Jump starting tractors

[grsthegreat]

Ive been jumping car batteries for 40 years. I guess im glad i didt know its dangerous to do. Not knowing this has saved my vehicles.

 

[LittleBill21]

Ive been jumping car batteries for 40 years. I guess im glad i didt know its dangerous to do. Not knowing this has saved my vehicles.

although I have jumped a ton as well. I will say the jump packs are easier and more accessible now, and with a 12v port on some of them, makes a lot more stuff usable.

 

[DieselBound]

@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.

I've had several MKIV VWs (fly-by-wire) and I've never had any such issue. I also have VCDS (tool that does 99.9% of what any factory tool can do), in which case if I had to I wouldn't be in a panic.

But, you gave the best advice yet: "Read the manual for the tractor. It likely has a procedure to "jump" a dead battery. Follow it."

 

[two_bit_score]

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

We have a booster pac that is over 10 years old. It’s been rebuilt once by a battery shop. We top off the charge whenever it’s used. Since getting it I dont carry jumper cables any more.

When I had the old booster Pac rebuilt they showed me a new one that was almost small enough to fit in the glove compartment that they said would do a better job than my old Pac.

The new Pac was a little more money than rebuilding the old Pac but if it ever gets weak again I’ll replace it with one of the new lithium pacs.

 

[mechtheist]

I recently bought one of those little starter devices and I was really impressed. Used it once about May and then again last night [I have a Tacoma that I swear came with gremlins]. It was fully charged back in May, no topping off since. Last night when I couldn't start truck, hooked it up, tried to start and it turned over fine but died, shoulda kept the key turned a bit longer, the 2nd attempt it started right up just fine. I checked the thing's charge state and it showed all 4 LEDs meaning it was still fully charged, that was surprising. I'm going to recharge it through a tester and see how much it lost.

As to jumping, if that causes your alternator/charging system to fry your vehicles electronics, it's a very bad design and the engineers behind the design should be sent to re-education camps.

I seldom hook up the negative cable to the frame, every once in a while it's more convenient but that's rare, I've forgotten why that's supposed to be the way to go but I think it might have to do with the gasses released by the batteries, not sure if that's even still a thing.

I always replace my vehicles batteries with deep-cycle batteries since even a single draining of most regular batteries will significantly degrade them, which is something I will inevitably do in time, a short time.

 

[bearthebruce]

Ref: Post #60

@LittleBill21 - You have heard of inductance? When the jump cables are disconnected, the inductance of the circuit is changed.

An inductor likes current to keep flowing at the same rate. If that current is abruptly changed (reduced in this case on the donor alternator), the voltage wants to fly to infinity in an ideal inductor. It is limited only by the resistance in the circuit in the real world.

Yes, I can see where a voltage spike could occur and that spike might have a damaging effect on components not properly protected.

Working in the auto diagnostic industry, I'm pretty sure most of the control modules have protection from such spikes. That said, can those protective devices clamp all voltage spikes and keep them from harming the control modules? That is a study I have not done. Hopefully the control modules designers have considered the spikes.

 

[bearthebruce]

I also have VCDS (tool that does 99.9% of what any factory tool can do), in which case if I had to I wouldn't be in a panic.

Thank you for being our customer. Don't leave home without VCDS! It should always stay with the vehicle!

 

[etpm]

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 a

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.

This link explains it well: https://en.m.wikipedia.org/wiki/Load_dump .
Eric

 

[LittleBill21]

This link explains it well: https://en.m.wikipedia.org/wiki/Load_dump .
Eric

ok but at no point is there a disconnected battery in the system, this is my issue here. the sink would just go to the now seperated battery.

 

[bearthebruce]

You are correct @LittleBill21 . The battery will act to absorb some of the energy. The question is how much and to what degree. @etpm is also correct that the voltage on the system may fly to a substantial high voltage.

Note the article does say there are protection devices built into the auto electrical system that should clamp the voltage to within a tolerable value. What they did not say is that if there is enough energy, these protective devices may and can be damaged so that the next time such an event occurs, they let the voltage spike higher. The protection device can only handle so many joules of energy before they are damaged.

Again, I would think that the vehicle control module designers have allowed for jumping a battery. I continue to say, check the vehicles operating manual to verify the proper method for jumping.