72V DC Motor with two 12V wind Generators

Hello, I have two 12v DC wind generators that can provide charge to a 72v battery bank. This bank is used to power a 72Volt Electric Motor. I have one connected to the first battery (the positive connect for the entire bank) and the other generator is hooked up to the other or last battery of the 72v bank (the negative connect). Is this proper? Or, what do you recommend? Which manner should I best have them connected to the battery bank in order to obtain the most efficiency (charge)? Thank you, Alex