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ammeter with alternator conversion


david lewis
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Your ammeter may be underrated for an alternator, which are mostly over 30A these days.

Add to that do you really want an ammeter, all unfused and so on in the dash, when a voltmeter is a more useful tool (for a alternator)

 

However, I would not swap just for the sake of it, but would if there was a reason, if you follow what I mean! so extra load on the cars electrics, or dynamo died, that sort of thing. Dynamos are still very effective...

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David might be lucky and have a shunt ammeter. I have one, it's actually a voltmeter in disguise! The shunt has a tiny resistance and sits in the battery feed. The "ammeter" measures the voltage across the shunt and has been calibrated to display the correct current. They used to be very popular but not so much these days. I also have a voltmeter. They tell you different things, the voltmeter tells you the condition of your battery, the ammeter the condition of your charging system.

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They don't call them worry gauges for nothing.... ignorance is bliss but once you have one, you can't stop watching it as you drive along... sort of a car-hypochondria! I found the voltmeter much less bother to fit than an ammeter, but as long as the ammeter is fitted with the correct and often heavy gauge of electric cable it should be ok, provided as Clive says it's sufficiently highly rated to cope with the extra power and show an accurate reading.

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I made a concious decision to just have fuel and temp gauges, to avoid that very issue. Bear in mind many moderns don't have a temp gauge, just a warning light, that is another possibility! Plus the temp gauge on moderns runs off the ecu, and most are programmed so the gauge reads central over a large range of temperatures, to stop drivers worrying....

Flipside is our last couple of moderns have a mpg gauge, normal thesedays I guess. Trouble is you start to obsess. managed to turn the current one off...much safer.

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 Trouble is you start to obsess. managed to turn the current one off...much safer.

 

Look up "mpg obsession" and you'll find a picture of me... :lol:

 

I have a volt meter (and an alternator). You do have to wonder just how useful it really is?

If you turn the key and nothing at all happens, either the battery is totaled or it's something like a fuse. The volt meter won't be any help either way.

If you turn the key, everything lights but the starter is sluggish and the lights dim then the battery is probably flat. The starter has just told you that, volt meter probably not much help.

If you turn the key and the lights are dim and the starter hardly turns if at at all, then as above, volt meter not much help.

If you turn the key and lights come on and the starter spins as it should then the battery is obviously OK. Volt meter was no use.

 

If it fails to start but the starter is spinning then it ain't the battery anyway....

 

In a nutshell - it's pretty bl00dy obvious if the battery is OK or not - the car soon tells you by it's actions. Knowing that the battery was at 9 or 10v instead of 12 or 13v won't make a blind bit of difference. You'll already know if it needs charging or not. :)

 

A handheld voltmeter is a very useful garage tool of course ;)

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And if your driving down the motorway and the lights start to dim?

 

That's why you need an ammeter!  Like I said before:

 

The voltmeter tells you the condition of your battery, the ammeter the condition of your charging system.

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