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Voltage at the gauge and real life discrepancy

M

metal-chicken

Regular Contributor
My Honda voltage gauge shows 12.5 - 13v while running which got me wondering if the system was charging properly (even though I've not had any issues).

So yesterday I took a multimeter out with me and checked the vintage at the battery switch and it was a solid 14v (plus a little bit) which makes me feel happier about the system.

How come gauges can be out by such a margin?
 
Metal-Chicken - I asked my dealer the same question when I first got my engine with the dual digital gauges. I actually permanently mounted an analog voltmeter to the battery switch. His explanation is that the voltage on the digital meter is generated through the ECU and is regulated to some extent by the ECU.

On my engine, the voltage shown on the digital meter is always a constant 13.4 volts. Whereas, my analog volt meter will vary from 14.0 to 14.8, depending on whether the batteries have been recently charged or not. It's been that way since 2008, so I stopped being concerned about it.

Maybe one of the Honda Tech's on this forum can provide a better explanation.
 
Can you put the voltage output on your MFD/GPS? I have Simrad gear and I'm able to put it on mine. It's a lot more accurate than the dash guage.
 
If the BF 225 is manufactured in 2010 or later, yes you can through the NMEA 2000 interface. If earlier, I don't think so since Honda has a proprietary electronics interface. A good electrical engineer could probably unravel it, but why bother. Is it possible that your Simrad MFD is getting it's signal straight from the alternator or battery?

If it's coming off the ECU, it is what it is. A different readout won't make it more accurate.
 
chawk_man said:
If the BF 225 is manufactured in 2010 or later, yes you can through the NMEA 2000 interface. If earlier, I don't think so since Honda has a proprietary electronics interface. A good electrical engineer could probably unravel it, but why bother. Is it possible that your Simrad MFD is getting it's signal straight from the alternator or battery?

If it's coming off the ECU, it is what it is. A different readout won't make it more accurate.
Click to expand...

It is getting it off the battery. My gauges read a constant 14v when running, but the MFD shows 14.3-14.5. When the motors are not running, I get a 12.3-12.6 usually.
 
Yes, I'm using a Blue Sea VSR. My 14v reading is coming from the Blue Sea switch as my batteries are fairly buried and I couldn't be bothered to uncover them!
 
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