Thanks Doc,thinking that way too, but may go for the cheapest option first to keep as a spare for other things.That way I can have a play with bike this week,will see.Interestingly, the bike came with a PC545 of unknown age, the two previous owners had been having major issues with no power. Putting it on charge with a smart charger, the battery looked to work fine, but kept topping up. Left it on and it nearly exploded, blew up like a football. Battery guy tells me that that would indicate a bad cell, possibly from new.
The bike, which had been a non runner for three years, started right up when hooked up the the larger Odyssey out of my Cali 1100.
Again, interestingly enough, I bought the Cali from a friend who had spent 1500 bucks chasing an intermittent total loss of electrical power over two years, I replaced the (red dog? mad dog ?) battery with Odyssey pc925 and it hasn't missed a beat in 20k miles.