Strange Problem with Car Battery

Folks,

I’m having an odd issue with one of my cars (a 2006 VW Jetta TDI).

It starts and drives normally, no lights on dash. But if I drive, shut the car off and then immediately try to restart it, it will barely crank. Sometimes will crank enough to start the engine, other times not. But if I let it sit for a while, it cranks and starts fine.

I haven’t timed it to see how long it takes to “recover” but certainly in a few hours it’s back up to full cranking speed/power like nothing happened.

Any idea what could cause this? I mean it’s almost certainly a bad battery but how does a battery magically recharge itself with the car off?

Check for a loose cable connection? Engine heat causing expansion may be doing it.

5 Likes

Battery cables are tight and all ground straps are too. I’d think expansion would make them tighter, no? This is perplexing.

Did you check the connection at the starter?

If that is OK, the starter may be going bad. Same cause, heat.

1 Like

Do a voltage drop check on the cables

2 Likes

I’ll do that but last time I had the battery out for some work (about 6 months ago), I cleaned the terminals and put terminal grease on them before reconnecting.

I’ll check everything again and do the test with the multimeter too.

Thanks.

1 Like

You’re 100% wrong. It’s the gremlins.

1 Like

If the battery test is good, you can repeat the same voltage drop test at the starter. You might need a meter that can record min/max since the meter will likely be under the vehicle. Again use clips on the battery lead stud not the lug. If voltage drops < 10v with weak crank then the cable or connections are bad. If the voltage does not drop then the starter is “likely” bad. There is one other possibility which is excessive friction in the engine but I’d change the starter before going there.

It is not a gremlin … he said it was a 2006 VW Jetta TDI

3 Likes

So what are the thoughts that the starter is getting hot, expanding against the case of the starter. Then once it cools off, the clearances are looser. If the starter is wearing to where debris is in the case, I could see that.

Okay still haven’t had time to check with the meter but this happens every time I drive somewhere and try to restart immediately after stopping.

I just drove a decent distance and arrived home. I’ve been home for 15 minutes. Just went out to try and it cranked up like normal - nice fast, strong cranking after sitting for just 15 minutes at 100 ambient.