Hi, I'm trying to charge up my maintenance free 12v battery using the following charger: https://www.tayna.co.uk/battery-cha...NHljpzaVaJyNu4ZbNYrETQ_kRyrGDoGYaAkSiEALw_wcB All connected correctly, RED light comes on to indicate its turned on, YELLOW light comes on to indicate charging but despite being on for around 12 hours total over 2 days (turned off overnight to be safe) it never turns GREEN to show fully charged. On top of this I've been monitoring the voltage using an multi-meter and before I started charging the battery it was at 12.58 volts and after a lengthy charge its dropped down to 12.42 volts. Is it meant to drop during charging or is something wrong somewhere? I'm puzzled by this.