I have a 24 volt electric bike system and an extra 12 volt deep cycle battery. The 24 volt system is made of two 12 volt batteries. Is there any advantage to connect the extra battery in parrallel with one of the 12 volt batteries.Would it increase the amp hours of the system or would the circuit of least resistance become the one used. I would only connect the 3 rd battery when needed and would charge it separatly

 

It would not increase the amp-hours of the system.