Slow crank on J.D. 450E dozer

[Cherokee140]

One bad battery and one good battery....the bad one will just kill you. Test each battery on its own. Could be you have just one that has given up the ghost. M1009's are the same kind of deal....or I guess I should say where.

Same goes with cables everywhere....if one is iffy you have the same kind of issues.

Personally I would charge the batteries one at a time, or if you have two chargers that is better. I could charge them with nothing connected to them if possible.

If all that is ok, you are to what you talked about, cleaning grounds and connections, then checking the starter and such. Last ditch would be a direct feed to the starter with a remote switch that would take as much out of the question as possible.

 

[Topher265]

As others said, you can charge one battery which will charge both because they are wired in parallel. I would advise charging each individually while they are not installed, so you can compare how long it took to charge each fully. Also, make sure they are both the same brand, age and type/capacity.

If each battery is okay, you should get an inductive clamp and a high quality DVOM to do more tests. If you don't know what either of those two things are, then it means it's time for you to take it to a mechanic. If you know what those are, you'll need them to do quick voltage drop tests to find what is using up all the volts from the batteries.

Once the batteries are known to be good, check the other simple things like oil level & quality, as well as air filter condition. Always start simple. If those are okay, then like Cherokee said it's time to start digging into checking the voltage drop of the starting system wiring to help find the problem. You could also take the belts off the engine and see if that makes a difference...just another simple/quick check.

 

[doxford jim]

I don't think the problems are the batteries. I have used only one battery on my JD450 for 9 years and my machine starts easily with no problems - and I live in the cold north. The problem lies in your starter - probably worn or stuck brushes. If there is not enough pressure from the brushes onto the commutator then the starter will not function properly. My suspicion is the brushes are the culprit.
HTH

 

[DieselMonk]

I've also got an old dozer that used to need 2 batteries to start and now it only uses one and starts with ease. Matter effect putting a second battery there now, doesn't make any difference anymore. But before I got to that stage I had to replace the battery cables and clamps. The old cables were so bad, they didn't carry any heavy current anymore from the battery to the starter. I didn't do anything to the starter itself.