LCD display not linear - 50% on display is nowhere near 50%

[Telkwa]

Thought this might be worth passing on. We visited the Sequim/Port Angeles area the last few days. Rode various chunks of the Olympic Discovery Trail, a work-in-progress that aims to tie Port Townsend to Forks. All the way across the top of the Olympic Peninsula.

One lovely day (air temp in the upper 60's - lower 70's and a home-brew Reflectix blanket wrapped around the battery) we went about 24 miles one direction. When we turned around my display said I had 70% charge left. I thought "Plenty". Got back to the car with the LCD flashing 10%.

Clearly the LCD display does not tick down in a linear fashion.

There are some up's and down's on the trail, but nothing drastic. The beginning point might have been lower elevation than the turn-around, but I'd guess no more than 100 feet if that. I pedaled 90% of the distance in Eco. 98% of the route was paved.

So my Haibike HardNine 1.0 with 400Wh battery won't last 50 miles even in Eco. Not with knobby tires and a 225 lb. guy onboard anyway. I can buy a 500Wh battery but that costs almost $1000. Give me a break. It'd be more cost-effective to buy a second e-bike that's equipped with a 500Wh battery!

 

[rich c]

You can find a Haibike with 500wh for $1,000? Link please.

 

[6zfshdb]

I don't know of any voltage sensing battery gauges that are truly linear. The voltage of a lithium battery does not drop in a linear manner as it discharges. A typical 3.6 / 3.7V lithium battery cell discharge voltage profile looks something like this:


The colors represent the variation caused by deviation from room temperature.

Some gauges use software in an attempt to "linearize" the curves but variations in temperature and discharge rate make this difficult to do at a reasonable cost.

Many gauges use a series of bars to indicate the remaining charge, like the one on my Pedego Interceptor. They aren't linear either but represent a range rather than a specific percentage.

• 5 bars - 100-80%
• 4 bars - 79-60%
• 3 bars - 59-40%
• 2 bars - 39-20%
• 1 bar - 19-0%

While less accurate, they are a bit less misleading IMO.

 

[harryS]

I looked up Olympia Discovery on the map. Looks very nice. Mostly paved? Maybe some day, I'll get out there with an ebike. Been to Seattle a few times. Always good.

I wouldn't be too disappointed. 400WH for a 36V battery is only around 11 AH. 50 miles is good. That's a rate of 8 wh/mile, low for most ebikers. What was your speed, around 13 mph?

It's difficult to have a battery display track the real capacity in a battery. If you ever looked at the voltage-aH curve for a battery, you would see that it's well beyond the ability of a bike display. What many people people do is use their experience to figure how many miles they get before it's time to turn around. Factor in hills and wind while you're at it.

Edit: I see someone has put up the transfer curve while I was typing.

 

[Roxlimn]

Range depends on how hard you pedal. Obviously, if you pedal on your own, the range is functionally infinite.

Giant's implementation of the PW motor system is fairly good. I have a 400 Wh and a 500 Wh battery. I bought the 500 Wh one for $500. As far as I can tell, the depletion on their monitor is linear from 90% to 30%, which is as far as I discharge the batteries. I am 200 pounds using Minion (VERY knobby) tires with about 20 pounds of cargo. I have made 80+ km on the 400 Wh battery using a mixture of Eco and Normal. Using Eco and some Off, I figure I can make 60 miles on flat terrain.

The range is user-dependent. When I'm weaker because of lack of saddle time, my mileage per Wh is noticeably lower.

 

[Telkwa]

OK, very funny rich - "Cost-effective", not "same price"

The Olympic Discovery Trail is almost all paved. Just a few short gravel stretches. We saw many cyclists on skinny tires. The ODT is quite remarkable once you've found it, but researching online is sketchy. There are downloadable maps available that apparently will go right on your smartphone but I didn't know how.

For those of us who don't live via their phones, there are some stenciled markers painted on the road, and some dinky little signs on some poles at some intersections. But its really easy to miss them. We found maps at some of the trailheads. The maps were a bit hard to follow and some of the text was tiny.

We missed the turn coming in to Sequim from the east. The ODT turns away from downtown Sequim and meanders thru a lovely little park. We found the correct route on the way back through town. We also missed the jog up to Crown Park at the western end of Port Angeles. Fortunately a helpful woman who's a sponsor of the ODT stopped to help as we stood on the side of the road looking lost.

The ODT isn't finished. They're working on the connection between Port Townsend and Blyn. And there are long stretches, such as the one west of the Lower Elwha River bridge, that put you on the road with the cars. The Lower Elwha bridge is really cool. Cyclists and pedestrians get their own bridge suspended beneath the car bridge.

The Spruce Railroad Grade is another section that isn't done but will be cool when it is. West of Lake Crescent is remote logging country. Trail's not done and we didn't explore that way.

Near Lake Crescent is the Adventure Route, a bonus for those of you who have knobby tired bikes and know how to use them. We pedaled a few stretches near the western end of the Route. Really cool single-track. Lightly used. We met two people.

Thanks for the feedback on batteries and displays and discharge rates!

harryS, you are correct. We probably averaged around 12 to 13 mph.

 

[michael mcvey]

I ride a Giant Road-E. The computer displays battery remaining using a percent metric. The display will show 100% at full charge, as you ride the display tracks the battery remaining. it goes from 100, 99, 98, 97....15, 14, 13...
It is extremely accurate and very linear to about 12%. At 12% it is no longer linear and drops to 1% or 0% very quickly.
I have two batteries and both react the same way. I trust this metric and have adjusted my thinking to 12% means 00.

 

[john peck]

I looked up Olympia Discovery on the map. Looks very nice. Mostly paved? Maybe some day, I'll get out there with an ebike. Been to Seattle a few times. Always good.

Hope you get the chance, Harry. I´ve ridden as much of the ODT as is open & a few bits not complete. It will make for an awesome tour if they
ever get it complete to Forks. Was just down riding the Historic Columbia River Trail on my way into eastern Orygun. A goodly portion got severely messed up near Cascade Locks by a fire caused by a kid playing with fireworks. When complete it will run from Portland to Hood River & beyond. Oregon is committed to this project. They are doing a super job of making it happen & construction is rapidly underway. What´s there passes some beautiful
waterfalls & has access to some great hiking trails though much is closed now to prevent further fires. (Too bad, I never use fire when backpacking:
one jerk with matches spoiled so much for so many.)
P,S. Eastern Oregon has lots of great, lightly traveled back roads.