Portable Generator mod question

(quoted from post at 18:45:00 09/14/12) I've got a couple of brand new generators made in 1999. They were special ordered by a telecom company that went out of business. The problem is - they are set up to make 36 volts DC which is of no use to me. I'd like to convert to AC or to 12 volts DC output.

The generator head is rated for 3000 watts surge and 2500 watts continuous. 67 amps at 36 volts DC. I suspect the same head was also use in 120/240 volt versions, but I'm not sure.

The engine is a Subauru EH25 and is setup to run on gasoline or propane and has electric start.

I was told this generator was custom made from an existing AC generator. True or not, I'm not sure. It's supposed to be a reworked Powe'r Guard R45 genset. Powe'r Guard no longer exists. It was taken over by Baldor and they have no info.

I pulled the cover off the generator head and there are three large wires coming out of it. They hook to a large terminal block. On the same block are two output terminals - marked AC - one is "plus" and other "minus" so the "AC" does not make sense to me since the output is DC. Then there's a small, sealed in epoxy regulator with four leads and four small wires - some go to small brushes in the gen-head. The regulator is made by Basler Electric - and is marked: Input 180-270 VAC 50-60HZ, and Output - 63 VDC at 2 amps. Maybe this makes the field current? The four terminals on it are marked F+, 3, F-, and 4. The two “F” wires go to brushes.

If this was an AC genset -would there be some sort of regulator? I've worked on big sets (15KW and 20KW) but have no experience with little ones like this.

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(quoted from post at 12:51:21 09/15/12) I've got Chinese generators all over the place. I've got two new KingCraft 3500 watt units I got new for $199 each at ALDIs. Also got a Jetman, and a few ETQ and Honeywell inverter generators.
Many make poor quality AC power. Good for most uses but very poor for some things (like running battery chargers).

My point being - I'm not in lack of generators. Main issue is I'd like to install one at a remote cabin I have that has a 12 volt battery bank and solar electric. I like to mount it permanently. I need a way to run a big 12 volt battery charger once in awhile and I'd like to use propane. Main reason being I've already got a 500 gallon propane tank there and there are no long-term storage issues with propane as there is with gasoline.

I've already got these new generators with the Subaru engines that run on propane plus they have electric start. I paid nothing for them and would like to get some use from them. I know the Subaru-Robin are one of the best small engines make.

If there was an easy way to get it to put out 13-15 volts DC it would be of use to me as a direct 12 bulk battery charger. If I can cheaply convert it to AC, I can still use it hooked up to a separate electronic charger (maybe).

Most portable AC generators do a poor job powering conventional battery chargers. A charger rated for 50 amps output will often barely make 20 amps when run off a portable gen. The exceptions are . . . inverter generators OR using a high tech electronic battery charger like Trace or Iota sells (very pricey). Also there are portable generator "enhancers" around that improve their AC output (again, pricey).

I have a battery bank that if run down, I can get by with a 50 amp charger. But, a 150 amp charger is much better. At present, one of my inverters has a built in 150 amp charger. But it requires clean AC power and it must be 55 amps at 120 volts AC. That is hard to do. One way to power it is to use a portable gen with 220 volts/30 amps and hook it to a step-down transformer to make 60 amps at 120 VAC (again, pricey).

Some people build engine driven DC chargers made from auto alternators and they work very well. A 5-6 horse engine easily powers a 150 amp DC alternator.

Back to my original point. I've already got these brand new units and they cost me absolutely nothing. If I can get some use from them without much investment, I'd be very happy about it. With small AC generators - I've looked at parts breakdowns and see no voltage regulators listed. So I'm wondering if some are only controlled by amount of windings and fixed RPMs?

By the way, I've got a 17 KW Fairbanks Morse genset already at the cabin. It puts out 70 amps on the 120 VAC circuit. But, it's got a four cylinder watercooled 140 c.i. Continental flathead engine that eats a lot of gasoline quickly. It's way too big for the job. A small 6-8 horse engine could accomplish the same task if set up right.

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(quoted from post at 10:07:25 09/16/12) Is there a chance that you could use a regulator from an automotive alternator to change what you have to a twelve volt alternator?
I have made automotive alternators into 120 volt DC generators by opening the alternators, bringing out three phase before the diodes, running that through three transformers, rectifying that output, and feeding it into the 12 volt regulator.

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