Jump starting tractors

[Username Taken]

At Witz' End - Throw away those old jumper cables... they could damage your car! - Autoblog

"Witz, wake up! My car won't start!"

www.autoblog.com

"As long as the cables are connected," Goss continued, "the two batteries act as buffers to contain maximum voltage rise. But as soon as the first cable end is removed, the systems go nuts. When the first cable is removed, the voltage reference is gone. It instantly changes from the level of two batteries and two alternators to one battery and one alternator.

"During this period of adjustment, the voltage regulator allows the alternator to climb to a very high voltage level. The alternators of both cars are unregulated for a few milliseconds, and during that brief time, the alternator can produce several hundred volts of low-amperage electricity. This high-voltage spike shoots through the electrical systems of both cars."

The effect is like a voltage surge running through a computer. It rarely destroys anything instantly but can weaken components of both vehicles, including engine control computers, alternators, sound systems or any of the dozens of electronic modules in modern cars, and there are usually no immediate symptoms because these parts are merely weakened.

But as the vehicles are used, those weakened components will eventually fail. And since those failures may be weeks or months later, you'll probably never realize that it was caused by your use of conventional jumper cables.

 

[bearthebruce]

@Username Taken - your quoted scenario makes sense. I could see the ECU getting confused for a few milliseconds and commanding voltage to spike if the reference voltage goes wonky.

I think the best idea is to change the battery with a fully charged battery on tractors that have lots of electronic controls. But, that too in modern systems can cause issues - setting fault codes, loosing learned parameters, blah, blah, blah.

When I learned that VWs loose their throttle position reference when a battery is changed and learned that one has to have a diagnostic tool to re-calibrate the throttle, I stood shaking my head. Drive by wire has advantages but it also has big disadvantages. Do they issue a scan tool with the car so you can do this? No.... so if you do not have the scan tool, you can get it to start and run it in "limp mode" to the dealer or repair center to have the throttle position relearned. Yeah, I would like to be 200 or 300 miles from a repair center and have this happen to me.

Read the manual for the tractor. It likely has a procedure to "jump" a dead battery. Follow it.

 

[JethroB]

What is the life of those jump/booster packs? And how often do they need to be charged when not used?

 

[Username Taken]

@Username Taken - your quoted scenario makes sense. I could see the ECU getting confused for a few milliseconds and commanding voltage to spike if the reference voltage goes wonky.

I think the best idea is to change the battery with a fully charged battery on tractors that have lots of electronic controls. But, that too in modern systems can cause issues - setting fault codes, loosing learned parameters, blah, blah, blah.

When I learned that VWs loose their throttle position reference when a battery is changed and learned that one has to have a diagnostic tool to re-calibrate the throttle, I stood shaking my head. Drive by wire has advantages but it also has big disadvantages. Do they issue a scan tool with the car so you can do this? No.... so if you do not have the scan tool, you can get it to start and run it in "limp mode" to the dealer or repair center to have the throttle position relearned. Yeah, I would like to be 200 or 300 miles from a repair center and have this happen to me.

Read the manual for the tractor. It likely has a procedure to "jump" a dead battery. Follow it.

VW does its own thing. Many shops won't even work on them. They just tell the customer, "Take it to the Dealer"

 

[LittleBill21]

At Witz' End - Throw away those old jumper cables... they could damage your car! - Autoblog

"Witz, wake up! My car won't start!"

www.autoblog.com

"As long as the cables are connected," Goss continued, "the two batteries act as buffers to contain maximum voltage rise. But as soon as the first cable end is removed, the systems go nuts. When the first cable is removed, the voltage reference is gone. It instantly changes from the level of two batteries and two alternators to one battery and one alternator.

"During this period of adjustment, the voltage regulator allows the alternator to climb to a very high voltage level. The alternators of both cars are unregulated for a few milliseconds, and during that brief time, the alternator can produce several hundred volts of low-amperage electricity. This high-voltage spike shoots through the electrical systems of both cars."

The effect is like a voltage surge running through a computer. It rarely destroys anything instantly but can weaken components of both vehicles, including engine control computers, alternators, sound systems or any of the dozens of electronic modules in modern cars, and there are usually no immediate symptoms because these parts are merely weakened.

