Trickle Charge Resistor on Inside top of Auxiliary Power Door

[LANCECASPER]

On my M20M I was looking across through the open battery access panel on the right side of the airplane over to the Left side and saw this wiring hanging there:

It looks like it goes into right side of the Trickle Charging resistor, which is the gold colored thing right behind it in the picture. I am guessing that the diode blew out - i think it's been this way quite awhile.

It looks like it is #20 in the diagram - that was used on M20M's thru serial number 194 (mine is 150) :

 

The other end of this loose wire traces back to here on the front of the pilot side (#1) battery relay:

 

Some qustions:

1) Would anyone with an M20M (Serial number 1-194) be willing to take a picture of their diode (like my first picture or the picture below) and post it here? This is so that I can verify that the wire came from where I think it did.

2) I sourced the exact resistor from Mouser but it looks like it is riveted on? Any thoughts there? It is very tight quarters back there.

 

Thanks!!

 

[Rick Junkin]

Here's a really bad picture from a while ago when I was doing some other work, but it clearly shows the same connector on the right side of the diode as you suspected. My airplane is #19.

Cheers,
Rick

[LANCECASPER]

1 hour ago, Junkman said:

Here's a really bad picture from a while ago when I was doing some other work, but it clearly shows the same connector on the right side of the diode as you suspected. My airplane is #19.

Cheers,
Rick

Thanks

 

Anyone have any ideas on how to get the old one out?

[carusoam]

The drawing clearly shows a wire coming out of both ends of the diode....

You either have a one wire diode, or the spare wire in your picture is no longer attached the way it used to be....

The two fasteners appear to be rivets.  A good mechanic will probably drill them out and replace pretty quickly.

see if you can get a picture of the end of the diode.  To prove it is broken, not just disconnected....  when calling Lasar, you might find that this is a sub assembly, not just the diode...

I think you may just want the broken diode swapped out with minimal hassle of removing anything else... it might need the whole bracket removed anyway...

Great pictures of the goofy two battery system that long Bodies use.... There is a bunch of diodes back there directing electron traffic flow....

something to consider... did you ever have a dead battery and let it get charged by the alternator instead of charging it by plugging in?  At least one diode in the system sees some high electron flow while this charge occurs.  The high electron flow generates some heat and may damage the diode...

Sorry to ask So many questions... the two battery / Gill thing has haunted me for years....  All the diodes in the system allow for variations between the two batteries....

PP thoughts only. Not a mechanic...

Best regards,

-a-

[LANCECASPER]

13 minutes ago, carusoam said:

Great pictures of the goofy two battery system that long Bodies use.... There is a bunch of diodes back there directing electron traffic flow....

something to consider... did you ever have a dead battery and let it get charged by the alternator instead of charging it by plugging in?  At least one diode in the system sees some high electron flow while this charge occurs.  The high electron flow generates some heat and may damage the diode...

Sorry to ask So many questions... the two battery / Gill thing has haunted me for years....  All the diodes in the system allow for variations between the two batteries....

I think it's been this way awhile, even before I owned it. In the logbook the previous owner replaced many, many #1 Gill batteries. I always use a Batteryminder on my Concordes so I never noticed a problem starting it, but I bet the #1 battery is not getting trickle charged during flight. The previous owner never used a batteryminder so he probably came out to a dead battery many times.

[Pissed'Ole-Pete]

On 10/24/2017 at 3:02 PM, LANCECASPER said:

 

On my M20M I was looking across through the open battery access panel on the right side of the airplane over to the Left side and saw this wiring hanging there:

It looks like it goes into right side of the Trickle Charging diode, which is the gold colored thing right behind it in the picture. I am guessing that the diode blew out - i think it's been this way quite awhile.

