Wiring question

[castaway]

My auto pilot (old Pinta) doesnt have an on/off switch in the wheel house. Which means that I have to dash below to flick the switch on the main unit.

I'm in the process of instaling a switch up topsides, but an aware of the problems /disadvantages in increasing the length of the cable run, especially to equipment like this which is a bit senstitive to voltage. ie if the volts drops, the unit shuts down until the engine is on again and pumps up the battery.

Can some expert tell me if by adding approx. 2mtr of 27amp cable and a switch, I will effect the performance at all?

Thanks Nick

<A target="_blank" HREF=http://www.yachtsite.co.uk/fairweather>http://www.yachtsite.co.uk/fairweather</A>

 

[Dean]

Check out the ANCOR wire web site it gives a formula to work out voltage drop wire size etc. I think!

Dean

 

[castaway]

Thanks Dean.. Quite a handy site except that the answer is given in AWG which I assume is American Wire Gauge and they dont have that in Halfords !! You dont happen to know how that relates to UK type wire size do you?

(I am definately putting a book about 12v boat electrics on my Xmas list) Its quite interesting, and as my boat has been nicely rewired fairly recently I dont want to mess things up.

Regds Nick

<A target="_blank" HREF=http://www.yachtsite.co.uk/fairweather>http://www.yachtsite.co.uk/fairweather</A>

 

[Joe_Cole]

Don't know if it helps but the table I've got shows a 18millivolt drop per metre on 30amp cable. On that basis a 2 metre run is unlikely to be critical

Joe

 

[VMALLOWS]

No it won't in the slightest. Assuming the boat you're talking about is the one in your profile. Your autopilot won't be taking any more than about 4amp max. You can wire an on/off switch in the main feed and I find this perfectly OK, but if you're not happy it might be easier (cheaper?) to wire a simple relay to the existing circuit. Simple one pole 12v relays ( rated at 25 amp) are about £5 at care accessory shops and are easy to mount. You'll only need a thin control circuit though make sure its correctly fused. Ask if you need more info.

Your problem with the pilot dropping out when starting the engine seems to be more related to the voltage simply dropping when the engine cranks. Would be better to switch it to another battery whilst starting.

 

[castaway]

Thanks for this (and all the other replies). Over the summer I was hearing nothing by warnings about voltage drop over long runs of cable, and as my old Pinta is a bit fickle anyway, I didn't want to introduce any further problems.

Regds Nick /forums/images/icons/smile.gif

 

[tome]

AWG2Halfords Converison

Try <A target="_blank" HREF=http://www.tnt-audio.com/clinica/awg_e.html>http://www.tnt-audio.com/clinica/awg_e.html</A> for converting AWG to sq mm (Halfords)