Dang, so this friend let a bad battery ruin his race weekend? Hate to hear you couldn't help him Pops.
Wilbur, I understand where you're coming from to a point. Those batteries cost a lot more than a cheap Walmart lead acid. Personally, I like the lithium batteries I use in our bikes. They hold a charge much longer than the lead acid batteries. Most of my bikes are total loss systems so if I don't have time to charge the battery between rounds, I at least have piece of mind that i'll be okay to make the pass. Eventually, lithium batteries will need charging during the race. I think many believe they will not go dead and just keep racing without proper maintenance. Also, if you ever let the voltage drop below the safe level in some brands, you will ruin the battery. A select few have low voltage features so the battery shuts down to save itself. All you need to do then is hit it with a charger to wake it up, and it will take a full charge.
My main reason for using lithium is the reduced size and weight of the batteries, more amperage for the size than lead acid and the ability to mount the battery in different directions. They also last longer- I used to replace the lead acid batteries once a year as a precaution- I put them in the lawnmower or street bike with charging system. Space gets tight in a purpose built drag bike. Smaller, more powerful batteries are a plus.