 

Are you certain its a diode??? I just checked the part number in your photo, "RH-25 20W" and it comes back as a  20 watt wire wound resistor. appears to be a 1 ohm +/- 1% Its purpose would be as a "fusesistor", a shunt for a meter, gauge, or feedback circuit. Without wiring diagrams it's hard to guess. The bracket it is riveted to is probably a part of the heat sink a 20 watt resistor would require.

https://www.westfloridacomponents.com/WW390BPK03/25W+1+ohm+1%26%2337%3B+Power+Wirewound+Resistor+Dale+RH-25.html

Edited November 2, 2017 by Pissed'Ole-Pete
additonal comment

[Pissed'Ole-Pete]

The "can" in the picture of 'where the wire went' is a photo of a relay (by the printed markings on the side) again without a wiring diagram impossible to determine function.

[thinwing]

Pete is correct ,that is a voltage divider resistor...the fins are for heat disapation...I've seen them used for auto use to drop 12 v to led voltage.I think it is a common resistor ,get a part number and try mouser

[carusoam]

What do Long Bodies use to take 24v down to 12v for the cigarette lighter?  Some of them have 12v at the cigarette power plug... since everything that gets plugged in there is different, a simple divider probably can't work very well.  A more complex transformer is probably used...

Some of the old 90s transponders are 12v units using a resistor for the divider function... KT74(A)... pissing away 50% of the good electrons to ground...

Best regards,

-a-

[LANCECASPER]

1 hour ago, thinwing said:

Pete is correct ,that is a voltage divider resistor...the fins are for heat disapation...I've seen them used for auto use to drop 12 v to led voltage.I think it is a common resistor ,get a part number and try mouser

The factory calls it a Trickle Charge Resistor. I mentioned in the first post that I found one at Mouser. I ordered it and it is an exact match. I haven't figured out how to get back in there to change it yet.

 

[Pissed'Ole-Pete]

22 hours ago, carusoam said:

What do Long Bodies use to take 24v down to 12v for the cigarette lighter?  Some of them have 12v at the cigarette power plug... since everything that gets plugged in there is different, a simple divider probably can't work very well.  A more complex transformer is probably used...

Some of the old 90s transponders are 12v units using a resistor for the divider function... KT74(A)... pissing away 50% of the good electrons to ground...

Best regards,

-a-

They don't quite piss them away, and certainly not to ground through a 1 ohm resistor.  We could get into the theory, but again without wire diagrams It'd be only a guess. Does any one on this forum have wiring diagrams for the TLS? and the link I posted earlier, westforida components, is to one of those resistors for $ 3.50.

[LANCECASPER]

Just now, Pissed'Ole-Pete said:

 the link I posted earlier, westforida components, is to one of those resistors for $ 3.50.

I bought the resistor last week from Mouser for about the same.

[Pissed'Ole-Pete]

22 hours ago, LANCECASPER said:

The factory calls it a Trickle Charge Resistor. I mentioned in the first post that I found one at Mouser. I ordered it and it is an exact match. I haven't figured out how to get back in there to change it yet.

When you do figure out how to get the old one out, you might want to get a bit of "heat sink compound", and apply a THIN layer of it on the new resistor where it mates up with "Bracket" before reinstalling the rivets.

Edited November 4, 2017 by Pissed'Ole-Pete

[LANCECASPER]

Ok, the metal bracket on which the trickle charge resistor sits was not hard to take out - just two pop rivets to drill out.

Now that the bracket is out any recommendations on:

1) how to get the old resistor off (drill baby drill?) UPDATE: 1/8 drill bit popped them right out and the hole is countersunk.

and

2) what to use to re-attach the new resistor (countersunk screw from the bottom so it's flush?)

Would something like this work (http://www.aircraftspruce.com/catalog/hapages/solidalumrivets.php?clickkey=4653)? How do I do it?

UPDATE: I ordered some 1/8" diameter, 1/4" length, soft (1100) aluminum countersunk rivets from Aircraft Spruce.

UPDATE: It's off and waiting for countersunk rivets from Aircraft Spruce.

 

[Raptor05121]

I'm in no way qualified so answer, but I'd guess simply drilling them out would work. But I will confirm putting some thermal paste is only going to help heat dissipation. I don't know if anyone local has any, but Artic Silver 5 (about $6) is commonly used on PC and radio components. Just two pea-sized amounts right on those nipples should do.

