04 ram 2500 5.7 running 16.5 volt

Pnied919

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2004
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I have an 04 2500 with the 5.7 and my volts don’t change rapidly but they move between 14.2 volts to up to 16.5 volts and it will stay one way or the other for 3-4 days at a time I have had the alternator tested 3 times and the battery is only 2 months old and these numbers are from a multi meter not just my dash gauge. Any help would be appreciated
 

Mister Luck

cassis tvtissima virtus
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There are several alt options depending upon what you have including the diameter of the alt pulley the ECU controls voltage demand through a sensor on the negative side of the battery post clamp or under the battery box.

Estimating your accessory consumption (headlamps hvac stereo winch etc) you may have more usage depending upon demand,in general though (if your truck came with a) smart charging sensor or a battery temperature sensor it is best paired with a AGM (Absorbent Glass Mat) battery because of temperature sensitivity, in some RAM’s they were delivered with non AGM batteries , you may want to check to see which type you have. I believe it makes more of a difference in extreme temperature environments than in temperate ones.
 
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Pnied919

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Same alternator just different times testing it. And it does have the battery temp sensor. With the glass mat, but ambient temps doesn’t change it. It is random I can shut it off charging at 14.5 and start it right back up and it just to 16.
 

Mister Luck

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The ambient temps are only going to affect the charging if extreme and it’s the battery’s actual temperature that’s being effected and targeting the sensor input.

AGM’s are different in that they have a tendency to be under charged to extend their life

When charging for maintenance AGM are required to use chargers that are implemented with microprocessors to monitor the process as to correctly charge the cells … a non-processor equipped battery charger could either overheat or shut off before charging is complete.

It helps also to know if you have the correct alt and pulley (diameter) size and that it’s rated max is at 160, 180, or 220V
 
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