First remark : if you can avoid using a battery and work with the people pedal power in stead, this is considerably more interesting for the environment
– car batteries a heavy compared with the energy they can store, they are designed for giving high current.
– deep cycle / cyclic / boat batteries can contain more energy because of the internal structure of the battery technology, allowing a deep discharge.
*input* : user power (ex sound system of 900W peak)
*input* : time of autonomy (ex one hour before charging)
*input* : voltage of the system (ex 12V)
*energy need* = user power * time of autonomy (ex = 900Wh for the sound system)
checking the battery parameters
– Gel and Absorbent Glass Mat (AGM) types of VRLA can be mounted in any orientation, but need to be ventilated.
– the depth of discharge (DOD) of a battery determines the capacity and the number of cycles, 60% is a good value for AGM batteries (check DOD documentation).
– the current of discharging lowers the voltage output, the higher the discharge current, the lower the voltage and the lower the capacity.
*battery voltage at the DOD* > voltage of the system (ex 6 cel Li-ion doesn’t work, ex when discharging in 3h (0,3C), after 3h the battery voltage drops to 11V)
*charge need* (Ah) = energy need / voltage / depth of discharge (ex = 900Wh / 12V / 60% = 125Ah)
ex DAB12-135EV 12V 166Ah 136Ah 342 173 286 B M8 43,3 http://www.dynoeurope.com/assets/dab-ev/DAB12-135EV-TDS-EN.pdf
The number of cycles of a battery is dependent on the depth of discharge.