OK the full story.
Mate sees an add in Pacific Flyer for LiPO4 batteries. Shows Mark, Mark likes.
Mark buys and receives 10 AH battery with all the bells and whistles. (in built computer board, button to release ten starts if battery inadvertently drained etc)
Didn't think 10 AH would be enough zapp but went ahead anyway.
Battery did start the 80 Rotax but only if handled with kid gloves. If cranked willy nilly it would trip out and require the button to be pushed. (Mark on back under aeroplane removing belly hatch to access button)
Was sure it would let us down sooner or later and of course it did.
Sent battery back to dealer, tested and sent back to me.
Let me down so sent back again.
Dealer pulled it apart, doubled the cells (20AH) deleted all said you beaut computer gizmos (including button) and Mark refitted to small funny looking yellow aeroplane.
Playing game so far.
Final outcome:
2Kg lighter than motorcycle battery, no nasty battery acid, no nasty hydrogen produced and if the story is to be believed (fingers tightly crossed) longer lasting than lead acid.
Sooooooooooooooooo, am glad I persevered.
(as long as it does last a looooooooooooong time.
Mark D