DC to AC inverter to power a battery charger

[Glock Diver]

With a subject like this, I almost can't believe you clicked on this thread!  


Let's say a fella has an on-board battery charger that he typically plugs in the night before a fishing trip, just to make sure he's got fully charged batteries.  

And suppose he forgets to do this one night, but remembers as he's leaving for a 2-hour haul to the boat ramp.  And let's say he has a DC-AC power inverter that plugs into a cigarette lighter.  And a 40-foot extension cord.  Now, ignoring the redneck aspects of this setup.... would it work?  Could I charge my batteries as I'm driving to the boat ramp?    With one of these:

[gran398]

We clicked...and absolutely you could/can.

And per the redneck reference, just like cooking pig as you're towing it.

 Just don't forget to disconnect the 40 feet at the ramp....

 

[Circle Hooked]

How many amps is the charger and how many watts is the inverter,it might be doable if your lighter socket would hold up,but for very long maybe not.

My dad was pumping up a large tire with one of those plug in pumps,as you can guess it was taking awhile,well before the tire was full the pump shuts off.

After some checking the fuse was fine but the heat melted the whole section of wire up to the plug. :x

[Glock Diver]

After some checking the fuse was fine but the heat melted the whole section of wire up to the plug.

That's the kind of thing that worries me... what kind of vehicle was it?   And why didn't that fuse pop?


Anyhow, it's a 10-amp, 2-bank charger.  The inverter is either 500 or 1000 watt, IIRC.

[John Jones]

Somewhere on the charger in fine print should be a watt rating as well.

Amps X volts = Watts
20A X 14V = 280 Watts
That does not allow for any inefficiencies in the charger circuitry, usually wasted as heat.  I would want an inverter rated 30% over the draw of the charger.  I would want a 400W inverter.

Vehicles with a tow package usually have the big round 7-pin trailer plug.  That puts 12V at 30 amps available on one of the pins right at the bumper.  I have thought about wiring up a plug with battery clips for just such an occasion but I won't because my onboard charger stays plugged in 24/7.

[John Jones]

After some checking the fuse was fine but the heat melted the whole section of wire up to the plug.

That's the kind of thing that worries me... what kind of vehicle was it?   And why didn't that fuse pop?

Cig. lighter fuses are usually pretty high rating.  Probably just rated higher than the compressor wire.  The compressor should have had it's own fuse inside the plug.

[Circle Hooked]

Mike a 07 GMC van,the wire was extremely small maybe 16-18 gauge.

Not sure how to do it,but when i tow my camper,my truck supplies power to the camper inverter which in turn powers all 12 volt functions like the slider,lights and charges my camper battery.

I have the setup John is talking about.

John he was repeatedly pumping up this tire as i learned later so maybe just to much is to much and the wire gave,i never looked at the fuse on the pump,which is still working from what i hear, i got involved when he was tearing the van apart to find the problem.

[Glock Diver]

Yep, I've got both a 7-pin and a 4-pin at the hitch on my F150.  

Well, I might give this a try one day and see how it works.  After I verify I have at least a 400 watt inverter, which I'm pretty sure I do.  I've seen those inverters power a blender, which I'm sure draws quite a bit... however, that's in spurts. (Only takes 5 or 10 seconds to make a margarita     and I would be towing for about 2 hours....

[John Jones]

Yeah, time will make a difference.

[slvrlng]

I would be worried about the buildup of heat in either the harness or the plugs as well. Maybe an easier setup would be a small generator strapped down and left to run on the deck. That way you wouldn't have such long runs of wire putting strain on things.
http://www.harborfreight.com/engines-ge ... 66619.html

In the new sale sheet I got yesterday this one is 109.99

[Capt. Bob]

I believe CJ (GoneFission) found that genset at $89 +/- from them at one time.

I often wondered how loud it really is.

[RickK]

They're pretty loud - Dave bought one and regretted it.  Try Honda - my 2000ei is very quiet.  I think Yamaha now makes a pretty quiet one too.

[DOCREED]

Yep, I've got both a 7-pin and a 4-pin at the hitch on my F150.  

Well, I might give this a try one day and see how it works.  After I verify I have at least a 400 watt inverter, which I'm pretty sure I do.  I've seen those inverters power a blender, which I'm sure draws quite a bit... however, that's in spurts. (Only takes 5 or 10 seconds to make a margarita     and I would be towing for about 2 hours....

so....you could make a lot of margaritas in two hours then.....

[gran398]

Sounds like the need is to top off the batts as you're going down the road. So how about wiring a heavy guage 12V feed from the truck batt to a rear bumper-mounted female plug, like for use with a travel trailer/electric winch, etc?

Then a run to the boat batts with alligator clips.

That would eliminate the other stuff....you'd charge straight from the truck, 12V to 12V.

[GoneFission]

Ok, here's a plan - and I've done this - most SUVs and trucks today have a 12 volt cigarette lighter outlet somewhere in the back of the vehicle.  Cut a 14 gauge, 2 conductor cord long enough to go from the tow vehicle to the cigarette lighter outlet on the boat.  Put a male plug on both ends of the cord and plug it into the tow vehicle and the boat.  Use bungees or rubber bands to secure the cord along the way.  Make sure the battery switch on the boat is "on" and the tow vehicle will charge the boat as you drive.  

The inverter to battery charger idea will work, but you are going from 12VDC to 120VAC and then back to 12VDC - each step will have losses.  Just go 12VDC to 12VDC and it will work better.  

Regarding the Harbor Freight 900W generator - it's not very noisy, and it would work fine to put it in the boat and let it run while you drove down the road to charge the batteries.  Just lash it down somewhere and make sure the exhaust points toward an open area so it does not damage any plastic or fiberglass...