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Electric bicycles FAQs the what, why and how

What's legal and what's not? The wording of the various State Departments ("Transport", or similar) vary along the lines of - a bicycle capable of more than 200 watts, if electric, or having a fueled motor is not permitted on a road. There may be some confusion about a. what "capable of" means. b. what is a road. A street, a lane, may not be a "road". c. whether a footpath or a bikeway is part of the "road". Otherwise national Parks and State parks and forests often have rule of no "motorbikes" - without being clear about electric bicycles are motorbikes. A bicycle with electric motor(s) capable of more than 200 watts or with any fueled motor is considered as a moped and needs to be registered ... but is unlikely to meet the requirements. What motors are there? There have been bicycles with electric motors for many years. In the past these were cumbersome contraptions with a bulky motor and drive belts, but modern electric motors have been developed that are so small that they fit within (a slightly larger) wheel hub, or on the bike chain. The most recently developed motors, which would be on most new e-bikes, have some feedback "intelligence" where the motor senses how much is being applied by you, the rider, and how much is needed to make the e-bike keep it's speed. Nearly all new electric bicycle motors are brushless 24volt or 36volt DC motors. Older, or cheap, particularly in Asia, electic bikes may have a brushed motor. That simply means the motors, like your power tools, have a pair of rotating contacts to change direction of the current twice per revolution of the motor. These need to be replaced sometimes. In brushless motors the current is sent as pulses from a controller sequentially to the many coils of the motor. There are two types of brushless DC motors : geared and ungeared. You can tell the type by its diameter. Ungeared motors have bigger diameter (about 2x). Ungeared motors have a slower revving motor that drives the wheel directly. Apart from the rotor directly attached to the wheel there are no moving parts. They are simpler inside but need to have a very high torque to start the motor which puts a higher load on the battery. The more compact geared motors have a high revving motor with planetary gears around it to match the slower revving wheel. They are more complex inside and the planetary gears make a whirring noise. The compact and lighter geared motors are generally 300 watts or less and the larger and heavier ungearedr motors are 500 to 1000 watts. Which is better? Probably neither. How much "assistance" is there? Some electric bikes are an "easy" ride, some are not an "easy" ride. The emphasis is on "assistance"...whether you assist the bike, or not, or whether it assists you some of the time, or all of the time. You can choose this. More on that just below. You should buy an electric bicycle with the intention of doing some of the work. After all everyone advising on health suggests having regular exercise is the way to live and stay healthy. The emphasis here is on "regular" rather than how much. It does not need to be much... a regular half hour is shown to make a huge difference compared with no exercise. This is why an electric bike will make a difference to your health. If you make it assist you. Where once you did not consider riding a bike to work, school, or the shops because it was too much effort, or because you got too hot and sweaty doing so, now you can ride the bike and not take too much effort, or get too sweaty.

The "assistance"?
All electric bicycles have had "pedal assistance". With that control the motor kicks in
when you have started pedalling and turns off soon after you stop pedaling.
In some countries (for instance Europe) this is the only permitted control. A throttle is not allowed.
While the motor is on feedback from the motor makes the controller add more power when you pedal
harder for hills. However the variable assistance is not very subtle and it is hard to dawdle the bike. 
Its difficult to manoevre through people on the path, or to give yorself a nudge to get through a 
narrow path without the motor kicking in too much. 
We are permitted to have a much more useful control - a handlebar throttle.
With this control it is easy to turn up or down the amount of assistance the motor provides...
as little or as much as you need, or want...
from doing your normal pedalling and giving that a speed and power boost to
taking it easy, and assisting the motor, a little, lot, or not.
The best e-bikes will have both pedal assist and throttle acting independently.  
PAS starts when pedal is turned, and stops when pedal stops - after a delay of about a half second.
There is a disc with a ring of magnets on the axle of the pedals, and a sensor on the frame.
Some bikes may have a switch for the pedal assist, or PAS. If they don't then
usually the PAS can be turned "off" by moving the disc with a ring of magnets away from the sensor.

