JD 7800 batterie drain

   / JD 7800 batterie drain #1  

Sibley

New member
Joined
Jul 7, 2014
Messages
5
Location
Nashua, MT
Tractor
John Deere 7800, 1994
I have a JD 7800 (1994) that drains the batteries in about 2 weeks. I have changed the batteries, the alternator, the key switch and the blower switch
to no avail!! Perplexed------Sib.
 
   / JD 7800 batterie drain #2  
pull the positive cable off the battery .... connect a small wattage light bulb in between the cable and the battery ....
if it lights, you have a drain ( not a bad battery ).

now start disconnecting ( or pulling fuses if you have any ) things, one at a time till the light goes out .... also check for "rubbed" through wires by shaking / moving wiring harnesses....
 
   / JD 7800 batterie drain #3  
On using a test light to find a drain I was taught to remove the ground cable not the positive cable. I was also taught when removing battery cables remove ground cable 1st and on re-installation install ground cable last.
 
   / JD 7800 batterie drain #4  
unless you are in Europe, then the Source to Drain is reversed ...

the reason over here for the neg being the last to connect is usually when "jumping" a dead vehicle . the NEG cable is connected to the block of the engine so if there is any spark , it is well away from the battery and any gasses floating around.....
 
   / JD 7800 batterie drain
  • Thread Starter
#5  
Thank you Joatguy------When I get some time I'm going with it.
 
   / JD 7800 batterie drain
  • Thread Starter
#6  
Thanks Tx Jim----another good thought!!
 
   / JD 7800 batterie drain #7  
your in for a long haul to find the issue if it is in the wiring, might suggest picking up some battery quick disconnect ends. so you are not constantly monkeying around with wrenches to remove cables from battery.

adding to what jaotguy noted, if after pulling fuses and relays to try and track down problem, (googling your tractor to see images) your tractor is large enough, i would assume the tractor has a few different spots were you can disconnect a wiring harnesses. so as to possibly split things up, to see if it drain is say on the engine wiring harness, or cab wiring harness, front dash wiring harness, side dash wirining harness, or other section of wiring harness.

a shop manual for your tractor, would give diagrams of were your wiring harnesses plugs are at. along with detailed info, of what color wire connects to what. to be able to fine tune your search.
 
   / JD 7800 batterie drain
  • Thread Starter
#8  
Thanks Boggen -----Already have quick disconnects----been do'in the disconnect for 2 yrs. !!
 
   / JD 7800 batterie drain #9  
last min thought, stinking rodents, mice to other, to simply vibration and insulation rubbing off in very ugly spots you may never be able to see let alone get to.

multi meter or a test light, with aligator clips, to different size pin ends, to test wire harness plugs. different sized solid wire, with dremal sanding bit to round ends of solid wire some. can help get into the female end of the plugs. i have been known to buy cheap test light kits and like. and butcher the stuff for the ends and splice the wires together, to get what i need. it looks ugly, but *shrugs* what ever gets the job done. with tractor battery disconnected, i have butchered a kids toy, for the little 9v battery plug, if i needed to test with a little bit of power, and use of a test light.

if a test light is a LED, be fore warned, it will only light up, in one direction and not the reverse direction.
 
   / JD 7800 batterie drain #10  
unless you are in Europe, then the Source to Drain is reversed ...

Please explain. Does negative cable on European tractors attach to starter & positive cable attach to frame? Thanks,Jim
 
 
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