B&C Regulator Sense Connection

[F18Sailor]

All,

I'm in the process of swapping my Hartzell/Plane Power AL12-EI60 alternator (P/N 99-1012) with a B&C LX60/LR3E-14 voltage regulator, primarily for the (supposed) increased reliability of the B&C product. Of course, my existing alternator is 2 years old with 231hrs of use, and is working fine...perfection is the enemy of good enough. I am also adding a Monkworkz MZ-30 standby alternator at the same time.

In any case, this seems fairly straightforward, with the exception of the voltage regulator sense circuit. The Plane Power alternator has none, so there is no existing wire/circuit breaker to draw from. I'm inclined to jumper pin 3 (sense) and pin 6 (alt field supply) on the regulator, as in my case I do not believe there is any other draw on the alternator field circuit that would lower the voltage below that of the bus. I will confirm this. Is there a reason not to do this? I can add a 2A CB and run the specified 22AWG wire to the alternator, but what feeds this circuit breaker? Alternatively, is there a location I can grab bus voltage? Starter solenoid?

For some additional reference, I am currently intending to mount the LR3E regulator firewall forward. Yes, I know this violates the B&C installation manual, but I'm not seeing a straightforward way to wire in this regulator with it sitting under the panel, and my current shunt/ANL configuration sitting firewall forward:


Now that I'm reviewing this, maybe it does make more sense to mount the regulator on the cabin side, since the only connection it needs firewall-forward is the field wire to the alternator (no high current wire required). Is this correct?

 

[bjdecker]

The MAP sensor connection looks a little melted -- maybe it's just the picture...

Yes, mount the regulator on the cool side of the firewall.

 

[lr172]

I'm inclined to jumper pin 3 (sense) and pin 6 (alt field supply) on the regulator, as in my case I do not believe there is any other draw on the alternator field circuit that would lower the voltage below that of the bus. I will confirm this. Is there a reason not to do this?

For some additional reference, I am currently intending to mount the LR3E regulator firewall forward. Yes, I know this violates the B&C installation manual, but I'm not seeing a straightforward way to wire in this regulator with it sitting under the panel, and my current shunt/ANL configuration sitting firewall forward:

Now that I'm reviewing this, maybe it does make more sense to mount the regulator on the cabin side, since the only connection it needs firewall-forward is the field wire to the alternator (no high current wire required). Is this correct?

I would NOT jumper 6 & 3. The instructions clearly tell you not to do this. They know their box and there is likely something going on inside on pin 6 that will mess with the sense voltage reading stability. They want a line from the main bus so as to help in getting a stable voltage source. Just add a ring terminal to your new line and add on top of any CB output lug.

I would try to get it behind the firewall as heat will reduce longevity of electronic parts. No need to be near the shunt or fuse, as the large output wire doesn't go to the regulator. There is only one line going from the reg to the Alt. Just snip the old power line from your old PP install. The CB / switch side becomes the power source for new reg and the line going to the Alt becomes the new field wire.

 

[F18Sailor]

The MAP sensor connection looks a little melted -- maybe it's just the picture...

Yes, mount the regulator on the cool side of the firewall.

I'll check, but I suspect that is an optical illusion. It is functioning correctly, but I am replacing the 9+ year old rubber hoses as a precaution.

 

[F18Sailor]

I would NOT jumper 6 & 3. The instructions clearly tell you not to do this. They know their box and there is likely something going on inside on pin 6 that will mess with the sense voltage reading stability. They want a line from the main bus so as to help in getting a stable voltage source. Just add a ring terminal to your new line and add on top of any CB output lug.

I would try to get it behind the firewall as heat will reduce longevity of electronic parts. No need to be near the shunt or fuse, as the large output wire doesn't go to the regulator. There is only one line going from the reg to the Alt. Just snip the old power line from your old PP install. The CB / switch side becomes the power source for new reg and the line going to the Alt becomes the new field wire.

Thanks Larry. I think I will install a separate circuit breaker to minimize voltage drops at the breaker.

Fair enough on the cabin side, and agreed on heat. I do think the firewall forward side, low, with a blast tube could be cooler then the firewall on the cabin side. However, its more subject to dirt/moisture etc. so I will look for a good spot on the cabin side.

 

[PaulvS]

+1 for the regulator on the cold side of the firewall. I used a fusible link to protect the wire for voltage sense pin 3.

One reason to not connect a jumper between pin 3 and 6 is that if the field supply is cut, e.g. CB pulled or popped, then there will also be no power to pin 3. The LR3 uses power from pin 3 to drive the low voltage warning lamp, so this function would be lost when it is actually needed.

It looks like the alternator wire may be rubbing on the lower engine mount tube?

 

[wirejock]

I installed a Blue Sea 4 position blade fuse buss. One position is the B&C sense circuit.

 

[F18Sailor]

I ended up adding a 2A Klixon circuit breaker for the sense circuit, and installing the regulator on the cold side of the firewall. I re-positioned the alternator input wire so that rubbing potential is gone. Thanks for all the tips!