But as the vehicles are used, those weakened components will eventually fail. And since those failures may be weeks or months later, you'll probably never realize that it was caused by your use of conventional jumper cables.

yea I'm sorry, I'm not buying this. the voltage reference is never gone, both have battery's where do they think the voltage is going?

if the batterys are even extremely different the voltages, the alternator can't sink enough over voltage to matter, because voltage only rises if current is maxed out,

I have full fielded alternators, they go up to 16+v on fully charged batteries. less on dead ones.

 

[etpm]

yea I'm sorry, I'm not buying this. the voltage reference is never gone, both have battery's where do they think the voltage is going?

if the batterys are even extremely different the voltages, the alternator can't sink enough over voltage to matter, because voltage only rises if current is maxed out,

I have full fielded alternators, they go up to 16+v on fully charged batteries. less on dead ones.

Because of the way some voltage regulators work it would be possible, if the alternator was charging two batteries and then one was removed, for a voltage spike to occur. This spike could be quite high. But I would think the spike would be in the vehicle with the good battery because the vehicle with the low or bad battery would still be pretty well loaded up. Unless the bad battery could not accept any current and so would be putting no load on the alternator.
Another important thing about jumping that should be mentioned is that most jumper cables and the connections they make are not up to the task of delivering the current required by the starter motor. When jumping a vehicle it is best to charge the low battery for a while via the jumper cables. Then, when starting is attempted, the low battery, if it is any good at all, will be able to dump a lot more current while the jumper cables will still help. This method can be the difference between starting and not starting. If this was previously mentioned in this thread I missed it and so apologize for repeating this information.
Eric

 

[LittleBill21]

Because of the way some voltage regulators work it would be possible, if the alternator was charging two batteries and then one was removed, for a voltage spike to occur. This spike could be quite high. But I would think the spike would be in the vehicle with the good battery because the vehicle with the low or bad battery would still be pretty well loaded up. Unless the bad battery could not accept any current and so would be putting no load on the alternator.
Another important thing about jumping that should be mentioned is that most jumper cables and the connections they make are not up to the task of delivering the current required by the starter motor. When jumping a vehicle it is best to charge the low battery for a while via the jumper cables. Then, when starting is attempted, the low battery, if it is any good at all, will be able to dump a lot more current while the jumper cables will still help. This method can be the difference between starting and not starting. If this was previously mentioned in this thread I missed it and so apologize for repeating this information.
Eric

and why do you assume that the good battery would not absorb it?

 

[LouNY]

Well when I jump off something for the last several years if I have a jump pak handy I try it first,
then the heavy booster cables come out.
The last 4 vehicles for jumping have been 3 RAMs and a Chevy they have all had 200 amp alternators.
I put the cables on my truck battery then the positive to the low/dead battery and the negative to a good ground.
Get back in the truck and bump the rpm up to 2500 or more and enjoy either the heat or ac for 5-10 minutes then go for a start.
Once the dead tractor is running I pull the cable off the battery and then the ground then walk over to my jump vehicle and remove the cables close the hood and then get busy.

 

[etpm]

and why do you assume that the good battery would not absorb it?

The good battery, close to if not fully charged, would put little load on the alternator. When disconnected from the low battery the alternator, which would have had a large load on it charging the low battery, all of a sudden would have a pretty light load. Some voltage regulators may not be able to keep the voltage from spiking in this situation. But I wouldn't harm the tractor.
Eric

 

[LittleBill21]

The good battery, close to if not fully charged, would put little load on the alternator. When disconnected from the low battery the alternator, which would have had a large load on it charging the low battery, all of a sudden would have a pretty light load. Some voltage regulators may not be able to keep the voltage from spiking in this situation. But I wouldn't harm the tractor.
Eric

voltage and current are tied. current has to drop for voltage to climb, and for voltage to climb, current would need to go up, and your talking very short timing here. I would like to see this on a scope to prove it, I have the equipement, not sure I want to spend the time setting it up.

if you have a link that describes this in detail I would love to read it. The boating community does this with HIGH sustained loads into battery banks, and as long as there is a battery in the line (in the case of a battery bank disconnect). the alternator seems to be fine. but maybe its more of a ecu thing, but ecu is tied at the battery, not the alternator. I don't see how the voltage can climb that high, but I am willing to learn if it can be shown.