Can i connect batteries (both 12v and SLA) of different amperage (100amp with 180amp) in parallels?
It depends a lot on what the charger is doing.  The simplest ones don't attempt to fully charge the battery and instead provide a constant voltage of 13.8 (or sometimes 13.6) volts, which will mostly but not fully recharge a lead acid battery of most any type. If your &quot;charge controller&quot; is that type then putting the batteries in parallel should work.  If the charge controller is a fancier one that actually monitors the rate at which the battery is charging and adjusts the charge current as it goes, then putting two dissimilar batteries in parallel could end in tears, because the way that charger works depends on putting the battery to a substantially higher voltage while it's still sucking up the current.  If one battery is fully charged but the other one is sucking ap all the current the charger can offer, then the fully charged battery will overcharge, a situation that can be bad for the battery but also for you if it swells up like a beachball then pops just as you walk in to inspect it.