What Is the Amperage Rating on My DC Outlet? - PeachParts Mercedes-Benz Forum

shertex · #1 03-24-2011, 08:43 AM

Does anyone know offhand what the amperage rating is on my DC power outlet (the cigarette lighter)? Trying to find out if I can use a particular air compressor with it. Car is a 1991 300D.

Thanks.

vstech · #2 03-24-2011, 08:46 AM

most are 10 amps, but the best way to find out is pull the fuse card and see.
keep in mind that everything on the fuse uses power, so if it's a 16A fuse, and it's got the radio, blinkers, cabin lights, etc... available power to the lighter will be reduced.

shertex · #3 03-24-2011, 08:55 AM

Quote:

Originally Posted by vstech

most are 10 amps, but the best way to find out is pull the fuse card and see.
keep in mind that everything on the fuse uses power, so if it's a 16A fuse, and it's got the radio, blinkers, cabin lights, etc... available power to the lighter will be reduced.

Looks like it's a 16A fuse....so I should be fine as long as I'm not using anything else on the circuit; compressor requires 15A.

vstech · #4 03-24-2011, 08:57 AM

if compressor requires 15 amps, I'd get a battery connected outlet, and use that... I'd not want to put THAT much load through the ignition switch...

shertex · #5 03-24-2011, 09:10 AM

Quote:

Originally Posted by vstech

if compressor requires 15 amps, I'd get a battery connected outlet, and use that... I'd not want to put THAT much load through the ignition switch...

Really? I would think that a circuit is designed with a margin of safety so that it could easily handle the specified load.

shertex · #6 03-24-2011, 09:35 AM

I checked with the manufacturer. Sounds like, at tire pressure levels, the current draw would be no more than 8A or so.

vstech · #7 03-24-2011, 10:41 AM

oh, worst it would do I'd think is pop the fuse if it pulls too much. still, for an air compressor that large, I'd use a dedicated socket directly off the battery.

JHZR2 · #8 03-24-2011, 11:27 PM

+1. There likely is a 150% overdesign in the conductors, but with age, time, corrosion, etc., everything gets to be a little worse for wear. I wouldnt want to run at the ragged edge of ratings, just because I dont want to know where the weak spot may be that turns into the fusible link before the fuse pops. Better to be safe than sorry.

Manual pumps get you some exercise too...

Codifex Maximus · #9 03-25-2011, 12:57 AM

Quote:

Originally Posted by vstech

if compressor requires 15 amps, I'd get a battery connected outlet, and use that... I'd not want to put THAT much load through the ignition switch...

+2 That is getting too close to capacity. A specially fused circuit with decent gauge wire would in order. With DC, there's just too many amps and not enough volts.

dude99 · #10 03-25-2011, 02:31 AM

you could always just replace the compressor plug with a pair of spring clamps (like a battery charger has) and clip in to the battery when you have to use it. Not the most elegant but will work. Added bonus of working on cars with broken sockets as well...

tangofox007 · #11 03-25-2011, 08:50 AM

Quote:

Originally Posted by dude99

you could always just replace the compressor plug with a pair of spring clamps (like a battery charger has) and clip in to the battery when you have to use it.

Adapters are available to do just that. No wiring modification required.

http://www.amazon.com/Roadpro-Battery-Cigarette-Lighter-Adapter/dp/B00065L2D8