Check those batteries.

[Asgard]

Well I think I managed to work out how to use my multimeter! and tested the battery in situ on the bike and it reads 12.85v is that ok? what should a good battery read? engine running or not? (as you can see im clueless on this topic!!)

If it's been sitting a day or 2 before that reading then its 90%* certain to be a good Battery




*N.B. Any Percentage figure quoted will have been arrived at after a quick inhalation through the teeth followed by 75%* guesswork

[Richard Simpson Mark II]

Even a very sad battery will usually show over 12 volts with no load.

Best way to test is to put voltmeter on, and turn all lights on without running the engine.

A sad battery's voltage will drop like a stone.

Some smartchargers can revive a battery, but not all batteries can be revived.

Don't use an ordinary charger on an Li Ion battery, you have to get an Li-specific charger.

Li-ions struggle at low temperatures...they may appear dead, but put the lights on for a minute and they warm themselves up

[Tonibe63]

A good battery should show 12.4 volts without the ignition on, with ignition on it shouldn't go below 12 volts, when cranking engine it shouldn't drop below 9 volts and with engine running it should show between 13.5 and 14.5 volts.
The important figure is the cranking voltage and experience of your own bikes sound when cranking it over is usually the first indication of a problem.
I started all the bikes in my garage today and they all sounded good and all fired up, non are on optimates and nearly 6 weeks since any of them ran.