Digitech Multimeter to measure amps not voltage
Submitted: Friday, Mar 06, 2009 at 15:23
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Findanomad
Hi all
Don't understand the whole elec thing much but can i use this multimeter to measure the amps in the battery . Voltage reading is fine.
Thanks
Reply By: Member - Phil G (SA) - Friday, Mar 06, 2009 at 19:37
Friday, Mar 06, 2009 at 19:37
MrNomad,
Good question. It can get confusing. It boils down to what information you want.
Your multimeter most likely has a couple of ways of measuring current (amps), and its best to have some idea of how many amps you're going to measure. Remember amps is always measured in series (i.e. use the multimeter like a piece of wire - never hook it up to both pos and neg sides of a battery)
With the multimeter leads in the same sockets (as you are using for volts), it will probably measure up to 0.2Amp (200 milliamps). This is not much current and is useful for measuring the current consumed by a circuit board, or a relay coil, or a battery isolator, or low voltage cutout etc etc
The 10amp setting requires the red lead to get moved to the third (unfused) socket. This is useful for measuring the current being used by a fridge or a light, or any other accessory that uses less than 10 amps.
If you want to measure more than 10amps, you need a new device. Either buy an ammeter that measures more (eg 20amp, 60 amp or whatever and hook it up, or if you want a spot reading, many prefer to use a clamp meter.
If you want to measure high amps continuously (eg you want to know how many amps are going into your aux battery) you will want to install a "shunt ammeter". This is not a true ammeter - it is actually a voltmeter that measure the small voltage difference across a small resistance (shunt) and translates that into how many amps is travelling thru the wire. That is the way most vehicle ammeters work.
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352613
Reply By: Mick15 - Friday, Mar 06, 2009 at 20:11
Friday, Mar 06, 2009 at 20:11
If you wanna see what kinda capacity your battery has - what kind of current it can put out, just go to a car battery place and they will load
test it - basically put a load across it and see how it copes as the load is gradually increased.
Ideally this should be hundreds of amps something like the cca rating, might be 50% of the cca and just turn the car over, not much room for error though.
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