You should have been able to start the car if it was connected with good jumper cables to another car that has a fully charged battery and whose engine is running. Maybe there wasn't enough current being supplied. If the cables are too small or the connection too poor, try this. Allow the run down battery a few minutes to take on some charge before trying to start. Try letting it charge for 10 to 15 minutes.

You did not state if the starter was able to rotate the engine. If there were no action, there are other problems to diagnose.

We need more information. Did the starter spin the engine with what seemed enough speed? When you turned the key to the ignition position, did you detect the sound of the electric fuel pump? Does this car have an anti-theft system?

Have you measured the voltage of the battery at no load? If it measures less than 12 vdc, it may have a dead cell.

Wait a minute; I'm making too many assumptions. I am assuming this is a late model car with the usual electronic engine control scheme. What make, model, and year is this car?

After you get the car started again, consider using a battery charger to keep the battery in shape. This can be done in one of two ways. Apply a standard charger for an hour each month or until the charger indicates the battery is charged. As an alternative, apply a low amperage battery tender style of charger. These typically supply no more that a couple of amperes and tapers back as the battery voltage rises. These can be left connected for long periods of time, but do read its instructions. If you are uncomfortable about leaving a charger unattended for a long time, apply it for 8 to 10 hours once or twice a month.

Thanks, jemdanday, for all that info.

It's a 2004 Toyota Corolla with no anti-theft device. When I turned the key the other day, the dashboard lights went on but there was no sound at all from the engine. I then connected to a good battery, engine running, using jumper cables with thick wires and clamps, but still no sound from the engine.

Yesterday, I measured the battery voltage: just under 8 volts. The first three times, I turned the key, again no engine sound. But starting with the fourth try, I could hear a constant clicking as I held the key. This was without connecting to a good battery. If I scrape off some of that yellow/green coating around the positive terminal of the good battery, would my chances of successfully jump starting be better? Any more advice appreciated.

Lets get back to the old battery in the Corolla. It has a 12 v battery and the battery is composed of 6 cells each at nominal 2 volts. You are reporting 8 volts indicating that 2 cells are dead. Those could be fully discharged or shorted.

Try charging the battery. If you can not apply a battery charger, do this. Connect the jumper cables and voltmeter to the bad battery. The connect one jumper lead to a good battery in a vehicle with its engine running, and temporarily hold the second lead to the good battery. If you do not see the voltage rise very much on the dead battery, disconnect immediately because you are trying to charge a battery with shorted cells and it is pulling too much current from the good system. Replace the bad battery.

If the voltage rises to 12 volts, allow the depleted battery to charge for 10 to 15 minutes, then try to start the Toyota. If the engine starts, disconnect the jumpers from the good battery and keep watch on the voltmeter. If the Corolla can not maintain 12 v, its alternator may not be supplying enough current. When fully charged with a running engine, the battery voltage will be above 12v and should never be above 14v.

At 8 v, very likely, your Corolla's system will not produce ignition sparks. and will not fire any cylinders.

Not knowing the history of your car and battery, I can only guess. At this point, my guess is that you battery has failed and should be replaced. If the battery is over 3 years old, its probably replacement time.

One thing that we have not determined is the health of the charging system in the Corolla. Upon replacing its battery with a good one that has enough charge to get things running, the voltage at the battery terminals should read a bit above 12v (with engine running). If not, the charging system is likely weak; If the voltage is less than 12 v, then the charging system has failed.

I recommend anti-corrosion washers on the battery posts. These are large impregnated felt washers that go over the battery posts and under the cable connectors. The ones that I have used are red and green. One goes on the negative post and the other goes on the positive post. The package identifies which is which. In my experience, these do help.

One other thing: If your battery had discharged cells and experienced cold for a couple of hours of more, maybe a temperature of 15F or less, the battery could have frozen. One serious damage is a cracked case that leaks battery fluid in the car. If it it not leak, freezing can do internal damage. (I do not know at what temperature a discharged battery will freeze. I do know that it can.)

The Corolla started! Thank you, jemdandy, for the expert advice. After connecting the batteries and letting the bad one charge up for 15 minutes, it started right up. I let the Corolla run for an hour with a lot of it at 2000rpms, as the owner manual recommended. The owner will be back next week, so I'm glad it's working again. Thank you.