I have tried a couple of their chargers over the years and had trouble with them. I have tried a lot of different chargers over the years in the portable type and on board and had issues with them also. They can be finicky. The only dead reliable on board charger I have had that I have gotten ten years or more out of have been the dual pro.
I always keep a portable type with the transformer in them,not the all electronic type.Napa has one i think its called the sportsmen. I use them to double check if another charger type is working right.The all electronic ones can just be glitchy.
You can pickup a gauge that measures the specific gravity of the acid in each cell. That tells you the condition of your battery per cell.You use a chart that tells you what the specific gravity should be.