PDA

View Full Version : Question about an inverter for my truck


OHOD
12-06-2011, 10:32 AM
I have a Dodge Ram 1500.
There is a power outlet next to the cigarette lighter that is used for accessories. Next to the outlet, it's marked "20 amp"

My question is this.
Does this mean that my truck can provide up to 12V DC at 20 Amps?
If I buy an inverter, would I get 120 AC and can operate a Skill Saw with it?

:shrug:

What would my maximum AC output be? 1 amp?

paul0660
12-06-2011, 10:38 AM
The Muppet skilsaw, yes. it can be inverted to 120V, enough for a laptop, maybe, not a motor.

ElvenSoul
12-06-2011, 10:41 AM
If you want to run tools of your vehicle; get air tools. Install a belt driven air compressor.

TrailerparkTrash
12-06-2011, 11:14 AM
Can you run a skilsaw? It all depends on the power limit of the inverter you want to buy. The bigger the inverter, the better. However, they also cost more money.

paul0660
12-06-2011, 11:18 AM
Can you run a skilsaw? It all depends on the power limit of the inverter you want to buy. The bigger the inverter, the better. However, they also cost more money.

12 volts.....(lets call it 13.5 with the engine on) at 20 amps is 270 watts.

A skilsaw is 6.5 amps at 110 vac minimum.............715 watts.

Not close.

There are way to do it, but the plug isn't it.

mej16489
12-06-2011, 11:28 AM
I have a Dodge Ram 1500.
There is a power outlet next to the cigarette lighter that is used for accessories. Next to the outlet, it's marked "20 amp"

My question is this.
Does this mean that my truck can provide up to 12V DC at 20 Amps?
If I buy an inverter, would I get 120 AC and can operate a Skill Saw with it?

:shrug:

What would my maximum AC output be? 1 amp?

Yes, that label indicates that you can draw a maximum current of 20Amps at 12vDC. Draw more then the rating and you will at a minimum pop the fuse - middle ground melt wire - worst case torch your truck.

Ultimately the AC output will be determined by the rating of the inverter. With inverter losses in the mix and a quality inverter, about the best you will be able to get is about 1.5 Amps at 120vAC. However, keep in mind that pretty much anything with a motor (i.e. skill saw) generally has a much higher surge current then their operating current.

problemchild
12-06-2011, 11:49 AM
Two things you can do.

Clamp inverter on to battery or run a special marine quick plug onto battery for easy connections.

Dont use the aux socket all youll do is blow fuses.

I put a 2k inverter in my truck and in my prius. A marine supply shop will have the 120 amp fuses and marine connectors if you want it done right.

http://priuschat.com/forums/attachments/gen-ii-prius-modifications/9182d1210906867-110v-outlets-in-your-prius-img_0944.jpg

Nothing like fresh brewed coffee on your trips.
http://priuschat.com/forums/attachments/gen-ii-prius-modifications/9183d1210906867-110v-outlets-in-your-prius-img_0947.jpg

http://priuschat.com/forums/attachments/gen-ii-prius-modifications/9185d1210906913-110v-outlets-in-your-prius-img_0954.jpg

GMG
12-06-2011, 11:51 AM
My son has an inverter on his work truck for the different power tools he needs for his job. There is not always electrical at his job sites.

I don't know what size inverter he has, but can find out if someone wants to know. I do know he doesn't run it off the power outlet on the dash.

TrailerparkTrash
12-06-2011, 12:16 PM
12 volts.....(lets call it 13.5 with the engine on) at 20 amps is 270 watts.

A skilsaw is 6.5 amps at 110 vac minimum.............715 watts.

Not close.

There are way to do it, but the plug isn't it.
Hey Paul, the OP is talking about plugging in an "inverter" to that 20amp DC Plug on the truck. With an inverter (DC to AC), he can run a an "AC" power tool of his choice. Again... It depends on the size (amperage output) of that inverter.

Simple. Next question?

cranemech
12-06-2011, 12:27 PM
I have a 1500 watt inverter wired into my service truck with 6 gauge wiring direct to the battery.

Don't use the plug for a load that large.

A skillsaw can draw 12-13 amps AC easily.

TrailerparkTrash
12-06-2011, 12:32 PM
I have a 1500 watt inverter wired into my service truck with 6 gauge wiring direct to the battery.

Don't use the plug for a load that large.

