How to troubleshoot a car not starting problem

Question

My car (a 2007 Honda CRV) has been intermittently starting hard, almost like the battery was almost dead but then it kicks in and is fine.

About 2 weeks ago I came out to the parking garage after work and it was dead. not completely dead just it spun up the starter and you could tell it wasn't quite charged enough because the starter slowed down very quickly and then eventually wouldn't even crank it over. I got the car jumped that time, but to get enough charge off the jumper cables we had to keep the RPMs up for about 5 min and then it only was just enough.

I went straight to our local repair shop and had them test the battery and alternator. Both checked out fine but when he first was checking it read unstable for a few seconds and then corrected itself.

From there I drove it about 20 miles, shut it off for about 20 minutes and it started right back up and I drove it home – roughly 20 miles.

It was good for about a week, then after that for about the next week it would do the intermittently act like it's drained thing but actually not start. At some point I noticed some mild corrosion on the positive terminal and thought it might not be getting a good connection. During the past week whenever it wouldn't start I would just pop the hood and twist the cable on the terminal just ever so slightly and the car would start right up.

Today I decided I'd clean the terminal and tighten the connections. After taking some Baking Soda and Water to the corrosion and terminal connection I cleaned and dried things up real good and now it won't start at all. The starter still tries to kick on but it never draws enough power to turn over.

I ran a trickle charge to the battery for about 3 hrs today (which is obviously not enough but it was just to see if it would give me anything at all) but still nothing. I checked the battery and it's at about 12.5 volts. My multimeter is a light duty job so I'm not that excited about putting it inline to measure the amp output while trying to start it but I think I measured it at about 100-ish amps while the car was turning 'on' (not starting). I believe the cold cranking amps on the battery is 400 something.

Where do I go from here?

Forgot to mention, the battery is only 19 months old. Warranty is 20 months full replacement. Not that it's all that relevant for troubleshooting but it seems odd it would go bad so soon if it really is anything to do with the battery itself.

Answer 1

Several thoughts:

• The most significant evidence to me in your question was"

  At some point I noticed some mild corrosion on the positive terminal and thought it might not be getting a good connection. During the past week whenever it wouldn't start I would just pop the hood and twist the cable on the terminal just every so slightly and the car would start right up.

  That makes me think, as you did, that the issue might be the batter connection. Cleaning is was the right thing to do, so just a couple of things to check there. First is to make sure that you know that the battery terminals are tapered. You can put them on upside down. If you do that it should be hard to get the terminal to go all the way down (i.e., it should be obvious, but might not be if the terminal was spread to make it fit). When the terminal is upside down it only makes a narrow band of contact and this could cause the symptoms you're seeing. Also, when you clean the terminals make sure to get the outside sides of the battery post and the inside of the terminal and clamp them firmly back in place.

• Also, if you could easily twist the terminal "ever so slightly" it was definitely too loose. Make sure it is on the right way around and if you can't tighten it to the point where it is good and solid replace it.

• Cheap ammeters (or the amp function of a DMM) are not up to measuring the current drawn by a starter motor. The best way to go would be with a DC clamp on meter. Those are not cheap (expect to spend in excess of $100 for a good one). But battery shops and auto parts stores are likely to have meter that can test current draw. You can also infer the draw from the voltage drop as you try to start. It should be significant.

• Finally, you may have a large "parasitic load" that is draining your battery. Take a look at the answer to this question for more information on how to troubleshoot that.

Answer 2

I had a very similar issue with my battery. Very similar characteristics, sometimes wouldn't start as if it had run out, other times it would be fine. Mech's tested it and pronounced it fine, and a couple of days later i had to jump it again, so I took it back in.

They eventually said it was the battery. What was interesting they said that when a battery isn't fully charged it's hard to get accurate results from it - they charged it fully and tested it again and then their tester showed some faults with it.

As mentioned by @dlu, check connection - that's sound advice., but if that doesn't make a difference, then you may as well get the battery replaced anyway if it's still in warranty. Then if you are still having problems, I'd start looking at all the other connections, check starter motor for any obvious issues (guess it's 9 years old now) and see if I can identify any other problems.

If I was still having issues, I'd also start thinking about double checking if I'd left anything on when I left the car, or considering the possibility of whether a fault could have developed that could be draining the battery.

Keep us updated.