[LANCECASPER]

44 minutes ago, Raptor05121 said:

I'm in no way qualified so answer, but I'd guess simply drilling them out would work. But I will confirm putting some thermal paste is only going to help heat dissipation. I don't know if anyone local has any, but Artic Silver 5 (about $6) is commonly used on PC and radio components. Just two pea-sized amounts right on those nipples should do.

I agree. I ordered some Thermal Paste from Ebay over the weekend should be in tomorrow.

[carusoam]

Don't forget to find a way to support the wire that was hanging off of it...

It looks like a little stress over a long time may have effected the mechanical strength of the big resistor...

PP Thinking out loud, not a mechanic or electronics tech.

Best regards,

-a-

[Pissed'Ole-Pete]

9 hours ago, Raptor05121 said:

I'm in no way qualified so answer, but I'd guess simply drilling them out would work. But I will confirm putting some thermal paste is only going to help heat dissipation. I don't know if anyone local has any, but Artic Silver 5 (about $6) is commonly used on PC and radio components. Just two pea-sized amounts right on those nipples should do.

Agree, a VERY THIN Film of Silver 5, to much is NOT better than to little of this stuff.

[Pissed'Ole-Pete]

10 hours ago, LANCECASPER said:

(http://www.aircraftspruce.com/catalog/hapages/solidalumrivets.php?clickkey=4653)? How do I do it?

CAREFULLY.... Just kidding.

check with your local EAA chapter. they may have a "hand rivet squeezer", if you cant find one....

 

Edited November 9, 2017 by Pissed'Ole-Pete

[LANCECASPER]

FOLLOW UP:

No good deed ever goes unpunished. The blown out resistor on the trickle charging circuit that I noticed in the first picture had probably been that way for years. It didn't seem to affect anything in the airplane as everything seemed to be functioning properly.

I drilled out the aluminum plate, drilled out the old resistor, replaced it and even replaced the two diodes on the back of the plate, just in case. As soon as I touched the positive lead to the first battery when I was reinstalling the first battery I was arc welding - pretty obvious that there was power touching ground. (probably why the resistor blew in the first place!). In the process I blew the battery relay. Just to be sure, I replaced both battery relays and the starter relay and disconnected the trickle charging circuit and everything is back to where I started. This is way above my pay grade so I'll make it part of my annual in January and follow up when everything is figured out.

Anyone with an early TLS (Serial # 1-194) (or M20R Ovation since they have the same trickle charging circuit) willing to trace the three wires that come out of that trickle charging circuit and tell me where all three go on your airplane? (Wires 1 (toward back of airplane) & 2 (next to #1 but closer to the front of the airplane) go to the diodes on the back of the aluminum plate and wire 3 comes out of the resistor)

Side View

Top View

[LANCECASPER]

Follow-up on this . . .

I decided to pull the wiring for the trickle charger and start from scratch.

I found the correct diodes and resistor from electrical suppliers. From my previous post I learned how important it is to make sure and correctly insulate the diode from touching ground . . lol. So I started over again just to be sure and put a new resistor and diodes and ran the three wires individually from the trickle charger to their destinations.

Also I did the Mooney service bulletin which deals with putting an inline Slo Blow fuse on each of the three wires.

M20-275 trickle charge service bulletin.pdf

 

Everything works the way it should. I now notice that when I get back to the hangar and plug in the battery tenders, within a minute or two the battery tender sees the battery at full charge and goes into maintenance mode. Before the batteries were much further discharged when I would get back and it took hours to get them to get them to this point.

I think in looking over the logbooks this circuit had not been working for many years. The previous owner went through many sets of Gill batteries, even much more often than the notorious Gill batteries last. My set of Concordes (one installed in 11/15 and one installed 5/17) may have been damaged, so we'll see how long I get out of these.

[slowflyin]

Strike up a win for persistence!  Congrats!