To even out my current coming in can I use 12v Gel batteries or should I go to a bank of wet cell batteries?

I have a chispito like wind generator and a radiator fan that I will place on the Air conditioner fan outside. When the Air Conditioner kicks on, I will be generating DC. My plan is to take both sources into a charge controller tied to a bank of 12v batteries, then into an inverter. I have purchased two 12v gel cell sealed batteries to get up and running with. Do I need to use wet cell batteries or can I go with the Gel Cell batteries? By the way my generator creates 3-6 volts in a good stiff wind anf my radiator fan creates 2-4.5 volts when the Air Conditioner is running. Thanks

Chispito produces 100 watts in a 30 mph wind at 12 volts DC. It starts charging a 12 volt battery around 7-10 mph, or 270-300 rpm.

My experience is mainly with Solar and there it is recommended that you need to produce at least 15 volts ( and up to 19) to safely charge a 12 volt battery/bank.
The Gell versus Wet cell argument is not relevant as long as they're Deep Cycle batteries.. Gell are about twice the cost of wet.
I'd be checking my multi meter if I was you. The output from your generator seems very low.
Rob Patto