Well the first one says charges 2 or 4 batteries at a time so its not a good charger already.

Your best bet is to buy a decent charger (MAHA or Lacross) with a 12v input then hook it up to a solar panel. Most of the solar chargers on the market are designed to be small backpackable chargers so they compromise size for speed and quality of charging.

You want to be careful of rapid charging anyway, the more rapid the charge the less the lifetime of the batteries. Charge them slow to keep them lasting a long time.