electrical drawl draining battery on 4020

bv

Member
what is the procedure to find the drawl on a 4020, new battery but when the tractor sits for a few days it drains the battery dead. Do you start disconnecting fuses or could it be in the alternator or what?
thanks again.
 
(quoted from post at 10:26:25 05/30/23) what is the procedure to find the drawl on a 4020, new battery but when the tractor sits for a few days it drains the battery dead. Do you start disconnecting fuses or could it be in the alternator or what?
thanks again.

Gas or diesel, serial number?

Was alternator original equipment or a conversion?

A good place to start would be to disconnect the alternator and note if the battery drain stops.

If alternator is OEM, voltage regulator will be EXTERNAL, and have a plug that can be disconnected, if a conversion, likely it will have an INTERNAL regulator and pulling a 2-wire plug out of the alternator will disconnect it.

Either way, also disconnect and tape up the output wire attached to the large output stud on the alternator.

From what you wrote, it doesn't sound like it's a 24 Volt diesel, IF it is, post back for more details that apply to that system.

This post was edited by wore out on 05/30/2023 at 10:41 am.
 

If 12 volt system disconnect battery ground cable from battery post or tractor frame & attach test light or VOM in that loosened connection. Test light should glow or VOM register voltage. 1 by disconnect/reconnect electrical connection watching for test light to not illuminate or VOM register 0 volts. Now light or 0 volts indicate loosened wire is connect to electrical drain.
 
If 24 volt try checking the post on the body of the starter to ground. This is the field coils of the starter. Seem to be the trouble spot on the 24 volt ones.If not 24 volt then just start unhooking things until the drain goes away.
 
My mistake it's a 70 model 2520 12 volt and original style Motorola alternator, I 1st thought it was the 4020.
 
amp clamp on alternator big wire would be a good place to start. You will have to know your meter and what it reads with nothing versus a slight draw. Dont have to unhook anything. Slight Voltage drop across that same wire when tractor is off might indicate draw at the alternator if you dont have amp clamp on on your meter it can be checked that way. And is what you would do on the small wire circuits to check for draw. Look for .4 to .6 volt drop where theres no resistors and the tractor is off. Question number 2 is whats your alternators output voltage when its running? Is it just running off what you give it for juice at the start and is just barely putting out 13.2 to 12.8 or so volts? For some reason Ive also had 3 of them running high in a newer pickup and 2 tractors in the last year at like 15 volts with a battery I knew was good and shouldnt need to be working hard at all in the previous 14 years I saw 1 on a wheel loader fry the batteries. Something supplier wise has changed...so would be worth checking how its doing.
Question or suggestion 3. New battery is confirmed good? Pull battery cables off. Wait your couple days and check the battery. Load testers have become pretty inexpensive or just take it in to your Napa or orellies and have them check it. You can check the condition of your cables at this time as a loose or cable on either end can cause this too. Jumped its running then once you shut it off its shaken loose throughout the day making hay...three days later try to start wont start till jumped when you complete the circuit externally. Good luck!
 
The 2520 with the original 12 volt Motorola alternator has a isolation diode plate mounted to back of alternator where the 12 volt battery cable connects. If disconnecting it when setting prevents the battery from draining down, Replace diode plate. That simple!
 

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