Gas powered 12Volt charger

kbellve

Observer
You would think there would be a ton of these things, a simple gas powered 12volt charger. What is easy to find is the 120AC/12V generators like the Honda e1000. The e1000 puts out less than 10amps on the 12V DC line. A car's alternator can put out from 50amps to 100+amps. The examples below put out 50 or 55amps, but there are versions that go beyond 100amps charging.

What I am thinking is getting is getting a 12V gas powered charger for my camper. My camper already has a 2000 watt A/C inverter that runs from 4 6V batteries. For extended dry camping, it would be nice to recharge the batteries in a few hours. Using solar is mixed, especially in highly wooded areas. Charging the batteries with my truck would take about 40hours (10amp/hrs for 40 hours for 400amp/hr battery pack).

So, after a search, I found serveral gas powered 12V chargers. The best one that I like seems to be only in Australia. No idea of the cost.

http://www.christieengineering.com.au/2.5hp.htm

The next one is a chinese knock off that I can get for about $300, but I think available in the US. It has lower noise output than the one above.

http://www.christieengineering.com.au/YK50A.htm

There are plans to make your own with a simple lawnmower engine and an alternator.
 

Pskhaat

2005 Expedition Trophy Champion
kbellve said:
There are plans to make your own with a simple lawnmower engine and an alternator.

Cool product! I was going to say that I've seen a few DIY kits to attach a single-wire alternator to a small Briggs&Stratton. It'd be interesting to use a redundant matching alternator from the vehcile that could be poached if need be.
 

Lynn

Expedition Leader
Edit: Pskhaat types faster than I do...

Just thought I'd include a link to a site with info on homebuilt DC generators:

http://theepicenter.com/tow02077.html

They sell parts.

Also, another option I am planning on investigating would be to get a mil surplus 28V DC generator and regulate it to 12V.

But I think a home-made one could be smaller than the mil surplus units, and easier to maintain from a parts availability standpoint. Another advantatge to the home-built is that you could use the same model of alternator on both the genset and on your vehicle, so if your vehicle alternator goes out you swap out with the genset.
 

teotwaki

Excelsior!
I am wondering about the purpose of having a gas powered 12V charger?

Surely not to bring on an expedition? I have dual batteries in my rig and I can force the second battery on if I had to give myself a jump start.

Bringing along a AC generator and a (AC-powered) good battery charger might give you more use out of the generator than a 12 volt specific unit where you had to run an inefficient DC to AC inverter.
 

Lynn

Expedition Leader
teotwaki said:
I am wondering about the purpose of having a gas powered 12V charger?

Surely not to bring on an expedition? I have dual batteries in my rig and I can force the second battery on if I had to give myself a jump start.

Bringing along a AC generator and a (AC-powered) good battery charger might give you more use out of the generator than a 12 volt specific unit where you had to run an inefficient DC to AC inverter.

It depends on how long you plan on staying in one place, what your individual AC / DC requirements are, whether you want to run your vehicle engine just to charge batteries, etc.

Running an AC generator and battery charger may be more inefficient, if your primary needs are DC.
 
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kbellve

Observer
teotwaki said:
I am wondering about the purpose of having a gas powered 12V charger?

Surely not to bring on an expedition? I have dual batteries in my rig and I can force the second battery on if I had to give myself a jump start.

Bringing along a AC generator and a (AC-powered) good battery charger might give you more use out of the generator than a 12 volt specific unit where you had to run an inefficient DC to AC inverter.

I beg to disagree. Check the pages for the outback generator. Guess where they go? The Outback in Australia!!

I think it is more efficient to go gas->12 Volt->Batteries->inverter to 110V AC. More of my appliances need 12V than I need 110 A/C. My 12V appliances include my water pump, furnace, hot water heater, refrigerator, and lights. My 110V AC appliances is my microwave, and TV/Satellite dish. So, it makes more sense to produce 12V power than to produce A/C power only to be converted to 12V power later.

Pros:
1) It puts out 5x as much amps at 12V compared to a A/C generator.
2) Easily charge your batteries faster using less gas.
3) Why pay for inverter technology in an A/C generator when you already have an inverter?

An AC generator would take forever to charge your 12V batteries. As I said, the EU1000 charges less than 10amps with the DC output. The UE3000 puts out 12amps at 12V. If you go A/C to a battery charger, you would get even less. My 110V AC charger does about 6amps at the 10amp setting. With my 2000watt (3000max) inverter connected to a 30AMP 120Volt AC source charges my batteries at 30amps max.

My truck will charge the batteries via the trailer connection at about 10-15amps at 12V.

If you goal is to recharge your batteries, than you can't beat a 12V gas powered charger. I believe it is more efficient, and cheaper, assuming you already have an inverter.

I could fully recharge my camper's battery once/week while dry camping. With an A/C generator, I would have to run it nearly once a day.

For an A/C generator, at 10amps/hrs, it would take 40hours to recharge my batteries versus 8 hours for a 12V charger.


Oh, cons?
1) Doesn't include a inverter.
 

BajaXplorer

Adventurer
Why would I not want to use my trucks alternator to recharge my auxilary battery? I could also upgrade my trucks alternator for less than $300 to 130 amps.
Am I missing something here?
BX
 

kbellve

Observer
I don't think this is useful for a truck with a dual battery system, unless you kill both batteries and need a way to charge them perhaps.

Let me just add..this is for large battery systems for things like trailers and campers designed for extended dry camping.
 
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HINO SG

Adventurer
Personally, I find that my 120V needs in the field are minimal and easily met with a small inverter.

There are a couple of places that make a 12V- only, or better yet, 12V& air conditioning compressor diesel powered unit for marine applications. That would be sweet.
 

teotwaki

Excelsior!
Okay, since I don't own a trailer I had not considered having to recharge those types of 12volt systems, especially with multiple parallel batteries. My truck has a 130 Amp alternator so it could easily recharge extra batteries if needed but running 8 cylinders is less efficient than 1 or 2 in a small genset. I can imagine that a gas generator versus solar power has already been debated with the bulk and cloudy day issues being the bigger negatives.

If a well-equipped trailer has an inverter then a 12 volt-only generator is not too specialized.

An earlier comment about a military 28 VDC generator is not a great solution as regulating that down to 12 volts introduces more losses. Maybe get a mil 28v generator and then replace the actual generator with a 12 volt unit of similar physical size?
 

ntsqd

Heretic Car Camper
About 40 years ago my granddad took a Delco 100 amp Generator (& regulator) & put it on a frame with a 3HP Tecumseh using a V-belt drive. We used it mostly to charge farm implement batteries when getting the implement ready for the next season's use of it.

Other than noise that system sounds like it would work for what you want. Were it me, I'd use a Delco 17SI Alternator. They're around 100-120 amps and big enough that you aren't likely to hurt one in long charge cycles.
 

njtaco

Explorer
I know this does not help with the efficiency question, but your batteries will generally last longer if SLOW charged, to keep heat down, as opposed to your goal (I'm presuming) to FAST charge them. This means ditching your 6V wet cells (I am assuming wet here) and investing in a high quality AGM that can take 15V plus (from the Christie Engineering site) if you want to fast charge your bank of energy.

Otherwise, I think your are on the right general track in skipping steps between gas/LP/diesel and your 12V goal. I'm not sure the cost/benefit will work out in real life, though.

On the motorhomes I've had the pleasure to work on ( <<== note sarcasm) the charge line to the coach batteries was generally protected by a 30A fuse or CB. This implies that even the deadest of battery banks could only charge at rates lower than this. Of course, YMMV.

Good luck on your search, and keep us updated. Despite my words, I do think there is a potential use here...
 

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