Be doubly positive about procedure when jumping a car battery

It was a day like any other day at first, but then the car battery blew up. I'd jumped hundreds of dead batteries before. And I knew to be cautious because of the explosive hydrogen gas a battery gives off. But when I jumped the dead battery in my wife's car, my caution must have slackened. The battery blew sky high. It sounded like a shotgun blast, shattering the top of the case and spraying the pieces all over the yard.

It was sheer carelessness. My mistake was making the last jumper-cable connection to the dead battery. When I did, it apparently caused a spark that ignited the hydrogen gas that's vented to the atmosphere from the battery's six cells. ``Most battery explosions occur when jump-starting a car battery,'' reports Dennis Hirschfelder of the National Society to Prevent Blindness, based in New York.

Mr Hirschfelder suggests that drivers of vehicles equipped with maintenance-free batteries get assistance from a service station before trying to jump-start a car with a dead battery.

Don't be deceived by the words ``maintenance free'' he warns. ``Despite their sealed appearance, these batteries do provide for the venting to the atmosphere of explosive hydrogen gas.''

But if you do have to jump a dead battery, here's how to do the job right: First, be sure the dead battery is not frozen. If it is, do not try to jump it.

Keep open flames away from a dead battery.

Be sure the two cars aren't touching. Set the parking brakes on both cars. Shift an automatic transmission into ``park'' and a manual transmission into ``neutral.'' Turn off both ignitions.

If the battery uses water, add to the correct level. Replace the caps and cover with a damp cloth.

Verify that both batteries are negatively grounded and are of the same voltage, either 6 or 12 volts. Your owner's manual has this information. Generally, six caps identify a 12-volt battery; three caps, a 6-volt battery.

Put on safety goggles or glasses, preferably goggles.

Connect one jumper cable to the positive (+) post of the good battery and the other end of the cable to the positive (+) post of the bad battery. Then clamp the other cable to the negative (-) post of the good battery and to either the negative (-) post of the bad battery or the engine block.(SEE CORRECTION BELOW)

Start the car with the good battery; then start the disabled car.

Remove the cable from the engine block or negative (-) post of the car with the dead battery first; then remove the cable from the other car's negative battery post. Finally, remove the positive cable from both batteries.

And be sure that anyone who stops by with his jumper cables to help you really knows what he's doing. It's possible he doesn't or that he may have forgotten the proper procedure.

You can write to the National Society to Prevent Blindness, 79 Madison Avenue, New York, N.Y. 10016 for one of its bright yellow-and-black stickers that give directions for jump-starting a car correctly. Enclose a stamped, self-addressed, business-size (No. 10) envelope. The cost is 25 cents a sticker. Attach it to a clean surface under the hood as close to the battery as possible. Then the next time your car battery needs help, and you have a pair of jumper cables in the trunk, you'll know exactly what to do.

On Monday, Feb. 3, the Monitor ran a story on jumping car batteries. It advised connecting the second jumper cable to the negative post of the good battery and to the negative post of the bad battery or the engine block. While many people do connect the second cable to the negative post of the bad battery, it is much safer to connect it to the engine block, the frame, or any nonpainted surface of the disabled car. If the cable is connected to the negative post of the disabled car battery, there is the possibility of this final connection sparking and igniting hydrogen gas generated in the battery.