# Giving my car a boost...

**URL:** <https://boards.straightdope.com/t/giving-my-car-a-boost/4755>\
**Category:** Factual Questions\
**Created:** [November 6, 1999, 4:11pm UTC](https://boards.straightdope.com/t/giving-my-car-a-boost/4755 "1999-11-06T16:11:00Z")\
**Posts on this page:** 2\
**Page:** 3

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**Author:** ![NanoByte](https://avatars.discourse-cdn.com/v4/letter/n/ecc23a/32.png) [@NanoByte](https://boards.straightdope.com/u/NanoByte)\
**Post date:** [November 16, 1999, 8:05am UTC](https://boards.straightdope.com/t/giving-my-car-a-boost/4755/41 "1999-11-16T08:05:00Z")

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MC (11-09 08:08):

Speaking of a voltage as a “load” makes no sense in electrical theory/engineering. Are the instructions worded that way? If you just run your alternator on your own healthy battery, you have it charging through some resistance into the 12-volt voltage source that is your battery. If you put someone’s battery that is dead, but is not shorted, across _ **your** _ battery, you have essentially the same thing. If you took _ **your** _ battery out of the circuit, leaving the bad battery in (which I wouldn’t expect you to do), maybe some condition is set up that is harmful to the alternator, but I wouldn’t, off hand, understand what that would be.

Almost all the time, a dead battery is simply the result of a light being left on or battery that won’t take a sufficient charge or a defective charging system (in the car with the bad battery), in all of which cases, the charging shouldn’t hurt the alternator in the servicing car. Almost always, a successful start will take the party to where they can go prior to their next stopping their engine.

torq:

I would call a shorted (across all cells) battery an _ **infinite** _ load, not a situation of “no load”.

Ray

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**Author:** ![cornflakes](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@cornflakes](https://boards.straightdope.com/u/cornflakes)\
**Post date:** [November 16, 1999, 9:28am UTC](https://boards.straightdope.com/t/giving-my-car-a-boost/4755/42 "1999-11-16T09:28:00Z")

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> [@](#):
>
> pmh: Free tip: After installing the battery, spread a thin coat of grease over the cable connections. This seals out the air and minimizes oxydation/corrosion.

I agree. Also, as cheesy as they seem, the little felt washers that go under battery lugs seem to work; I’ve had better luck with them than with grease alone.

> [@](#):
>
> Actually, the wiring harness does contain a ‘fusible link’ (or equivalent), A high resistance wire (or slo-blo fuse) designed to melt at about 1.5X the max normal operating current. Sadly, though, it does nothing for short duration pulses.

You’re right, the link won’t stop any voltage spikes that could kill the IC compnents (that got past the battery and all the filter caps???) I was more thinking along the lines of a varistor, a zener (God forbid! I’ve worked around British bikes!!!) or some other voltage surge suppressor that would shunt voltage spikes to ground (it’s been a long time since I covered this in school, but isn’t a varistor a resistive device that has a high resistance at low voltages and has a low resistance above a threshold voltage?

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