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B&C LR3C-14 voltage regulator Failures?

Darrel Starr

Registered User
Plymouth, MN
Sunday evening as I turned downwind at twilight with everything turned on including all the lights on, LED pulse lights, (20 amp load on my B&C 40 amp alternator), the 5 amp P&B field circuit breaker popped, the alternator went off line and the low voltage light started to flash. I pushed the CB back in but it popped twice more. I landed and put the plane away. Since then I found this very similar incident on the VANs RV site.
http://www.vansairforce.com/community/showthread.php?t=110131
I have 324 hrs, this RV had 375 hrs before the B&C voltage regulator failed.
Does anyone out there have a similar story? B&C seems to think the P&B circuit breaker is at fault or something else in the wiring. I will go through their trouble shooting routine but it seems most likely that the voltage regulator failed.
 
bad breaker? maybe, (and that Van's guy FAILED to install per big warning in install directions!)

but i bet you have an "overvolt" conditioning happening.. B&C uses a "crowbar" design to trip the field breaker(like throwing a crow bar across terminals to QUICKLY kill the field before damaging avionics)

your regulator is operating properly, keep reseting that breaker and ya might fry a radio, did i mention shut the expensive stuff off till it's figured out?

figure out why it thinks it needs to put out to many volts..

bad ground/connection to/at buss or battery reg terminals 3 or 7, big load/short coming on and offline, wire chafe, dead/shorted cell in battery...

google aero electric b&c crowbar
 
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Check all the crimps. I had field breaker pop intermittently for past few years, could not find problem. Turned out to be bad crimp at alternator field wire.
DENNY
 
I maintain several and have not had any issues.

I've had similar, though intermittent, experiences with mine. It hasn't happened in awhile, but somewhere around the 800-hour mark, the CB would occasionally pop and it seemed to happen in conjunction with the under-seat battery reaching a fully charged condition---it wouldn't happen until 30 minutes after starting. I initially suspected that oil residue might have contaminated something as I do have a fair amount seepage out the front main seal. After reading the B&C Troubleshooting info, I decided it must be a poor connection somewhere---which can be tough to isolate. It hasn't happened for the last 30 hours or so, so I haven't dug any deeper.
 
Greg Jones, the General Manager @ B&C, has been very helpful advising & offering help. I will go through the troubleshooting procedure hopefully today.
 
Not a solution or answer to your problem, Darrell, but I'd highly suggest not resetting a tripped circuit breaker more than once. If you reset it, and it trips, don't go there again. As Mike noted above, it might get really expensive.

MTV
 
Yes, I see the issue. I was trying to shut off stuff then resetting the CB but not a good policy.
And on further review, it is not a good idea to troubleshoot any non life threatening issue while setting up to land.
 
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Ditto what Mike said. Connections are super critical for the sensor circuits of this reg.

Get a copy of the wiring diagram off B&C's website. Make sure the reg and alternator are physically connected exactly like the diagram shows. Some guys used to jumper the sense terminal (#3) to places like terminal #6 instead of the bus bar. In some conditions this can spoof the sense circuit, so insure that terminal #3 is actually connected to the bus bar through a breaker or fuse.

The ground at terminal #7 is also sensitive. I like to run that wire all the way to the case on the alternator. That insures that they are both at the same ground potential.

You can run the aircraft with a digital volt meter on the bus, so you can observe what is actually occurring when the breaker pops.

Let us know what you find.

Web
 
Darrel I had my voltage regulator go out on me, I have the B&C 8 amp alternator what I found the cause to be was when I bolted it to the firewall I bolted through the fire blanket which caused it to overheat.... it needs a heat sink so i bought a new reg. and I built a stand of and have had no problems so far. That all happend at about 380 some hours.
 
Email to Greg Jones at B&C

Greg, I just ran through the 6 step troubleshooting guide. My results are recorded below and I believe they all "pass". So I am assuming my next step is to replace the circuit breaker right? If I send back my voltage regulator, can you run it through more thorough checks -- just to make sure?

1. Resistance from battery to Pin 7: 0.2 ohms, from battery to case: 0.2 ohms
2. Bus voltage: 11.6 volts, Pin 3 voltage: 11.8 volts
3. Pin 6 voltage: 11.5 volts
4. Pin 4 voltage: 10.25 volts
5. Field terminal voltage: 10.3 volts, Alternator field resistance: 3.7 ohms
6. Alternator "B" lead voltage: 11.7 volts

I included a picture of my circuit breaker panel so you can see why I don't want to change anything -- I think I will cut apart the current 5 amp P&B breaker to see if I can see any damage. Then I will install a new one and just plan to install a new one every 100 hrs (2 yrs) or so.
 
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Will put a charger on it. Made no effort to charge it after it picked up the load on downwind. An Odyssey PC680 5yrs old.
 
I would still look at every crimp. Push pull on the wire of EVERY crimp. Mine was hard to spot but it was there once I saw it.
DENNY
 
The 5 amp B&P Circuit Breaker has a "Weld Berry" on it. So is this the "Cause" or a "Result"? I also have sent the Regulator back to B&C for further tests, thanks to the graciousness of the B&C General Manager, Greg Jones.
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Darrel, Did you find any parts floating around in that CB? On this cutaway of the CB, on the left hand end of the bi-metallic strip, the arm that goes up and under the piece that is epoxied is missing from your CB. Is it's function to hold the CB closed? Perhaps the arcing occurred during your attempted resets and that piece was not there to solidly hold the CB closed? Thanks to Bob Nuckolls of Aero Electric Connection for the cutaway. Jim
 

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I will turn it over & see if anything falls out. The cutaway you have is also published in Wikipedia with both open & closed views. It is the toggle switch version of the P&B circuit breaker so there are a few different parts on the left side.
 
I will turn it over & see if anything falls out. The cutaway you have is also published in Wikipedia with both open & closed views. It is the toggle switch version of the P&B circuit breaker so there are a few different parts on the left side.

I did not notice that my pic is the other style CB, in studying how they work that would account for the difference.
 
Ditto what Mike said. If the battery is faulty/low the system will work too hard to try to replenish the voltage and over work the regulator. What was the volt/ amp meter reading when it went off line? I would bring the battery all the way up and check.
 
Charged the SBS J16 (PC680) battery for a while. It quickly came up to 12.6 volts. Took it to "Batteries +" store where they recorded a cranking amps of 228 vs a Spec of 170. They then put a 100 amp load on it -- it held at 10 volts for at least 10 seconds so it passed that test also -- the battery is OK.
 
Wayne (Flybynite) just walked into the hangar, picked up a toothpick and wiped the "weld berry" off the triangular piece inside the breaker -- it actually was a glob of grease. So with that new information, we can find nothing wrong with the breaker. B&C gets the regulator today to test.
 
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Greg Jones at B&C reported yesterday that the regulator failed the incoming bench test (would not OV).
They replaced a transistor and a diode and it then passed the digital bench test. It ran on the extended bench test for a while and now is being shipped back. Greg at B&C has been very responsive to this problem and repaired the regulator at no charge.
 
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Greg Jones at B&C reported yesterday that the regulator failed the incoming bench test (would not OV).

meaning??? you had an OV condition(for another reason), and it was not crowbarring ????

that sounds like you are not out of the woods yet then.... keep the expensive stuff turned off.....(an alternator will HAPPILY put out 1000+ volts when fubar happens... thats what the normally separate OV protection is for, but B&C's is contained in the regulator housing..)
 
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