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Sure you can run a battery charger with a portable generator, but why not cut out the middle man, especially if you’re off the beaten path where you don’t want to haul around a large generator? This would be especially great for charging up an electric trolling motor battery or camper battery when you’re 150 miles from the nearest outlet.

Weighing in at 26 lbs, this 2.5hp generator can charge a 12V battery up to 55 amps an hour. It uses a 55cc 4-stroke Honda engine to drive a Bosch alternator. The generator consumes about 1/5 of a gallon an hour and has a tank large enough to run for an hour and a half. The panel features an LED readout and a switch to choose between low and high charge rates.

This little generator is made in Australia and it isn’t cheap. It ships with 10 foot leads terminated with alligator clips and runs $1350 AUS, or about $1200 US. If anybody knows of a little gas-powered charger like this that’s made a little closer to North America, let us know in the comments.

Outback Battery Chargers [Christie Engineering]
Outback Battery Chargers [Energy Matters]

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34 Responses to Gas-Powered Battery Charger

  1. Gil L. Braverman says:


  2. Emis says:

    Here’s a 2-beer project … round up an old gas mower and some junk yard parts and make something similar yourself for much less money–


    These guys even already sell the brackets and parts.

    You’ll want to add a small 12V battery to this so that you don’t burn out the alternator w/o one, but @ $1200 for the unit above, I bet you can round up quite a few junk yard units as replacements.

  3. Toolhearty says:

    Gil L. Braverman Says: Sweetness

    I think the one submitted by Emis is sweeter by about a kilobuck.

    (now if I can just find a B&S 5HP Quantum motor that isn’t doing anything)

    I suspect the super cheap import would end up being a waste of money.

  4. Bob says:

    The Honda generators already do this.

  5. @Bob:

    The Honda generators already do this.

    I can only find 1 generator they sell that does 12V DC charging and it weighs 68lbs.


    Or am I missing something?



  6. Toolhearty says:

    Benjamen Johnson Says:
    I can only find 1 generator they sell that does 12V DC charging and it weighs 68lbs.

    …and would you want to leave a $1600 generator sitting in the back of your truck?

  7. fredb says:

    You need to look harder Honda EU1000iA at 12V – 8A DC output at Dry Weight of 29 lbs and
    DC Charging Cord for EU1000, EU2000, EU3000is, EU3000 Handi,
    Charge any 12V automotive type battery.

  8. Cameron Watt says:

    Leave a generator in the back of the truck? Sure, just bolt it down….or…chain it to something heavy: I usually have a welder in my truck so I just chain smaller things to it.

    If you’re going to go the homebrew route and want something truly reliable then consider incorporating something to limit current so you don’t bog down your engine or cook your alternator. A small battery will help to a point but not with extended high-load situations. A task like resurrecting a dead battery bank on a boat or RV can be quite a job for a little alternator.

  9. @fredb:

    Thanks, I was only looking at the summary pages for the generators. I figured that 12V charging would be a feature that you’d want in the summary especially for generators in the play category, but I guess I was wrong.

    Am I reading the specs right that even the Honda EU3000iSA only puts out 12A? It’s going to take over 4 times as long to charge a battery as the one I posted.

  10. Toolhearty says:

    Cameron Watt Says:
    Leave a generator in the back of the truck? Sure, just bolt it down….or…chain it to something heavy…

    You’re right, I have seen plenty of tradesman with generators bolted to the bed (usually truck mechanics), but these guys usually aren’t far from their trucks. I was thinking of the guy who puts his boat in the water for a day of fishing and leaves the truck back at the dock.

    …consider incorporating something to limit current so you don’t bog down your engine or cook your alternator…

    Any suggestions?

    By the by, isn’t your a welder a generator and don’t they have inverter outputs for power tools? Just seems like that would be the case.

  11. fred says:

    @ Toolhearty

    Our truck-mounted Miller Trailblazer welder has a dual generator system so as not to bog down the welder with a parasitic draw. I think the auxilliary out put is something like 10kW – but this isn’t a tool we haul around to charge batteries.

  12. rg says:

    I know a few people who have used the Chinese $129 special, and it works really well. I’ve seen them on sale for as low as $99 Candian(!). 2-stroke, so a tad noisy, but not that bad. I also know a guy who had his EU2000 stolen. He wasn’t happy.

    “…consider incorporating something to limit current so you don’t bog down your engine or cook your alternator…
    Any suggestions?”

    A lightbulb, or a big resistor.

