After the charger turns off we take the cart out in the woods and it lasts 15 to 20 minutes. It does fine going up hills but after a few hills it starts slowing down till it kicks out to a stop. We let it sit for 5 or 10 minutes and it goes again for a bit. It goes 10-15 mph on flat ground and doesnt seem to have a problem losing power. I have tested voltage once charged and each battery reads 8volts and after it cuts out it still reads 8 volts. Also tested the batteries using a hydromiter after charged they all read good and after it comes to a creeping stop they still read i the good. Any ideas on what the problem could be? Thanks in advance for your help!