Pinecone Posted October 25 Report Posted October 25 I was at my avionics shop yesterday, and while I was there, I mentioned that the amp displays (I have dual alternators) seemed to be displayed as load meters, but were reading like ammeters. That is, the display went from 0 up to some number, like a load meter. An ammeter normally has center 0 with + and - from there. He checked, and tweaked them, but it seems that in flight with my panel, the airplane is only drawing about 4 amps of current (28 volt system). And this is with lights on, but all of them are LED. So I have over 3 hours of battery life from my 13.6 amp-hour battery. Cool. Quote
Ragsf15e Posted October 25 Report Posted October 25 3 minutes ago, Pinecone said: I was at my avionics shop yesterday, and while I was there, I mentioned that the amp displays (I have dual alternators) seemed to be displayed as load meters, but were reading like ammeters. That is, the display went from 0 up to some number, like a load meter. An ammeter normally has center 0 with + and - from there. He checked, and tweaked them, but it seems that in flight with my panel, the airplane is only drawing about 4 amps of current (28 volt system). And this is with lights on, but all of them are LED. So I have over 3 hours of battery life from my 13.6 amp-hour battery. Cool. I think you should try it with the engine off and turn everything on. See what it reads. Mine also reads ~4 amps but that’s the current being supplied to continuously charge the battery, not the total load. Quote
MikeOH Posted October 26 Report Posted October 26 6 hours ago, Ragsf15e said: I think you should try it with the engine off and turn everything on. See what it reads. Mine also reads ~4 amps but that’s the current being supplied to continuously charge the battery, not the total load. I agree that 4 Amps seems a bit low, but at 28V that is 112 Watts which is possible if not transmitting. If 4 amps is going CONTINUOUSLY into a battery, something is wrong with the battery! Either the battery gets topped up whereupon there is zero current in, or it's being discharged if the alternator can't keep up with the load. Quote
Ragsf15e Posted October 26 Report Posted October 26 13 hours ago, MikeOH said: I agree that 4 Amps seems a bit low, but at 28V that is 112 Watts which is possible if not transmitting. If 4 amps is going CONTINUOUSLY into a battery, something is wrong with the battery! Either the battery gets topped up whereupon there is zero current in, or it's being discharged if the alternator can't keep up with the load. I believe you, but even with a new battery, that’s what the jpi shows. It’s probably just a function of how/where the ammeter is wired. I bet if i had an old analog ammeter it would look like zero. Sometimes the accuracy of digital is more than we need. 1 Quote
toto Posted October 26 Report Posted October 26 20 hours ago, Pinecone said: I have dual alternators Out of curiosity, did you have to get a field approval for the second alternator? I didn’t remember this from your avionics thread. Is it a B&C or something else? I keep wanting to put a backup alternator on my accessory pad, but I’ve been hesitant to go down the field approval road. Quote
Rick Junkin Posted October 26 Report Posted October 26 20 hours ago, Pinecone said: He checked, and tweaked them, but it seems that in flight with my panel, the airplane is only drawing about 4 amps of current (28 volt system). 20 hours ago, Ragsf15e said: I think you should try it with the engine off and turn everything on. See what it reads. My system also shows 4-5A with all of the avionics on both on battery power and with the engine running/alternators online. My TLS/Bravo originally had load meters and they used the same shunt. But I only have one amp indication on the G3X, not one for each alternator. I have that on my list of questions when I get the airplane to them in a couple of weeks for a few minor squawks. Quote
Ragsf15e Posted October 26 Report Posted October 26 22 minutes ago, Rick Junkin said: My system also shows 4-5A with all of the avionics on both on battery power and with the engine running/alternators online. My TLS/Bravo originally had load meters and they used the same shunt. But I only have one amp indication on the G3X, not one for each alternator. I have that on my list of questions when I get the airplane to them in a couple of weeks for a few minor squawks. I might try to turn on the avionics, engine off, and try pitot heat on. I think id also try that with the engine running. Most mooneys are wired as an ammeter showing current to/from the battery. A load meter showing total load is used on other models (Piper) though so maybe your shop wired it that way? The G1000 I fly shows ~34amps in cruise with 3x g1000 screens, Gfc 700, LED lights, and 2 x pitot heats. It’s not a good comparison, but it’s a lot more. Quote
Rick Junkin Posted October 26 Report Posted October 26 4 minutes ago, Ragsf15e said: I might try to turn on the avionics, engine off, and try pitot heat on. Yup, I've done that while looking for the best combination for my poor man's battery capacity check. I don't remember the exact numbers but the load looked reasonable. The original TLS had load meters vs AMP meters, one for each alternator and one for total buss load. 1 Quote
Scottknoll Posted October 26 Report Posted October 26 I was showing 3-4amps in cruise, and it turned out the EIS was programmed incorrectly. If I recall they have to program the shunt information into the EIS and the Ovation didn’t fit the standard Garmin settings. I happened to put a clamp-on ammeter on my battery cable to check something unrelated. The clamp-on was reading double the EIS. Quick setting change in the GI-275 and it was reading properly. It usually settles down to 1amp in cruise now. 1 Quote
McMooney Posted October 26 Report Posted October 26 doesn't sound to far out there, without the fuel pump and pitot heat, everything being led, i really could imagine my plane being under 8 amps, even while transmitting. think the fluke and i have a date at the hangar Quote
Pinecone Posted October 26 Author Report Posted October 26 I have a 252. Most of them are dual alternator from the factory. Although, from the build sheet the second one was optional. The original set up was a 3 needle load meter. One for each alternator, one for total load. But there was no room in the panel for this, and the Garmin EIS covers the issue. No, the Garmin is setup to measure alternator load. That 4 amps is continuous. If it was charging amps, it would be more near 0 after a short period of running (unless the battery is a bit low. Quote
toto Posted October 26 Report Posted October 26 47 minutes ago, Pinecone said: I have a 252. Most of them are dual alternator from the factory. Although, from the build sheet the second one was optional. Drat, okay. Thanks - I’m pretty clueless when it comes to M20Ts… Quote
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