Join Date: Jun 2013
Location: South of England
Here's what I would do. Buy a charger designed for use with a motorcycle battery, preferably a "smart" charger that can detect the appropriate charge rate for the state the battery is in. When the battery is fully charged start the bike and let it idle for a while. Measure the battery voltage at the battery terminals with the engine ticking over and lights on. Should be more than 11 and less than 13 this is not the important reading. Increase the revs to about 3-4K and repeat measurement, should be more than 13.4 and less than 15. If these readings are OK then your charging system is OK, but you still may need a new battery. The AGM batteries (no vent tube, no topping up with distilled) have a lower self discharge, the old "wet" batteries need a refreshing charge if not used every 4 to 6 weeks. All batteries do slowly go flat if not charged. Unless you ride all year round fairly regularly you will need a charger. I would recommend the relay mod to minimise the voltage drop to the ignition coils and also the mod to increase the pickup signal from the ignition coil pickups. Batteries need capacity (the ability to keep cranking at a decent rate for a decent time) They need to be able to supply sufficient current without the voltage dropping too far. As they fail they loose these factors. If in doubt get it load tested.
One can never have too many alternative forms of transport.