A great deal depends on the type of charger. In Britain there are the old-fashioned ones that keep dishing out a charging current regardless of the state of charge the battery has reached. These will charge a totally flat battery but must not be left on permanently, as they will "cook" the battery.

The more modern sort is a "smart" charger, which has nothing to do with Ashcroft but is a charger that senses the state of the battery and stops charging when the battery is full. If you leave it on permanently this sort of charger just adds a slight "trickle charge" from time to time, and in fact it's recommended that they ARE left on all the time. These will not however charge a totally flat battery, as they depend on electrical feedback from the battery and a flat battery can't give that.

In theory there could be a yet more modern type of charger that would do both, but I've never heard of it. Maybe someone technical can add something here?

So, if your charger will charge a totally flat battery it's almost certainly unwise to leave it on permanently. Probably the best thing to do is to read the manual that came with the charger, or look up the manufacturer and contact them.

Batteries need to be taken care of ! Adding correct kind of water , and charging correctly will determine the life . The battery water should stay above plates ,but dont fill battery all the way. Get a lestronic charger (automatic), when the battery is 75% full it starts lowering the amperage till it is trickle charging .
Timer chargers stink they are killers , get a lestronic auto. charger(sharks ). Get battery water and keep full above plates, make sure you run Battery LOW every now and then it makes em stronger. You should start with new batteries. WARNING never mess with a battery after or during charging .

if your batteries are cooked then charge them for a couple hours and do your errands and slowly you will have to replace one or two dead batteries every couple of months .
Most cart comps have a bat. tester . They can tell you the shape of each battery by testing . My Bats are 3 years old and I drive about 18 miles with four large people often .

Sorry for taking so long, I couldn't remember the name of the process. Desulfate your old batteries before installing the new ones and it will help keep the new one alive longer.

http://www.ehow.com/how_4964905_renew-golf-cart-battery.html

http://www.skoolie.net/forum/viewtopic.php?f=6&t=3812

We used to do this with the big 8D and 4D batteries on the TMM boats to keep them alive longer.

Will these charge a battery that has gone totally flat?

see what you can learn here! Thanks everyone. My charger is locked up in a box. I have run the cart right into death. Each day it went a little less far and I know I need two replacements as Polo checked them for me and gave me the sad news. I'm asking all around.