D22 battery problem

[D22NZ]

I have the 2012 D22 dual battery model I went to drive it the other night and the battery warning light and water in diesel light came on the dash i drained the diesel filter and i decided it to drive it anyway while driving my headlights went super dull and all of the dash lights basically went out so I pulled over turns out the negative terminal for the battery on the left side was loose so I cranked it up and it seemed to solve the problem everything seemed to be working as it should the warning lights on the dash were still on tho after driving for about an hour the next day when I went to start it the batteries were dead and wouldn’t start. I’ll currently charging the batteries up at the moment not sure if it could be the alternator but it seemed to be working as It took over an hour to get home and the lights did not dim at all

 

[tweak'e]

if the alternator doesn't work you will run out of power very quickly and the engine will run badly very fast.

check how the 2nd battery is done. i'm not sure they where a factory item, at least on the nz new models.
a common problem with dual parallel batteries is they both need to be in good condition and the same battery. treat them like they are one battery. if one is bad replace both. yes its expensive but just changing one tends to ruin them both and you will forever be buying new batteries. its something we found with the early dual battery toyotas.