This is the datasheet for the battery I was looking at: http://www.batteryspace.com/prod-specs/LA-12V1.2.pdf
I will be charging it at room temp (which for me at the moment is 22 deg C) so 20 is a plenty close enough value. And the datasheet actually says to ignore temp variations unless outside range of 5 to 35 deg C which I am not.
So from my understanding form a code perspective all I need to do is set PWM value such mosfet sees 4V at gate such that current is limited to .1A. And taking the datasheets average value of charge voltage for cycle use for 6 cell battery is how I came up with 14.7V so it would seem that's correct.
So here's my scenario:
The battery will use up as much current as is available (.1A in this case) until it gets closer to 14.7 at which point the current will start to drop off? Is that it?
If so then I am confident my circuit should work.