P2 MOTOR : only available as rear motors (front
motors are presently made too wide for most front forks it maybe possible at later
time to get some made to suit 10.5cm dropout width between front forks but
presently they are made to suit 12.5cm front dropout width as used on chinese style
ebikes).
Only available as a brushed type motor. Motor weighs about
3.5kg.
A Geared Motor (planetary type gears and brushed type motor) good for Hill Climbing and not going
too fast, top speed about 23-25km/hr.
The 24volt version can be used with a 36volt controller to get top speeds of
about 30km/hr.
Picture below shows P2a motor in a steel framed mountain bike ( found thrown
out on a clean up day!). I recommend using steel framed bikes if at all
possible. Although aluminium framed bikes are very lightweight they do pose some
difficulties for installing hub motors.
(see http://www.users.bigpond.com/solarbbq/bestbiketype.htm
for some info on different types of bike to use, aluminium frames though I think
are quite ok with this motor as its quite a small motor and not of very high
power output compared to some other motors).
Bike below I'm using P2a motor with two lots of 24volt 8ahr Nimh batteries in
parallel. Controller is 24volt 15amps max. I haven't measured the range as yet
but have been doing rides of about 8 to 10km with a very long hill steep in some
sections (batteries nowhere near flat at end of the ride),
I will install a drainbrain meter soon and get some good data on it). I find the
24volt motor is probably a little slower than I would like so I will at some
stage put a 36volt controller on it and a 36volt battery system (probably
nimh or sla
agm batteries) to get a bit higher top speed.
Motor P2-A : 24volts version or 36volt motor: $280aud
Freight options: 1. EMS air freight with internet tracking allow 14 days
$70aud for freight to any country.
From the time I get your order it will take two to three days to prepare the
order depending on how busy Shen is, so you have to allow for that 2 or 3
days into the time frame for the kit to arrive, but best too allow one fortnight
in total for delivery.
I want to keep one motor as cheap as possible so that there's something affordable for the budget back yard tinkerers (like me: I still spend alot of time in the shed, will it ever end???) but of good quality (for example the Heinzman motor made in germany is a geared motor with nylon gears and would cost near 3 or 4 times the price of this motor).
This version comes not laced into a rim so you'll have to spoke it in yourself or get a bike shop to do it. Instructions on how to lace a hub motor into a rim can be seen here
It has inner planetary gears so its very good for hill climbing but top speed is about 23-25km/hr. They come with motors of differing maximum rpm motors inside the hub depending on what size rim you have to use it in. So a motor for a 20" rim will have a higher rpm then a motor for a 26" rim, the gear ratio inside the motor remains the same about 6:1 ( errata: after dismantling a motor and checking the gears it is actually is 10:1 gear ratio)
The freewheel mechanism seems a very robust design. It allows the motor
to be engaged when power is applied via the throttle but when there is no motor power applied the wheel can rotate
freely without the motor being engaged. It means the wheel can spin like a
normal bike wheel when coasting or if pedalling with no motor power on, also it
will most likely extend the life of the motor as its not engaged all the time
only when the power is on. I find that the resistance against the wheel spinning
is almost negligible, if you were to have a normal bike and a bike with this
motor installed rolling down a hill next to each other you find the normal bike
would roll down more slightly more quickly as there is some resistance, but the
amount is quite low. It would be possible to reduce this rolling resistance by
using oil in the freewheel mechanism instead of grease but I don't think is
necessary unless you really want the freewheel to have the least resistance
possible. The freewheel has 10 roller bearings (compare with the P3 motor which
has only 5 bearings used) so its resistance to freewheeling is slightly higher
than the P3 but is very low and certainly not a problem for pedalling.
Opening the hub there is an electric motor (brushed type) with a set of
planetary gears at one end of the motor which drives the hub via the freewheel
mechanism. So the motor remains stationary and the end plate where the gear
cluster is installed is where the power is transferred to the out hub and
finally to the bicycle tyre.
The motor has 3 inner planetary gears, two are made from nylon to keep the motor
almost silent and one is made from metal to get a long lifespan of the motor
(there is a very low noise that is audible when sitting on the bike, but it is
certainly a very soft noise not audible from any distance away from the bike) .
