Here Foxwell NT510 code scanner feedback on BMW battery reset which is quoted from a real user’s review, hope it helps.
If like me you arrived here because you need to reset your ecu and/or learned throttle values and this seems the only way to do it, (which by research this seems a fairly overpriced and shonky option, developed and made in China) I’d like to recommend an alternative. First to clear the throttle values and reset the ecu, you don’t need a tool, (my example is a 2009 honda accord euro/acura tsx). However doing the much recited (on youtube etc) idle learn procedure doesn’t work on its own and the car stubbornly continues to idle high, run poorly and use extra fuel.
So to get to the point, battery cable reset procedure was needed to reset the ecu (and pretty much all other modules and clear any data). To do the battery cable reset- follow this: 1. Remove negative battery terminal. 2. Remove positive battery terminal. 3 Be sure you arent going to make contact with the battery, for later steps possibly even remove it from the car if needed 4. Connect the battery cables together either using a jumper cable or clamp them together if they reach. 5. Turn on your key to on (not ACC, to on). 6. Leave for 10 minutes. 7 Turn your key back to off, reconnect positive and then negative and THEN follow the idle relearn procedure you will find pasted all over the internet and youtube. You will also need the radio code and possibly relearn your auto windows, for which there is good info for on youtube.
To read your codes, try buying a blue tooth elm327 (for around $5 off ebay) and downloading the torque app. This also can supply quite a lot of data from the ecu but can’t write anything. Armed with Foxwell NT510 code scanner and the battery reset procedure I think you may avoid this expensive option.