The best charger for your purposes will depend on the type, size, brand and number of batteries in your array. AGM batteries use different charge profiles than do typical flooded lead acid batteries, and that charge profile is critical to optimizing battery performance and life. Big batteries take bigger chargers, especially with big AGMs. Certain brands, like Odyssey, like higher input voltages (14.7+) than other batteries that are happy with input voltages as low as mid-13s. The best source for generic multi-battery chargers is generally in the marine market, since boats tend to have multiple batteries and are often hooked up to shore power for recharging and conditioning the batteries. If the batteries for the throwers are not close enough together to charge off a single charger, then solar is definitely worth considering. If you are planning to haul the batteries into a shed for recharging, the better chargers will not only charge but will recondition and desulfate old batteries, extending their useful life. A higher amp smart charger will work faster for obvious reasons, but when it is in multiple battery mode, it will generally time-slice the charge depending on the number of batteries connected at any given time. Generally you don't want to discharge FLA or AGM batteries below 50% of rated capacity, even for deep cycle batteries, so monitor state of charge fairly carefully when they are out in the field. A solar panel and controller will make this task much less onerous. Solar controllers and smart chargers will put the battery into a float or maintenance mode when full charge has been achieved, and this will tend to extend useful battery life. The best high-tech smart chargers seem to be coming from companies like Ctek, Schumacher, and Optimate, but there are lots of others out there. I have one from each of those three manufacturers, and they each function somewhat differently and for different purposes. Be sure your batteries can accept the maximum amperage that your charger will deliver. As an example, my particular Schumacher is a 40-amp unit designed for high amp, high voltage charging of Odyssey AGMs, but Optima cautions to never use that charger on an Optima AGM. My Ctek delivers 14.7V+ so works fairly well with Odysseys, but my Optimate maxes at 14.6V and can't muster a full charge on a big Odyssey, but works great on everythng else. It all makes a difference, and you local battery shop may not appreciate the subtle differences. Costco sometimes has great deals on solar setups, but a stray pellet or shard of broken clay can take out a panel, so placement is important.
