What size fuse???

Post by **rocket** » April 16th, 2007, 10:39 pm

I installed a ciggarette lighter plug on my boat this evening so I can run my gps off 12v. I used a 20 amp fuse, but Don't know if this the correct size. I'm afraid this might be too big.
Anybody know the correct amp fuse for this application?

Post by **mjsigns** » April 16th, 2007, 10:44 pm

10 amp would be my guesstimate.

Post by **MudDucker** » April 16th, 2007, 10:56 pm

Most gps's have a fuse already in their cigarette lighter plug. If you can screw the tip of the plug off, you can see if there is a fuse. If so, it don't matter what size you use for the plug in as long as it is at least as big as the one in your gps plug.

leonreno · Post by **leonreno** » April 16th, 2007, 10:57 pm

If you were only going to use it for the GPS then the best way to determine the right fuse would be to look at the power requirements on the label for the device, it should list DC amps. Ad a little to this figure and you are good. But, if you might use it for other things I would say 10 amp is about right, but most 12volt adapters probably come with a fuse I would think. The GPS probably does not draw that many amps though. My Garmin GPSMap 172c only draws 2.0 amps.

Post by **tin can** » April 17th, 2007, 5:32 am

Not sure about all brands of GPS, but if you have a Garmin, MudDucker is right on. There is a fuse in the plug.

Hit-n-Miss · Post by **Hit-n-Miss** » April 17th, 2007, 7:53 am

Hope you used a marine grade cig lighter or it wont last 2 months.

Post by **rocket** » April 17th, 2007, 8:05 am

Yes it's Garmin. I guess I should have checked that first

Post by **rocket** » April 17th, 2007, 8:05 am

Hit-n-Miss wrote:Hope you used a marine grade cig lighter or it wont last 2 months.

It's marine grade

Thanks for everyones help

Post by **Barhopr** » April 17th, 2007, 8:15 am

I know my 376C only has a .5A fuse.

Post by **rocket** » April 17th, 2007, 12:54 pm

Barhopr wrote:I know my 376C only has a .5A fuse.

Trade ya for my 176C

Post by **Barhopr** » April 17th, 2007, 12:58 pm

rocket wrote:
Barhopr wrote:I know my 376C only has a .5A fuse.
Trade ya for my 176C

You know I would, but I've already drilled holes in the boat for it.

Post by **mjsigns** » April 17th, 2007, 1:01 pm

I've got a Garmin also... I should have checked it before responding... I've never had to replace that fuse.

Post by **rocket** » April 17th, 2007, 1:11 pm

Barhopr wrote:
rocket wrote:
Barhopr wrote:I know my 376C only has a .5A fuse.
Trade ya for my 176C
You know I would, but I've already drilled holes in the boat for it.

Minor details

grim reeler · Post by **grim reeler** » April 17th, 2007, 2:37 pm

My lowrance uses a 3 amp fuse.

leonreno · Post by **leonreno** » April 18th, 2007, 9:23 pm

Even though your GPS plug has a fuse in it you still need one at the battery for the 12 V Adapter. One, is you may not always have the GPS plugged in but you may plug in something else. But the main reason is the fuse in the GPS adapter is to protect the GPS unit, and the fuse at the battery for the 12v adapter is to protect the boat from a short between the battery and the 12v adapter. If you short the wire between the plug and the battery the fuse in the GPS plug will not do any good to protect the battery and your boat. And I would go with a 10 amp or less fuse, those wires on the plugs are usually small, so go small with the fuse. You would probably be good with a 5 amp fuse.