WELCOME to BGW !!!
I don't know a brand off hand but I like the little 'led' type with the bars. So the more charge the more bars. They take minumal juice and can be hard wired with no worry about leaving them on all the time. Go to any one of our sponsors and search' voltage indicator'. Here is the install:
http://www.buggiesgonewild.com/elect...-club-car.html
Note:
6 volt batteries are empty at 6 volts. You should own a voltmeter to check your pack and see at what bar you need to recharge. For me after I lost a bar I was down quite a bit and at 2 down I needed to recharge to avoid stressing my batts. gd. luck