The power of the "assistance"?
We are allowed to have 200watts of assistance. 
That is the motor can have 200 watts output. This is because that is about what a reasonably fit cyclist
can do unassisted. (A Tour de France could manage double that, and for 4 hours, but not you or I) 
So what can 200 watts do? On flat going 200 watts will go 25kmh, plus or minus depending on the set
of the motor (or what its maximum is set to be) and of course less on hills, depending on the slope.
With the 200 watts plus something approaching that from you and gears you will be able to ride 
up just about any hill you would want to go up. And it will be much easier, and several gears higher
than it would be without the motor.
In US the permitted power is 750 watts, and there is discussion about raising the limit here to maybe 250 watts.
Extra power does not give a proportional increase in speed - because wind resistance increases rapidly,
and motor loses efficiency at higher speeds, but on hills at lower speeds the extra speed is
more nearly proportional to the extra power.
How far will an electric bike go?
On one recharge that is. 
That depends on...
The bike, the battery, the terrain, the ride, the day, and you, it's rider 
1.The bike....it's weight, its condition, whether the tyres are fully pumped, and whether
the wheels spin freely, and the brakes don't drag
2.The battery....its voltage, its AH, the ampere-hours, and its age...
(the product of the V and the AH is watt-hours, and that is the energy available to make the bike go,
although there will always be some energy left that can't be used).
The capacity of any battery reduces with its age (see below) 
3.The terrain....hills have a very big effect
4.The ride....the speed, the stopping and starting
At full speed the range could be a third less than it would be at around two thirds of max speed -
because the efficiency of the motor is much less when it is running close to its maximum speed, and
frequent stopping (wasting energy) and starting (motor is inefficient at low speed) will reduce the range,
especially if you start with full throttle (causing a bigger current from the battery).   
5. The day....less if it's windy, or very cold and
6 you, the rider...how much effort you contribute yourself - 
As a guide, a fit cyclist could sustain about putting out energy of about 150-200W, 
which is just what they allow us to have as "pedal assistance" with an electric motor. 
You will see greatly varying quoted "range" on advertised models, but always go by the V x AH
and divide that by 6 to 10 and then take off some for age of battery, and that they never
use all the energy. The higher the Volts, and the higher the AH the longer is the range.
Tips for getting a greater range. 
    1. keep tyre pressure up (this also reduces the chance of a puncture)
    2. accelerate slowly, and 
    3. anticipate stopping and use the momentum to glide to a stop. 

What types of battery are there? 
At present there are two types of battery commonly used...
Sealed lead acid batteries and various compounds with lithium.
Its weight versus cost. About 3 times as heavy versus 3 times as expensive.
While the cost of lead acid batteries is largely determined by the cost of industrial lead and
sulphuric acid, both of which are rising, the cost of the lithium ion batteries is largely
determined by the technology rather than the cost of the lithium compounds, and is likely
to become less with volume production. The sealed lead acid batteries are made with 2, 3 or 4
small 12 volt batteries connected in series within a case. "Sealed" means just that...
no vent, no need for topping up, no need to be kept upright.
The lithium batteries are like a bigger laptop battery. They are made with a stack of many 
3.7 volt cells in series. There has been, and continues to be an evolution of various 
lithium compounds, co-compounds, and compositions aimed at better performance, delivery and "life".
The lithium batteries used in electric bicycles are generally refered to as being "lithium-ion".
The "lithium-ion" is the cathode of the battery. There has been an evolution of lithium-ion formulations.
The most commonly used is Lithium Manganese Oxide (LiMnO2). 
A better cathode formulation than the common LiMnO2 is Lithium Iron Phosphate (LiFePO4, or LFP).
A battery with LiFePO4 can have twice the life, (up to 2000 charges) and is much more stable and safer in use.
These are likely to be the batteries powering e-cars, e-trucks, e-buses, and e-bikes too.
They cost a little more (about %20) but the extra cost is worth it for the extra "life".  
Why aren't LiFePO4 batteries used more? Probably because they cost about 20% more.
A technology for the near future (just starting to be used for electric bicycles) are capacitance
batteries...A giant capacitor about the same size and weight as a lithium battery and also holding
about the same energy but, at present costing more, whose advantage is very rapid charging.

