Chosen Solution
Hi, I’ve noticed my macbook pro has recently started lagging quite severely when its running from the battery. As soon as the magsafe is disconnected everything lags including the cursor. I have tried the SMC reset, etc. but no change. I did have an issue with my battery indicator but I have since replaced it and it was ok. Any ideas? Thanks
Jeff - No doubt you have a very odd problem here. I was thinking what could cause such a strange problem. Then it hit me! Your charger supplies the needed power to run and charge your battery 16.5Volts but your battery is only 10.95Volts. Your system has to boost the voltage up using a FET to step it up the rest of the way. But what would happen if the FET was bad? Then the batteries voltage would pass but its just enough to run your system (just slower when running on battery Vs the charger). So your main logic board has a problem in the power section. Are you up to replacing a few SMT components or do you just want to replace the logic board and be done with it?
I have heard a number of people having the same problems, and have found it is usually caused by the magsafe charger not being properly grounded. Usually because the charger is a poor 3rd party replacement that causes problems when being connected, or to do with using the wrong generation of charger. (if you have a 13" macbook pro, you need a 60W magsafe charger, and 15/17" require 85W chargers) If you use the original white tipped magsafe with a unibody aluminium macbook pro, you may have intermittent trackpad and isight issues (or any devices that are connected via USB), but if you touch the palm rest, it usually stops… as you are grounding the machine. If these are the symptoms you are seeing, replace the charger with an apple original, but make sure its the range that was previously shipped with your machine (there is a white tipped one for earlier generations, then an aluminium right angled version for later unibody machines) I hope this helps.
it looks like people are getting a bit confused here… firstly, single user mode is not the same as safe mode (which is what machead3 is referring to), secondly, the 13" macbook pro doesn’t have 2 graphics chips like the 15" model does, so you cant swap between them, although there are energy saver modes that effect the battery life of the machine… none of those functions will cause the machine to lag or slow down though. Firstly, are you comfortable opening up your machine, or would you rather have someone else look at it for you? i can give you suggestions to track the fault down, but dont want to suggest anything that you wouldn’t be comfortable doing yourself. Any internal connection can cause the machine to lag that communicates directly to the logic board. things such as the HD (but you would usually either hear abnormal noises coming from the drive, or the beach ball instead of lagging, but its still possible), it could be your HD flex cable (which you can eliminate by booting from an external drive via USB or FireWire), or it could be anything else, such as your iSight camera, airport/bluetooth card, ram module, ram slot, etc. The thing to do would be to eliminate the faulty component. you can start by booting up in safe mode by holding down the left shift key when you start the machine. this will boot it in a simplified version of the OS with most of your hardware functions disabled… then i would open it up and disconnect everything that is non-essential to the machines booting needs to ensure you the fault isn’t with the main logic board or the ram slots, then re-connect one device at a time until the fault re-occurs. I have seen an iSight controller board cause the fault you are seeing on an 2011 range. although it is seen as a USB interface when connected, it passes both data and power, so can cause interference if it is defective. i hope this helps
I fixed mine by replacing the HDD Cable. Thought it was a bit of gamble but I read elsewhere that others have had the same problem with mid 2009-2010 MacBooks. The Cable only cost me £15 and was very easy to replace.
