When I bought my campervan, the sellers warned me if the IP67 was completely dead, it wouldn't recharge from my campervan engine battery when driving. My question is what percentage is too low before this happens? I'm really struggling to use the leisure battery for longer than a day or two, even when ive moved it, and have used little power (fridge off). Many thanks, apologies for the lay man terminology and lack of understanding.
If you want to charge leisure from the alternator, ideally a DC:DC charger should be fitted. Sometimes a split charge relay is fitted instead, this is less sophisticated, but fine with batteries of the same chemistry.
To avoid damaging your leisure battery, suggest you charge it urgently.
To trace the IP 67 problem, you need to check its supply (fuses etc.) and wiring to the leisure battery. Might be better to get a specialist involved. The charger may still be under warranty, it's 5 years, not sure if this transfers to you, but I think it does.
