Piston Slap: Don't Jump to Conclusions!

TTAC commentator Towncar writes:

I just recently had a dead battery on the Town Car, so learning how to properly jump start a car battery has been on my mind. I’m telling you, there’s a lot to say on this subject once you get into it!

1. Do you really have to put the negative clamp on some exposed part of the cars body, which will probably be inconveniently located and totally greasy, when the negative battery terminal is sitting right there, handy and probably clean enough to make contact?
2. What about those things that are supposed to plug into the cigarette lighter and give you a jump that way — will they work or burn the car down?
3. And those little pocket-size jump boxes — any good?
4. Can you damage the electronics in a modern car with a jump? (Assuming you don’t reverse the clamps.)
5. And have you seen those plugs they have in the grilles of some service vehicles — they just stick in a cord, the other end has clamps, and there you are. Why doesn’t every vehicle have a plug like that? A plug-to-plug connection would get around the whole clamp business anyway.
6. Or why don’t cars just have two batteries?
7. Or why don’t they all have battery run down protectors? Should you install one of those protector things if your car doesn’t have it?

Sajeev answers:

Talk about a loaded query! Let’s do this thing:

1. Yes because a spark can ignite a de-gassing battery. Granted I am SUPER GUILTY of this, but after a bit of Googling I learned my lesson. And all batteries vent, no matter the design? If you don’t have a clean ground, clean your engine and check the condition of your negative battery cable/grounds…killing multiple birds with two stones.
2. I assume they work, just not with the speed you’d expect. Backfeeding juice is limited by the wire/fuse size, but hey, if I can backfeed power to a hurricane-damaged house with a gas generator wired via the dryer connection…why not?
3. See #2
4. Possibly but not likely: that’s what fuses (and fusible links, if equipped) are for.
5. Cars are too expensive and littered with fail points as it is: no thank you!
6. See #5 and keep in mind that many modern, fuel/emissions efficient sports sedans weigh not much less than your rather simple Town Car.
7. Run down protectors are a good idea, but I’d never spend the money or time to install one on an older vehicle. That’s what jumper cables in the trunk are for.

Final thoughts, Best and Brightest?

[Image: Ford]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.