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2002 Acura RSX. Battery is fine all lights come on in car. Car will even almost start just missing that last step. I am only able to overcome the last step when I use jumper cables.

  • Battery is not good, just because it light lights, does not mean it will start the engine. Replace the battery. – Moab Aug 6 '16 at 17:22
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    How have you determined that the battery is OK? Get a voltmeter and measure the voltage across the battery terminals while the car is off, what do you read? (Or take it to your local auto parts chain and have it tested.) How old is the battery? – Jason C Aug 6 '16 at 17:22
  • I just charged the battery. Is there a way to test without a voltmeter. If not I will bring the battery in. – user262430 Aug 6 '16 at 17:26
  • Multimeters (with voltmeter function) are $12-$15 at Walmart :) – tlhIngan Aug 6 '16 at 17:27
  • So the consensus is it must be the battery even if all light in the car come on and the car almost starts? – user262430 Aug 6 '16 at 17:31
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It very well can be a bad battery even though the lights come on.

Starting the car is the single hardest thing (draws a lot of amperage) for the battery to do. If it is becoming weak, it will become harder and harder for it to crank the engine.

The lights and other accessories may still work because they draw less amperage (which the battery can still support).

Take the battery to have it load tested. That will determine if it is still good or not. If it is, then you need to start looking at the battery leads (large gauge wires) that go to ground and to the starter. If they are damaged or corroded badly, they can prevent proper amperage draw for the starter.

Since you said it starts with jumper cables, it is most likely a bad battery.

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As CharlieRB pointed out, just because the lights come on doesn't mean the battery is ok. However, there are a few other things it could be.

It could be that the battery is OK, but is not being charged sufficiently by the alternator. It could also be that the battery and alternator are ok, but that you could have what is called voltage drop. This means that the wire between the battery and starter is developing high resistance for some reason, and is not allowing sufficient amps to get to the starter. You could also have a starter problem.

If you really want to figure this out yourself, you should go out and get a cheap multimeter. Basically, you should see 12.65 volts with the car off, and over 14 volts with the car running and no loads turned on. You should also watch the multimeter while someone else cranks the car and see that the voltage doesn't drop below about 10 volts while cranking. If those things are OK, do a voltage drop test. Connect the red lead to the battery positive, and the black lead to the opposite end of the cable going to the starter and iirc you should not see anything larger than about 0.7 volts.

Here's a good video on testing a battery with a multimeter.

It could also be a starter problem, which you can read about here.

  • Just got a multi-meter will test soon and update the thread – user262430 Aug 23 '16 at 12:45
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I had that problem once; good battery but "Jumping" was occasionally required to start it. My problem was I had used a special research ( not commercial ) corrosion inhibiting grease on the battery terminals. The grease would seep between the terminal and clamp. Removing the clamp and wiping it would fix the problem for a week, then the grease would seep back. I know, hard to believe, but I lived with it for about a year. So, clean your terminals.

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Is your battery a side post by any chance? I have had the internal connection to the side terminal go bad several times. Jumper cables would start it, the battery was fully charged. Unfortunately I found no option but replacing the battery. I now have dual terminals, top terminals in case my side terminals break.

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Could be one of several things:

  • bad ground wire from engine to fire wall,
  • dirty or corroded terminals or wire to starter,
  • bad wire from negative battery terminal to body,
  • bad/dead cell in the battery (battery is bad),
  • alternator not charging properly (to check alternator start vehicle and disconnect the battery; engine should still run. If it shuts off alternator is bad.)

Check all your connections on battery, starter solenoid, and starter. Clean all connections in the starter system, positive and ground.

A vacuum leak could cause it not to crank: if a vacuum line is cracked it can suck to much air and will tell the brain/computer/ECM that the mass air flow sensor is getting improper air to flow ratio and cause it to in turn send signal to fuel injectors to run lean or rich, but it would most likely push an engine code in that case.

  • You have a lot of good data here, but could you reformat your answer so it's a bit easier to read? :) – kyle_engineer May 24 '18 at 20:36

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