What is the "life" of a battery? 

There is no predetermined "life" as such.
It's just that by the time the battery only has 60% of its original capacity it is losing capacity,
and usefulness, quickly and for most purposes needs to be replaced soon, and so that's it's "life"
The battery factories test their batteries with a series of charge/discharge cycles.
Of course they don't get on a bike and ride it for 2 hours each time, but instead discharge in the
laboratory through a resistive load. They produce a capacity versus discharges chart and a certificate
saying 300, 800 or 2000 etc discharges to reduce the battery's energy to 80% of original.
In practice, on the streets, however, a battery will not do so well. 
There are many factors that affect how long a battery will give a useful service.
To start with all batteries will deteriorate by a small % every month, however they are used,
and even if not used. Other factors affecting the battery include rough treatment, 
and being kept or left in a hot place (or being left in the sun).
Partial discharge/recharges should give proportionally more recharges.
Neither type of battery should be left unused unrecharged for more than a few months,
(particularly if it was flat at the time it was left)...
however they should also not be left for a long time fully charged either.
About half charged is better.
LiFePO4 batteries fade with time much less than do common "li-ion" batteries.

More About Lithium Batteries 
For the science of, the advantages of, the problems with, the history of, and future of
the various types of Lithium-ion" battery I suggest those of you interested in delving further into it refer to :
Li-ion batteries on Battery University
Li-ion polymer batteries on Battery University
LiFePO4 Li-ion batteries on Battery University

Taking Care of a Lithium Battery? 
The lithium battery is the most expensive part of your electric bicycle.
It is very worth while your taking good care of it. It will have its own built in Battery Management System
that should protect it against its being short circuited, its overheating, or cells within it that don't
do their equal share of taking a charged and giving it back. The BMS is not a 100% guardian.    
They should not be overcharged. The charger should power down when the battery is charged, but if the 
charger indicates "charged" disconnect it anyway. Leaving chargers "on" will reduce their life in any case. 
The charger should turn off when the current is low.
Note also that 36 volt battery chargers are NOT all the same. Do not use one meant for a lead-acid battery
to charge a li-ion battery, or LithiumIronPhosphate or vice versa. 
LiFePO4 batteries are charged at a slightly higher voltage than Li-ion batteries (43.8v vs 42v) and 
should have a charger meant for LiFePO4 batteries. A "LiIronPhosphate" charger will overcharge a Li-ion battery.
To avoid risk of short circuiting the battery, (particularly the ones with single pin plug/socket)
connect battery to charger before connecting charger tothe power.
The batteries will age quicker when fully, or nearly, charged. The more time they spend fully charged the less will
be their life. If the bike is not going to be used soon then leave charging until soon before you expect to use it.
Also frequent topping up is not recommended for similar reason. The power from the battery is quite constant 
until about 70% of the energy is used. It's a misconception that a full battery gives more power.
Li-ion batteries do not have a memory effect. You don't want to risk running the battery flat, but if your
use is generally short trips then it is best to go around 2/3 of battery range before recharging.
Temperature extremes have a big effect on life of a battery.
The life reduces more if used above 50degC or below 10degC.
They should not be left in sun, or stored in a hot place. 
If it has been in sun or hot place allow it to cool before use. 
Parking your bike in a place with full sun every day will be the greatest factor in reducing the life of the battery.   
The battery ages more slowly if stored in a cool place, even in refrigerator
(not freezer), but then do allow it to warm up before use.
Your battery should not be left unused unrecharged for more than a few months,
lest the constant trickle of current used by the battery's management system take the voltage down to a critical level.
(Particularly if it was flat at the time it is left)...However they should also not be left
for a long time fully charged either as that too reduces life. About half charged is better. 
There is a much misinformation about "li-ion" batteries. To be better informed follow the links above.

