Date and Time are lost when reconditioning battery?

When I let the battery go to zero on my MBP 13" (mid-2009), I have to press the start-up button to get it to work again. There's a sleep image where it should be (/private/var/vm/sleepimage), but the system for some reason doesn't recognize or use it. In terminal, I've checked that the system is set to "sleep & hibernate".

Here's my problem (well, one of them ;) ): when the machine comes back on after reconditioning the battery, the Date and Time are set to January 1, 2001, and my home Wifi connection password has to be re-entered. I've reset the PRAM, the NVRam as well as the SMC controller according to Apple's guidelines. And yet it still loses the date/time/wifi PW after reconditioning.

My battery has 357 cycles, and the capacity is at 4246 (new: 5450) for a loss of about 20 minutes of usage time.

On older Macs, there used to be a small 2nd battery that was used to maintain basic low level memory parameters in the event of a total loss of power. Does this still exist on MBPs? If so, is it possible to buy and then replace it? Or is there another problem of some sort?

My MBP losing this basic stuff is really annoying...