Battery drain, advise on battery (-) terminal disconnection

[AntoineD]

Hello everyone. I bought a Ford Focus in 2019 (Mk4), ecoboost 1.0, 129CV. Everything works well, I like the car, the driving experience, and the engine response.

However, I have a battery issue almost since the beginning. The battery is drained after two-three weeks of being parked. Unfortunately, I am becoming an expert on "reviving" the car. I saved a lot of money thanks to a portable jump starter…

The battery has been replaced at least once, twice if a I trust on a ford dealer that changed it for a new one when car was on guarantee.

I left the car to a couple of ford dealers, but for them everything was ok. After-sales service quality is very poor and shame, they go for the quick, easy, and cheap fix.

I am almost convinced I have a parasitic draw. After some hours the car stopped, a clamp meter recently bought measures around 300mA on the cable of the negative terminal. FordPass is disabled, and the car has no heated seats.

I need to take the car in a professional electrical engineer in order to analyse where the draw is, but meanwhile, I would like to prevent the battery drain when I go out for 2-3 weeks. I am thinking to disconnect the negative terminal, but someone told me this is not recommended as it might affect another internal battery for keeping the key code of the car and car settings.

It this true? Could anyone tell me if I can disconnect the battery for 3-4 weeks without messing around?

Thanks in advance,

Antonio