BT-E6010 battery w/ E5000 died 4 miles early w/ no reserve & no warning

[Catalyzt]

Ooh, but a sour note today: I only got 28 miles from approximately a 90% charge (could have been anywhere from 81 to 99%) on Seeker's Shimano BT-E6010 battery.

Last time I checked, which was about 700 miles and a year + ago, I was still getting around 40 miles with 4,000 feet of vertical, though that was calculated from a single long ride with a full charge. The last 28 miles were over the course of 10 days, a 12 mile ride and then multiple short rides.

What's worse: I had no reserve and no warning. Display was showing about 3 miles in HIGH, 7 in NORM, 9 in ECO. I changed battery modes-- I think I was downshifting from HIGH or NORM to ECO-- after a steep climb and BLAM, no assistance, and range readings were suddenly 0 for all three modes. (Seeker did get me to the top of the hill, bless him.)

Again, just under 1,500 miles on the odometer, bike is 2 years and nine months old. We will see how it does from a full charge-- I will charge it to 80%, wait until I need to ride, top it off to 100%, wait 20 minutes before riding, and try a longer ride. It could be that the display and controller are just miscalibrated-- e.g., it was unable to estimate how many miles I had left, or maybe it wasn't really 81-99% charged-- the controller got psyched out because I don't charge it to 100% anymore, like I used to when I was young and foolish (a year and a half ago.)

Weird. (Also posted in the 'Motobecane - I bought one' thread.)

Any thoughts? I am kind of training for another long ride in the Verdugos in the early spring which will be well over 35 miles. Lots of long flat segments where I'll use almost no motor, but several long, very steep segments as well.

 

[TrevorB]

The estimated range is based on battery voltage (36v) reading at time. Capacity in the individual cells does vary so when range was estimated one or 2 cells may be almost flat. NB voltage drops off dramatically in last few % eg from 3.0 to 1v. Our old Shimano 400wh battery use go from 23% to 8%. In summary with batteries don't rely on last 20% being useable.

 

[Catalyzt]

The estimated range is based on battery voltage (36v) reading at time. Capacity in the individual cells does vary so when range was estimated one or 2 cells may be almost flat. NB voltage drops off dramatically in last few % eg from 3.0 to 1v. Our old Shimano 400wh battery use go from 23% to 8%. In summary with batteries don't rely on last 20% being useable.

I know it's based on voltage, which is maddening-- particularly on a 17 miles into a 34-mile round trip, ascending a steep grade, when the bike tells me it only has 8 miles left, and I know based on experience it had over twice that much.

Did you find that the range estimate (or number of bars shown 1] got worse as improved after balancing the battery, and 2] did it improve after balancing the battery?

The other thing that was weird: The readout on the display AND on the battery still showed 1 bar remaining, and not even blinking as it does in reserve, when no power was available. I turned it off and turned it on again-- same thing.

I'll take it for a spin first thing tomorrow, really hope it isn't something worse.

 

[TrevorB]

I know it's based on voltage, which is maddening-- particularly on a 17 miles into a 34-mile round trip, ascending a steep grade, when the bike tells me it only has 8 miles left, and I know based on experience it had over twice that much.

Did you find that the range estimate (or number of bars shown 1] got worse as improved after balancing the battery, and 2] did it improve after balancing the battery?

The other thing that was weird: The readout on the display AND on the battery still showed 1 bar remaining, and not even blinking as it does in reserve, when no power was available. I turned it off and turned it on again-- same thing.

I'll take it for a spin first thing tomorrow, really hope it isn't something worse.

The display worked in % not bars. I never use range estimate as they are never accurate as to many variables. Always fully charged the battery, why partially charge a battery unless storing for extended periods?

 

[Catalyzt]

The display worked in % not bars. I never use range estimate as they are never accurate as to many variables. Always fully charged the battery, why partially charge a battery unless storing for extended periods?

80-20% charging rule. Not charging the battery to 100% (except briefly, occasionally, when full range is needed) extends the life of the battery, even if it sits idle for a few days. My display does not have a percentage readout, I am only estimating percentage by the number of bars. The range estimate has, up to this point, been useful when I'm repeatedly climbing the same terrain-- e.g., I know "8 miles" really means "16 to 20" at a particular point on a particular ascent.