Alternator Issues

DAT · Post by **DAT** » Fri Jan 01, 2016 4:03 pm

Today I was flying my M5 235 with an O 540 J. It has a 24 volt starter and alternator but everything else is 12 volt. The batteries are two 12 volt Gill in series. It was a patrol airplane for a sheriff's department ... ergo the 24 volt start and alternator system. Apparently they needed 60 amps to pull all the police radios.

The alternator field fuse popped out as I was cruising along. I resent the small field fuse and the alternator came back on line but at full charge ... close to 60 amps. It eventually popped the big alternator fuse. I reset the fuse when I landed and the alternator came back on line but would go up and down as the rpms increased and decreased.

What do I need to look at .... regulator??

Thanks for any suggestions.

gbarrier · Post by **gbarrier** » Fri Jan 01, 2016 4:27 pm

Probably so.

Do you really need all that stuff. Why not while you have an excuse put that thingt on a diet. Drop back to one 12V battery and replace the starter, alternator, and regulator.

TomD · Post by **TomD** » Fri Jan 01, 2016 4:49 pm

My M5 is a 1977 and has a straight 12V system. Sounds like you can lose a lot of weight and complexity with little effort.

DAT · Post by **DAT** » Fri Jan 01, 2016 7:09 pm

I'd like to put her on a diet. She's really heavy with all that stuff. What's involved? Remove the starter and replace with a Skytec lite weight, get a new 12 volt alternator, get rid of one battery. What about the regulator, inverter, solenoid at the battery? Is there anything else that has to be changed out?

gbarrier · Post by **gbarrier** » Sat Jan 02, 2016 5:09 am

Sounds like you have it figured out.

Yes, solenoid (get that from Sky Tec also) and regulator (sounds like it's shot anyway).

What does your inverter power? May just be sitting there. What radios do you have? Are they 12 or 24V? If 24 you will need a power converter.

DAT · Post by **DAT** » Sat Jan 02, 2016 6:21 am

I was told that everything in the airplane other than the starter and alternator are 12 volt. I have the standard panel with two nav/coms, xponder, adf, loran. I removed the adf and loran and put an Ifly 720 in their place. There is an inverter under the back seat. All gauges and lights are 12 volt. I understand that the 24 volt conversion was done at the factory for the sheriffs Dept but the factory hasn't been able to tell me what I need to do to switch it back.

aero101 · Post by **aero101** » Sat Jan 02, 2016 9:32 am

If done at Maule Factory, they should have paperwork, wiring diagram, etc, etc for this conversion. If done privately, there should be a field approval, STC, or something documenting conversion with wiring diagram, etc... Somewhere there's a paper trail on this I would bet? Have you ordered an aircraft record CD from FAA? Lot's of stuff I find no paperwork in logs, but in fact, it's on file in the aircraft records..... Good luck, and by removing all the 24v stuff, you can probably lighten up 50Lbs or so?

Kirk · Post by **Kirk** » Sat Jan 02, 2016 1:35 pm

I'm pretty sure Maule configured several aircraft for law enforcement with a more robust electrical system for all their E gear.

I looked at one quite a few years back that still had a loudspeaker built into the fuselage. A lot of extra weight.

Kirk

DAT · Post by **DAT** » Sat Jan 02, 2016 9:23 pm

It was done at the factory when it was almost new in June of 80. No 337 shows up on the disc from the FAA. I'll check again with the factory.

I agree that it would save at least 50 lbs. Maybe the tower will quit saying to trailing traffic ... "Caution wake turbulence from Maule Heavy on 2 mile final!"

DAT · Post by **DAT** » Wed Mar 02, 2016 7:28 pm

In January I posted that I am having alternator issues with a 24 volt system. See the first post to see what the problem is. I replaced the voltage regulator with a new one and it is doing the same thing, which is showing a 55 to 60 amp charge. I then tested the batteries and one was 79% and the other 82%. I replaced both of them. Same issue. I took the alternator and and regulator to a repair shop to have them load tested. Both tested ok. I then went through and tested the field wire, grounds, other alternator wires and found nothing out of the ordinary. We checked to make sure the starter did not stay engaged. It's ok.

I called the factory, who did the original conversion in June of 80. They don't have any paperwork. Nothing shows up in the 337's. Bruce has made the same suggestions some of you have made, which include the things that I've already tried.

I gave up and took it to a shop and they haven't found anything yet. It's charging 33.4 volts. The regulator does not kick in nor does the over-voltage take it off line. The 60 amp breaker has not tripped but the one time, when the field breaker popped, then I reset it, which started the whole problem.

I'd like to change the system to 12 volt but don't want to spend the dollars necessary to do it, therefore, need help to figure out the problem.

Does anyone have any ideas as to what it might be or where I can get a wiring diagram or pictures of another conversion that somebody else has?

Thanks.

Curtis · Post by **Curtis** » Thu Mar 03, 2016 4:17 am

I have a wiring diagram. you can PM me.

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