OT Jump Starting a Newer Vehicle

super99 · Nov 20, 2017

Saturday morning on WMT, Cedar Rapids, Ia radio they have Jay Cassill and the car geek hour. He was talking about jump starting a newer car or truck. He recommends hooking up cables or start box and leaving it hooked up 10 or 15 minutes before trying to start the dead vehicle. After it starts, leave cables hooked up for 5 minutes before unhooking them. His reasoning is that the alternator will send a surge thru the electrical system if the battery is too low trying to build the charge level back up quickly. That power surge can destroy your radio or other sensitive electronics on your vehicle. I haven't had to jump a car or truck in years, tractors, yes. I was taught to unhook cables as soon as the dead vehicle starts and let it run to charge up the battery. I guess his method makes sense. Chris

RM-MN · Nov 20, 2017

If the voltage regulator is working the voltage will go to 14.2 and stay there until the battery is charged. If it burned out the radio you have other problems that probably are related to the dead battery.

Russ from MN · Nov 20, 2017

I have always ran the good vehicle for a few minutes before trying to start the dead one, as long as they are similar. I don't do that with motorcycles or when jumping a 6 volt with 12, and I have done that successfully a few times. I have never heard of leaving them connected after starting, I don't think I will do that.

David G · Nov 20, 2017

I think letting it charge for a few minutes is prudent, doubt it needs to be hooked up more than a few seconds after starting.

Arvin Haslem · Nov 20, 2017

I always turn on the lights and heater fan motor of the vehicle giving the jump to absorb voltage spikes while I hook up the jumper cables.

Steve@Advance · Nov 20, 2017

I agree with leaving the jumpers connected for a few minutes to try to build the dead battery up before trying to start.

That is if the person doing the jumping is willing to wait around for that to happen. Typically getting a jump, you are at the mercy of the person offering to help.

As for leaving the cables connected, never been a fan of that. I've had strange things start to happen, relays clicking, general confusion over the give and take. I get them off ASAP.

Now, there is a real danger of a surge when the cables are removed under certain conditions. One is if the reason it needed jumping was because one of the cables was not making connection with the battery, as in loose or corroded. The other would be if the battery had failed internally, an open connection so the battery was not there to take the charge when the engine started. Either case would be the same as disconnecting the battery when running.

Jump starting any vehicle should only be done in an emergency. Trying to bring up a discharged battery with the alternator can over heat the alternator or burn out a fuse or fuse link. Trying to jump a totally dead battery is asking for trouble.

Stephen Newell · Nov 20, 2017

Just re-enforces my theory that everything electronic is designed by someone on crack or some other drug. Who has 20 minutes to kill trying to get a car started to go to work.

showcrop · Nov 20, 2017

(quoted from post at 17:33:47 11/20/17) Saturday morning on WMT, Cedar Rapids, Ia radio they have Jay Cassill and the car geek hour. He was talking about jump starting a newer car or truck. He recommends hooking up cables or start box and leaving it hooked up 10 or 15 minutes before trying to start the dead vehicle. After it starts, leave cables hooked up for 5 minutes before unhooking them. His reasoning is that the alternator will send a surge thru the electrical system if the battery is too low trying to build the charge level back up quickly. That power surge can destroy your radio or other sensitive electronics on your vehicle. I haven't had to jump a car or truck in years, tractors, yes. I was taught to unhook cables as soon as the dead vehicle starts and let it run to charge up the battery. I guess his method makes sense. Chris

I was taught that the electrical equipment DRAWS current and that the generating equipment fulfills the need, except in the case of an opportunity draw such as a short circuit or a major high amperage source such as lightning, where it can get pushed. People seem to love to talk about power surges.

NEKS · Nov 20, 2017

Jump started a New Holland 100 HP tractor about a 2014 model. Had enough juice to run the radio. After getting it started the radio never worked again. Now you guys have me wandering what to do next time.

old bc · Nov 21, 2017

The lithium jumper pack I have says to unhook it
with in 30 seconds of starting or it will damage
the unit.

Mike M · Nov 21, 2017

Motor Week Pat Goss suggests to NOT EVER jump start these newer vehicle's ! Just too much electronics to get damaged. Also says it may not show up right away but could months down the road.
While he does have a valid point I still needed mine jumped once to get back to work from lunch on a weak battery. And I also jumped my lawn mower off my car so I could finish mowing and put it in the garage where I could remove and replace the battery.

BarnyardEngineering · Nov 21, 2017

With answers from "experts" being all over the map, this is just another one of those subjects where there is probably NO RIGHT ANSWER, and it probably DOES NOT MATTER what you do.

These people are coming up with all sorts of smart-sounding reasons why you should do it their way, and they make it sound really convincing, like they know what they are talking about. The truth is, they don't. Either they are going off what they heard at the coffee shop like everyone else, or they had a problem one time that they would've had no matter what they did.

Some of this is just as silly as saying, "I scratch my right buttock three times before jump starting a car, and never had a problem. If you scratch your right buttock three times every time you jump start a car, it will work fine."

