Max power from cigarette lighter socket

[GPT]

I've been struggling to find out what is the safe maximum power I can get from my E36's cigarette lighter. The reason I ask is that I have an HTC Desire smartphone and when using it as a satnav or anything else power hungry it uses up more power than my current 500mA charger can supply so if my battery is already low when I get in the car it won't last the journey.

Is it possible to buy higher powered ones and what is the safe max?

Any links to chargers would be most appreciated.

Thanks.

[Eggman]

It's usually a 15A fuse for the cigar lighter - more than enough for any charger you're likely to plug into it.

[t84]

15A on my Focus.

[Grrrmachine]

Most cars are 15A, but there'll likely be other stuff running off the same loom. Admittedly trivial stuff; dashboard computer, glovebox light, maybe even a stereo if the car's old enough, but best check your wiring diagram if you can find one.

If you want more juice, the safest option is to run a new switched-and-fused wire from the battery, triggered by a relay from the ignition. But the one you've got should be able to provide enough juice for what you've mentioned.

[Eggman]

More to the point, does your HTC Desire charge using a USB socket? If so, you can get any number of 12v USB adaptors in places like Maplin, certainly ones capable of supplying 1A. I can't see your phone drawing any more than that.

[Ozzie Osmond]

12v x 15 amps = 180 watts max

A charger won't get within a million miles of that. Imagine the heat from three 60 watt lightbulbs.

[thunderbelmont]

Some cars are fused/rated at 10A.
Older cars can sometimes have 8A fuses in the fag lighter feed.

Get it wrong and it can smell nasty!!!

[hairykrishna]

When we were driving across Europe we ran 2 laptops off the fag lighters on our S class. You don't need to worry about 500mA.

[cyb]

You need a more powerful charger, but there's something about the way it's wired so the phone recognises it like the mains charger and not a PC or it will only draw 500mA. Check out info in these threads :-

http://forum.xda-developers.com/showthread.php?t=6...
http://forum.xda-developers.com/showthread.php?t=6...

[matchmaker]

Most are rated at 120w.

[GPT]

cyb said:

You need a more powerful charger, but there's something about the way it's wired so the phone recognises it like the mains charger and not a PC or it will only draw 500mA. Check out info in these threads :-

http://forum.xda-developers.com/showthread.php?t=6...
http://forum.xda-developers.com/showthread.php?t=6...

Very useful thanks.

I've ordered a Belkin one that is supposed to be wired correctly so we'll see what happens with that. Apparently the phone needs 950mA to build charge when running full pelt.

[mph1977]

as others have said the sockets will supply 10 or 15 A @12 volts - 120 or 180 watts - it is usually marked on 'none lighter' lighter socket's flip top lids as such

[thunderbelmont]

matchmaker said:

Most are rated at 120w.

120W @ 14.2v (with engine running and alternator charging) = less than 10A..... (8.45A)