[Matt Gibson]

I'm building a new control box for my van mount, the other one is all cracked and broken, been like that since i bought the machine 4 years ago, so gonna get a new electrical box and swap over all the switches, dials, gauges. I want to put a digital voltage meter in the new box, and there are loads on eBay, but I'm having trouble getting my head around the wiring. Some are 2 wire, which obviously means they will stay on all the time, which i don't want.

Others are 3/4 wire, which i don't really understand. 2 wires for the battery, then the other 1 or 2 wires are for "measuring" Do these go to an ignition source, to turn the display on and off? Do they go anywhere?

I would like it to come on when i turn the key, and go off when i turn the machine off, just like my hour meter.

Any thoughts please?

[chris scott]

Use a 2 wire as normal but route the "+" via your ignition key.Breaks the circuit when you turn the key off.

[Ashley Brothwood]

The only problem with wiring it to the ignition is if it crosses over to another circuit joined to the key.

The easiest option i would say is to get the two way and put a toggle switch at some point along the positive wire. You can pick these up for around £2 from maplins or you can get ip65 switch built into a housing so you can switch it on and off when ever you need it with the added Benifit of the housing being waterproof

[Matt Gibson]

Cheers for the info guys but i think ive worked it out. red goes to power, to power the unit on and off. black goes to earth for the unit and earth for the reading, and green goes to the batter for reading.

ive ordered one anyway, so itll either work, or ill wire it wrong and it will blow up..

[BDCS]

It'll come with a wiring diagram specifically to help you wire it up - maybe best to wait til it arrives before you worry too much.

[Matt Gibson]

Carl, how many amps should a switch for my boiler be rated at?

Like i said, im replacing the control panel, and want to replace the boiler on/off switch.. its one of those grey ip55 type switches with a rubber cover.. what amp rating would i need?

[chris scott]

5 amp will be plenty

[Matt Gibson]

Really? The minimum is 10amp, i was going to go for a 20 just in case.. can you damage anything by having a switch rated too high?

Sorry, electricals arent my forte.

[BDCS]

You run your boiler off a 1000 watt generator which will only give about 3 amps - you won't do any harm with a bigger switch other than to your wallet 

[chris scott]

http://www.supercircuits.com/resources/tools/volts-watts-amps-converter

[Matt Gibson]

http://www.supercircuits.com/resources/tools/volts-watts-amps-converter

Thanks Chris, but means nothing.. I have no idea how much power my built in genny on my machine is producing, probably has a sticker on it but ive never looked. Not good with all the amps boll0cks.. but thank you both for clarifying it.. i feel much better about not blowing myself, and my machine up now..

Now all i need to do is get a little LED, so i know when the boiler is switched on.. i like lights.. come on, who doesnt.

[chris scott]

http://www.maplin.co.uk/c/components/leds-and-displays#
http://www.maplin.co.uk/p/hylec-apl-emergency-startstop-control-station-yellowblack-version-n30qq

[Matt Gibson]

That switch is a monstrosity..Plus, my machine starts with a key... Im going for the lowkey, clean lines, subtle.. I dont 

[Matt Gibson]

http://www.ebay.co.uk/itm/LED-Chrome-Dash-Indicator-Warning-Light-12v-RED-/121052502160?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1c2f4a9890

[Matt Gibson]

While i'm on the subject, i need a battery isolator switch, cause ive gone through several batteries and cat trace the problem, my service guy thinks because the main positive cable straight from the battery is running so close to the frame, its leaking charge over long periods. He recommended a isolator switch.

What amp should i be looking at for one of these? just want one of the smallish red key ones so i can put it out of the way.

will 100 continuous be suitable?

[BDCS]

This http://www.ebay.co.uk/itm/Battery-Isolator-Cut-Off-Power-Kill-Switch-100A-12v-2-Keys-Waterproof-Cover-/360601089017?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item53f57ff3f9

or

http://www.ebay.co.uk/itm/Battery-Disconnect-Switch-Isolator-Cut-Off-Switch-/360417021066?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item53ea874c8a

either will do the job

[Matt Gibson]

Cheers mate

[chris scott]

A word of warning about the key type isolators. Buy the best available my experience of these is the cheap one "melt". Especially if the stater is lazy or the battery not fully charged. The load on them doubles and they self destruct, Buy Durite or  Lucas .

http://www.durite.co.uk/pdf/2012/3/03.10_Switches-Battery_isolators.pdf

http://www.lucaselectrical.co.uk/files/category/192221844926092012165344_LucasSwitchgear2008.pdf

[BDCS]

He's starting a pressure washer not an Austin Champ

[chris scott]