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gwhy

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About gwhy

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    E-sherco E-bmx

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    Bristol
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    Male

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  1. it looks like they are cylindrical cells not pouches .. but could be wrong.. but if they are pouches then there is something very wrong with them
  2. yes each bms looks after each pack, but the more packs you p the less voltage drop you get because the over all rating of the combined packs will now have a much higher c rating. the reason for being careful when connecting bms packs together is because if one pack is flat and the other fully charged the fully charged pack will dump massive current into the flat one and this can damage the bms's in both batterys. the listing states its a 1000w battery @ 58v this will be the cont current of around 20A (1000/58= 17.5) ..... I have no idea why the description says is 50A cont (but it may well be ) but this do not add up .. 58v x 50A = 2900W ? best guess is that the battery is only rated 1c discharge this will make it a 1000W battery, and the bms is over rated for the cells . lots of sellers spec there batterys like this and it dont make it a bad battery , discharging at a higher C rating reduces the life of the advertised cycle life.. most of the time ( on the flat and at a steady speed the the discharge will only be around 1c)
  3. most low output bms's have issues when the bike is pulling a heavy load for a longer period of time. this very rarely happens on a road bike but off road can be more of a problem, i do think a 8 year old new rider should not have any issues . on the flat current comes down very quicky once the bike is moving, it may become a problem if for example you try to give it a handful whilst pointing up a hill from a standing start. but if the contoller is set to limit the current @ appox 20~30 then at least the bike should keep moving and not trip the bms. when you added a additional pack to your 36v bike it would have become more peppy because there would have been less voltage drop when accelerating, unless you also altered the current limit on the controller.
  4. most bms's allow a peak much higher then they are rated for but only for a very short period i.e no more than 500ms then shut down the battery if the current dont come down to (or below ) its cont current rating, 1000w bms on 14s would be around a cont of approx 20A. A bms dont limit the current it just shuts the battery down if the current is higher then the specs of the bms, its the controller that limits the current. I would borrow a lithium battery pack ( if you can ) and use a watt meter to see what the peak currents are when the bike is being used. yes you can p battery packs together to double the peak current and the cont current but you must be aware that both battery must be identical voltages before connecting.
  5. the voltage should be fine, but the power of these packs may not be suitable for the 20.0 if they are rated at 1kw (58v ) which is round 20A cont, but you do not know what the peak current is for the bike and how long or how high the current will the bms be allowed to over shoot I think the current setting for the standard 20.0 is around 40A ( but i know on the 20.0r it can be set upto around 120A ) but can peak much higher. the packs will be a good buy for a standard 250W/500W ebike but not sure about a off road bike like the 20..
  6. what are the dimensions of the motor they use. i.e diameter and length. engine braking is a function of the controller, not because is the motor is brushless
  7. the armature should just pull out of the other bearing, be careful that you dont damage the brushes if the whole bearing comes out of the housing still attached to the shaft as the bearing will hit the brushes, try just tapping the mounting ears of the end cap while holding the armature in the air.. but dont go mad with the hammer :-).
  8. the tamers are no longer available.. sorry. I have posted a few other options that you can experiment with listed with in this oset thread.
  9. If it were me I would just replace the plug and socket with a much better suited ( off the shelf ) Plug and socket. i.e xt60's
  10. with the charger connected to the battery the voltage should come down to more like 48v and will only get upto the (aprox 55v) when nearly or fully charged. measure your battery voltage with it disconnected from everything first, if it flat and the battery is still ok then this will be around 47v ( if its lower then you prob have a faulty battery ) a fully charged battery should be around 52v (off the charger )( the aprox cutoff voltage when your battery is being charged will be around 56v) basically the charger voltage should drop down to more like what the battery voltage is when you test it when not connected to anything, if it dont drop down when you plug the charger in then the most prob reason is either faulty battery or a bad/no connection from charger to battery.
