while gliding, a small amount of battery still gets consumed i.e. a/c, audio equipment and headlights usage.. i.e. after 2 cycles of gliding, one bar of battery gets dropped and consequently on 7-8 cycles of pulse and glide, battery gets to 3 bars and then i intentionally try not to p&g but to keep running ICE with very little pressure on the pedal to consume less gas.. and one the batter gets back to almost full state, i pulse and glide again .. the loop continues.. and i hope its not bad for the battery :S
Should not be bad for the battery, but for me I find that P&G on battery power only makes sense on gently rolling hills. If you're doing it enough to deplete the battery then you take a hit with generator charging.