VEX Battery won't charge but says it is charged

Trying to charge 7.2v VEX batteries on a smart charger from BEST kit. Light on charger starts green despite battery not charged. 6.7v according to the voltmeter. No change with fast vs safe. 30 minutes searching and cannot find an answer on VEX site, this forum and general search. Supposedly the smart charger will continue to trickle even when it registers a charged battery. We have 3 batteries, one is charging normally and the other 2 won’t charge, no change in the voltage after an hour on charger.

Sounds like you have a couple bad batteries. Here’s a good article about VEX batteries, from our freinds at Renegade Robotics.

Maybe the battery has some dead cells, if your batteries are over 2 years old I would highly recommend replacing them.

If anything I believe this not to be batteries that are not working, I think this sounds more like connection problems with the plugs. Try using the batteries on a different charger than the one you’re currently trying to use.
Some advice I usually do at competitions:
Also, there are some times where the chargers fake being green after they’ve been red only for like 15 seconds so at competitions when I have batteries that are green and I’m not using them I shift all of the batteries to the left to the next charger so I can ensure that the chargers don’t lie about the charge, then taking the batteries at the end. Just make sure that the batteries don’t get hot maybe even bring a fan to blow on them while they are being charged.