We've had a CTEK M300 smart charger keeping the batteries topped up while living on the boat here in a marina in the UK. The instructions recommend doing an annual reconditioning charge, which they say will apply a maximum of 15.8 volts and 3A for 4 hours for deeply discharged batteries. My batteries have not been deeply discharged and are only a year old, so presumably the process will be shorter (though at 480AH they are near the upper limit of the charger's stated capability).

I happened to be talking to a distributor today who said the reconditioning could take several days. That doesn't sound right to me, at least for batteries in good condition.

Since we're living on the boat, I don't want to disconnect the batteries (especially if it were to take a few days). My reefer can handle up to 17V, and we'll keep any delicate electronics turned off.

A couple questions: how long is the reconditioning likely to take? Any particular issues running the reefer and a few lights if it ends up taking more than a few hours?

Thanks.