Battery Disconnect

[John Joseph McVeigh]

You should install a battery disconnect switch on the negative (ground) side, as this provides maximum safety by interrupting the path to the vehicle's chassis, preventing sparks and shorts if the positive (hot) side accidentally touches metal, and it's the standard practice for most vehicles, preventing issues like alternator power sustaining the circuit even if the positive is cut.

An accidental bridge between the positive (“hot” in a negative-ground system) side of the electrical system and a piece of metal at chassis-ground potential will not result in fireworks if the isolation switch is on the positive side of the circuit – and if the switch is open (as opposed to closed) – unless the engine is running and the alternator or generator is producing EMF.

If an inadvertent bridge occurs while the engine is running, it will not make a difference whether the isolation switch is on the positive side of the battery or the negative side of the battery, because one terminal of the alternator or generator will be ohmically bonded to the engine block and the tractor’s chassis. Sparks will fly regardless of whether the battery-isolation switch is on the positive rail or the negative rail.

However, the battery will be protected if the battery-isolation switch is open when an inadvertent short circuit occurs… but the alternator or generator might get roasted (if its armature is turning and the device is generating electricity).

 

[GrandpaSmurf825]

anything like a car or truck with a ECM or PCM computer then everytime you disconnect the battery the computer has to go through a relearn process . on cars and trucks it takes 5 miles of normal driving of stop and go and a long run for it to relearn. I can imagine it's the same with the tractor. the computer will have to go through a relearn process. I would not recommend a disconnect on it.

My last new service truck before retirement was a Freightliner FL70 with a Cummins QSC 8.3 and Allison automatic transmission. It had a factory battery disconnect right below the driver seat. Killed everything. If it was going to be parked for more than just overnight or the weekend I would turn it off. I never had any issues from it.
Farmer I help has a John Deere combine that has a factory disconnect on it that kills all power and it doesn't have to relearn anything. It sets for months without being ran. There are a lot of pieces of equipment as others have mentioned that are equipped with battery disconnects as standard equipment. I don't dispute what you say but but there are certainly plenty of instances that prove it to be a non-issue as well.

 

[John Joseph McVeigh]

My last new service truck before retirement was a Freightliner FL70 with a Cummins QSC 8.3 and Allison automatic transmission. It had a factory battery disconnect right below the driver seat. Killed everything. If it was going to be parked for more than just overnight or the weekend I would turn it off. I never had any issues from it.
Farmer I help has a John Deere combine that has a factory disconnect on it that kills all power and it doesn't have to relearn anything. It sets for months without being ran. There are a lot of pieces of equipment as others have mentioned that are equipped with battery disconnects as standard equipment. I don't dispute what you say but but there are certainly plenty of instances that prove it to be a non-issue as well.

The rebooting process that the Tractor Control Module on my Ventrac 4500Y goes through if I have removed power using the battery isolation switch is near-instantaneous. Within a second or so of reapplying power, the tractor is ready for action. The module does not engage in engine management or emissions control. The engine is a Kubota 3-cylinder Diesel rated at 25 hp.