I have an '87 DS, 36v. I just finished customizing it and replaced the batteries. When I charge them it seems to take forever. The meter on the charger starts around 25a and after 12 hours of charging is only down to about 10a. I sometimes get a battery smell when it has been on the charger for a while. Should it take longer than 12hrs to fully charge? I have been hesitant to leave it on while I am away from home.