Range query

[Black Dog]

Can someone tell me if this is a reasonable range to be expected? The bike (16AH battery, hub drive) is described as having a 60 mile range with reasonably fit rider using medium power. I have just experienced a totally dead battery after 43 miles, with unfit rider using full power. (I am averaging over 14 mph doing this, so a lot of the time I am above the speed where the bike assists.) Actually, the range I had was less than that, taking into account a serious loss of power over the last approx 10 miles. Say 35 miles of useable power at max?

The exact usage was 32 hilly miles full power, no issues. Then 7 hilly miles on full power where it failed to get me up a hill that it had breezed up a week before. At this point the battery was showing a red light and one green (full is red and three greens). Then 4 flat miles on half power (3 lights out of 6), then nothing. No lights at all.

Not a problem to me, I was just wondering if this was reasonable. If it's to be expected, then I will recharge every day while commuting, not every other day as the maths would suggest, that's all.

 

[jackhandy]

What motor & how many amps is full power?

My Ezee 14ah batteries normally take me about 27 miles when assisting all the way to 16mph with 3_4,000ft total climb.
I can make them last about 40 miles if I keep my average speed down a bit & contribute more.

Full-on, it'll pull 22 amps.
I've never experienced such a dramatic drop in grunt as you, when the battery is nearly empty, but the difference when I connect the spare is noticeabl.

 

[Deleted member 4366]

Range and LED lights are meaningless. There's so many external variables and every bike is different. Cut-off speed, wind, hills and weight are the most significant factors - not counting yourself.

The more watt-hours in the battery, the further you can go for the same pedal effort. The type of bike can make a difference. Obviously, one with thin 700c tyres and a streamlined riding position will use less power than a a MTB with fat knobbly tyres and wide handlebars. For similar bikes, I don't believe that there's a lot of difference in efficiency regardless of what type of motor provided that you're not causing the motor to run outside its comfortable speed.

A 16ah battery should be able to do 60 miles under normal conditions with a cut-off at 15mph and an average speed of 14 mph. For an averagely unfit rider of average weight over average terrain, I normally work on 30 miles per 10ah at 36v.

 

[Black Dog]

Thanks for the replies, The motor is a Dapu 250W in the rear hub, not sure what the full-power draw is. The battery is 37V, 592Wh.

I think I have all the variable factors stacked against a good range. I am starting to get fitter, but would still regard my athletic abilities as modest. The route is hilly (with some VERY steep sections that bring my speed down to 5 mph even with hard pedalling), I weigh 17st and it is often windy. I guess looking at d8veh's rule of thumb I am not too far out at 35 miles of usable range. What surprised me was the abrupt drop off. From 2/4 LEDs lit up (after several hours of non-use, so not affected by recent power draw) to zero in about 4 miles of flat, gentle riding. I'll need to watch out for this when I am commuting.

I never trust a fuel gauge on my motorbikes, but reset the trip every time I fill up and go by the mileage. Perhaps it will be wise to do the same on the ebike.

Thanks again, chaps.

 

[Jimod]

I would always charge the battery everyday if commuting. It's better to have plenty of charge left when coming home than to be wondering if you're going to make it.

Your range doesn't sound to bad if it's hilly.
Never trust the LEDs on the battery or the power meter on the computer. You now know you can go 35 miles with no problem and 45 if you really needed to.

 

[Black Dog]

I would always charge the battery everyday if commuting. It's better to have plenty of charge left when coming home than to be wondering if you're going to make it.

Sounds like good advice. Do I take it there is no advantage to depleting the battery completely before recharging? Do these batteries have no memory effect? It's a lithium polymer type.

Your range doesn't sound to bad if it's hilly.
Never trust the LEDs on the battery or the power meter on the computer. You now know you can go 35 miles with no problem and 45 if you really needed to.

Just what I was thinking. Thanks for confirming.

 

[Jimod]

Sounds like good advice. Do I take it there is no advantage to depleting the battery completely before recharging? Do these batteries have no memory effect? It's a lithium polymer type.
.

Some people say fully discharge a couple of times then charge regularly, others say don't bother with the couple of discharges. I'm not a battery expert, I just re-charge whenever I use the bike.

 

[Deleted member 4366]

You get more power if you charge your battery every time you use it. Never run your battery flat unnecessarily. That's where problems occur.

 

[Jonah]

The batteries do not have a memory effect. As others have said, best not to discharge fully. On many battery gauges, once the first light goes out you're fine on the flat but the next big hill will rapidly see the battery sag. Many bikes show significantly reduced power when the battery is not fully charged. This will depend on the chemistry of the battery and how evenly it delivers its charge. Your experiences appear normal.

 

[Black Dog]

Thanks all - very clear now.

The instructions with the bike said to charge 12 hours, discharge it fully, charge again and then charge as required, so I have done all of that.

 

[RobF]

A single full discharge is often recommended, but after that charge as often as possible.

The battery will work better and last longer if it is used higher up the capacity scale.

No harm in running the battery low if you have to for a particular journey.

I charge my bikes after each ride, unless I have literally only done two or three miles.