A question for the electrically minded

Message

Syltiz · #1 Post by **Syltiz** » Sun Jan 13, 2008 5:05 pm

Im useless with eletrical stuff. I want to put a 12v socket under the seat of my bike as most of my bike trips are camping trips and this would be massively convenient.

Can anyone tell me please what ampage wires and inline fuse I should have?

Thanks

D-Rider · #2 Post by **D-Rider** » Sun Jan 13, 2008 5:17 pm

Well it really depends on the current that you will draw from it with whatever you plan to run from it.
General rule of thumb is to use a fuse rated at twice the current of the maximum load you will be running. Go for a slow blow fuse if you will run anything with a large inrush current.

Wires again will depend on what you plan to run off of it - but thicker is better from an electrical point of view - balanced out by the fact that thicker is harder to install. So, as I say, depends on what you will be running.

Syltiz · #3 Post by **Syltiz** » Sun Jan 13, 2008 6:06 pm

The items i have in mind are mobile phone charger and a mini 12v compressor (air beds, flat tyres, blow up dolls etc

)

Fausto · #4 Post by **Fausto** » Sun Jan 13, 2008 6:11 pm

And you'll still be expecting the bike to start in the morning ?

It really doesn't take long to inflate an airbed with lungpower alone....

Samray · #5 Post by **Samray** » Sun Jan 13, 2008 6:26 pm

Fausto wrote:And you'll still be expecting the bike to start in the morning ?

It really doesn't take long to inflate an airbed with lungpower alone....

The doll could go pillion and be inflated as he travels.

Aladinsaneuk · #6 Post by **Aladinsaneuk** » Sun Jan 13, 2008 9:48 pm

insert gratutious comment about blow jobs here.....

Samray · #7 Post by **Samray** » Sun Jan 13, 2008 10:04 pm

Aladinsaneuk wrote:insert gratutious comment about blow jobs here.....

It was the word 'ride' I had trouble avoiding.

D-Rider · #8 Post by **D-Rider** » Sun Jan 13, 2008 10:32 pm

So swiftly passing over the many uses of the compressor (other than noting that it could also be useful to assist in roadside puncture repairs ..... to the tyres - not the doll! .... well, I suppose to either - but I meant the tyres .... and why does Sam refer to the inflatable as "he" .... whatever ....)

Do you have any info about the compressor - such as the operating current. (BTW as it will be powered by a DC motor, it will have a large start up current)

Pierre · #9 Post by **Pierre** » Mon Jan 14, 2008 12:10 pm

http://www.maplin.co.uk/Module.aspx?Mod ... 4&doy=14m1

http://www.maplin.co.uk/Module.aspx?Mod ... e&doy=14m1

and a 3amp fuse. Comes to about £4

I didnt use the inline fuse , I just cut the plug end off , wired it into the fuse block in the fairing and mounted it on the fairing bracket. Little cap keeps it watertight when i remove my satnav.

Syltiz · #10 Post by **Syltiz** » Mon Jan 14, 2008 1:47 pm

Thanks Pierre... thats basically the kit I have, although im mounting mine under the pillion seat (its closer to the doll that way)

D-Rider... so do I understand correctly that the wires/fuse need to match the amount of current the compressor will be pulling off the battery? And by "large start up current" you mean it would draw lets say 8amps on startup and then 3 thereafter?

I will check the compressor tonight... its just a small portable job, but lets say it pulls 3amps to run (ignoring the start up current for now).. then my wires and fuse should be minimum 3 amps?

D-Rider · #11 Post by **D-Rider** » Mon Jan 14, 2008 2:23 pm

Yeah, the kit that Pierre shows should do for most things. TBH I have a similar arrangement on mine but with a bit more circuitry that ensures that it doesn't stay on by mistake and needs to be deliberately activated after each time you turn the ignition on.

Just find out the normal operating current for the compressor you are planning to use to see if the standard 3A fuse will be OK. If it is not enough you can almost certainly fit a bigger fuse - I expect the wiring is fine for quite a bit more if necessary. Don't worry about the startup current too much - the fuse will not be a quick-blow (none of your previous comments Pete

) and will have some overhead compared to the operating current.