Charging voltage question..

Bedifferent

Old man on a bike
Joined
Dec 11, 2014
Messages
1,813
Location
Coldwater, MI
Ride
2015 Rocket 3 Touring
Several years ago I updated my voltage regulator/rectifier to a SH847AA series regulator/rectifier. I later installed a small dual USB port with a small digital volt meter display in it as well. I did this for being able to charge my phone and being able to use it for GPS and such while riding. Anyway, I notice the charging voltage seems to run at 14.7 to 14.9 volts almost all the time when riding. I have verified this voltage with an accurate VOM and the voltage is no more that .1 volt off from the display. Everything seem to be okay and it's not like my battery has ever exploded, but it does concern me as being a little high relative to what normal charging voltage should be...like with a car. I would consider around 13.8 volts to be more normal. Any thoughts on this voltage forum members?...@DEcosse maybe?
 
When Tuneecu is connected, charging 14.9V
 
Typically an alternator should put out 14.2 to 14.4 volts for most effective charging of 12 volt battery. Gassing of battery starts around 14.5V and excessive gassing of battery can occur above 14.7V which can cause drying of battery cells and damage.
 
think the manual states that if the voltage is above 15v the rectifier needs replacement. Also above that voltage you can get issues with the turn signal indicators
 
Frans said:
think the manual states that if the voltage is above 15v the rectifier needs replacement. Also above that voltage you can get issues with the turn signal indicators
Click to expand...
I have not noticed any issues yet on the turn signal front.
 
Well, my battery seems good as I also keep it on an optimate all the time. I am on the third year for this battery which is a year longer than I usually keep a battery. I usually swap them out every two years because that's the way I am. A Yausa AGM battery. Considering my actual VOM reads .1 volts less than the display on the USB port I'm right on the edge according to your information. I'm not sure if and AGM battery suffers the same fate as a regular lead acid battery. I have never found it neccessary to check any of the AGM cells [r add any kind of distilled water on that type of battery.
 
14.9 is higher than I have typically seen on an SH847 so that number is a little surprising
I'd definitely go more with the actual DVM than a USB device - and I wouldn't discount checking against another DVM just to be sure. Just because it reads similar to your on-board doesn't necessarily guarantee either - or both- are in spec. (but not to say they are not, either)

A lot depends on the load too - is this with dual headlights running? Std Incandescents (55/60W)?*
*Edit - check there - I see it's a Touring - so same question re at least the headlight & does it change with the aux lamps on?

And if your battery is in top condition and fully charged, it is not pulling any significant current either (suspect it probably reads a little lower right after it's been started until battery reaches full charge again)

Regardless 14.9, is not going to cause problems - many car alternators put out 16V - I know mine does! And being applied to the same lead/acid technology battery.
 
Thanks DEcosse, It pretty much reads in the range I mentioned and it never seems to change. I would expect it to throttle back after startup and charging stabilizes but for most part it continues on in that same range. To be honest, 14.7 to 14.8 is were it rides most of the time. I have several high quality meters, so I'll check it again with each meter including a older Simpson analog meter. As for current draw, it is probably minimal as all of the front running lights are LED lights. Not led bulbs but actual replacement LED lights made by Truck-Lite. I believe the headlight pulls a maximum of 2.94 amps with the auxiliary lighting considerably less. The headlight is also on the Eastern Beaver relay wiring as well as I put that in when I was running the standard halogen bulbs. I've been running this way since all last year so I guess I will put it on the back burner for concern. Thanks
 
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