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69BahamaYellow Samba Member
Joined: April 22, 2011 Posts: 535 Location: Talbott, TN
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Posted: Wed Mar 02, 2016 7:23 pm Post subject: Alternator light stays on until I rev the motor slightly |
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I just upgraded my stock 55amp alternator to a Bosch AL108X that has been boosted to 110 Amps. When I start the bus, the alternator light stays on until I rev the motor slightly, and then it goes out and stays out from idle through full throttle operation. I've checked the voltage output and it is 14.1 volts at idle with no accessories running, and 13.86 volts with lights, radio, and heater fan on. The alternator light never stayed on after starting with the stock 55 amp unit. Has anybody else seen this happen? |
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aeromech Samba Member
Joined: January 24, 2006 Posts: 16898 Location: San Diego, California
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Posted: Wed Mar 02, 2016 8:20 pm Post subject: Re: 1979 2.0L fi Alternator upgrade (55 to 70 amp) |
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Sounds like no problem to me. Question is, why would you need 110 amps? _________________ Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound |
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69BahamaYellow Samba Member
Joined: April 22, 2011 Posts: 535 Location: Talbott, TN
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Posted: Thu Mar 03, 2016 5:58 am Post subject: Re: 1979 2.0L fi Alternator upgrade (55 to 70 amp) |
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The extra amps will be for an A/C install, I'm working on. I wanted to post the alternator question here, so it's easily searchable for others with the same problem. There's a ton of good info on this site.
The alternator seems fine to me too, but it's like I have to "wake up" the voltage regulator, when I first start the engine, and the last thing I want is to start off on a long trip, knowing something could fail, with no easy sources of spare parts.... |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5680 Location: Manhattan, Kansas, USA
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Posted: Thu Mar 03, 2016 6:32 am Post subject: Re: 1979 2.0L fi Alternator upgrade (55 to 70 amp) |
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The "wake it up" thing was common on at least the diesel Rabbit cars and Cabriolets. I had several of each and they were all that way. Also had a Corrado that did it and a Corrado that didn't.
The only time at all it was a "problem" would be if I were to start the car with the intention of idling it for a while (which is very, very rare for me to do), the alternator wasn't charging if I didn't think to blip the throttle after starting.
I say don't worry too much about it. _________________ Dave Cook
President, Wild Westerner Club
1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing |
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johnsilverlakes Samba Member
Joined: July 22, 2015 Posts: 96 Location: Silver Lakes, California
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Posted: Thu Mar 03, 2016 8:17 pm Post subject: Re: 1979 2.0L fi Alternator upgrade (55 to 70 amp) |
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69BahamaYellow wrote: |
I just upgraded my stock 55amp alternator to a Bosch AL108X that has been boosted to 110 Amps. When I start the bus, the alternator light stays on until I rev the motor slightly, and then it goes out and stays out from idle through full throttle operation. I've checked the voltage output and it is 14.1 volts at idle with no accessories running, and 13.86 volts with lights, radio, and heater fan on. The alternator light never stayed on after starting with the stock 55 amp unit. Has anybody else seen this happen? |
I had that issue with my 70amp alternator. I installed a volt meter to monitor actual charging. It wouldn't charge above 12 volts until the motor was reved. I kept thinking it was a voltage relay. I ran it with that issue for many years. Recently, I pulled the engine to fix some oil leaks. I decided to clean all the electrical connections at the harnesses and eliminate non stock wiring...Long story short. It must have been a faulty connection. Now, no problems with the charging system! _________________ 1976 Westfalia
Manual Transmission
Federal Emissions |
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69BahamaYellow Samba Member
Joined: April 22, 2011 Posts: 535 Location: Talbott, TN
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Posted: Mon Mar 07, 2016 6:06 pm Post subject: Re: 1979 2.0L fi Alternator upgrade (55 to 70 amp) |
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I double checked all my connections from the alternator to the voltage regulator, and there were no issues. Then I ran across this article about "waking up a Porsche 914 alternator" (essentially the same as a bus). At the very end, it said the alternator warning bulb in your dash needs to be at least 2 watts to give enough current to wake up a Bosch alternator at initial startup. I checked mine, and it was only 1.2 Watts, so I changed it to a 2.3 watt bulb, and that solved the problem. Unbelievable.......
http://www.pelicanparts.com/techarticles/914_alternator_troubleshoot/914_alternator_troubleshoot.htm |
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aeromech Samba Member
Joined: January 24, 2006 Posts: 16898 Location: San Diego, California
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Posted: Mon Mar 07, 2016 7:07 pm Post subject: Re: 1979 2.0L fi Alternator upgrade (55 to 70 amp) |
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Good find, thanks _________________ Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound |
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Wasted youth Samba Member
Joined: July 06, 2012 Posts: 5134 Location: California's Hot and Smoggy Central Valley
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Posted: Fri Dec 03, 2021 8:45 pm Post subject: Re: 1979 2.0L fi Alternator upgrade (55 to 70 amp) |
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Interesting. The red LED indicators for BATT and OXS behave exactly the same way on my 1981 Vanagon. They stay on until you give the accelerator a little goose, just like on my '73 bus.
LEDs are low wattage. Don't know what I'd do to resolve that. |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5680 Location: Manhattan, Kansas, USA
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Fri Dec 03, 2021 11:13 pm Post subject: Re: 1979 2.0L fi Alternator upgrade (55 to 70 amp) |
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Wasted youth wrote: |
Interesting. The red LED indicators for BATT and OXS behave exactly the same way on my 1981 Vanagon. They stay on until you give the accelerator a little goose, just like on my '73 bus.
LEDs are low wattage. Don't know what I'd do to resolve that. |
2016 was the last post before you. Old thread. But if you have LED as the alt warning then it won't work as well to excite the alternator I think. Might ask Telford. _________________ “Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
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