multitester/battery drain

Anonymous-0 · Nov 30, 2008

Using a multi tester checking alternator for battery drain. Only get reading on ohms. Is this enough to cause my problem? I'm thinking I need a diode. This is a conversion on an 806

I don't understand everything I know about electricity.

dave guest · Nov 30, 2008

Just get a small test light(bulb with 2 wires) disconnect a batt cable and hook bulb in between cable and batt post. If bulb lights, you most generally have a drain. Not sure about newer tractors, but newer cars lot of them will show drain that is not really there. Multimeter is not much help on old tractors, need analog tester with moving needle, but then you gotta watch plus and minus or burn out meter. Ohms is for readings where you do not expect any voltage. Ohms the meter is using its own little batt to read through meter.

Janicholson · Nov 30, 2008

Put the meter on volts. touch the alt body with the neg test lead, and the big terminal on the back with the pos test lead. A reading of battery volts with it connected is correct (not running)
Disconnect the big lead. Place the pos test lead on the wire you took off, and the other lead on the post. (not running) if there is more than 0.25 volts (1/4 volt) a diode inside the alternator output bridge is leaking more than it should. if small (tenth of a volt, it is OK. One volt or more will discharge your battery in a few days or less. JimN

tn terry t · Nov 30, 2008

(quoted from post at 22:39:06 11/30/08) Using a multi tester checking alternator for battery drain. Only get reading on ohms. Is this enough to cause my problem? I'm thinking I need a diode. This is a conversion on an 806

I don't understand everything I know about electricity.

thats ok i dont understand all i know about your question LOL are you talking about a diode in line with the wiring on your alternator? if your 806 has a manual shutdown not a electrical shutdown you dont need the diode in line. the best way ive found to check for a short is to take a test lite and clip the allagator{SP?} clip to the battery cable and take the other end and touch the battery if it lites up any you have a short some where

Bob · Nov 30, 2008

What alternator, Delco 10-SI style? 1 or 3 wire?

A SIMPLE test is to disconnect the alternator completely (tape up the loose wires to prevent letting smoke out of the wiring).

Does the battery then stay up?

If it is a 10SI-style 3-wire unit, the #2 terminal will aways be "hot", key on or off.

The #1 MUST be only "hot" with the key switch "on", or when there is engine oil pressure, if the conversion is set up with an oil pressure switch.

Even if it is a manual-shutdown diesel, it's a good idea (despite what some alternator "experts" will tell you) to have an "idiot lamp", a resistor or a diode in the lead to the #1 "switched excite" terminal, as this will prevent alternator damage under certain conditions. (Having to do with a loose wire or even a little resistance in the circuit between the alternator's large output stud and the battery.)

Janicholson · Nov 30, 2008

You can do it that way, but 4 volts will not light a test light enough to make a believer out of the person using it. but a four volt draw will deplete a battery. JimN

El Toro · Dec 1, 2008

Your regulaor may be the cause of the battery drain. You can install a master switch between the tractor frame and the negative battery cable. This will isolate the battery from ground.
You will need another short battery cable from the tractor frame to the master switch and connect the existing ground cable to the master switch. The military has used these for years.
Hal

multitester/battery drain

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Anonymous-0

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