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Battery drain problem

O

old

Well-known Member
Location
Camdenton Missouri
I have a D-17 12 volt system with a 10SI alternator on it. If I leave the battery hooked up it drains the battery over night. I think I found the problem but want to be sure. Ya I could go out and use one of my other tractor to check but this is easier LOL. If I put a meter between the battery and the + cable I read 12 volts give or take a few, ignition off or on. If I unhook the big post wire on the alternator I read zero volts. Is my thinking correct that I have a problem with the alternator or do I still need to look more as to why the battery goes dead. Thats the only wire I find that draws current at all times so thats why I think I need a new alternator.
Thanks
Hobby farm
 
I'm pretty sure you found your problem. Try this.. put a test lamp inbetween your alt charge wire and it's post.. if it lights up.. your alternator has a shorted diode... ( or the field is staying powered thru the #1 line.. )

soundguy
 
#1 only has voltage when ignition is turned on. I don't own any test lights because I have the meters instead so figure why have a light LOL
 
Charge up battery and leave the wire off overnight. If the battery is drained not the problem, if it is still charge you probably have found the origin maybe not the complete problem but the origin of the problem.
 
Use a spare trailer lamp.. etc something smaller than a headlamp.. etc.... Should be able to just hold the bottom of the bulb to the charge post, and then touch the wire to the bulb metal side..

soundguy
 
Ya after I posted back to you I got to thinking about the little light bulbs that come with new gauges and I have 3 or 4 of them laying around because I never hook them up on tractors any how
 
Well now I don't know whats up. I tried a light bulb and it does not light up when I put it between the wire and the big post. It does light if I hook to ground but I know that is correct. I have left the battery hooked up this time but the wire going to the big post on the alternator off to see if tomorrow I have to charge the battery. If I do than I know the problem is some where else if I don't then its back to being the alternator and maybe an off/on type of problem
 
What kind of resistance is the alt pulling when you stick the meter on it?
I assume that the alt is the only 'load' you're finding on the electrical system with the battery disconnected and the key off?

Rod
 
Old,
Part of the diode trio is shorted, any auto supply shop will sell a rebuilt 10SI for $49 (lifetime warranty). You end up with new brushes,bearings, bushings, diodes, and regulator. Way cheaper than replacing all in yours.
 
Don't know where you get yours but I only pay $35 for the ones I get and thats life time warranty also but you do need a core which I have. Shoot most of the time I take one back and they hand me one for free figuring its was one of theres any how since I buy 5-10 a year any how
 
TTry this ,place a screwdriver blade against the rear bearing of the alt.,if it is magnetized,there problem with alt.That is with all wires connected and engine off. Old way to check for alt problems
 
Did that and nope it isn't. This one has me chasing my tail lol Thats like yesterday I had voltage from the big post to the wire today none
 
Had another thought,If i rember correctly ,many times the big wire (battery post on alt) will show voltage on test meter but will not show any amps drain,and can be normal. Might look for other problem before buying a new alt.
 
use a ammeter and put it on mA. disconnect the ground and put one lead on the - bat terminal and the other on the neg cable end. your meter will show the drain on the battery. start unhooking things like the alternator and see if the draw goes down on your meter
 
Most likely the alternator or a bad battery.Might be a wire somehow.One way that might work to check is take the hot battery cable off and just as you get it off the post of the battery see if there is a spark.If theres a spark,batterys good probably and there is a draw,maybe alternator or shorted out wire,maybe cigarette lighter?
 
I had the same problem when I converted My MTA to 12V and installed an alternator. I had to buy a alternador with a relay in it so the circuit would open and not drain the battery. When I start up I have to advance the throttle until the relay clicks in and then it stays in until I turn off the switch. I bought the alternator at a tractor show from a guy 6 years ago, who remanufactured them He had a table full. Brissco
 
I might think battery also but I have tried 2 or 3 of them and all have had the same problem. Leave them hooked up and in 24 hours there dead. But if there in another tractor they last forever so its the tractor not the battery. I'm beginning to think this alternator has an intermittent problem
 
If it does it with the alt disconnected, try pulling the wire from one component at a time and leave it.. till you find one.. might be an intermittant short?

soundguy
 
Yep and if I hit the right bump it shorts hit another one just right and it goes away. About to drive me to drink. Well thats not true I do like my beer afat a long day of fighting strange problems LOL
 
Better put that meter on the 10 amp range.A shorted alternator diode will draw more than ma or milliamperes.And old rule in electronics says use the highest meter range when dealing with unknowns.
 
Wrong,an alternator that is charging will attract a screwdriver.At rest residual magnetism wiil attract a screw driver.
 
If that alternator has a lifetime warranty I would pull it and have them check it on the stand.
Hal
 
I have owned meters since 1950 but still use test lites.They work fine on automotive systems.A test light across a fuse holder can track down short circuits.A sharp prod on a test light can get through dirty surfaces and insulation.A test lite can locate a bad battery connection.No need to handle an expensive meter and connect test leads,a third hand would come in handy.A neon test lite can id ac or dc volt and tell you if power tools or appliances are hot above ground.I have a few neon test lights on the bench and in tool boxes.
 
OLD,
Are you sure you have the alternator wire right? If you swap the leads to the regulator the battery will run down. If you look at the internal regulated alternator you have three terminal from left to right. The first is the stud marked battery. The next, a 1/4 inch blade should have a switch 12 volt thru a diode or resistor and third the right most 1/4 inch blade which many poeple connect to the battery stud.

Kent
 
Yes its wired correctly I do 12 volt conversions all the time and can almost do it in my sleep any more. I probably do 10 plus a year and have been doing them for decades
 
Hi Rich,

What you might wanna do is hook up your test lite, take off the belt and slowly rotate the pulley and see what you get. I'm thinking a problem with the rotor.

Another thought, what voltage do you see on the battery with the engine running? Engine off?

T_Bone
 
If you disconnect the hot wire,(12Volt pos) at the alternator, does your battery still run down? Is your alternator a standard automotive type, with out internal switch? If so you need the switch in the alternator. Auto Zone sells tractor alternators or used to, but 6 years ago I tried 2 of them, they wouldn"t charge. The flea market one is still working fine, mowed hay all day today with the tractor. Brissco
 
How many ohms in the circuit to the alt?
I've been relatively amused with reading about all these contraptions to test the circuit...
Ohm it out. There shouldn't be anything on the BAT wire if the alt is functioning correctly. If there is a load there then the cutout relay probably isn't working, or that would be my guess.
I know the ohm meter is the easiest way to chase out a ground or fault in a circuit...

Rod
 
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