Looking for info on a 3KW, 36 VDC genset

The Genset was made by Pow'r Gard - which was bought by Baldor. I called Baldor, and they
say they have no info on it. Date on the box it came in is 1999. Engine is a Subaru-Robin,
overhead-valve 8 horsepower and is set up to run on LP gas. It's brand new - old stock. Baldor thinks it might have been special made for an air-force base. I know very little about large DC generators. This one is rated 3 KW max, and 2.4 KW
continuous at 36 VDC at 62 amps. On the back of the generator-head - are three large wires.
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.

I'm' trying to come with an alternative way to charge my 48VDC battery bank. It is 22,080
watt-hours and 460 amp-hours (eight Surette S460 6 volt batteries). I have a 5200 watt
solar-array.
My Outback inverters do not accept AC current made by electric gensets - since most do not
make clean enough power. So, I want to have a backup method of charging the batteries, thus
the DC genset. If I could get it to put out 53 VDC, I could charge the batteries direct, or run it through a controller.

Any info or ideas appreciated.

I once mess up bad passed up a 50kw diesel genset in excellent condition for 8K (:

Gerald J.

Is this an alternator with external power rectifier? The regulator indicates an input from 180 to 270 volts AC. That would hint at a transformer and rectifier, if that is the proper regulator for that unit.

Raising the field current should increase the voltage, but there's generally decreasing effects as the field core saturates. So I can't be sure that raising the field current alone will raise the voltage as much as you need.

I begin to lean towards a common 5 KVA 120/240 volt AC alternator with engine from most any make that I figure is reliable and then a standard 48 volt battery charger. It would be of benefit if the charger is smart and keeps the charging current up as the battery charges, but samples the current and the standard float voltage regularly to detect when to cut back the charge and finish with a bit of gentle taper. That style of charger makes the best use of fuel.

As for regulators, I've built several, my most recent is running a steam turbine driven generator on a steam locomotive on the Boone and Scenic Valley RR.

Gerald J.

The regulator that is on the unit is original - this genset is brand new, in the box. It was custom made for some telecom company that went under. Made by Pow'r Gard that was bought out by Baldor.

In regard to running a stand-alone battery charger with a AC genset - that often causes problems. That, because most AC gensets do not make good enough AC to run a conventional battery charger properly. Most battery chargers require a voltage peak of 170 VAC (with what we call 120 VAC house current). 120 VAC from the grid is always at a peak of 170 VAC. But, most AC gensets peak at around 150 VAC. That has little effect on anything - except battery chargers. Most conventional battery chargers will barely put out half their rated output when plugged into most AC gensets. The inverter-gensets are exceptions - because they produce DC at first, and then run it though a high-end full-wave inverter (e.g. Honda inverer series). The other exception is using an especially made high-end battery charger that works differently and will accept low-peak AC from many gensets. And, a third work-around is a voltage enhancer AC box that ups the genset voltage by 10%. They sometimes work, and sometimes do not - with battery chargers. I tested some of my AC gensets with a standard industrial shop 80 amp battery charger. Plugged into any of my gensets - it will put out 35 amps max - yet put out the full 80 on grid power. I tried it on my Homelite 4400 watt genset. Coleman Pulse 1800 Watt, Honda 1000 watt, large 20KW Fairbanks-Morse genset, Detroit Diesel-Delco 13 KW genset, and a Generac 15K PTO powered genset. None run standard battery chargers properly.

There are some companies that specialize in high-end electronic chargers that work on a different principle - e.g. Iota. So, I'm just trying to figure which route will be the most cost-effective.

36 VDC is still common in telecommincations use. Seems anything I find that is modern was made for that industry.

As far as tweeking it, I don't know. I do know that the actual output of those 1.5-3kw military gen sets is much higher than they are rated at. you may not have to do a thing to it.

Just series a battery(s) to make-up the output voltage required. This would be the same as your PV's in series to meet your controler input requirement.

To recharge my 36vdc golf cart, I series three 12vdc chargers of different sizes. The only draw back to this arrangement, there is no charge regulation. In your case your planning on using external regulation so it wouldn't matter. I would also install a kill relay on the genset when the battery bank is fully charged. I would also add a blocking diode on your PV's if you don't have them now.

By chance are you using the new MMPT PV charge regulation? If so hows that working out?

T_Bone