Max sized inverter from a cigarette lighter plug

icedragonmx

Adventurer
Just wanted to check the math on this idea for maxing out the available power from a standard cigarette lighter plug found in my Xterra.

If Watt = Amps x Volts and an inverter runs at 90% efficiency then the total required for a 150 watt inverter at 90% would be at 167 watts correct?

So working back the Amps required would be 14 amps on a 12 volt system to power a 167 watt system.

I was looking to see if the Go Power! GP-SW150-12 150-Watt Pure Sine Wave Inverter could run continuous without requiring a dedicated supply line from the battery. This is in a newer vehicle with a factory 55amp/hr battery. If I am right, a 300 Watt system has too much draw for a cigarette lighter plug and would require a dedicated cable for power. Would a regular cigarette lighter plug be able to supply 14 amps continuous? I know a heavier gauge direct line to the battery would be better but just wanted to see if this would work with no modifications.

Thanks for any feedback with this.
 

jonyjoe101

Adventurer
some of the older 12 volt receptacles where rated 15 amps, I don't know if the newer plastic ones can handle the 15 amps. If it has a 15 amp fuse in the fuse box it will.

But the weak point is always going to be the the actual 12 volt plug on the item. The cheap ones are known to melt at around 12 amps. Heavy duty plugs will do the actual 15 amps continuous. They are made of heavy plastic that can handle the high temperatures.
 

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icedragonmx

Adventurer
Realistically, I wouldn't trust a lighter plug with anything over 10 amps even for brief periods.
This is what I had been reading, thanks.

some of the older 12 volt receptacles where rated 15 amps, I don't know if the newer plastic ones can handle the 15 amps. If it has a 15 amp fuse in the fuse box it will.

But the weak point is always going to be the the actual 12 volt plug on the item. The cheap ones are known to melt at around 12 amps. Heavy duty plugs will do the actual 15 amps continuous. They are made of heavy plastic that can handle the high temperatures.
Thanks for the detail! I had done the math and then started second guessing the included cigarette lighter plug pictured in the advertisements. Using http://circuitwizard.bluesea.com/ helped with what would be needed with the recommended wire being AWG 12. If I need to wire the truck for it I might just up size to the 300 watt model to have more available. Laptop would need 150 watts to charge alone and I may want to run a camera battery charger (x2) too. Cheers
 

rayra

Expedition Leader
Another consideration is to upgrade the outlet and its wiring, adding dedicated and beefier wiring for it, off a new fuse. But there aren't a lot of things that need a larger inverter, which ought to have its own dedicated wiring anyway. A better method might be have a small inverter for the receptacle and a heavier duty one for bigger loads, separately wired. Then you can 'right-size' which inverter you are using, less loss that way. And 'two is one, one is none', if you are relying on an inverter.
 

icedragonmx

Adventurer
Another consideration is to upgrade the outlet and its wiring, adding dedicated and beefier wiring for it, off a new fuse. But there aren't a lot of things that need a larger inverter, which ought to have its own dedicated wiring anyway. A better method might be have a small inverter for the receptacle and a heavier duty one for bigger loads, separately wired. Then you can 'right-size' which inverter you are using, less loss that way. And 'two is one, one is none', if you are relying on an inverter.
Thanks, that's a good idea with upgrading the original dash plug for a smaller inverter and then (if needed) hard wire a second supply for a larger 1000W inverter for a microwave and Dewalt high speed 20v charger etc. etc.

Wonder how much loss I would see using a 1000W Go Power pure sine inverter for just a 150W constant load (2hrs max).
 
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rayra

Expedition Leader
I've got a low-budget 1000W in the back of my Sub, I run some power tools off it once in a while. Had a 300w? 150w? plug-in two outlet, Black & Decker labeled that I kept up front for re-charging a laptop and runnign some Christmas lights on the roof rack, but I managed to let the magic smoke out it a while back, I think some debris got in thru the vent slots and shorted it out. I mention them both as there was quite a bit of heat difference between the two. That's pretty much all 'loss', so I'd think it would be much better to 'right-size' inverters to your power needs, if you want or need to cut it that close on power usage. But I'm not going to chase the math on it much. I'm not boondocking for a week+ or living in my car.
And once I get my rooftop solar panel integration finished (feeding my Aux power steup), I really won't care to figure it out.

 

TriBeard

New member
I'm not sure what you're looking to power exactly, but I've had both the 1000w and 2000w under the driver seat of my ram 2500 (not at the same time). The 1000w (or 1500w) would be a great fit. The 2000w is tight, but it fits. I ran two 0 or 00 gauge wires (they were some bulk jumper cable that o'reily sold by the foot) from the battery through the grommet for the clutch and then under the carpet. Works very well for my laptop, power tools, even a small air compressor.
 

icedragonmx

Adventurer
I've got a low-budget 1000W in the back of my Sub, I run some power tools off it once in a while. Had a 300w? 150w? plug-in two outlet, Black & Decker labeled that I kept up front for re-charging a laptop and runnign some Christmas lights on the roof rack, but I managed to let the magic smoke out it a while back, I think some debris got in thru the vent slots and shorted it out. I mention them both as there was quite a bit of heat difference between the two. That's pretty much all 'loss', so I'd think it would be much better to 'right-size' inverters to your power needs, if you want or need to cut it that close on power usage. But I'm not going to chase the math on it much. I'm not boondocking for a week+ or living in my car.
And once I get my rooftop solar panel integration finished (feeding my Aux power steup), I really won't care to figure it out.

