I like amp and voltmeters. A voltmeter will tell you you have a problem, but an ammeter will tell you in conjunction with the volt meter where the problem is while the engine is running.

Plenty of volts and charge current when running, but won't start in the morning = battery issue

Low volts + plenty of charge current = alternator issue

Low volts, no charge current = alternator issue

High volts (14v +) and plenty of charge current = alternator issue (which makes it an issue to your battery)

etc etc..

A voltmeter will tell you you have a problem, but you will already know this by the time you look at it (when the engine has started to stutter). An ammeter on its own won't tell you much either.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

A voltmeter is the safest gauge for an amateur to fit.
An Amp meter is the most dangerous gauge for an amateur to fit.

Are you any good at fitting electrical stuff?
Yes = Amp gauge.
No = Volt gauge.

How about this?

They don't work down here.

That's a good point, solder your fittings and heatshrink the terminals. A nice easy wire installation with a professional finish will cause you no problems as a rule of thumb. If it looks good, and had no tight stretches, no sharp rubbing edges and clean joints at the ends then it will work well for many years.

It is difficult to position a ammeter such that you get a meaningful value from it. Placing it in series with the alternator will only ever give you a positive current. Putting it in series with the fuses will only give you a negative measurement. You have to create a bottleneck where all the power needs to flow in or out of the battery circuit to get a useful reading. Around the solenoid is a good place to think about designing this solution. You have to think very carefully before you start soldering...

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Go an buy yourself a moke with no roof. It'll rain for 40 days and nights after that.

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One should never skimp on the zip ties.

I sold a Moke with no roof (or much else) to 1071 down past your way, so it should be raining already.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Does anyone make inductive-loop-pickup automotive ammeters?

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Simon

The adventures of an owner builder in the Tallarook Ranges

Every instrument maker in the world makes at least one inductive loop ammeter, but these are only usable on AC circuits, not DC.

The method they use when measuring large DC currents is to use a shunt. The shunt is a short piece of copper which will cause a known voltage drop for every ampere which goes through it. eg. 1mV/A which means that a 10 amp current will produce 10mVolts across it, 20A = 20mVolts etc etc. These work well, but are a little cumbersome in an engine bay. But they use a shunt in the back of the ammeter gauge to drive a voltmeter movement.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Duh, of course Haven't had my coffee this morning...

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Simon

The adventures of an owner builder in the Tallarook Ranges