Author Topic: Simply way to adjust automobile alternator voltage  (Read 12485 times)

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dnix71

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Simply way to adjust automobile alternator voltage
« on: March 08, 2011, 06:26:58 PM »
Is there a simple way to lower the set voltage on my van alternator? It's overcharging the battery (14.5v+) The battery isn't harmed much but it lowers my fuel economy.

In olden times I would just pop the shell on the regulator and turn a set screw. Now it's all internal and solid state.

joestue

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Re: Simply way to adjust automobile alternator voltage
« Reply #1 on: March 08, 2011, 07:02:18 PM »
it is possible to make the regulator think the battery is at 14.5 volts.
you may have to remove it from the alternator. this can take some work.

it would probably be easier to stick a diode in series.
Schottkys are 0.3 to 0.4  silicon is .7 or as much as 1.1 under load if its rated to more than 600 volts.

 

RP

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Re: Simply way to adjust automobile alternator voltage
« Reply #2 on: March 08, 2011, 07:38:19 PM »
Unless it's a true design flaw, there's something broken or failed, not out of adjustment.  A good start would be cleaning all electrical connections between the alternator and the battery.

DanG

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Re: Simply way to adjust automobile alternator voltage
« Reply #3 on: March 08, 2011, 08:02:52 PM »
14.5 is not overcharging an auto starting FLA battery - and the battery itself and running loads would determines current levels are being supplied & that would be what would load up the alternator. Remember when the battery becomes charged it rejects current input and might not clamp the regulated voltage down so what you're seeing is normal. Without charging the battery the alternator is not doing much work at all.

I've changed the internal regulator on an LT-1 Camaro way back when - it had an annoying habit of causing all lamps to dim deeply and then spring back up about 15 seconds after starting the motor. The Chevy dealer sold me the part and I did the job under a streetlight at night, it lasted 135,000 miles and was on the second battery when it was traded off. Unless you know what the OEM part spec level is you might not be getting an improvement.

David HK

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Re: Simply way to adjust automobile alternator voltage
« Reply #4 on: March 08, 2011, 09:47:40 PM »
I am not sure if this reply helps, but the attached URL will take you to an article about the use of automobile alternator for battery charging.

Its worth a read if nothing else.

http://www.scribd.com/doc/5657744/Build-Your-Own-12-VDC-EngineGenerator

David in Hong Kong