What if it raining? Is that a problem? 
No more so than with any bike. The electrics are sealed and water runs off the battery and motor.
Of course one has to be careful with wet roads but puddles or wet roads are not a problem
because the bike is electric. Just avoid deep water, and leaving the bicycle out in the rain 

I see some have gears, some do not. Are gears necessary? 
In a word, no. As mentioned above, the new electric motors are "clever" in that 
they sense how much power is needed, and apply more torque as necessary, and, unlike older motors, 
can deliver power efficiently over a wide speed range. 
With the bikes with a hand throttle you turn up or down the power as you choose.
With 200 watts of power you only need to assist the motor on medium hills.    
Even without gears you won't have to stand up and push, for a start, or going up hill, 
like you may have had to do on an older non-electric bike without gears. 
Nevertheless most e-bikes have gears so that when you need to assist the motor
going uphill it will be easier with the low gears

Why is there such variation in the cost of different bicycles? 
3 things make most of this difference 
    1. Aluminium alloy frames are much more expensive and magnesium alloy even more. 
    2. Lithium-ion batteries are about 3 times the price of lead-acid ones. $350 vs $120
    3. 36V, and the higher AH versions, are more expensive than the 24V batteries, 
(especially so for lithium-ion batteries). 
Having derailleur gears, especially Shimano, adds significantly. 
Other extras such as lights, baskets, carry racks, a good soft seat also make some difference. 
Look at these things when comparing. A 36V alloy e-bike with lithium battery could be about
twice the cost of a 24V steel e-bike with lead acid battery and similar frame. 
With so many variations on offer it is best that you try various bikes to find what suits best. 

How heavy? how light? 
It's simply cost vs weight. 
Alloy electric bicycles with lithium batteries can be as low as 21Kg 
while steel electric bicycles with lead batteries can be up 48kg.
A 36volt SLA battery is about 14.5kg and a 36 volt lithium battery is about 4.5kg.  
The two factors to gain or lose weight are the battery and the metal of the frame. 

What is the cost of running? 
The power cost is small...36Vx10AH is about 0.4 of one KWh, and your electricity 
supplier sells you 1 KWh for about 22c. A full recharge is therefore about 8 cents or about 0.2c/km
It is not often mentioned but if used often the bigger cost would be the eventual cost of replacing 
the batteries. A lead battery will last about 8000km, or about 1.5c/km,
lithium-ion batteris about 18000km or 2c/km 
and the lithium iron phosphate batteries about 35 to 40,000km, or about 1c/km.
There are ways for extending the life of a battery. (See above)

What benefits are there in having an e-bike? 
    1. To you ... your health, your fitness, your weight, your convenience, and the cost saving 
    2. To your environment ... a lot less CO2 in the air, and more fuel staying in the ground 
It's a cost saving option 
At 2 cents per kilometre it's a tiny fraction of the cost of driving a car. 
(Fuel cost $1.43 for 13km = 11c/km, depreciation $3000/20000km = 15c/km) 
(An occasional taxi, and rented car cost a lot less than owning a car). 
And all those short public transport trips? They add up! 
In most cities typically any ride, even a short ride, is about $3.40. 
It's the healthy option 
Because an e-bike is much easier to ride than other bikes you are much more likely to actually ride it, 
and do so more often, even regularly, and so, be healthier, and get fit, for almost free. 
it's the greener option 
E-bikes are a very environmentally friendly solution, especially if otherwise, you would use a car. 
The CO2 from you riding along (plus some more at the power station to do the recharge) 
is less than 1000th of the CO2 and other stuff coming out of a typical car. 
And that's not allowing for all the extra cost of all the engineering for the whole road system. 
It's so much the better if you eliminate or reduce the commute and small trips you make with a car.
Perhaps you can do without the 2nd car in the family, as a start.

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