Watch the pack voltage as it goes up, when it levels out stop the charger. Or at least before it drops much. Much being about 0.03v for a 6 cell pack to be safe. Make sure the old meter is working well enough, might be a wise idea to use a separate digital meter if you have access to one. Also keep tabs on the pack temperature, it will heat up as it reaches full charge, you don't want to get to the point where it's uncomfortable to hold.