CAMit 3300 40A Alternator

[racaldwell]

Does anybody know if I need to buy a voltage regulator like a B&C LR3 for my new CAMit 3300 40A alternator or does it have a built-in regulator? My engine is wrapped up in dessicant packs in the crate in the back bedroom so it's not so easy to see what is in there.

Thanks, Rick
Xenos 0057

[LarryEWaiex121]

Rick,

The Camit alternator has a built in regulator. I've got about 70 hrs on my Camit now and its performing like a top. Just finished condition inspection and leakdowns and overall condition showed excellent.
Your going to love the engine and hopefully by the time any of us guys need rebuild parts we will have found some path forward? With reasonable care it should go at least 800-1,000 hrs before needing topped. That's my hope.

Larry
Waiex121YX, Camit 3300, Skyview

[racaldwell]

Thanks Larry, that is good to know. I am making up my wiring diagram now so I'll take off the LR3 regulator I have depicted. Are there just field and alternator feed connections on the alternator?

I am really looking forward to the day I get to fly behind my new Camit. I hope I don't see the day of ordering Jab solid lifter cylinder parts but at least that choice is there.

Rick

[racaldwell]

Larry,

I have been looking for some type of overvoltage module for the Camit 40A alternator. I am confused by the choices I am seeing as they seem too small for the 40A capacity. What are you using for overvoltage protection?

thanks, Rick

[racaldwell]

On further research, I see that Aeroelectic Bob shows that internally regulated alternators can not use the overvoltage module because there is not a field wire to turn off. He says there is only a signal start wire to turn on the alternator and this wire will not shut it off. So he recommends a contactor in the B lead so the pilot can shut off the alternator in case of run away before the battery fries.

This sounds more complex by adding another component. I am curious to what others have done.

I am thinking of using the Earthx battery and it will shut off when it senses under or over-voltage. So maybe that is all that is needed as far as battery protection is concerned.

I am also thinking of using the MGL Avoiguard for all avionics. That would protect them in case of alternator run away. I plan to put a small battery on the avionics side of the Avoiguard so when I have the engine off for soaring, I can still have the avionics on and not worry about running the main battery down when I need it to restart the engine when the thermals die.

Rick
Xenos 0057

[sonex1374]

The B&C OV module can be used to control a relay that in turn controls the alternator output. You can route the alternator's +12 volt output to the normally open contact of a 40 or 50 amp relay, and the OV module controls the relay coil. If it senses excessive voltage it trips the 5 amp CB on the coil power circuit and that shuts off the coil completely, deenergizing the relay and opening the relay contacts. The alternator will still be spinning and trying to supply current, but at least it won't be able to get into your electrical system.

Jeff

[sonex1374]

I am thinking of using the Earthx battery and it will shut off when it senses under or over-voltage. So maybe that is all that is needed as far as battery protection is concerned.

Rick
Xenos 0057

The advanced circuitry in lithium batteries is designed to protect the battery. This both keep your expensive battery from dying prematurely, as well as not catching fire during use (always a good thing)! The circuitry will do nothing for your avionics though. If the voltage reg goes bad and the alternator pumps 40+ volts into you bus, the expensive boxes will fry after the battery disconnets itself and can no longer soak up any of that alternator output. You could trade saving a $300 battery at the cost of $1000's in avionics.

Best to have a dedicated way to stop energizing the bus from the alternator, and an OV module is a simple way to do that.

Jeff

[racaldwell]

Thanks for the reply, Jeff. Reading up more on this led me to the same conclusion you say. I have found a more sophisticated way of opening the contactor on the B lead from the alternator in case of overvoltage instead of blowing the fuse or CB. Perihelion Design makes an overvoltage module to open the contactor at 16V without shorting something. It also has indicator and reset capability.

I was hoping to find a way to avoid the additional contactor but it seems this is the only way to ensure the high voltage is shut off at 16V. The MGL Avoiguard will protect the avionics connected to it from overvoltage but I still will have fuel flow, fuel level and all the contactor coils in the design that I would not want to put very high voltage to in case of a failed internal regulator.

I am thinking I am nearing the final revision of my electrical design for this project. I'll post it soon.

Rick
Xenos 0057

[sonex1374]

Rick,

Any sort of automatic OIV protection is OK, but the important thing is that you have something. The simplest form of OV protection is a voltage monitor that you periodically look at, and if you notice that it's too high, then you manually shut off the alternator. This can work, but then again it could be many minutes before you noticed the volt meter reading during your normal instrument scan. Better to have some electric widget working the issue for you without your involvement!

The crowbar OV module is simple and reliable, and I wouldn't worry about the unit using a CB to do it's job. 1000's of these units are in circulation, and they have a good track record. The Perihelion unit is good also, and uses an internal relay to accomplish the same end effect.

Jeff