how to test for voltage drain
disconnect a batt cable from it's terminal. Put a digital volt meter (DVM) inline, one probe on the terminal, other probe on the cable u just took off.
a normal drain is 500mA or less. If you are above that you have something pulling. How do ya find it?
Start taking fuses out of the fuse box until the draw drops off significantly. Certain electrical items are gonna pull a few milliamps, normal. But if you are seeing 1000mA draw and you pull the fuse for the opc and current drops from 1000mA to 250mA (for example), you know that the opc circuit is where the problem lies. At that point grab your wiring diagram and research where the opc fuse is, and then trace out what components are on that circuit. Write them down. Now, go back to your tractor (or whatever) and locate those components you wrote down. With the fuse back in the box so you now have a drain again, disconnect one of those components that you have written down. If current draw drops off, that component is your drain. If not, reconnect and move onto the next component.
300mA ain't gonna pull your battery down in 5 days, in my opinion but if you think it might be, disconnect your work light and see if your drain goes away (if you ain't already done it). Also, if the worklight has a little switch that has a light in it, I can't tell you how many of those stupid switches Ive had to replace...they fail and the little bitty led will kill the battery over a length of time. I don't like them and I generally remove the ground from the back of the switch, at a minimum, and/or replace the switch with a standard non-backlit switch of some sorts. It is very hard to find decent electrical switches anymore, 99% of them are cheap GARBAGE with high failure rates. OEM if you can find one to fit where it needs to and don't over power it. IF the switch is labeled 5A, don't try to put 50A through it. U get the idea
oh by the way wen you get your wiring diagram make darn sure you get the correct one. Some of the crap online is for overseas tractors or canadian tractors or whatever. They are not reliable the only reliable way to get the correct one is to order it and they are not cheap.