We have a 2000 Rav4 that's been sitting for quite some time. We jumped the car and it started right up. After running it for a few minutes we turned on the headlight. Immediately after that, everything died including the engine. Now nothing works regardless of whether we try jumping the car. Any thoughts?

Thanks,

Jim

lets start with your dead battery, yep, dead. Meaning that one or more cells (you have 6) are dead. The internal plates have touched each other or they are done. If you look at the indicator on the battery it might even be showing fully charged, well that only shows you that cell, the other 5 are not indicated. I cannot imagine that it is the original but if it is, well done, now get a realy good battery with a high CCA number (772 or higher). They start at about $140 (cdn).

Jumping the battery is just that, its a by-pass taking it out of the equation. Once the engine comes to life you un-hook the cables, and then your running off the dead battery. Since it wont hold a charge the alternator is useless and whatever charge that remains will not operate the electrical system and shuts down.

Good so far.



Nope. Sorry. The battery is completely dead so the engine cannot run off the battery. There is nothing to run off. It is running off the alternator only. The alternator is not useless. Unlike a battery an alternator will not go bad simply because it has not been used for several years. The battery was jumped and the engine was started from the power of the other battery. Once the engine started the alternator kept the engine running. However, the alternator was also working extremely hard trying to charge the completely dead battery. The alternator didn't really have a choice in the matter, the dead battery was a huge power draw. When the lights were powered up the alternator could no longer keep up to the demand and the computerized fuel injection/ignition system, which requires significant amperage, failed to function due to voltage drop and the engine died. With the battery still stone cold dead the entire car was again without power. Replace the battery and the car should be fine.

It is absolutely necessary to remove the battery from any vehicle that will sit for long periods of time. Remove the battery from the vehicle and bring it indoors and put it on the trickle charger overnight once every 2 months or so to keep it charged up. Leaving the battery in the car subjects it to continuous cold weather without ever warming up or being recharged and the clock will continually completely drain the battery even if it is not illuminated in as little as a few months. An alarm system will drain it far more quickly. Also cars equipped with remote starters or remote door lock FOBs will also drain batteries quite quickly as those systems always remain powered up on standby awaiting a signal from the FOB.

Nope. Sorry. The battery is completely dead so the engine cannot run off the battery. There is nothing to run off. It is running off the alternator only. The alternator is not useless. Unlike a battery an alternator will not go bad simply because it has not been used for several years. The battery was jumped and the engine was started from the power of the other battery. Once the engine started the alternator kept the engine running. However, the alternator was also working extremely hard trying to charge the completely dead battery. The alternator didn't really have a choice in the matter, the dead battery was a huge power draw. When the lights were powered up the alternator could no longer keep up to the demand and the computerized fuel injection/ignition system, which requires significant amperage, failed to function due to voltage drop and the engine died. With the battery still stone cold dead the entire car was again without power. Replace the battery and the car should be fine.
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I see your nope and raise you a 'I dont think so',

The alternator is not self exciting like a generator is. The field must be supplied (excited) with 12vdc (from the battery) in order to induce magnetism in the filed winding. While in perfect operating conditions: the magentic field is broken by the pole pieces (rotor) that spins through this field to produce alternating current (ac) in the alternator, this current then passes through at least three diodes which rectify the ac and converts into useable 12+ volts direct current (dc) voltage. without the battery your alternator is as helpfull as your air conditioning compressor in charging your vehicle.....

...that doesnt solve the main problem on what killed the battery in the first place...if any or all of those diodes I mentioned were to stop working, voltage will be allowed to pass through this and create a circiut, dead battery in no time,,,,...the point being, once you have the power source fixed, you must insp the alternator. Then everything else...

The alternator will generate power as soon as the engine starts up because once the engine is running the alternator is turning thereby making power. The battery is no longer needed for the purposes of supplying power to run the engine so disconnecting the cables will not by itself kill the engine. Since the battery is part of the electrical system the alternator has to try to charge the battery. A completely dead battery is a tremendous draw. Running the engine's power systems AND charging a completely dead battery is very likely the absolute limit of the alternator's capabilities and in older vehicles with smaller (lower output) alternators it would very likely be a task beyond the alternator's ability and in those cars the engine might then possibly die if the jumper cables were removed too soon before the car's own battery could take some charge and help out..

The battery died due to a long period of inactivity.

please stop trying to correct me, I do this for a living...

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