SonexBuilders.net

This is for those running a 14+volt regulator and an Earthx battery. When you measure the voltage at the battery, does it get “pulled down” by the battery to 13.1 or 2?? My dynon voltmeter never seems to go above 13.2 during flight. I think I am running a stock VR so my output volts could be lower. Have not measured it yet.

There are multiple places in the system to take voltage readings, each is relevant in different ways.

For the battery, the only voltage that matters is the one you are measuring, and if your measurement is accurate then it is too low.

Another important voltage is the voltage that is SENSED by the voltage regulator. The voltage regulator will try to adjust the output of the alternator so that the regulators SENSED voltage is as prescribed.

So, what it sounds like is there is some resistance in the circuit to the battery. The voltage regulator is driving the alternator output from a sensing location that has less resistance. This probably means that the output from the alternator is in the correct 14.2 approximately voltage, but by the time the electricity gets to the battery it is down to 13.2.

One (careful) suggestion then would be to try to get the voltage regulator to SENSE from a location that is at approximately the same voltage as you are reading at the battery, ie sense directly from the battery. Be careful though, as this may push your alternator output to well over 15v. The voltage at your main buss should not be allowed to sit this high.

Better would be to figure out where all the resistance in your charging circuit is and remedy that.

Score you start in that, you should verify that your voltmeter is accurate.

Good luck, Gordon

My voltage starts off around 13.7 and as the battery recharges it heads up to 14.4, from what I've written down. Not sure how high it will end up after a longer flight. Most of my flights have been about a half hour.

I’m just wondering if that VR is putting out anything, toward the end of a 1 hour flight, I was down around 12.8 or so. Never played with these lithiums. As a first step I want to see what putting 14 volts on a fully charged Earthx and extrapolate from there. I know what an AGM and SLA battery do. My sonex with pc680 shows 14.3 volts at runup.

I have the Aerovee 2.1 engine and the normal VR. Looking back at pictures I have taken over the last 2 years, in flight after a few minutes the voltage is usually 14.5 or 14.5 or 14.6 volts.

waltb wrote:This is for those running a 14+volt regulator and an Earthx battery. When you measure the voltage at the battery, does it get “pulled down” by the battery to 13.1 or 2?? My dynon voltmeter never seems to go above 13.2 during flight. I think I am running a stock VR so my output volts could be lower. Have not measured it yet.

I have the exact same issue. Any update on remedies? I've purchased 2 new regulators to try. Exspensive if it turns out that isn't the issue.