The overall gear reduction ratio is 10:1, which means for every ten
revolutions of the internal motor rotor the outside wheel revolves once. This makes
this motor particularly good for hills at slow speeds. I'm really impressed by
the quality of manufacture of this motor, after opening the motor up and
dismantling I see there has been a huge amount of effort gone into developing
this motor. The gears seem extremely well made and have helical type gear teeth.
Below I've numbered the parts: 1 is drive gear from motor rotor (12 teeth), 2 is
bottom teeth of planetary gear (38 teeth), 3 is top teeth of planetary gear (21
teeth) and 4 is the sun ring (69 teeth). (note: the sun ring I've just sat on
the gears for the photos normally its attached to the freewheel mechanism
and held in place by six screws on the freewheel plate). Overall gear ratio is
about 10.25 : 1
Each planetary gear has two bearings: one on top (shown) and one below
(not shown). These gears are very well made!
The ring gear is also very well made and to a high degree of accuracy ( most
likely computer controlled lathes).
The motor itself is brushed ( infortunately the company is not producing a
brushless version). On one side
of the motor armature is the commutator on the other side is the metal drive
gear.
The stator casing holds the magnets. The magnets are neodymium type which are about 4
times the strength of ceramic magnets. I think almost all ebike motors these
days will use neodymium magnets as it means the motor size can be made quite
small but still have quite decent power. (A motor using ceramic magents would
probably be about 3 or 4 times the size to get the same power/torque).
The only problem I can see with this motor is when its time to change the
brushes. Its likely a few years before they will need changing but it looks like
the motor needs to be completely dismantled to gain access to the brushes. Thats
about the only thing I can see wrong with this motor.
They've also gone to the trouble of puting a rubber '0' ring seal on the motor
plates to stop any water from getting in. I would say this motor is definitely
on par in quality and design with the Heinzmann motors from Germany which also
use nylon gears and are brushed (but cost about 4 times as much!!!).
Note: in the above pictures I've removed all the grease from the gears to make
for some nice clear pictures. All the gears a packed with grease before leaving the
factory, they seem to put quite an excess of grease in the motor which means
there is plenty in there which hasn't been used when its time for a regrease
(probably once every 12 months would be sufficient to keep motor in good running
order but I think secret to the lifepspan of any geared motor is a regular
regrease I think if the motor was under heavy use each day, then maybe every 3
months would be necessary, but 6 months intervals should suffice, at least every
12 months it should be done).
Below the motor dimensions:
TORQUE GRAPHS
Below are the torque graphs for the two motors I presently have. One motor is a
24volt version which is the first torque graph (this motor can also be run on
36volts using the same controller that comes with the kit). The other motor is a
36volt version which can be run on 36volts or 48volts using the same controller,
its shown in the bottom graph.
In the future when I run out of 36volt motors I will only order the 24volt
version, as its quite adequate running on 24volts. More top speed can be gained
by running the 24volt motor on 36volts ( this simplifies things for me when
ordering if I only have to order one type of motor).
I'll have to put some info up on comparing geared and gearless motors at certain
rpm, as its at the low rpm range where a geared motor shows
some torque advantages over a non-geared motor. No info was supplied with these graphs on what size rim the
torque values are for, so I cant work out the torque values for different size
rims unfortunately.
What's in the kit:
1. motor (24volt or 36volt)
2. controller 15amp max. current draw (with max. power adjustment screw, minimum
setting approx. 250watts)
3. throttle with led lights to monitor battery voltage (twist or thumb type
available, plain throttles also available if required)
4. spokes to suit your rim size
5. left and right brake handles with cut off switches (cut off switches connect
to controller and cut off motor power when brakes are applied)
6. 3 speed clusters supplied on the motor
(haven't put together any install instructions as yet for these motors but
should be no problem for someone with basic mechanical skills with pushbikes,
all wiring comes already connected except for batteries which are not included
in the kit)
Some Notes on this motor:
1. this motor can handle considerable weight without problems (for very heavy
weight and hills the P3 motor would be more suitable, also if your into doing
jumps over gutters and your riding style is aggressive then P3 motor would be
better) so is suitable for
use by heavier riders or with heavy sealed lead acid batteries.
