We won't know the definitive answer as to whether these new German batteries are any good for another 18 months to 2 years. It's only after the initial euphoria subsides and you settle into the relentless cycle of usage that committing brings, that the battery's true worth is revealed.
As eddio eludes too, the new German battery boasts better performance and longevity than the Panasonic, but sadly the manufacturer's confidence is not forthcoming in terms of warranty. It's up to the individual to interpret why that is.
My 10 Ah Panasonic battery, is now 26 months old and despite struggling through the winter, isn't doing too bad now that the weather is picking up. For the past six months, I have been charging after each leg of my commute, keeping the charge level in the battery between 30 and 70 %. This seems to have stabilised the battery degradation and I'm confident of being able to nurse it through to Autumn. I'm also optimistic that it may make it through next winter, in which case summer 2012 may be on the cards.
I was despairing at the rate of degradation, but since adopting my new battery charging regime, I'm a little more hopeful. I do tend to use the bike on low assist quite a bit, so the lower current demands on the battery my also be helping.
If I were buying a new battery today, I'd probably go for the new 18 Ah one. I don't know why, I just would.