That's a great idea for a removable system that is enclosed. Do you need to have the lid up during use for the heat build up? A system like this would be great for me with a winch power cable disconnect so I only have to have the system in the truck when needed. This would be a next level build with the microwave and a spare 100Ah battle born battery.

My current off grid living is normally limited to 2 weeks at a time so for now I just wanted something small that could power the camera batteries and laptop (150w) and small items like a electric razor etc. The largest battery I can fit is a Odyssey PC2150ST for maybe 50Ah usable. No solar, just the recharge from driving around.
 

rayra

Expedition Leader
well I put a 40mm computer fan on the front face of the box amid the other set of power ports (there's 12VDC cig, 5VDC USB and 12VDC APP connections on both the front and rear faces of the box). When I turn the rotary switch to provide power to the inverter, the fan comes on. The inverter draws air in the exposed face and vents warmed air into the box. I usually just leave the box open anyway, as a reminder to myself to cut the power supply when I'm done.
I'll also soon have a solar charge controller mounted to the lid of the box. And am still considering stuffing (4) 10AH wheelchair batteries in the box as well, to further increase my 'House' power. But that will take some fancier wiring to isolate / protect things. I'm trying to do too many things with the same setup.
And when I add the solar controller I'll have a smaller APP connector coming thru the cargo area bulkhead, just like the big connector, connecting the roof-mount panel location. And I'm also setting up that folding panel so it can still be used as a ground location, with a longer wirign setup. And then I might alter one of the 12VDC cig sockets to teh controller. Or maybe just leave things as is and 'backfeed' the setup. Not really sure yet.

My original design intent is to run another 1/0 cable extension back out of that box, thru a bulkhead coupling and back under the vehicle to a plug set in the rear bumper, akin to my relocation of the trailer plug / harness. And likewise a 1/0 extension from the under-hood Aux to the front grill / future brush guard. Then I can plug a hitch-/carrier-mounted winch in at either the frotn of rear of the vehicle. And when not in use the front and rear APPs can be switched off. Be dead for fording or vandals. That's the original purpose for the big rotary cutoff inside the box, to cut off power to the rear winch plug. And/but I hung the inverter off the same supply stud, so the cutoff does double duty. And since I was running the heavy cable to the back for a winch anyway, it was easy to decide to add all the other options too. The main cable run is already there.

Maybe I forego the cabling back out of the box and under the vehicle and just mount another big coupling on the same face as the inverter. With the LIftgate like it is, it would be easy just to put a long enough lead on the winch itself and plug the cable in and shut the hatch on it (maybe). I'm going to rearrange the stuff on that faceplate anyway, for other reasons. I could put the large APP connector at the bottom, so it's a straighter shot out under the Liftgate seal, instead of an S-bend just to get out.
 

Bikersmurf

Expedition Leader
For laptops I'd recommend a power supply that runs directly off the cigarette lighter without an inverter. I picked up one for my HP laptop for about $35 with no losses from the inverter.

I have a 300w sine wave inverter that I run off the cigarette lighter. I don't run anything heavy off it though.

In my other vehicle I've got a larger inverter that is very close to the batteries. I then have a power bar to get power where I need it. I'd recommend having the inverter as close as possible and also using heavy gauge wiring to it.
 

pluton

Adventurer
+1 to running a dedicated line--mine's 12Gauge red black zip--from the battery to a dedicated cig socket somewhere in the car. I put mine in the center console storage thing. Fuse near the battery end.
Most cig sockets are fused either 10A or (rarely) 15A. Every 12 watts at 12Volts is 1 amp. Therefore, 96 watts is 8 amps. From a 10A fused socket, looks like a 150W inverter is probably the limit. Of course, you could run anything from a 150W to a 2000W inverter, as long as you didn't draw enough amps from the cig socket to blow the 10A(or maybe 15A) cig socket fuse.
 

Nd4SpdSe

Adventurer, eh?
I want to say 400w. I had a 400 that had the cigarette adapter, but my 800w was made to go directly to the battery, or I want to say that it did both, and said in the manual to go directly to the battery if above 400 draw.
 

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icedragonmx

Adventurer
For laptops I'd recommend a power supply that runs directly off the cigarette lighter without an inverter. I picked up one for my HP laptop for about $35 with no losses from the inverter.

I have a 300w sine wave inverter that I run off the cigarette lighter. I don't run anything heavy off it though.

In my other vehicle I've got a larger inverter that is very close to the batteries. I then have a power bar to get power where I need it. I'd recommend having the inverter as close as possible and also using heavy gauge wiring to it.
This might be a more efficient option if I can't get the inverter to do everything. Saves the loss from 12v to 115v back to 14v. I was more interested in keeping power available for all the smaller items listed but may be better to individualize them.

Thanks to everyone for sharing their systems and hints! Cheers. I will update as I get things working!

Edit - have the unit now and it works without any changes to the factory Xterra system. The socket cluster is on a 20amp fuse and the Go Power 150 watt unit was running cool even with a laptop charger and camera battery charger both running at the same time. Looks like I am good to go without upgrading the fuse and/or the wires. The Go Power unit looks to be top quality!
 
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