I'm pretty new to solar panels and basically, I'm trying to charge a 40V 4Ahr lithium ion lawn mower battery using solar panels. 40V solar panels aren't nearly as common of a size as 12V so I'm thinking maybe I could just wire up a few solar panels in series to stack up the voltage but I'm now unsure of how I should go about that.
Say I did four 12V solar panels in series to get 48V, could I safely charge the 40V battery with that? Is it dangerous to supply more voltage than a battery is rated for? I would have a solar charge controller of course but I'm not sure if that would help with supplying too high of a voltage.
Or maybe I should just do three 12V solar panels to get 36V? Would that harm the battery at all supplying too little voltage?