In series or parallel
To keep my mind active during the lockdowns, I’ve restored an NSU Prima scooter which was hidden in the garden shed for 30 years. It is near-ready to start thanks to the NSU workshop manual, which had helped with gear and engine build problems. But I’m stumped with its battery, as the space in the front legshields won’t accommodate a 12v battery needed for its Siba Dynastart, so I assume I need two 6v batteries. But how do I join these together as none of my wiring diagrams help? Will four batteries somehow wired in series and parallel be better? And why two 6v batteries? Ease of accommodation perhaps?
Jason Harvey, email.
The Siba Dynastarts were originally fused with two 6v batteries connected in series (positive to negative) with the set’s remaining positive and negative battery poles connected to the machine’s electrical system as per the wiring diagram you have. Assuming you acquire suitable batteries, you don’t need to boost the amp hours by connecting two pair (each pair connected in series) in parallel.
In period, few if any 12v batteries were available for motorcycles and in turn NSU designed the Prima’s legshield bodywork to take two 6v batteries.