Another Electrical Question
Thread Starter
Burning Brakes
Joined: Feb 2002
Posts: 1,154
Likes: 25
From: Jasper GA
Another Electrical Question
Is there any way to check the net current flow to (or from) the battery with the engine running? My alternator is putting out the specified 14.1 volts at idle, but my battery is consistently below full charge after driving say 50 miles with no lights, radio, etc. on.
Thread Starter
Burning Brakes
Joined: Feb 2002
Posts: 1,154
Likes: 25
From: Jasper GA
It does look like the Mastech meter would do it. Two more lame questions: would it be used on the positive or negative battery cables, and how can I tell whether the current flow is to or from the battery?
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Well,,,,,,,,,, You would have to insert the digital AMP METER "BETWEEN" the alternator and the battery
The LARGE "BATT" terminal on back of the battery is the alternator output to the battery. Make up a eyelet wire pigtail that you can secure to the BATT connection and put the meter leads between those two connections.
The amp meter can be connected in either polarity. You will just need to figure out what sign that you need to see on the meter.
The Alternator supplies CURRENT to the battery so put the POSITIVE amp mater lead on the BATT terminal and NEAGTIVE lead on the wire going to the battery.
That should provide you a POSITIVE current flow indication.
Warning!! If you insert the amp meter between the BATTERY and the POSITIVE battery cable; when you crank the engine it will OVER DRAW the ammeter. The meter usually reads 10 AMPS max and the starter draws a LOT more than that!!
Bill
The LARGE "BATT" terminal on back of the battery is the alternator output to the battery. Make up a eyelet wire pigtail that you can secure to the BATT connection and put the meter leads between those two connections.
The amp meter can be connected in either polarity. You will just need to figure out what sign that you need to see on the meter.
The Alternator supplies CURRENT to the battery so put the POSITIVE amp mater lead on the BATT terminal and NEAGTIVE lead on the wire going to the battery.
That should provide you a POSITIVE current flow indication.
Warning!! If you insert the amp meter between the BATTERY and the POSITIVE battery cable; when you crank the engine it will OVER DRAW the ammeter. The meter usually reads 10 AMPS max and the starter draws a LOT more than that!!
Bill
Race Director
Joined: Apr 2007
Posts: 11,150
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From: South Western Ontario
You could use it on either cable.
The meter will have an arrow on the clamp and it will show + or - for the current value.
What is the voltage at the battery when the alternator is producing 14.1V? If that voltage is getting to the battery then the battery should be charging just fine.
The meter will have an arrow on the clamp and it will show + or - for the current value.
What is the voltage at the battery when the alternator is producing 14.1V? If that voltage is getting to the battery then the battery should be charging just fine.