  11. a bigger front sprocket or smaller rear sprocket will actually put more stress on the motor/controller and battery.
  12. there should be no slack in the chain on a oset as the chain stays at a fixed length , you need a tensioner on a petrol bike (engine in the main frame ) because the distance changes as the suspension goes up and down
  13. I look at a clutch on a petrol bike is torque control and the throttle on a petrol bike is speed control and when riding a petrol bike you mix the 2 to achieve nice smooth riding.. the power control sets the maximum current limit ( i think depending on the oset controller ) if that control was used as a clutch function on the handlebars then this may solve the problem but then you will also need to move the rear brake on the handlebars to a foot brake.
  14. I would like to try to throw some light on this subject if I can, There are 2 types of motor control ( controller ) there is speed control and torque control and some controller mix these 2 to blend these types of control. The current going through the motor generates the torque and the voltage regulates the velocity ( speed ) . With a speed type controller the max Current that is allowed through the motor is fixed at a maximum level at any throttle position i.e 100A , so for example when you twist the throttle this send a voltage to the motor proportional to the throttle position ( so the more voltage the faster the wheel rotate ) which sounds fine but the problem with that is very slow throttle control is difficult.. think of this extreme example of a speed based control at very slow speeds: you are approaching some large slippery stones at a very slow speed ( maybe 1/3 throttle position ) and the approach is flat, at that moment the Current will only be high enough to produce enough torque to maintain momentum on the flat as you come to the first stone the front wheel hits the stone and decreases you momentum but not enough so that you come to a stand still and the bike still moves forward, when the rear wheel hits the slippery stone this then decreases the momentum even more by which time the front wheel have also dropped into a ridge and if you did not increase the torque the bike will become stationary so you twist the throttle a little more to try a push the front wheel through the ridge , you may have to increase the throttle much more than needed to achieve this ( because the voltage to motor generates the needed current ( torque) you may have to increase the throttle position to 2/3 just to keep up the bikes momentum to overcome the ridge ), all is good upto this point but as soon as the front wheel comes out of the ridge the current then drops but you still have a 2/3 throttle speed demand at the rear and this can then break traction on a slippery surface and so the cycle continues. There are good torque controllers and there are bad ones, the kelly controllers allow you to mix the 2 types through the programming software and can achieve pretty good results, but ideally the 2 systems should be independent of each other unless you also setup electronic motor breaking ( normally done through the throttle). Torque based only control would be comparable to riding a petrol bike at full throttle all the time and using the clutch to regulate speed, which is fine when there is a load on the bike i.e uphill or over stuff, but riding down a hill velocity will just keep increasing unless you also shut the throttle off , and this is where a blend of torque a speed is needed to maintain good control of the bike. I think this is why a lot of people have problems with the osets ( electric bikes in general) for very slow control, a electric bike needs quite a bit of torque (on a speed based controller this can mean you need to twist the throttle 1/2 of its travel before it generates enough current at the motor) to start moving but the instant the rear wheel starts spinning the torque ( current ) drops but speed is still dialled in to 1/2 throttle (speed), some people learn to compensate others dont this results in very jerky throttle control at very slow speeds.
  15. a 10ah battery with a 10c continuous discharge will be fine, a 20ah 10c would be much better.. the 10ah 10c rating = 100A cont discharge and the 20ah 10c rating = 200A cont discharge.. but all hobbyking batterys that I have played with they all have over spec'ed C ratings and a 10c rated battery normally comes out as a 2c cont rating .. they can peek a lot higher so this is not so much of a problem on a small bike so rule of thumb would be at least 10c cont with 15c peak ( spec'ed) for a 10ah battery, I still have a 10c 16ah 48v battery that i used on a daily basis ( complete charge and discharge cycle every day , 5 days a week for 3 months ) often pulling 80A+ at certain parts of my journey for maybe 30seconds at a time , towards the end of the 3 months the capacity drop did start to become noticeable but I still have them and are now around about only 8ah but this was after around 3.5 years of major abuse. they have around 200 charge/discharge cycles total.
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