  13. MeasureOnceCutTwice says:

    The neatest version I saw was made by a guy who had to maintain a fleet scattered around a big complex. He mounted an old alternator to a mini-bike and used the mini-bike engine to drive it. I’m hazy on the details, but I think he drove both the alternator and the rear wheel simultaneously – with no electrical load the alternator didn’t bog down the engine for driving, and when charging he propped up the rear on the kick stand and just let the wheel spin. Pretty simple.

  14. ambush says:

    You’re very unlikely to burn out an alternator. The current limiting device is the design of the alternator. It simply can’t output more current than its rated output.

  15. Cameron Watt says:

    @Toolhearty: Use an externally regulated alternator and a voltage/current regulator or just a current sensing relay to cut field current when the load gets to be too much. It doesn’t need to be too fancy.

    I have auxiliary AC on my machine but it’s not inverted. By the way, I’ve seen old Lincoln Pipeliners that produce DC and run it to a household outlet; if you’re just running a grinder with a universal motor then it’s not an issue.

    @fred: I’ve put a few hours on a Trailblazer 302; it’s a good power supply. You can put a fair bit of load on the AC outlets without effecting weld performance. I was doing a handrail job with one and we plugged a Miller Maxstar to the auxilliary power plug; each running 3/32″ electrodes; a dual-operator set on the cheap! It wasn’t too demanding but would never work on my old Hobart; nice though it is.

    As for the seperate windings to generate weld and auxiliary power, it’s a great idea. Independant windings solve a couple of problems but if they’re connected to the same engine and a heavy load on one drags its speed down, then the other will be effected….but for most work the issue is purely academic.

    @rMeasureOnceCutTwice: The mini-bike idea is the coolest thing I’ve heard of in a while! I’m jealous that I didn’t think of it myself. I used to do maintenance in a distribution centre with a large fleet and I was thinking of wiring in a DC coupler so I could just plug-in a set of jumpers rather than open up the hood each time….never did. If I had heard of the mini-bike idea years ago, I would have used it for sure! …however…It’s bad enough when guys “borrow” tools but that would be one good for a joyride.

    @ambush: Not all alternators are created equally. There can be quite a difference between an alternator’s maximum rated output and what it can generate continuously.

  16. Paul says:

    Small engine plus 1 wire alternator plus small battery is the win!, But seriously why not just carry a jumper box, you can get one for about $29, for $60 you can get one with a nice sized battery in it, a 12 outlet, a flashlight and a compressor, you don’t have to worry about gas going bad, leaking… just charge it a couple times a year.

  17. Ben says:

    The jump boxes only work to a point. I have Diesel pickup that will not start with a jump box because the don’t have enough current to get the glow plugs hot and then turn over the engine.

  18. Will says:

    The Outback battery charger above is now made in the US by ALTEN Battery Chargers (www.altenbatterychargers.com). I’ve used this charger to start a completely flat Bomag roller in about a 1/2 hour. This is the smallest unit, but they also make larger units, including diesel-powered units that backup off-grid power (eg SCADA systems). The concept is that when solar or wind isn’t keeping up, the battery charger starts up automatically to keep the battery bank from running flat.

    Folks that work with batteries and understand DC power, recognize the inefficiency of trying to work with AC generation. Besides, AC generators that offer a DC outlet, only provide around 4amps. The battery charger above produces up to 55 amps at 12 volts. Like my father always says, it’s all about using the right tool for the job, and working smarter, not harder – I’m still trying to figure that one out!

  19. Darrell says:


    At the bottom of the page there is a good one, I have read all about it and am ready to purchase.

  20. Dwayne Vernon Larson says:

    As far as, ‘Portable Generator Already Does That,’ Meaning Charge in 12volt Fashion? Sure Dey Doo, but that’s usually 8.3amps @ 12v.

    Sure, Honda/Alten, $948- “OOOOOOCH!!!!”

    The 5hp Engine Spinning a ‘one-wire’ Alternator? Well, OK.

    The Only Problem Being; Folks are Used to Seeing Those 800w, 1000w, 1200w,1500w, 2000w— Small 2-cycle or a Lucky Inexpensive 4-cycle
    Generator, Luckily with 12v- Output.

    Well, a YANGKE 55A 12,20,50amp Adjustable 12v charger/Power Supply
    is a Great Idea- though 2-cycle- Where Do You Purchase One? I Heard $279.

    Pretty Sketchy Accessibility to Say the ‘LEAST!”

