ECM took care of my hard start issue when it was cold out.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon