Home made welder by day, DC generator by night

oil pan 4

It turns out I have already built 90% of a DC battery charger and it works.
I took a Honda GC200 v belted it to an AC Delco DR44G alternator that I had upgraded to a much heavier "250 amp stator", external rectification provided by some used MRI machine parts and externally powered field excitation.
All I use it for is a welder. With the little GC200 engine it makes about 95 welding amps at 24vdc and makes a maximum of 87vdc open current voltage with 12v of field power wide open and 20v at idle. The alternator is over driven 1:2.
The crazy thing is it works really well, its one of the better DC machines I have ever used. I think because it's rectifying 1,000Hz 3 phase AC to DC.
Only problem is I would like to have more in the neighborhood of 120 to 130 welding amps for a lot of things and really 150 to 160 amps would pretty much do everything I would want a portable machine to do.

All I would need to do is add a voltage regulator to it and a bigger engine. I'm thinking about a 13hp engine.
If I were to go off grid I would most likely use a forklift traction battery, two 24v batteries in serries. At least 1,000 to 1,200AH, or as big as I can afford and still be able to move around.
I'm thinking it should be able to make 50 to 80 amps at 55v with out any issue and with out running it wide open.

Would as little as 50 amps help any for a pre morning bulk charge?
Because in the winter I normally get up 1 to 2 hours before sun rise and I could fire up the generator for a bit with a little fuel and leave it to run its self out of gas if I suspected the battery was real low or wasn't going to get a full charge off sun power.
Or should I go wide open, burn a lot more fuel and try to get close to 70 to 100 amps?
I think best fuel economy on these engins is some where around 2,200 to 2,500 rpm.

mike95490

You really don't want to plan on a generator running out of gas.    When charging batteries, you are pushing hard and heat soaking everything, engine is hot and loaded, alternator is hot....  If you loose gas, and it shuts off, all that built up heat starts cooking insulation, loosening glue and varnish on the insulation and to suddenly loose all cooling, stuff is going to cook.   And it's not good for the engine either.  Like driving on the interstate for 4 hours, you overheat when you pull into the gas station and switch the engine off.

Estragon

Any morning amps would help make up for the short winter days. Whether it would be enough obviously depends on the size of the deficit. 55v might be on the low side if the bank is cool/cold, but shouldn't matter much for early bulk stage.

oil pan 4

I was going to use a 167 amp although that's been up graded to 250 amps at well under 100 amps or less to prevent cooking on shutdown.
I can check it with my flir i7 to check the temperatureof the stator.
If I'm going to run it wide open, at 150 or more amps not going to let it run out of gas.

mcgivor

@oil pan 4  Was doing some research on welding and came across this page, thought it may be of interest to you.

http://diy-welder.com/buildit.shtml