Wondering if anyone can tell me what is going on regards to my volts dropping from typical 12.5+ to 10.1 as I was leaving Prosser this afternoon. I shut down nav lights and lighting and it took about ten minutes to climb back to 12. I am thinking its time for a new stock alternator from Vans. I ordered my kit in 2014, so I think its the Plane Around set up. Also thinking of putting that second alternator in and welcome any thoughts. Thanks in advance.
Van's Air Force
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Volts dropped
- Thread starter Thor RV10
- Start date
Uh, what's going on is your electrical system is all screwed up. When the alternator is running properly, you should never see 12.5+ volts; more like 13.5 volts minimum if it's going to charge a standard lead acid battery; more like 14.1+ if it's an Odyssey sealed battery. If you see 12.5 volts it means your alternator is already off line. How it can climb back up from 10 volts, which is pretty much dead, when you don't measure anything higher is a complete mystery to me. Exactly where in the system is this measurement made?
rv7charlie
Well Known Member
Assuming an accurate voltmeter, it dropped from 12.5 to 10.1 because your alternator was never charging. Otherwise it would have dropped from ~14.x volts downward when the alternator stopped charging.
It's worth doing a little troubleshooting before ordering an alternator; lots of things can cause loss of charging.
Charlie
(Aeroelectric list is your friend.)
It's worth doing a little troubleshooting before ordering an alternator; lots of things can cause loss of charging.
Charlie
(Aeroelectric list is your friend.)
Batteries (any power source, really) drop more voltage when they're under more load; that's why you should always test a battery with a load on it. OP said voltage came up when he shed the nav lights; reducing the load will generally produce an increase in voltage.
I'd look at the alternator (for charging, and providing the baseline power), but I'd also consider that the battery may be going soft if the nav lights cause that much drop. If the alternator has been weak for a while, the battery is likely to have been called upon to assist many times, which would wear it out.
Thanks for the advice. Rob Hicmans son Brian is going to take a look (I dont think Rob told Brian yet) at it tomorrow after work here at AWO. I suspect the gauge might have malfunctioned. I now recall the number is around 14.5 and I am running two Odyssey batteries as I am running with EFII for both electronic fuel injection and dual RLC. Ignition. Thanks again, Thor N63TM
DennisRhodes
Well Known Member
Yes as others have said , charging system is the first place to look. It may be as simple as a loose or disconnected wire from the Alternator. Or possibly a loose belt if it is a belt drive setup. Loose or bad Ground straps will also prevent charging. Worst case may be an alternator but I would check out these other things first . How do I know this? There's a perfectly good alternator setting on the shelf in my hanger.
Carl Froehlich
Well Known Member
For your set up, low buss voltage is a "land right now" condition.
First rule, believe your indications and take action. Troubleshoot for a bad gauge on the ground. I offer however that from what you discribe your voltage indication is working properly and you lost your alternator output.
Carl
David Lowe
Active Member
Charge the battery
I would also charge the battery before the next flight..... just in case you need its full capacity !
I would also charge the battery before the next flight..... just in case you need its full capacity !
WrightsRV7
Well Known Member
back up power-a definete yes you should
Just curious, do you have a backup power system at all? Seems you are entirely dependent upon one master switch, one battery, one charging system to keep you in the air? Certainly your thought on a back up generator coupled to an emergency power buss is a good one and a must do, not an option. I really think you were very lucky to stay in the air, you might think about writing a thank you letter to Odyssey, if that had been a Concord or Gil normal aviation battery...
Just curious, do you have a backup power system at all? Seems you are entirely dependent upon one master switch, one battery, one charging system to keep you in the air? Certainly your thought on a back up generator coupled to an emergency power buss is a good one and a must do, not an option. I really think you were very lucky to stay in the air, you might think about writing a thank you letter to Odyssey, if that had been a Concord or Gil normal aviation battery...
Jesse
Well Known Member
Amen to that!!!
It is very possible that your alternator is either not putting out power due to a bad voltage regulator or a loose belt or a number of other reasons. If you have a 12V power outlet, get a volt meter and see what it reads when the engine is running to verify the voltage.
Thanks for advice all. I have been at it tonight and am taking the alternator in to a shop tomorrow. The alternator is not showing a charge but hooked up to a meter and run with a drill it puts out better than 13. I have an earth x batter (was confused with an earlier plane battery) and I run with two, plus a back up battery behind the panel for instruments. It has been tested to run 45 min. With the additional Earth X battery, so from that regard i felt like enough safety has been built into the system. I am now thinking very seriously of an addl. alternator now.
Thanks for the invite, Will do! I love your little airport, plus lunch at the Red barn.
