The 40lb should push the boat just fine. I'm not sure how long the group 24 battery will last. The charger will be fine, but I take it that you are a casual fishermen and if I didn't run the boat that often I would put one of those 2 amp trickle chargers from Walmart on the battery and just leave it on charge. Be sure and check the water from time to time. This will help the battery to last longer. I ran a group 27 on a heavily loaded 1542 with a 55lb thrust and could crank bait all day at around 1.7 without the battery going dead. I used a cheap, sealed, marine trickle charger that came from Walmart and plugged it in immediately when I got off the water.

Good luck with this. Hope you catch lots of fish and welcome to crappie.com.