    If I had the Money & Shop- I’d Make & Merchandise a:

    Small, Try for 4-cycle Little 12v Generator/Power Supply that would be a

    Multi-Voltage Battery Charger for Charging Battery Banks for Home Power & Be a Temporary 12v DC Power Supply

    I think it Could be Made & Sold at a Profit for $129 & Hook-Up Ready for Accompanying Battery, 16volt- for Jumpstarting Motor Vehicles

    like I’ve Heard Said; “What do You Do in the Middle of the Desert Camping in a Motor Home or RV when All the Batteries Accidentally Go Too Dead to Start the VEHICLE.



  21. Sam says:

    The G12-55 model I just purchased works awesome!
    It has a low setting @ 14.2Vdc and High setting @ 14.8Vdc
    I hooked it up to QTY 3-12V batteries in parallel and my batteries were 1,3 and 5 years old. I had my batteries charged up to 12.6 Volts in 15 minutes. This charger is fantastic and I take it everywhere I go and never have to worry about a dead battery. I use it for my motorhome,quad machine,car,truck and have never had to worry about my batteries. I recommend this charger to everybody! It has saved me from getting stuck in the outback. Also, while it charges it supports a load of up to 55amps at the same time. What a life saver this has been for me! I give it 5 stars!!!!!!!!

  22. Joe says:

    I bought the G12-55 from http://www.altenbatterychargers.com
    They are in Ferndale, Washington American Made!
    I love that part! Support American JOBS!
    They have an LED model @ $998.00 and Digital @ $1098.00
    This little unit weighs 26lbs and is small. I love it!
    No more battery troubles for me. I highly recommend this to anybody looking for battery charging on the go anywhere,anytime on land or sea. A jumper box can’t compete. How do you charge your jumper box when your in the outback?

  23. paul matteoni says:

    have been using similar, home made unit,to charge the batterys powering my cabin in alaska for the last 16 years. unit is a 35 yr old honda 8hp, belt drive to a delco 60 amp regulated altinator. 25gal. avg. pur year. am now putting together a new unit on a 6.5hp.hope it last as and trubble free as the G300 has been.

  24. bobby gallagher says:

    I bought one of their units for my off grid home and every 6 months it breaks. I have sent in for repair 4 times so far. Next time it will be 5! Do not buy these! The hype is all bull! They can’t make mine work. A simple alternator to gas engine anybody can do this! Their pricing is so overinflated. I will never buy one again and recommend to all never buy! Their a rip-off!

  25. sonny fitzgerald says:

    I bought one and it keeps breaking at coupler that joins the 2 shafts. Everytime I send it in they fix with the same coupler and every couple of months it breaks again. What a hassle. Don’t buy one!!!!! Over priced for what you get and it doesn’t work. Buyer beware! Remember I told you so! There is way better stuff out there. Check a company called Alpha inWashington!! There the best!!!!!!!!!!

  26. paul matteoni says:

    check unit avalible from Backwoods solar sandpoint idaho about $800 turnkey or parts. Intended for use as backup charger in solar instalations.

  27. John Burd says:

    Given the sophistication of modern automobile engines and fuel systems I was wondering if anyone knew how different the fuel consumption would be between this Honda (or a Chonda or a Briggs) set up with a simple carborator etc would be compared to installing an industrial strength alternator in an automobile and holding the engine at say 2-3k. This solution would obviously be of no use for most purposes but for say adding a few watts to an off-grid solar system to get through a few cloudy days on the cheap it might not be too bad.

  28. Frank says:

    I’m looking for something really small to replace or supplement a 10 watt (up to 40 watt perhaps) solar panel used to charge a 12 volt (33 Amp hour) battery. It would need to operate untended, and be self starting and stopping. Noise is also a big concern so it would need to be as quiet as possible so as not to disturb a neighborhood.

    Any ideas? Drop me a line.

  29. wayne says:

    Any idea how or ware I can get a similar unit 12vdc 120amp petrol diesel or gas in the UK preferably with auto start I feel there is a massive market for this product in the UK not only from the liveaboard boat community but from caravan and outdoor hobbyists but try as I may I can’t find a UK supplier of this or any other similar product any help from anyone would be much appreciated

  30. joe bob says:

    Iv got a lil jump box thats lighter than a weed eater n has 12 or 24 volt option and a common house hold outlet on the side as well if u need to run any tools while your stranded or somewhere without power. Its a two stoke motor. And in fact its more than likely a weed eater motor itself that powers the unit. Way lighter n more efficient than anything iv read so far. Its made by tecumseh and is called a lightning charger.

  31. joe bob says:

    Theres also a badge on the side saying ATI power products. I guess tecumseh just made the engine

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