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Battery light stays on

7164 Views 16 Replies 8 Participants Last post by  broggyr

Just wondering... I have a 1986 GT18 that the battery light stays lit all the time. I asked a mechanic why that is and he really wasn't sure other than it has to do with the engine cycle or something????

Today I was mowing and ran the thing out of gas, filled it back up and went to start it and it just clicked and didn't want to turn over. Waited about 15 minutes and it started up fine, but the light is still on.

Any reason why??? Does this tractor have an alternator?? The battery is only a year or two old.

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nascarillustrated, take note of what broggyr said. That is most likely what is wrong with yours. I have a similar set up on my GT18. The Voltage sensor is a little black box. The electronics inside illuminate the lamp in the 'Battery Discharging' light when the voltage at the battery drops below something like 12.2 VDC(don't quote me on that.)

If you are handy with a multimeter, as WNYTractorTinkerer said, check the output of the alternator by reading the battery voltage with the engine off. Should be in the neighborhood of 12.5 VDC, depending upon the condition of your battery. Once you start the engine, wait a couple of minutes, then check the battery voltage again. It should be higher than your first check. The amount depends upon which alternator your tractor has. Look all over the engine for a rectangular aluminum box with green plastic in the center. If you find one, that is the voltage regulator. In that case, with the engine running, battery voltage should be around 13.8 - 14.2 VDC. If you find no regulator, then your tractor has the Tri-Circuit alternator. With the engine running, you will see upwards of 16 to 16.5 VDC, this is normal for this type of alternator.

Either way, as long as the alternator is working, and you have a good battery, you don't need the voltage sensor or the 'battery discharging light' for normal operations of this tractor.

Good Luck!

Seth K. Pyle
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