Wisper 905SE not getting the mileage I expect

DGC

Just Joined
May 31, 2015
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I was getting poor mileage from my original 10 year old 14Ah battery, not surprisingly, so I recently had it
re-celled and to a slightly higher spec (14->15.6Ah). This has noticeably improved the mileage over what I was
getting out of the previous battery but it is probably still 50% lower than what I would expect., i.e. I'm
now getting approximately 20 miles instead of nearer 40.

I think there may be a problem which is being disguised or hidden when the motor is engaged but if I am
cycling on a flat road at say15mph with the motor engaged and then I turn the power
off to the battery in-flight, all of a sudden I feel a lot of drag and it becomes extremely heavy to pedal without
motor assistance. This is far more than the effect of just pedalling a heavy bike, low tire pressures or wind resistance. Without
pedalling, the bike is quick to slow when it should be just coasting along on the flat.

When the bike is stationary and individual wheels are raised off the ground, both wheels will run freely
so there is nothing binding and nothing rubbing.

It almost feels as though when power to the motor is turned off in-flight I can feel a drag and
although this isn't obvious when the motor is running, I feel this drag may be why I'm not getting the
mileage out of a battery charge that I expect.

Anyone recognise this scenario and can you offer any advice?
 

Wisper Bikes

Trade Member
Apr 11, 2007
6,283
2,252
69
Sevenoaks Kent
Hi, the drag you are feeling when the bike is turn off is the motor drag, basically it's similar to turning a hugh dynamo. 20 miles isn't good though, please may I have all the stats, and certainly check the tyre pressures. It may be that the motor is reaching the end of it's life and needs replacing. Please feel free to PM me.

All the best, David
 
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