Crazy Horse · Nov 21, 2017

Our local AMA rescue trucks make hundreds (probably thousands) of jump starts every day when it gets cold up here ....... I'm sure they know what they're doing or they wouldn't be doing it for a living. I don't remember them waiting around for any amount of time once the dead vehicle fires up. If anyone has the time, maybe 1) take a look in your owner's manual to see what they have to say or 2) phone the dealer who sold you the car and ask them. Probably get a more accurate answer than asking here on an old tractor forum.

jimg.allentown · Nov 21, 2017

If a battery is completely dead, most jumper cables simply will not conduct enough current to start the dead one. That would be the reasoning behind leaving the cables connected for a few minutes before trying to start the dead one. That allows the dead battery to absorb some charge before trying to start.
Leaving the cable connected after starting is not necessary for any reason I can think of. Assuming that the dead vehicle was not the result of a failed battery or charging system, There should be enough output from the alternator to run the vehicle.

However, alternators were never intended to be used as battery chargers. Their real purpose is to maintain the electrical load imposed by the vehicle's accessories and to maintain the battery at full charge.

Dean · Nov 21, 2017

Sounds like an old (or, perhaps new) wives tale.

Your vehicles electrical system is protected against load dump (surge).

Charging a dead battery from the vehicle alternator will damage nothing if all else is well.

Dean

JDEM · Nov 21, 2017

Sounds like a bunch of nonsense to me. Every time you start a car there is an instant surge of charge current. I kind of wonder what this "expert" gives as a reason why newer vehicles are somehow different? Granted some have no regulators in the alternator and a chip in the main computer does the work. Same voltage-sensing principal. By the way - I just helped my 80 year-old mother-in-law buy a new Ford. Many of the new Fords on the lot had dead batteries. Dealer jump-started the new Escape she tried out. No problems, and nothing "burnt out."

Ken Macfarlane · Nov 21, 2017

I think the unhooking asap comes from the issue that some charge regulators don't play nice connected together. If you have a nice dead battery with long jumper cables to soak up the charge and dampen voltage spikes its not so bad. In particular I have a pair of early 4 stroke outboards with yamaha powerheads. If you connect them to a single charged battery at the same time and start both, one stator will burn out. Many of the newer models are protected from this and its not a problem. Its pretty expensive to find out if they don't publish it.

Comes up more often when you have a small kicker motor with a charge circuit as you're less likely to have multiple batteries.

Ken Macfarlane · Nov 21, 2017

Maybe not but the 100 amp alts with computerized voltage regulation that come in everything these days make about the finest battery charger around.

buickanddeere · Nov 21, 2017

The concern is burning out the alternator with a dead battery which the electrical system sees as nearly a dead short . The 20 minutes of charging puts some charge on the dead battery to reduce the alternator load.

showcrop · Nov 21, 2017

(quoted from post at 05:53:21 11/21/17) With answers from "experts" being all over the map, this is just another one of those subjects where there is probably NO RIGHT ANSWER, and it probably DOES NOT MATTER what you do.

These people are coming up with all sorts of smart-sounding reasons why you should do it their way, and they make it sound really convincing, like they know what they are talking about. The truth is, they don't. Either they are going off what they heard at the coffee shop like everyone else, or they had a problem one time that they would've had no matter what they did.

Some of this is just as silly as saying, "I scratch my right buttock three times before jump starting a car, and never had a problem. If you scratch your right buttock three times every time you jump start a car, it will work fine."

Barnyard; it appears that you need to put your email address up so that we can all send our posts to you to screen out the worthless and erroneous ones, in order to insure correct information only on these forums.

Brian Jasper co. Ia · Nov 21, 2017

For a while they do. Forcing the alternator to run the car AND recharge a dead battery is the number 1 cause of repeat alternator failure. A 6.0 Powerstroke needs 60 amps to run the engine only. Lights, HVAC, radio are above and beyond. They typically were built with a 110A alternator. So how long is an alternator going to live being maxed out for an extended amount of time...

Brian Jasper co. Ia · Nov 21, 2017

I've heard him on the radio, but he's hit and miss on reality. Jump starting new cars....miss...

Roger in Wisconsin · Nov 22, 2017

Agreed

notjustair · Nov 22, 2017

Could be. I was in a rush and jumped the 4440 one day. The spike in volts burned out the TeeJet sprayer monitor which was apparently very sensitive. That was an expensive lesson. Any time I have any sort of electrical issue the first thing I do is uplug all of the monitors. I put a new digital radio in it a month ago. I think I'll pull that fuse, too.

mj · Nov 22, 2017

'If God intended for humans to work with electrons He would have made them big enough to see.' :lol:

cbop · Nov 22, 2017

(quoted from post at 02:25:19 11/21/17) The lithium jumper pack I have says to unhook it
with in 30 seconds of starting or it will damage
the unit.

Not only will it damage it, it will likely blow up or catch fire. They are not designed to take a fast dump of amperage into them

sotxbill · Nov 22, 2017

WOW... like the guy who says to turn on all the lights and a/c to help the battery come up faster????

ITS THE INTERNET... where everything you read is....... usually wrong....

Unless the other vehicle has a dead short...... voltage regulators will not let the voltage go above 14.2 volts...

In the late 60s... they drove a car across the usa,,, with no battery, only a motorola alternator.. as a pr stunt.. yes. the regulator sets the maximum voltage at all times... Every morning they would jump start the car, then continue on the trip with no battery.

OT Jump Starting a Newer Vehicle

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