On the battery thing: I had one leaking, luckily I noticed it in time and replaced it by a reasonable brand (Varta) version of the same type (although... I do remember the Varta had only 1 ground pin instead of the 2 pins the original had) as used by Commodore.
Now on the accelerator path....
The A3000 I used to own (my brother has it now, must start annoying him so he gives it back.. ;-) was the lowest available at the time. An 030 at... 16 MHz, an early system as well as it shipped with the kickstart disks, luckily it had the Kick 2.0 ROMS installed as well. It served me well for more than a year or 5. Then I got a good deal on a A3640 accellerator with 25MHz. Unfortunately... It didn't work out of the box. It seemed that some modification to the MoBo was needed. I don't know the exact modification (it had to do with soldering... ) as I ordered an Amiga dealer (Vesalia in Germany) to take care of it. From then on it worked perfectly. So... does it happen that you've got one of the early systems?