The slight issue with the LIDL charger is that it's not great as a trickle / maintenance charger, IMHO. You have to turn it on using the button and select a mode before it does anything.
Leave it on your battery over winter and one power cut means your battery is not protected.
It will also not even start to charge a battery whose voltage has dropped below 8 volts or so, as it can't decide if it's a 6 or 12 volt battery.
Other than that it's fine. mrs. KW's MX5 went flat over Christmas. Put that charger on once I'd used a crude old charger to get the voltage up to 12V and it recharged the battery overnight with no issues.
Was about to post the same thing, its about 9.5v on my one, anything below that its hopeless.
It's odd, as the manual implies that it will trickle charge until the battery reaches a plateau and decide what voltage it's levellling off at, but mine won't even power up, or tries to charge at 6V and immediately decides the battery's full.
Guess there's normally a reason why something's cheap!
My CTek is a better bet, although it's 12V only and only 800mA.
Mine just says error below 9.5, can't do anything with it when it goes in that state, you need to kick it with a normal charger for a while, then it works.