I use my car approximately 6 months a year and keep it on a battery tender when not in use. Just got a new battery and it’s an AGM which requires a different charger. Also, just ordered the auxiliary battery which is also AGM. Does each battery need its own charger or are they some how connected and only one is needed. Dumb question, but had to ask.

 

Only one tender needed.

 

On my ctek MXS 5.0 battery conditioner there is actually a button to select AGM batteries, might be worth looking into those units.