Testing 6V Batteries
While chasing down a charging problem with my truck last fall I had my two 6V in series batteries load tested at an auto parts store. They tested bad and Costco replaced them since they were about 8 m...
Forum Discussion
Bottom line is that if they don't power anything after charging them, they need to be replaced. I'd suggest you find the source of the draw that is killing the batteries or you'll be destined to a life of battery replacement. It may also lead to a bad situation after setting up at camp.
You do have a disconnect switch or remove a battery cable while in storage?
In a previous career, I maintained a fleet of over 500 6V batteries. They are very forgiving and hard to kill. If you have to keep replacing them, there is either a constant draw or they are not being charged right. From your OP, it sounds like a mix of both but we don't know how you are using them and what they power. Sharing that may bring better results.
You do have a disconnect switch or remove a battery cable while in storage?
In a previous career, I maintained a fleet of over 500 6V batteries. They are very forgiving and hard to kill. If you have to keep replacing them, there is either a constant draw or they are not being charged right. From your OP, it sounds like a mix of both but we don't know how you are using them and what they power. Sharing that may bring better results.
