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Author Topic: Looking For Gas Powered 12V DC Generator/Charger Advice  (Read 26497 times)
WA6MJE
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« on: November 02, 2012, 10:51:47 PM »

I have two 100AH deep cycle batteries for emergency use, and several smaller gel batteries.  I can charge this with a 50W foldable solar panel. That works, but works slowly, and not well on overcast days.  I would like to supplement that with a small gas powered automatic battery charger that can charge at maybe 50 amps to bring my 100AH batteries back to charge quickly.  The generator/charger is needed for a more sustainable power source when the solar panel is not up to the job. That would complete my need for off grid power, without having to run a 110V generator all day.

The problem is that almost all of the current small gas generators are 110v AC systems, with very small DC outputs in the range of 8 amps.  I cannot tell by the literature of any of them if the 8 amp charger is "automatic" or if I would need to keep an eye on it to avoid over charging, which is not what I want to do.  8 amps would take 6 hours to charge a half-depleted 100AH battery, longer than what I would like to listen to and wait for. 

Surprisingly, there is very little I can find on the market.  I found the Alten G1255D here..

http://www.alten-dc.com/gasoline-powered-dc-generators/item/149-12-volt-55-amp-gas-powered-battery-charger.html

That seems like the only solution, and very pricey. 

Does anyone have any other suggestions (other than DIY)?  Or, I have looked at dozens of 110 v system, and not found any with much more than 10amp 12V systems. Does anyone know of a 110v system that ALSO has at least 30 amps of 12v "automatic" charger feature? 

 
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K1CJS
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« Reply #1 on: November 03, 2012, 03:33:34 AM »

Your best bet is a small AC generator and a plug-in charger unit.  On all too many of the generators that you see, the 12 volt charger is a simple magneto that gives 12 volt pulses off a magnet and coil arrangement--that are meant for charging/maintaining a starting battery only.
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KCJ9091
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« Reply #2 on: November 03, 2012, 06:42:26 AM »

I have two propane gensets that are capable of 200 amps at 28 vdc.  The problem becomes finding a 28 to 12 converter big enough to do the job or balancing the load on the batteries so they discharge at the same rate.

I had little luck finding a high current 12 vdc genset.
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W4WXT
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« Reply #3 on: November 03, 2012, 06:55:45 AM »

Mornin Rene,
   Here is what, I myself use.... I bought a genset from my local hardware store along with a Black & Decker smart charger. Now, the charger is DSC microprocessor controlled as well as automatic temp compensation built in. It will charge wet, gel & agm batteries. Charge rate is 2, 10, 25 or 75 amp with a battery reconditioning feature to de-sulfate the batteries if need be. It is fully automatic, electronic so you can use the equipment while charging with NO RF interference. I think I paid $65.00 for the battery charger itself. The genset was $400.00 with 40A service and a 8 gal. gas tank. Hope this helps. God bless my friend
.  Smiley
« Last Edit: November 03, 2012, 06:59:02 AM by KS9LBW » Logged
W8JX
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« Reply #4 on: November 03, 2012, 07:05:27 AM »

Your best bet is a small AC generator and a plug-in charger unit.  On all too many of the generators that you see, the 12 volt charger is a simple magneto that gives 12 volt pulses off a magnet and coil arrangement--that are meant for charging/maintaining a starting battery only.

I agree. I would suggest a 25 amp automatic charger and a 800 to 1000 watt portable generator. such a unit would be easy to carry too. A 50 amp charger would need a bigger generator. Stanley makes a nice 25 amp automatic charger.
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KC0UKR
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« Reply #5 on: November 03, 2012, 05:49:12 PM »

I agree with the rest,if you are running a gas genset anyway why does it matter if it is 12vdc or 120vac that you use to charge a battery?

I use a variety of chargers with generators just for this purpose.
I have a few Xantrex which are very nice but any car battery charger will do it is not Rocket Science really.

Ed
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WA6LII
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« Reply #6 on: November 04, 2012, 06:28:02 PM »

Years ago, my Grandfather showed me how to make a "putt-putt".  You take a 5 hp horizontal shaft gas powered engine and connect it to an older model AC-Delco alternator. The 70's model alt will have a positive voltage connector and a 2 pin connector. Connect it to a 12 volt battery and connect the 2 pins together and you will charge the battery in no time. If you remove the battery, connect the pins, the alternator will self excite and you can power a brush type 120 volt motor (drills, saws, etc.) and incandescent light bulbs!  I carried one in the trunk of my car for years.

