During lockdown I have borrowed a car battery charger but am totally confused what to buy for myself. I need to keep a 'resting' car battery topped up, and I would like to boost the stop-start version in my Tucson as it is only getting short runs lately. I see chargers advertised from about £15 to well over 10x that amount. Although I have access to mains for the caravan maybe that battery would benefit from charging maintenance out of the battery box too! What would readers recommend to me please?