I was sitting in a parking lot with my radio, fan and some other electronics running. Then about 25 minutes later I had problems starting up my 2008 mini cooper. The engine was turning but it wasn't starting. After letting it sit 10 minutes later, it turned on. I drove back home and let it run for ~15 minutes. I turned it on and off twice just to make sure things were good and it was working fine.

I think it has something to do with the battery. The problem is, if my radio and fan usage for 25 minutes drained the battery to the point that it couldn't successfully start the engine, why would it then work 10 minutes later?

 

Did you first try and start it with the radio and fan and other things running, then 10 minutes later try and start it with all of those things off? If that is the case then it could be as simple as you were using less power from the battery the second time.

 

From the start we turned the fans and the radio off but it still took some time to turn on.

 

First, be aware that you can run JUST the Radio by pushing the Volume Control after the car is completely shut down (even with key/fob removed).

This will be a lot less Battery drain than with ignition on and it will shut itself off after :30 minutes, but you can do it again.

My new MINI suffered a dead battery one morning within a week of delivery (would not crank the engine) and I put it on a trickle charger for 24 hours, have had no problem now for past ten months.

MINI uses a maintenance-free 'gel-cell' and you can look at the 'green-eye' to check battery health.

I have the ScanGauge with system voltage as one selection, it shows 14.1 Volts, indicating healthy charging when running.

When shut-off, it only shows 12.2 Volts, a sign of a slightly weak battery and 11.7 - 11.8 Volts the next morning, a sign of a low battery charge, but as I said, I have had no starting problems since that first weeks incident. I have also run the HiFi many times, for hours with engine off.

I did call the Dealer (137 miles away) that morning and had the incident recorded in my file,
I will request a 'Load-Test' when I go for my first annual service, if it should fail that,
I would expect a Warranty Replacement.

 

I've run other electronics before in my past cars without draining the battery to the point that I had a hard time starting it, but when the OP said he had the fan on, doesn't that raise a red flag with anyone else? I'm pretty sure you should never have the interior fan on in any car for a long while without the engine on as its a significant drain on the battery with the mechanical movement. Am I remembering this wrong?

 

Mini batteries drain way to easily...

 

All automotive batteries act just like what the OP said. When you are using electric things in the car, it takes power from the "upper" charge in the battery. Once you turn everything off and wait a while, the "lower" charge rises to equalize the level of power in the battery. That is why the car started after sitting with everything off for 10 minutes.