Kalkhoff 18ah Battery - a slow upgrade?

[nuppynup]

I recently received my new 18 ah battery for my Pro Connect. It came fully charged, though I stuck it on the charger just to make sure it was fully topped up. Anyway today was the first chance I had to try it - my daily commute to work; a 22 mile round trip. My initial feelings are that it is somewhat sluggish, on average around 1.7 mph slower than my old 10. Has anyone else found the performance of the new battery somewhat less than expected?

 

[bazwaldo]

It has been pretty cold today with snow and sleet.
Probably the low temperature has more to do with the sluggish feeling performance.
I swapped over my Bearpint Ebike to a new warranty replacement 16AH Lipo battery today for the first time and it seemed to perform less well than my directly sourced Chinese 12AH LiFePO4 battery which I have been using for the last fortnight.
The bigger 16AH battery seemed to dip down to 2 or even 1 light more easily than the 12AH LiFePO4 battery.
Both batteries got me home on a full charge during my 26 mile round trip commute.
It's too early to compare the 2 but I decided the cold temperature was the main factor in the difference.
If we have milder weather again you may find the 18AH battery performs more to your expectations.

 

[rog_london]

I was looking on the Kalkhoff site earlier, and they do have a graph which indicates the expected battery CAPACITY against temperature - with maximum capacity at 20 degrees Celsius, but around 93% at freezing point. This sounds good, but in practical terms it doesn't mean much at all - read on....

Most people don't notice the reduction in capacity (which I'm told in some technologies can be as much as 30% at freezing point), but what you do notice is the drop in voltage under load, which can make the bike much more sluggish to ride - and consequently you are likely to be drawing more current for longer, which appears to show a much bigger reduction in capacity.

This is to be expected, because a battery works by means of a chemical reaction which produces current, and all chemical reactions are affected to a greater or lesser degree by temperature variations - so 10 degrees Celsius can make a huge difference to how a battery behaves.

Kalkhoff suggest that in cold weather you should bring your battery into the warm for a while before using it, and always before putting it on charge, though it is better stored pretty cold - they recommend (conservatively I feel) 10 degrees Celsius is a good storage temperature. Once the battery is warm it does generate some heat in use and therefore may well maintain its temperature while you're riding - though any benefit will vary between types and capacities - and how hard you use it.

Storing a battery cold is also a pretty obvious aid to longevity - you can slow down the age-related changes in this way. Not too cold though - not in your freezer!

Pity that doesn't work for the rest of us.

Rog.