I have a 64Ah EFB car battery in a 2018 Volkswagen car with start/stop technology. I have an Optimate 5 charger which supports EFB and AGM start/stop batteries:https://optimate1.com/om5ss/
I would like to understand if I need to disconnect the battery before charging it. If so, both cables or just the negative?
Some say not disconnecting it can damage the ECU, some say they have been charging without disconnecting for decades and never had any issues, some say it depends on the amperage - my charger has a 4A output.
Before I get crucified because similar questions exist, yes, I have seen lots of similar questions, but 1) none with a definitive, technical, thorough answer, and 2) none which relates specifically to EFB and AGM batteries.
The owner's manual doesn't say anything specific - it only says that I should bring the car to an authorised dealer to have the battery charged because they have the right equipment , which is ludicrous!
Any ideas? Thanks!