Ebike Battery Lifespans

[ministashy]

A little over a year ago, I decided to take the plunge and convert my bike into an e-bike using Clean Republic's Hill Topper kit.  Overall, up until this point I've been very pleased with its performance--I live at the top of a long hill, and having the kit has cut at least 20 minutes off my commute each day.  However, recently it's been dying before the end of my commute.  The battery is rated for 20 miles under normal conditions, and I've owned it for about 15 months.  I don't have a long commute--only about 6.8 miles all together, and the battery is only used for roughly 3.2 miles of that.  But--I do use it every workday, so a rough estimate tells me I've put around 2100 miles on it.

Given the mileage, is this kind of performance drop normal?  Clean Republic rates their batteries as lasting 1-2 years, so I'm within the ballpark--but buying a new $250+ battery every year or so just seems a bit excessive (and not very environmentally friendly).  I'd be interested in hearing what other e-bikers think--and whether there are any other, longer lasting battery options I should consider. 

[BikingViking]

I've had my battery for around 2½ years now. In the beginning it was good for around 20 miles, now it's more like 15 Most of the performance drop happened in the first year, since then it's been a very slow decline. I use it 5 days a week year-round, and my commute is long enough to require charging it both ways. It's a LiFePO4 battery.

One thing I've read is that it's really important to never let it run completely empty. Most batteries have some sort of built-in protection against this while using it, but if you don't use the bike for a a while, you should still charge the battery once a month or so.

[ministashy]

Sorry, I had a typo in my original post.  My battery was originally rated for 12 miles, not 20.  Still, I haven't been pushing it hard, and it hasn't been sitting in storage--it gets charged after every use, and I'm down to about a third capacity in a little over a year.  :(  I'll go back to Clean Republic if I have to, but I'm wondering if there are any battery brands/kits with better lifespans I should be looking at.

[BikingViking]

I'm afraid I can't be of much help there - my battery isn't branded and it came with my bike (which was a pretty cheap made-in-china-bike whose manufacturer has gone out of business).

[BikingViking]

Hmm, I just thought of something. You say your battery is rated for 12 miles - when it was new, did you test if it would actually last that far on your commute? When I've been shopping for electric bikes, I've generally found that I can count on getting about half the "rated" distance. I think they make those statements based on some kind of ideal conditions - not hilly, no headwind, rider not too heavy and pedaling hard. Well, I have a hilly and windy commute, I'm somewhat big and rather lazy. For me, a working formula for expected range in kilometers with a given new battery is: AH*V/10 (AH = ampere hours, V = volt)