Jumper cables and possible surge issues to car electronics

[videobruce]

According to Pat Goss of Motorweek, you should "throw out your jumper cables" because of the potential of power surges when jumping new vehicles. This may not happen at the time, but surface weeks or months down the road (no pun intended) when 'weird' things start happening. Similar to computers when a bad PS, processor etc. ends up causing unusual unrelated program errors.

I believe he has mentioned on one of his programs there are cable assemblies available that have some additional 'surge' protection included (something connected in line) to prevent this.

He has been very adamant about this. What do you guys say?

[crank.it]

hey bruce-where can I go to see and hear what mr goss has to say....any links ...crank.it

[videobruce]

Quote:hey bruce-where can I go to see and hear what mr goss has to say....any links ...crank.it

Your local PBS affiliate.

[Harvester]

I suppose anything is possible, but by following the generally-accepted procedure of connecting the positive cable first to both batteries, then connecting the negative cable to ground on both vehicles, the probability of producing a damaging transient voltage is reduced. With that sequence of connecting cables, if a spark occurs, which it probably will, the transient voltage will be attenuated by the length of the booster cables and by the ground mass (the vehicle) and the batteries on the negative side. Any power-consuming accessories should be turned off, as much as possible, as should automatic headlights, when boost-starting a disabled vehicle. After boost-starting a vehicle, the two engines should be brought to approximately the same speed before disconnecting the booster cables, which should disconnected negative first, then positive.

It seems to me that there are many more potentially damaging transient voltages being produced during normal operation (starter solenoids at a couple of hundred volts), ignition systems (primary voltages at 300-400 volts peak) to be concerned with a spark from booster cables, although that kind of spark can be powerful and of fairly long duration compared with solenoid and ignition voltages.

After all this is said, I wouldn't discount the idea of damage caused by boost-starting, but I wouldn't loose any sleep over it, either. Automotive electronic components have evolved over quite a few years, and it didn't take manufacturers long to realize that dead vehicles from electronic failures are bad for business. Also, many electronic components have an Automotive Grade, which carry specifications that are higher than MIl-spec for severe service.

And in a practical sense, what will a service truck do upon arrival to your dead car when you call them? They'll probably try to boost-start the car, unless you specifically tell them to tow it away. Then what?

Beyond the original question, after boost-starting a disabled vehicle, I have recommended letting the engine idle, turning on the high-beam headlights, windshield wipers, heater/AC, and stepping on the brakes. If the engine keeps running, it is a good indication that the alternator is functioning; if the engine stops with all that load, probably the alternator is not working, and the vehicle is likely to stall at the first intersection where the engine is brought idle and the brakes are applied, especially if there are any other electrical loads on the system. Better to find that out in a parking lot than at an intersection- after the service truck left.

Harvester's view.

Harvester

[videobruce]

Quote:many electronic components have an Automotive Grade, which carry specifications that are higher than MIl-spec for severe service.

Never heard of that before.

Quote:after boost-starting a disabled vehicle, I have recommended letting the engine idle, turning on the high-beam headlights, windshield wipers, heater/AC, and stepping on the brakes. If the engine keeps running, it is a good indication that the alternator is functioning

If the alternator was bad, wouldn't the engine die without turning lights and accessories on??

[Harvester]

Re the first quotation, the component catalogs list specifications and grades of service. Typical grades are commercial for general purpose and consumer products; industrial for more durable components; military for severe service; automotive for service peculiar to the automotive environment. Automotive and military grades are not necessarily the same, and a specification in one grade may exceed the same specification in the other grade, depending on the certifying test, and what is considered important for the application.

Re the second quotation, yes, and sometimes the boost-started engine will stop upon disconnecting booster cables. Often, the dead battery will get enough charge from the boost vehicle to keep the disabled engine running for a short time. Without an ammeter in most vehicles now, it is not apparent if the alternator is functioning, so I use the electrical load technique to provide a quick check on the alternator. It may not be functioning fully, but more than likely it is functioning enough to keep the vehicle running long enough to get to a shop. I could have clarified that point.

Harvester