Here is an interesting idea for batteries:

http://www.allbatterysalesandservice.com/browse.cfm/4,5576.html

No need to remove the battery box lid, but if you need to, it's a lot easier that some of the single battery boxes I've seen.

Then, install the self watering adapter:

http://forkliftbatteryonline.com/Automatic.Battery.Watering.Systems.html

The water tank would sit on top and you could always see the current level.

Why spend more time than you have to on batteries?

GipCTravelers