How do I find which is bad, alternator or voltage regulator?

[maple flats]

Concerning the battery, it is almost new, and I bought a gel battery, which should handle vibration better than a lead acid battery, I'll see. This battery was bought from my local farm supply and it had a mfgr date that was only 2 months old when I bought it. If it's bad, it is still in warranty.

[rusticretreater]

You probably should check if your tank has an internal screen at its outlet.  I have seen a number of vids of guys siphoning their tanks to get the crud out after the screen clogged.  Depending on your tank, it may be difficult, it may be hard or maybe you can remove it and drain it well.

[maple flats]

I got the chem in both the bulk tank and the tractor tank. looking in, the tractor tank only shows 1 spot of black "algae", and when I put a piece of EMT in the big tank it showed I only have about 3" in the bottom. This is a 150 gal round tank that sets on a flat end, thus very little fuel in it. Once it runs out I'll wait to see if I ever want to get in filled again, since it's at my blueberry fields and I put those fields up for sale last week. Too much trying to keep up with tending them. If they don't sell, I'll clean the tank before it gets filled again. It has the biocide and fuel cleaner in it now, and I pumped enough fuel back thru to get it mixed well.
I didn't get to run the tractor yet, likely tomorrow because the 3 spare fuel filters arrived today so if the filter gets plugged, I can swap it out.
I can't see very well into my tractor tank, the filler has a 90 bend in a short way from the cap, looking in required a mirror on an extension and then it was extremely hard to see anything in there. Worse come to worse, I may need to remove the tank, but with the cab and configuration  of the whole thing, it may need way too much to make it worth it. My tractor is a Mahindra 3616 with a full cab and the front windshield fits around the fuel tank and they are sealed together with a black adhesive sealant.

[moodnacreek]

Assuming the tractor has headlamps, turn them on at slow engine speed and when you rev it up they should get brighter meaning it is charging.

[maple flats]

Great idea, but the headlights don't work anymore.

[scsmith42]

My "biocide" story...

For 20 plus years I've run diesel equipment here on the farm with no issues.  This included heavy equipment that sat for 3-4 years w/o being used.

In 2020 I purchased a Sterling Semi with 900K+ miles on it.  Turns out that the tanks had black slime inside them, so I treated them with a Biocide.

I've had a 500 gallon storage tank on the farm for over 20 years, but a few years ago I picked up a used portable 500 gallon double wall tank that I mounted to an old military trailer.  I use this rig to pick up fuel at the local jobber / gas station and transfer it to my farm tanks.

Being the genius that I am (NOT), I decided to treat my 500 gallon storage tank too.  Rather than put the biocide in the storage tank, I added it to my trailer mounted 500 gallon transfer tank so it would mix up well before going into my storage tank.  Turns out this was one of those things that was "better in theory than practice...."

Life happened; I left the treated fuel sitting in my transfer tank for a week or so before I got around to transferring it to my storage tank.  Because it take 30 minutes or so to fill up my elevated storage tank, I usually start the pump and then do other chores for a half an hour.  Unbeknownst to me, while sitting for a week in my transfer tank the biocide cleaned up the inside of the tank and once I started pumping fuel into my elevated storage tank it promptly clogged up the gears on the fuel pump and smoked the pump!  Of course, the fuel filter is downstream of the pump so once I replaced the pump I had to keep cleaning out the inlet screen. i finally gave up - used a separate pump to empty the tank and then took a pressure washer to it's inside in order to clean the residual gunk out of the tank. The biocide had cleaned it off of the tank walls, but turned it into some type of black grit that kept clogging up the strainer.

If I would have just left things alone, it would have save me a couple of day's of aggravation and a few hundred bucks for a new pump!

[SawyerTed]

In the marine industry, "fuel polishing" is a real thing.   It's a fancy name for pumping the fuel out of the tank, externally filtering it, then returning the "polished" fuel to the tank.  

There's lots of DIY fuel polishing information on the web.  The process gets the algae and gunk out of the tank before it gets to the engine filters.

I've done it a couple of times, the setup cost about $50 to filter 500 gallons.  

[rusticretreater]

I have siphoned my fuel out of the tank into a large funnel that has a filter screen in it.  I have also blown air through the fuel line into the tank, to stir things up and then reached into the tank with a net used in fish aquariums.  You can get a surprising amount of stuff out of there.

[Ianab]

Great idea, but the headlights don't work anymore.

You said you have a multimeter, so you can do the same test. A 12V battery will read 12.? when it's not being charged. Maybe 12.8 at full charge, down to 12.1 when it's effectively flat. When it's being charged, the voltage across the battery should be close to 14V. That's why you can see the change in the headlight brightness, 12V vs 14V is noticeable.
So either test will give you a clue, If you aren't getting ~14V at the battery with the engine at fast idle, then you look at the alternator / regulator / wiring. If you are getting the charging voltage, that suggests the alternator etc is working, and you need to look at the battery itself (not accepting charge or self discharging) or a parasitic load drawing it down. 
I guess the only trap would be if the parasitic load was actually the alternator? Someone mentioned a faulty diode in the alternator, so keep that in mind when looking for a parasitic load. 

[maple flats]

Sorry for the delay, first I had a minor case of Covid, then my wife got it too. I'm mostly better now and finally yesterday she was a little improved.
Back to the tractor issue. I got the tractor running, with a new fuel filter and a biocide + a fuel cleaner in the tank. I got the rest of the mowing done without issue. The tractor then sat for 6 days while my wife and I had covid, and the tractor started ok, this time it didn't hesitate, but fired up as it should. I did test the output of the alternator when running at about 1600 rpm (pto speed is just north of 2400 rpm). The meter read slightly over 14V. Thus I must have a phantom draw. I'll eventually add a battery disconnect, but until then I'll put it on the charger every few days. I can charge it using my plug in charger or I just got an PWM CC (charge controller) for my 50 watt panel. I'll hook that up after I pack more syrup. Right now I'm low on dark syrup and I have 4 full SS barrels, all dark. That is my job before the solar charger.
Previously I had a MPPT CC for to 50 watt panel, but it failed. I then learned that a MPPT CC  draws some power all of the time and if the solar panel doesn't get enough sun the MPPT CC can actually draw the battery down, thus I ordered the PWM CC.

[maple flats]

After several unscheduled delays, I will get to wire the  shop to run a 120v receptacle thru the wall to power a maintainer in the next day or 2. 
Tomorrow I need to load up lots of syrup and restock the outlet where I sell my syrup, sales have been thru the roof the past month, and it's not looking like Christmas type buying, that is still on the horizon. 
Once I get the syrup stocked, I'll run the power to plug in the maintainer to keep my tractor battery fully charged, a week or 2 later I should have time to try to figure what the phantom draw is on the battery. If that fails, I may just keep running the maintainer. 
I also have one more sawing job, I need to replank the bed on the 16' gooseneck trailer I jointly own with my brother. I have the logs waiting, the first one is started, flat on 2 sides. I just need to find a helper, After my yearlong layup from 3 major surgeries, I still have not built up my strength enough to handle 16' 2x8's alone without a major struggle, and 1 major struggle caused to 3rd surgery last year, a huge hernia. I now try not to over do it!

[barbender]

I am always looking for smarter ways to handle 16' oak decking. It's a killer!

[doc henderson]

 

 

shop built in 2005, and just got my plug on the south end of the shop, by the splitter.