John in Christchurch has sent in this report about the distance traveled on each light with the new 15 amp hour eZee battery. I think it is instructive re the variability of the voltage drop and shows you can’t always estimate the remaining capacity just from the monitor LEDs in percentage terms. The lesson from this is that it is important to measure our remaining useful distance on the handlebar odometer as well as from the LED interface. This is a problem with all brands of bike, by the way, as the voltage on bike batteries is not an extremely accurate way of determining capacity. There are lots of variables that affect the draw that will skew the battery monitor readings a bit. Headwinds, tailwinds, hills, and ambient temperature are primary spoilers of voltage calibration.
Not to worry though, as you will still get a very useful readout from the monitor and you have the trip computer giving you the best measure of distance to go on a charge. I think the distances achieved with our new Sony Hi-capacity cell battery are impressive. We are expecting longer lives out of the batteries as well. The promise of dense battery capacity is upon us.
Here is John’s report.
It has taken me more than a week to find the time for a long ride on the flat to test the new battery until it stops. This I have now done over two days. On Wednesday I did 64 km and without any charging, did another 16 this morning until the battery cut out. All this was on the flat and on the 3rd pedal-assist power setting. The winds were moderate with some head and some tail. The distance traveled between lights going out was as follows:
1st green light out 16 km
2nd green light out 35 km
1st orange light out 43.5 km
2nd orange light out 67 km
Red light out 80 km (this is total distance on one charge).
What is interesting to me is the large variation in the distance covered on any one light. I am not sure if this is due to inaccuracy in the indicator or reflects the amount of head or tail wind.
I am inclined to give it another trial on a higher speed setting and then on a hill ride. You suggested that the battery would improve after several charge cycles.”
Yes, John, you will definitely see an increased capacity after several complete charge cycles of the battery. Your results are consistent with my experience with the variability of terrain and rider-assist. Thank you for reporting this. It’s a good indication for others about to interpret the lights. The remarkable thing about lithium batteries is that you got almost identical power from the largely discharged battery as you did from the fully charged battery.