Re: Charge n' Troll???????
True -- one dead battery and you are done for the day. It takes two batteries in series to run a 24 volt motor. Therefore both batteries must be the same physical size and capacity. However, in a series wired, 24 volt system it one battery will not generally go flat before the other as current is being drawn from both in equal amounts. The only way one battery would degrade significantly before the other is if it was defective or in the process of going to battery heaven due to old age or abuse. Physical size of the battery is just that (how big it is). Physical size is indicated by the Group Size designation and will be the number 22, 24, 27, 29, 31, etc. Bigger the number -- bigger (physically) the battery and generally the higher the reserve minutes. If you read the label carefully on a deep cycle battery it will have numbers such as: RESERVE MINUTES 205 @ 23 Amps. That means the battery can deliver 23 amps (the test specification for most deep cycles) for a period of 205 minutes (or a little under 3.5 hours). If your troller for example, drew exactly 23 amps at one particular speed setting, it would run constantly for 3.5 hours AT THAT SETTING. Most 12 volt motors for example at full speed and maximum load draw around 46 amps which just happens to be double the 23 amp rating. In that case, and at that speed, the battery would last only 1.75 hours because the motor is drawing twice the power (23 x 2 = 46) so it would drain the battery in half the time. Batteries may also be rated in AHr (amp/hour). That number means the battery can deliver 80 amps for one hour, or 1 amp for 80 hours or any combination that works out to 80 AHr. So compare labels carefully and you will note that one group size 27 battery may or may not have the same AHr or Reserve Capacity as another group 27 battery. One last detail. Two batteries in series doubles the voltage of the system 12 x 2 = 24) but available current (amps) is equal to that listed on one battery. Two batteries in parallel provide only 12 volts but the capacity is equal to the sum of both batteries.