[bill-e]

Google it and you will get varying answers but all of them state that you need a charge controller to prevent overcharging.

One rule of thumb I found was to take the AH rating of the battery and divide by 10 and that will tell you the maximum wattage of a solar cell without a charge controller....using that logic an 80w panel would only be acceptable without the controller on an 800ah battery pack.

Personally I think you need the controller or risk damage to your batteries.