Also should add, to keep your new batteries healthy longer, take your charger with you and plug in at work. Lead acid battery chemistry does not tolerate deep discharge well. Yes, I know there are "deep discharge" lead batteries, but they sacrifice other factors to get it. Lead acid cells like to be constantly topped off and can be trickle charged long term. I keep my Electrec plugged in whenever I'm not riding it. The OEM charger is "smart" and reverts to a low current trickle when the batteries are full. Good luck with your new batteries!