my battery is dead!!

the only things that were on were the dome light and the glove box light (overnight). how long would it take for the battery to go down to 5 volts using just those lights? could there be some kind of voltage drain that I don't know of?

also, which is better: trickle charging the battery, or using a charger to put 12V into it and starting the car that way then let the alternator charge the battery?

If you read the fine print when you buy a new alternator they say that using the alternator to charge a low battery will cause harm to the alternator. It would be best to use a charger to get the battery back to 12 volts before starting it.

I'm not sure of the exact time it would take to deplete the battery but you would be surprised how fast even the small bulbs will drain a car battery.

As HMSPORTS says, it takes a surprisingly short time to drain a battery with even small current drains. (Moreover, we shouldn't assume the battery is fully charged just because we ran to the post office and back.)

Using your alternator is an expensive, and very inefficient, way to charge a battery. If your Z is a hard-starter like mine is, you will have to drive quite a few miles for the alternator to just "replace" the charge you used when starting it up.

IMHO, a small, cheap battery charger should be Basic Tools for anyone with an old car. You don't need an expensive one with all the bells and whistles. In addition to old cars, I also have boats (with electric motors) - my no-frills charger paid for itself years ago.

I have this left over from my motorcycle days (which aren't completely gone!).

I have what is called a "Battery Tender". It comes with either clips or a hard mount plug adapter that connects to the battery. It charges at a rate of 1-1/2 Amps and will shut off automatically when fully charged. Then if your battery drains a little, it will turn back on and charge until the battery is fully charged again.

This unit will set you back about $45-50, but it works great for a car that sits long periods of time without being driven.

First I would get the batt cells checked to see if it will hold a charge. The acid level in your battery may need topping up as water will only evaporate. Trickle charge is always better for your battery as it reduces the risk of over charging or overheating your battery.

  kmack said:

I have this left over from my motorcycle days (which aren't completely gone!).

I have what is called a "Battery Tender". It comes with either clips or a hard mount plug adapter that connects to the battery. It charges at a rate of 1-1/2 Amps and will shut off automatically when fully charged. Then if your battery drains a little, it will turn back on and charge until the battery is fully charged again.

This unit will set you back about $45-50, but it works great for a car that sits long periods of time without being driven.

I bought a Battery Tender Jr. for $32 from Pep Boys. Works great.