A skillsaw can draw 12-13 amps AC easily.

Yup, it all depends on the size of one's equipment (amperage draw of the AC driven tool) one desires to use with the vehicle's wiring system and the size (output capability) of the inverter. One must do their homework to figure out how they want to go about it.

paul0660
12-06-2011, 12:38 PM
Hey Paul, the OP is talking about plugging in an "inverter" to that 20amp DC Plug on the truck. With an inverter (DC to AC), he can run a an "AC" power tool of his choice. Again... It depends on the size (amperage output) of that inverter.

Simple. Next question?

Works for me, but it will melt everything between the truck battery and the 12v outlet even if you put a penny in the fuse socket. (old time reference there).

It's really simple if you are ignorant.

He's a she btw...........but does all right.

wash
12-06-2011, 1:38 PM
If you want to do a lot of stuff like this, there is probably a kit out there for adding a second alternator and independent battery.

They will usually use a big ~200 amp GM single wire alternator which makes hook up simpler.

That's about 2,800 watts of power which should be good enough for most light duty power tools.

Since it's an entirely independent system, you can still drive home if you fry something.

They can also be used as an emergency arc-welder or plasma cutter if you want to add more stuff. Lots of off road drivers get a setup like that.

I think an independent system is really nice because the place you are going has no power, it might not have telephones or cell phone signal so the last thing you want is to get stuck.

The down side, with an extra alternator, battery, inverter and wiring, your truck probably will gain 80 lbs.

TrailerparkTrash
12-06-2011, 5:26 PM
Works for me, but it will melt everything between the truck battery and the 12v outlet even if you put a penny in the fuse socket. (old time reference there).

It's really simple if you are ignorant.

He's a she btw...........but does all right.
Penny in a fuse socket??? Are you speaking from experience? It's just not clicking for you apparently. You didn't don't understand any of my explainations evidently so it makes sense what you're saying. Probably wise to take your own advice and just not mess with a vehicle's wiring system and an inverter. You wouldn't want to melt your truck...... again. :cool:

By the way, I guess I should take out my inverter in my truck and not run a circular saw or drill off of it anymore either. Dang, I've been using that off and on now for about 3 years. What have I been doing wrong????

TheChief
12-07-2011, 4:48 AM
Hello OHOD,

I was also looking recently to add a larger inverter to my truck and here is what I found:

-The largest inverter I could find for a cigarette lighter port was 400watts, which is about 3.3amps (watts/120=amps). This does not take into account the the rating of the circuit, just what is available with a cigarette lighter type adapter

-If I wanted more than 400watts, I would have to go with a wired connection direct to the battery. Going this route opens the door to some pretty big inverters out there like this 2000watt monster:
http://www.amazon.com/Whistler-Pro-2000W-Watt-Power-Inverter/dp/B003R7M6CS/ref=sr_1_1?ie=UTF8&qid=1323265359&sr=8-1

It looks like a skillsaw is beyond the range of a cigarette lighter based inverters though. You should be able to look up the power specs for it online and make your decision there.

One thing to note, there are alot of cr@ppy inverters out there so do your research before pulling the trigger and read the reviews.

TimRB
12-07-2011, 7:12 AM
Paul's analysis in post number 5 is correct. He even used a "best you can possibly hope for" set of conditions. As has been pointed out, a Skilsaw can actually use much more current, and also the inverters are not 100 percent efficient. You will always get less power out of an inverter than you put in.

Tim

Sub95
12-07-2011, 8:44 AM
I have a older cobra 2500 running - spike 5000 watt inverter in my trailer it has 4, 2 gauge wires ran to it, i can run anything i need off of it.

for a skill saw you would need atleast a 2000 running watt inveter and would have to be hooked to the battery and truck running while using it if you only have 1 battery.

by the time you pay for everything you need to put one in, for a little more money you could get a used small honda 2k generator.

GrizzlyGuy
12-07-2011, 10:02 AM
What would my maximum AC output be? 1 amp?

The answer is PIE. No really, it is PIE!

P = I * E

P is power in Watts, I is current in amps, and E is voltage in volts (engineers use E instead of V because voltage is the Electric potential difference). Anyhoo...

Assuming the inverter is perfect with no conversion losses (it isn't, see what Tim said), assuming you can really get 20A in at 12V, and assuming no other losses in your system (another invalid but simplifying assumption), then Power In = Power Out.

