oting that your 'Lidl - Parkside' battery has four charger connectors, I found the same on an 'Aldi' own product. I was intending (trying) to repair a blown Parkside charger for a friend so I went into things quite deeply. I worked out how (generally) the battery and charger work together - as a simple fact, but was initially curious as to why the Aldi battery and charger needed the fourth connector. I'd already worked out that the connection commonly marked 'T', was the connection the battery used to tell the charger when the charging had ceased. I also determined that it was the battery that stops the charge, not the charger ... all the charger did was turn on the fully charged LED to tell you - the user. I noted that the 'T' connection from the battery was supplying a train of positive going pulses of around 0.7volts to the charger while ever the battery was charging. The pulses appeared to be switching on and off a transistor, which in turn passed the pulse to a 'ring counter' circuit that controlled the red and green LED's. Fairly straight forward, though quite technical, but that was the Lidl 18v set-up that had blown apart. So, could the Aldi charger help me..?? The answer was, "no way"..!! It was far more sophisticated with - dual circuitry, because it could charge Aldi's new range of both 20v and 40v tools. And that's where that 'fourth' connection comes into play, by telling the charger which battery has been connected. My problem was that I couldn't work out how this happened thanks to unidentifiable chips and semiconductors - idents rubbed off purposely. The lesson learned is that each manufacturer's set-up - battery and charger, all do the same thing, but in their own unique way, and they aren't telling us how they work.