My battery doesn’t exist
Q I recently bought a Mid 2009 MacBook Pro. The machine has spent the last couple of years being used as a desktop replacement, always plugged into the mains adaptor. When I try to boot it from battery, nothing happens. If I check with System Information, it reports there is no battery installed. I have tried replacing the battery and resetting the SMC but this hasn’t made any difference. Do I need a new logic board? Ciarian Russell A It might just be the battery sensor. An Apple Authorised Service Provider ought to be able to replace this for you, but it’s actually not impossible to do yourself. If you are comfortable with opening the case of your MBP, there are normally a few replacement battery sensor parts on eBay for £10-£20.
In fact, you may not even need a new sensor. I’ve seen cases where the sensor simply comes loose and sometimes shows 100% charge and at other times 0%.
That’s the best case scenario. At the other end of the scale, it’s possible that you have a fault on the logic board itself (a dry solder joint or a cracked circuit board track that prevents the battery sensor from communicating with the SMC). There isn’t any economical way to repair that. You would have to resign yourself to keeping the MacBook Pro as mains-only machine or else sell it to someone else on that basis and get another one. Second-hand laptops are always a bit of a lottery.
Battery sensors for MacBooks are quite a common second-hand part available for sale on eBay.