2. the 24volt motor can be run on 36volts without getting hot, one way to
increase the maximum top speed (i'm not sure if it adds any more torque by
going to a higher voltage I suspect it does but some others disagree with me on
that).
3.the controller has a fully variable maximum power output screw (minimim setting
is about 250watts) which means if
your using lithium or nimh batteries you can to some degree adjust the maximum amps which can
be used by the motor to suit the batteries (to adjust the maximum amps
accurately it is necessary to adjust the resistance of the buzz bar inside the
controller see
controller section ). The controller also has a low
voltage cut off point, it is set to suit sealed lead acid batteries (its
not adjustable, well not easily adjustable, requires changing some resistor
values, but I am trying to find a controller that has a variable low voltage cut
off screw, something that seems not available as yet at reasonable cost)
4. There are two different versions of the motor depending on what rim size you
have also. The gear ratios remain the same but the max. rpm of the motor itself
is different.
Below P2a after being laced into a 26" rim ( rim a strong steel
one from old mountain bike), right hand picture below shows motor installed in a
bike (bike is upside down in the picture). Aluminium rims are also very
suitable for use with this motor, also aluminium rims greatly improve your
braking ability (in the wet also) if you have caliper type brakes with rubber
pads.
INSTALLATION INSTRUCTIONS: (under construction)
1. spoke the hub motor into your rim as described here
2. you'll need about 15 to 15.5cm of width across the rear frame to install
the motor without making any adjustments to the width of the motor which can be
done by taking off some of the thread on the left hand side of the motor which
is for a drum or disc brake.
Although the picture above shows 14.7cm for the width by the time you add a
couple of washers its just over 15cm you need.
Thats going to mean pulling out the rear frame to accommodate the motor. An
aluminium frame you wont be able to pull out as it will weaken the frame but a
metal frame should be no problem as they are quite flexible.
There should be a spacer tube, a torque washer and a nut on the axle side with
the motor wires coming out of it. There should be a 3 speed cluster already
installed on the motor (on the side with no wires), there should be one nut, one
torque washer and two plain washers as shown below.
. 
The side with the wires is installed as shown with nut and torque washer on
outside of frame. The tube spacer goes on the inside of the thread on the
motor.
Wiring Diagrams For Brushed Controller:
The motor will come with the brake handles (with controller cut off switches),
controller and throttle already connected together and to the motor.
I've put the wiring diagrams here just for peoples reference if needed.
If your using the thumb type throttle with led lights for battery voltage on
the throttle then controller will come connected like this below:
If your using the twist type throttle with led battery voltage indicator wiring
is like this below
You can change how the brake handle controller cut off switches are arranged if
you like as below. Both the pairs of yellow/black/red wires coming out of
controller can be used to turn off controller power to motor. Using either the
yellow and black , or red and black wires, when they are connected together the
controller stops sending power to the motor. You could if you wanted put a
temperature sensor on your batteries (nimh or lithium) or in your motor which
could turn off the controller if a certain temperature is reached, using the
red/black/yellow wires.
Note: The cut off switches only stop power going to the motor, whenever the
controller is connected to the batteries it will use about 50mA of current. So
you should put a suitable on/off switch to disconnect batteries from controller
when bike is not being used. You need a switch with a current rating of about
20amps. I do have some key switches available which can be used or the large
on/off switches in some jump starter units are ideal (they can handle very large
currents no problemo). Also puting a fuse on the positive battery wire with a
rating of about 20amps is a good idea.
Some results using drain brain meter:
P2a motor using 24volt Nimh packs (2) 8ahr each in parallel.
15km ride: flat to medium hills, pedalling effort low
amphours used =6.8, watt-hrs used=165, watthrs/km=10.5, max. amps =16.3, max. power =
390watts (power in, not power out!), max. speed motor alone =25km/hr,
Power used with motor on full power and wheel off the ground = 40 to 50watts.
%enjoyment=100
Using the 24v motor running on 36volt you will get slightly over 30km/hr but
little increase in torque.
Using the 36v motor running on 48volts you will also get higher top speed but
little increase in torque.
beware of spray ebike company: more info
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