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Building a DC generator


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I've been needing a DC generator for charging a 12 volt battery bank.  AC generators work awful for charging batteries, and AC generators hooked to high-end battery chargers gets kind of convoluted.  I know that they used to be fairly common for campers and RVs back in the 70s and 80s. Now they are super-specialty items and very expensive.  So I just built one with a new 6 horse Harbor Freight engine and a Delco 140 amp CS series alternator.  So basically 2000 watt generator that can charge up to 140 amps at 14 volts.  A little bigger then the ones that used to get sold with lawn-mower engines.  Hopefully it will work well.

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Very nice.

Is it a one wire alternator with a self exciting voltage regulator?  Seems almost foolproof.  Did you add anything electrical except two wires to the battery bank?  I'm looking forward to hearing how it works.

I've been using a Harbor Freight 900 watt 2 cycle generator with my converter and an external battery charger to charge my batteries where appropriate.  It works, burns little gas, but it isn't efficient for bulk charging.

Have to say, I love the belt guard.  In the farming community where I grew up, kids missing fingers reminded us to be careful.  Thanks for taking the time to post.

fleamarketvendor

 

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whats truly funny is that the add you show lists the sporta charger as being $359 US prepaid. I am assuming this is an old advertisement because mastercard is referred to as +

"mastercharge"  in it still... That predator engine with coupon and the alternator were probably had cheaper than that today; nicely done, usually things these days are more expensive not less so this is awesome. gotta love the HarborF.

 

Edited by Totem
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Two wire hook -up.  I don't want a one-wire self-excite circuit.  I want the ability to turn the field/excite current "on" or "off" with a toggle switch.

I've messed around for years with using portable generators hooked to battery chargers to use on battery banks.  It's a crap-shoot.  Many portable generators will only run a conventional battery charger at 1/3 or 1/2 its normal rating.  Not a big deal when just charging one battery. Huge problem when charging multiple batteries.  I have a Trace/Xantrex combo 2400- watt inverter and 120 amp battery charger.  I've had it hooked to six different portable generators.  None would let it work over a 50 amp rate.  But when I hook it to my tractor PTO powered 17KW generator - it works at full capacity.   Xantrex no longer makes unit like that. Now the come with sophisticated electronic battery chargers that will work on any generator.

I've got to put a 120 amp and fuseholder on this charger along with 15 feet of #2 copper cables with good alligator clamps at the ends.   THIS would up turning into a research project.  I had no idea what sort of BS is going on these days with deceptive marketing.   Many places are selling #2 gauge jumper cables and sometimes reels of #2 stranded cable and it is copper-clad aluminum and NOT copper.  So a set of #2 gauge cables like that are only equiv. to #4 or #6 copper. WHAT A RIP OFF!   I see a lot of BS now-adays when trying to buy things - but this takes the cake.   But - I guess near everything is now that way.  I got ticked off last night when I thought I bought a gallon of ice cream since it was in a cooler marked "gallons of ice cream."  Got it home and it's not.  Smaller container with Metric BS on it.  Same goes for a gallon or parts cleaner I got last week.  Got it home and found out it is now only .75 gallon but still in the 1 gallon container.   I thought it was highway-robbery when chain stores started selling 20 lb. propane tanks with only 15 lbs. of propane in them.  So they sell them 3/4 full and get away with it. Now seems near all sellers are running some sort of scam like that. 

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1 hour ago, Totem said:

whats truly funny is that the add you show lists the sporta charger as being $359 US prepaid. I am assuming this is an old advertisement because mastercard is referred to as +

"mastercharge"  in it still... That predator engine with coupon and the alternator were probably had cheaper than that today; nicely done, usually things these days are more expensive not less so this is awesome. gotta love the HarborF.

 

Those "Sportachargers" are from ads in 1985-86.  The only new equivalents I see now are made in Australia and cost over $1300.   And they are only rated 55 amps.    I got the HF engine brand-new for $89 on sale a few years ago.  The Delco CS144, 120 amp alternator I also got new from a factory close-out for $69.  The pulleys and belts ran me $50. Most expensive part is going to be the 15 foot #2 gauge copper cables. HD alligator clamps, 120 amp fuse and holder, etc.  That stuff ran me around $75. So in all - not counting the steel I got from a old bed-frame - there's around $300 in parts.  Note though - I have plenty of old engines and old alternators laying around so new stuff wasn't really needed.  But the new engine and alternator was already here in my "old stock."   I have no heated shop where I am for the next few months - so when it's cold and miserable outside - I'm working on indoor projects in a heated basement shop. I wish I could find a way to get my Chinook in there.

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