Multi meters

You can do most electrical jobs on a boat (or a car) using just a car sidelight bulb with two lengths of wire soldered onto the terminals and minature crock clips at each end.

But it's not as much fun as plugging your laptop into the OBD2 connector!
 
The UT 203 clamp multimeters sold on ebay for c£20 can measure both AC & DC current as well as AC & DC voltages etc. (DC current clamp function particularly useful for checking alternator output without disconnecting wiring.) Not got one yet but seems like good value
 
Thanks for all your advice,it's all so damn complicated I think I'll go down the 12v battery route & a bit of wire for now.At least that's something that I can understand!
(The masts been in a rack 2/300 yrds from the boat for years so I think it might be wise to take out each individual bulb & test it.That way I can clean the connections & hopefully avoid going up the mast :eek: )
 
If this is a new (to you) boat and you don't know the history of the lamps then good plan, as well as cleaning the contacts and checking/cleaning the connectors, is to replace all the bulbs that are out of reach (yep costly unfortunately). Saves you having to do it at an inconvenient time.
 
I know nothing about multimeter's & have never owned a boat with a diesel engine in it before so is this a crucial bit of testing kit?

No, it's not crucial (whatever type of engine you have got). But a cheap multimeter is a very good diagnostic tool for general electric work on the boat. Mine probably cost about a fiver and I use it maybe half a dozen times a year to check bits and pieces (bulbs, fuses, batteries, switches, wires etc).
At that sort of price it seems silly not to have one.
 
+1 for a test bulb.

If you buy a cheapo multimeter then dont keep it on the boat. There was a fairly poor analogue meter on my boat when I got her and I replaced it with a cheap digital meter but that lasted only just over a year, its replacement has just died about a year later, I have now rescued the original analogue from the depths of a locker and it still works fine so I am sticking with that and a test bulb.
 
I know nothing about multimeter's & have never owned a boat with a diesel engine in it before so is this a crucial bit of testing kit?

Not crucial, but incredibly useful. You can check amps flowing at a variety of places... Check voltage ditto, continuity, and so on.

When something electrical doesn't work, most of the advice here will involve doing some tests of voltage and/or continuity.
 
Buy a cheap one - but also buy some cables with large clamps that can easily connect to battery terminals and alternator studs. Decent cables will cost you twice the price of the multimeter!!!!
 
OK people this is getting exciting (thanks for the mention of youtube & how to operate the things by the way.I don't know why I did'nt think of that).
I have homed in on two contenders.One has the virtue of being dirt cheap & delivery should be swift,having as it does a UK supplier.The other that is from Hong Kong is a nice grey & yellow colour with a particularly pleasing simple looking design it seems to me.It has the added features as far as I can see of being able to do a continuity test with the buzzer feature & being the new wonderful clamp type it would appear that I can go round looking for live wires.How can anyone resist a feature like that?
What does the panel think?

http://www.ebay.co.uk/itm/270948386151?_trksid=p5197.c0.m619

http://www.ebay.co.uk/itm/AC-DC-Dig...&otn=5&po=LVI&ps=63&clkid=8149934695405821576
 
For a boat you would ideally need both - as they are designed for different jobs. The pretty grey and yellow one is mainly an amp meter. Its voltage range is 600 volts with an accuracy of only 1% - no use on a 12 volt boat where the difference between a fully charged battery and one that needs charging is only 0.6 volts. We have the other one - with expensive cables from RS components with big clamps. This one has the continuity buzzer.
 
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Your option No 2 won't measure DC current flow (which is what you've got on a boat) and is maybe less accurate than option 1. I've had (similar to) option 1 for many years and has done everything I've ever needed.
 
Go for the cheap UK one. Or since you are in the Solent area why not go to Maplins (Portsmouth or Southampton) and get one of their cheapos? There's even a cheap analogue one so you are not dependant on batteries!

Why is it that you find you have left the thing switched on and drained the battery when you urgently need the darn thing? My expensive digital has auto switch off but I won't leave it on the boat.
 
Your option No 2 won't measure DC current flow (which is what you've got on a boat) and is maybe less accurate than option 1. I've had (similar to) option 1 for many years and has done everything I've ever needed.

I discovered this to my peril when I bought a cheap clamp ammeter multimeter from Maplins - they don't read DC Amps. Luckily, Maplins refunded without question.

£30 is about the cheapest I can find for a clamp multimeter that reads DC Amps. The UNI-T 203 or 204 .
 
Cheap is fine if you know the limitations

I have several cheap digital multimeters (~£5) and find them very useful for DIY fixing of boat electrics, where most of the time I only need to test either continuity or voltage. I've never needed to measure DC current. However, I did throw away what was probably a perfectly good battery because my multimeter said it would only charge to 12.05v, then discovered later that the multimmeter's calibration had drifted. The cheap ones have a crude variable resistor inside for calibration, and the calibration also drifts when their batteries get low. As a stable calibrated meter is so expensive, I can live with this shortcoming. The other weakness I found was that the probes are liable to become detatched from the wires. You can still use them, but it's more fiddly.

I'd say you can do 95% of what you need with a cheap multimeter, but if losing the extra 5% bothers you, you need to spend a lot more money.
 
I have DC clamp ammeter.
It's useful for getting the big picture of starting problems, charging etc, but not very accurate at small currents of a few amps.
Useful tool but you may need a conventional ammeter as well.
 
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