73's
Walt
« Last Edit: November 04, 2012, 06:30:56 PM by WA6LII » Logged
ALCO141
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« Reply #7 on: November 05, 2012, 10:08:26 AM »

i would just pick up one of these:

http://www.eham.net/ehamforum/smf/index.php/topic,84334.0.html

they go on sale for 79.99,  add the charger of your choice and you are set, also will run a fridge , maybe even a furnace, read the customer reviews for some tips on getting the most from this generator.

i have one as do a couple of friends of mine and they find them quite usefull.

alex
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K5LXP
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« Reply #8 on: November 05, 2012, 10:27:30 AM »

You take a 5 hp horizontal shaft gas powered engine and connect it to an older model AC-Delco alternator.

OK in a pinch but not worth the effort.  The gas engine can't spin the alternator fast enough to achieve full output unless you use pulleys and a belt.  Even then, a "beefy" alternator isn't much more than a kilowatt at 12V, and converting it to 120VAC adds cost and complexity in the form of an inverter.

Been there, done that:

http://www.qsl.net/k5lxp/projects/Lawnernator/Lawnernator.html


Quote
If you remove the battery, connect the pins, the alternator will self excite and you can power a brush type 120 volt motor (drills, saws, etc.) and incandescent light bulbs!

You get a poorly regulated rectified 3 phase DC.  OK for some loads, not OK for others.


Mark K5LXP
Albuquerque, NM
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K1CJS
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« Reply #9 on: November 06, 2012, 04:43:42 AM »

i would just pick up one of these:

http://www.eham.net/ehamforum/smf/index.php/topic,84334.0.html

they go on sale for 79.99,  add the charger of your choice and you are set, also will run a fridge , maybe even a furnace, read the customer reviews for some tips on getting the most from this generator.

i have one as do a couple of friends of mine and they find them quite usefull.

Small units such as this one will not run any sort of large motorized equipment because of the starting current requirement of such equipment--especially a refrigerator or a furnace.  For such uses you need a minimum 2000 watt generator set, not an 800 watt one.
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W8JX
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« Reply #10 on: November 06, 2012, 06:26:01 AM »

Small units such as this one will not run any sort of large motorized equipment because of the starting current requirement of such equipment--especially a refrigerator or a furnace.  For such uses you need a minimum 2000 watt generator set, not an 800 watt one.

A lot of modern refrigerators will indeed run on a 800 watt unit, my side by side will. The nice thing about 800 to 1200 watt generators is that you do not get a hernia lifting/moving them around by yourself. When you get to 2000 watt and bigger units they start to get a lot heavier. 
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N3QE
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« Reply #11 on: November 06, 2012, 07:17:39 AM »

Many of the small "inverter generators" have a 12VDC out jack. It is only a tiny fraction of the total unit power.

E.g. Honda EU1000i specs 12V out at 8A.

They are really nice generators for 120V out. Around here, street musicians use them to power their amps, and in an outside street environment (traffic etc.) the hum of the generator is barely noticeable.
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K1CJS
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« Reply #12 on: November 07, 2012, 03:48:03 AM »

A lot of modern refrigerators will indeed run on a 800 watt unit, my side by side will....

It's not the 'running' wattage that is in question, it's the amount of power needed to start the compressor unit AND the blower unit in the refrigerator.

Also, agreed that a lot of the newer energy efficient appliances take less power to run--but not everybody has the newer energy efficient units to begin with.
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W8JX
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« Reply #13 on: November 07, 2012, 07:06:16 AM »

A lot of modern refrigerators will indeed run on a 800 watt unit, my side by side will....

It's not the 'running' wattage that is in question, it's the amount of power needed to start the compressor unit AND the blower unit in the refrigerator.

Also, agreed that a lot of the newer energy efficient appliances take less power to run--but not everybody has the newer energy efficient units to begin with.

My side by side is 10 years old. You can hear fan/blower start then compressor which soft starts. It is around 300 watts running
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LA9XSA
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« Reply #14 on: November 08, 2012, 03:58:17 AM »

Also consider practicality and safety: You probably have your battery bank indoors. You absolutely MUST run the generator outdoors to not contribute to the usual CO poisoning death statistics. If you were going to have a long run of 12 V DC wiring from the generator to the battery bank, at high amperage, you'd need very thick cables - perhaps costing more than the generator itself. Higher voltages transfer the same amount of energy with less amperage, meaning less resistive losses and one can use thinner cables.

If you're going to charge batteries on the "battery charging" output, it's meant for carrying the battery next to the generator, not for charging big battery banks.

Look into getting a generator with both 120 v and 240 v output by the way. Some equipment like well pumps, sump pumps, etc. actually run on 240 volts.

For a more gee-wiz, but far less efficient, way of getting 12 volts, you could look into Peltier elements.
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