smithk993

My 01 with 30k miles is having problems staring. It's like the battery is dead, dash lights come on but just clicks and won't start. I put a charger on it for couple of minutes and it starts OK. Runs fine after. The voltage gauge shows 13 volts. I've run it for a while and next day same thing.

I took it by and Advance Auto and they tested with their meter. Says battery is fine, it's about 1 year old, alternator is showing charging OK. We shut everything off and they said it showed a draw of .9amps. This was with everything off including pulling the light in the front trunk. Does this sound like a normal draw or is this enough to run the battery down so quick?

Looking for ideas before I have to go to the dealer!

Thanks.

nick49

Clicking is the solenoid making contact but there is not enough current to turn the starter motor. Make sure the battery cable connections are tight. If so, it sounds like the battery. Sorry, don't care what who ever tested it says. I've gone thru 6 or 7 batteries between the Boxster and 996 in 15 combined years of ownership.

The worst killer of batteries is sitting for a few days letting the accessories consume the current. This drastically weakens the battery irreverasbly. Eventially the battery will discharge quicker and take longer to recharge until it becomes useless. I should know better, I've understood this for almost 40 years but about 18 months ago put a tender on wife's Boxster, no more problems.

You need a battery! ... hate to recommend my least favorite place to shop, but Walmart had the best warranty, and somewhat important, the best price.

Your .9 amp draw is about 11 watts, like burning a license plate light continually. (illustrative, I actually don't know the wattage of that lamp, but it's close) This is enough to make the car not start if not run for a couple of days.

mdd

The current draw with everything off and the alarm set will likely be in the 900mA range for about the first 20 minutes. Seems that some modules stay partially active for a while. After 20 minutes of being locked, it should drop to less than 50mA.

If it really is 13V (as in 13.0V read with an accurate meter at the battery) with the engine running, that's way too low. Not much battery charging going on there. What happens to the voltage when you turn on the AC and headlights?

Feel free to give me a call and we can get together to take a look. I could help you poke around a bit before resorting to the dealer visit.

Centauro97

Electrical diagnostics let you really play detective.

You're ruled out the starter and main battery cables since it jump started OK. With a low battery and just started the voltmeter may only show 13 volts initially. With the RPM increased it should increase closer to 14 volts then hold near idle.

Battery chemistry is very interesting. Read up on sailboat electrical systems if you really want to learn about electrical systems and batteries.

The short version is that lead-acid batteries charge pretty quickly to about 80% capacity then can require hours of charging to reach 100%. As you start, drive short trip, stop, restart...repeat, your battery stays at less than 80% charged causing the plates to sulfate. Which reduces its charge capacity, repeat, until it looks good on a quick voltage test but has little to no reserve capacity.

Load testing is only performed, correctly, on a fully charged battery. Not sure what test was done on the battery. Do you know? BTW is Advanced Auto where it was purchased (and where it would be warranted?)

nick49

All good advice, and another thing to consider is a weak battery will pull lots of current from an alternator and the charge on the volt meter will be lower than what is actually being put out. With a fresh fully charged battery the alternator output will register higher. With a suspect battery, the voltmeter reading is not represenative of actual voltage output.

BostonDuce

It takes hours for the car to go into full sleep mode.

Check for weak cables, or connections before you start throw down the checkbook.


BD

mdd

If you do not set the alarm, it is true that it could spend hours in a high current state.
However, set the alarm (using the lock button on your key) and it will be in low power mode within about 20 minutes.
To get the alarm activated and everything in low power mode with the hood open, you must flip the hood latch closed manually before pressing the lock button.

Kevinmacd

13 volts is to low, you should see about 13.8volts I suspect you may have lost a diode in the bridge. Not enough to keep up with the acessories and charge, therefore, not charging enough. Enough to keep the car runing but not enough to charge the battery to it's full potental. Can you put an amp meter on and start turning on accessories. This will definity tell you, or take it to a shop that can put a load on the system.