Auto Starter added to R175 Changfa CHP unit

[veggie]

My latest build is a Changfa R175 unit with the hopper removed in favor of a blanking plate and external cooling system connections.
Also mounted to the engine (on top in place of the fuel tank) is a Leese 12 volt 160 amp alternator. (pictures later)
Heat and battery bank charging power can be pulled from the unit.
Also planned is an automatic stater which takes it's signal from the battery charge condition (A set of contacts on the solar charge controller).
The auto-start module that I have is meant for AC generators and takes feedback in the form of 120AC power to tell the start module that the engine is running.
As soon as 120AC is sensed by two dedicated signal inputs on the controller, the cranking cycle is stopped.
If a signal is not received, the controller tries a 10 second crank again. (Three times total).

Problem:
The output from my generator is 12vdc and NOT 120AC.  
Any ideas on how I can "trick" the controller or somehow signal the AC input connections that the engine is started.

thanks,
veggie

[mobile_bob]

connect one of those cube rectifiers to two of the three stator posts
this will give you a 12volt isolated signal from the stator, which will only
come to life when the alternator starts to charge.

with this 12vdc power a relay

with the relay trigger a small inverter to provide the 120vac you need.

i don't recall, but does the 175 have the oil indicator bulb typical of its older brothers?

bob g

[veggie]

Hi Bob,

The 175 has a little bonnet that pops up when oil pressure is sensed.
I can remove it and add a pressure switch if that is what you have in mind?
I had the 50watt micro inverter already, but could not think of a way to energize it
only when the engine has started.
Good idea Bob!
I could use an oil pressure switch to energize the inverter.
Like this.....

veggie

[Tom Reed]

You could do that, but it looks a little more complicated than necessary. Bob's rectifier suggestion is cleaner and will leave your oil pressure bonnet open for when you decide to all the low oil pressure shut down. A 6 amp rectifier is only a couple of $.

[mobile_bob]

i use both methods as a redundant solution to exactly what it is you are trying to do.

i use the rectifier to power a DOT automotive cube relay, it works very well
and gives me both an open and a close position spdt

if you remove the little plastic globe and insert a short 3/8pipe nipple
(it is close enough to the same thread that it will fit just fine)

on top of the nipple screw on a brass female 3/8"npt to 1/2" tube fitting, it is the one
that allows a 1/2 inch copper tube to be connected to a 3/8" steel pipe.

remove the ferrule and replace it with a nylon ferrule

now you can fit a microswitch into the ferrule half of the fitting

all that is left is to cut a short piece of hardwood dowel (3/8" diameter) and adjust
its length so that  the microswitch is activated when the oil plunger rises.

the micro switch also has a n/o and n/c set of contacts, use as needed to control the
ground side of a starter solenoid relay coil.

i use it to do the disconnect on startup when the oil pressure is up, and also i use the other set of contacts to disconnect the fuel solenoid if the oil pressure drops or fails, which in turn allows for a safety shutdown on loss of oil pressure.

i use a syncrostart/murphy fuel shutdown solenoid, actually i use a pair of them, one sets the speed to 1800rpm the other sets it to 1200rpm and if both are disengaged of course the engine will shut down.

the micro controller controls the the power to the fuel solenoids, the oil pressure control system controls the ground to the fuel solenoids.


works very well, and provides redundancy and multiple control handles which means there are several layers of safety.  the microcontroller can effect a shutdown, loss of alternator belt will effect a shutdown, loss of engine oil pressure will effect a shutdown, among others.

bob g

[veggie]

Guys, I have not seen one of those "Cube rectifiers" before.
Are they typically available at any automotive store ??
What's the proper way to describe it to the parts guy ?

thanks,
Veggie

[mobile_bob]

they look like this

http://www.ebay.com/itm/35v-Amp-1000-Volt-Bridge-Rectifier-/321028711545?pt=LH_DefaultDomain_0&hash=item4abecd6479

basic little full wave rectifier bridge, i think even radio shack has them

bob g

[veggie]

Thanks very much Bob. I ordered one.
Using the unrectified output lugs on the Leese is a great idea.

Thanks again,
veggie

[mobile_bob]

fwiw, and you may already have considered the following

if you are using a balmar or other controller that has a field start delay
you probably cannot use the alternator stator as a trigger source to disengage
the starter circuit

reason being the delay period will keep the starter engaged until such time as the field ramp up takes place.

if you are using the oem regulator all will be fine, it is fast enough to use
as a trigger source.

just wanted you to know, if you didn't already.

you could time out the start sequence with the controller if it has that function, as another level of safety, that would help to assure the starter disengages after a predetermined amount of time.  might be useful to limit the cranktime anyway.

the oil sensor method works very well, in my experience. there is just enough delay to assure a startup without tripping out the system, at least on my 195.  having the ability to provide for low oil shutdown is a huge plus in my opinion.

the way i programmed my micro, was to allow for 3 start attempts of 20 seconds, with 60 second rest between attempts, after which it sets a lamp indicating a failed start attempt.  the micro keeps the line hot for the full 20 seconds and i rely on the alternator stator sense circuit in series with the low oil pressure micro switch to disconnect the ground side or in other words provide negative logic control over the relay i use to switch the starter solenoid.

lots of fun huh?

there are so many ways of getting up the mountain, you just use the approach your most comfortable with that gets the result you are after.

good luck
bob g

[Ronmar]

Uuum OK, What do you use the batteries for that you are charging?  IE: do you have an inverter running off of those?  If you have it available, it might be simpler to divert a line of this 120V inverter power thru an oil pressure switch or a 12V sense relay attached to the alternator output(only energizes when the alternator rises above 12V)?

[veggie]

Uuum OK, What do you use the batteries for that you are charging?  IE: do you have an inverter running off of those?  If you have it available, it might be simpler to divert a line of this 120V inverter power thru an oil pressure switch or a 12V sense relay attached to the alternator output(only energizes when the alternator rises above 12V)?

Ronmar,
The battery bank and inverter are in another building (Greenhouse) so it's a lot easier for me to add a micro inverter to the generator's control box and keep everything integral with the engine/alternator package.
Having the option to use either the Oil pressure switch or the AC lugs on the Alternator is great. Have not decided which route to go yet.

Bob, I do not have a Balmar so your rectified 12VAC idea should work fine. 

veggie

[mobile_bob]

yup, if you are using the oem regulator it will work just fine.

i used 4 of those little axial diodes that come in the 100pack from radio
shack to put together a full wave rectifier because i didn't have a cube handy

it was sort of a test the theory of operation sort of thing, now that i know it works
i plan i replacing the diodes with a cube.

same cube the st head uses, so having spares around is a good idea anyway.

bob g

[BruceM]

If the controller isn't potted, I might be able to help with a mod to bypass the 120VAC input requirement.  
Contacting the vendor might be fruitful also, what you're doing isn't that uncommon and they may have a solution for a logic level input signal in lieu of the AC.