I am the battery assasin.

It turns out that the farts smell was indeed from the batteries leaking. they were leaking because they were overcharged. they're overcharged because I used the wrong charger on my brand new batteries..

When I bought the batteries I bought six because they were intended to go on a 72 volt bike. I got a nice charger for them. when I transfer them to the smaller bike I grab my shiny new charger and threw it on there and it was getting very weird readings on the voltmeter while I was charging. now I know why. I have a $220 mistake to learn from and I no longer can ride the bike that I just finally got rolling. Life f****** sucks sometimes.