Checking specific gravity I find some cells on both batteries low. I decided to put a charger on each one, one at a time separately. But was wondering. I suppose it is ok to disconnect the cables from them and it not have an effect on any electronics after I reconnect them.
Anyone have a comment on this? I don't see it being problem as someday maybe soon I might have to disconnect and replace them if the charge don't come up. They were new in 2014.

 

What year 250/350?
A disconnect won’t cause any issues. At 5ish years, they could be timing out. 5 or so is about all i get out of mine, but Nothern Ca, winter in the snow belt can be harder on them.. Quite often one of the batts will start to fail, and being a parallel system, the weak batt pulls them both down.

 

It is a F250, 2015, purchased in fall of 2014. I agree, they are coming to end of life in their fifth year. 750 CCA I imagine they will be quite expensive.