As Paul showed above, the power in is 12V * 20A = 240W. Or if your input voltage is really 13.6V, then the power is 272W.

Over on the output side at 120V AC instead of 12V DC, the power would also be 240W. To determine the current, go back to PIE and solve for I: I = P/E = 240W/120V = 2A.

But again, the system isn't perfect and an inverter's efficiency can be as low as 50% for a crappy one or as high as 95% for a good one. If you have a typical one at around 80%, and we neglect wiring and other losses (safe to do if you use large and short wires on the 12V side... you are realistically looking to get out about .8 * 2W = 1.6A for 12V in, or 1.8A for 13.6V in.

I know I just gave you a ridiculously long answer for a simple question, but now you know how to do the analysis yourself the next time around. :)

TrailerparkTrash
12-08-2011, 3:10 AM
Paul's analysis in post number 5 is correct. He even used a "best you can possibly hope for" set of conditions. As has been pointed out, a Skilsaw can actually use much more current, and also the inverters are not 100 percent efficient. You will always get less power out of an inverter than you put in.

Tim

If in post #5 you're talking about using the DC "plug" to hook up an inverter to, then yes, I agree it's not gonna work. Perhaps that's where the confusion is between Paul and me. However, I'm trying to explain that inverters can be simply connected to the vehicle's DC electric system (battery) and an inverter can not only run a skilsaw, but a big enough inverter can run a microwave oven, or a large coffee pot! Lots of things can and DO run off of inverters connected to a vehicle's 12 v DC system.......

Dutch3
12-08-2011, 4:06 AM
I think the startup surge is the limiting factor. I have a 750W inverter connected to a battery with AWG 6 cables. It has 40A fuses on the input side. Granted, it is a cheap inverter and probably not very efficient.

I have attempted to run a circular saw on the inverter, and it instantly blew the input fuses. Plugging in a small refrigerator produced the same result.

RickD427
12-08-2011, 12:42 PM
Don't forget about the battery.

There's a lot of good guidance in the above postings about the size and connection of the inverter. For your application, you're probably going to need a direct battery connection with heavy wire.

Inverters are used extensively in marine applications. Marine engineers learned long ago to have separate batteries for engine starting and for everything else. The inverter only draws current from the "everything else" battery bank.

It would be very uncool to find that you could not start your truck after using the Skilsaw.

I'd recommend a second battery with a cut-out switch to perform the same function in your truck.

In the long run, a good 2kw gas generator may be a better option. I have very good experience with the Honda.

Flyin Brian
12-08-2011, 12:57 PM
Hey Paul, the OP is talking about plugging in an "inverter" to that 20amp DC Plug on the truck. With an inverter (DC to AC), he can run a an "AC" power tool of his choice. Again... It depends on the size (amperage output) of that inverter.

Simple. Next question?

So in your first "explaination" you are saying it's ok to plug an inverter large enough to run a Skil-Saw into a 20AMP DC plug...

If in post #5 you're talking about using the DC "plug" to hook up an inverter to, then yes, I agree it's not gonna work.

but in your second "explaination" you say it's not gonna work. Which is it?

TrailerparkTrash
12-08-2011, 3:02 PM
So in your first "explaination" you are saying it's ok to plug an inverter large enough to run a Skil-Saw into a 20AMP DC plug...



but in your second "explaination" you say it's not gonna work. Which is it?
It all depends on the amperage draw of his skil saw Flyin brian. How big of a skilsaw does he have? Its very possible to run an inverter from his plug IF the saw has a smaller electric motor that does not pull a higher number of amps.

Again, the OP's question is a little vague and so are any answers to the question. There are muti variables here that are not fully explained. (ie amperage draw of the saw, coupled with wattage output of the inverter he has). Bottom line in a nut shell..... Yes an inverter can be connected to a 20amp DC recepticle. Home Depot sells little tiny inverters. Skil makes small power tools too that can run with smaller motors that is very well possible to run on a capable inverter out of the DC plug. Try plugging in a big Sawzall with a motor that pulls 15 amps from an AC outlet and an inverter connected to the DC "plug" and it probably wont run in that case.

This analogy of simply asking "will my cigarette lighter plug run my saw" is almost akin to trying to get a medical diagnosis off of webMD, without personally visiting a physician. Trying give a definitive answer to an electrical power question as originally presented, is going to net a similar unclear or definitive answer on the subject in my opinion.