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.
When I watch the boy on the 20r he's no real issue with the power delivery. what I notice is the "snatchiness" at very low speeds as the chain takes up slack.
I suppose they don't run a tensioner as it would wreck the motor bearings but you wouldn't run a petrol bike without one.Keeping the chain correctly tensioned will help this but wont solve the issue,maybe a very lighty sprung tensioner would work?
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
I think the thing with a oset compared to a petrol is you have no clutch to slip when riding in tricky conditions, this would defiantly help with the wheel spin problem feed the power in slowly using clutch and throttle or rev it up and dump the clutch for big stuff.
I watch my son on his oset 20 he has just moved up to that size bike but if I turn the power up so he can wheelie over a log the power is too instant on slow turns. I don't see a way around it,
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.
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.
After 2 years of successful hobby king lipo usage in my lads 36v oset were now moving onto a 48v.
Question, what is the minimum acceptable C rating for the battery?
There is a lot of high capacity batteries but they are all low c rating 12 seems about average.
Cheers
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.
they didnt say, they just asked me to do the tests and let them know the numbers, FYI the batteries were all around 12.6 v and went down to 8.5v on load
So thats a total of around 34v for the 4 batterys, did the bike cut out at that voltage? . that is pretty low and to be honest I would expect it to cutout, I have a recollection that the lvc is around 36v for the oset 48v controllers
thanks for your replies, Oset have rung me back and were extremely helpful, I'm going to do a battery test when its under load (hold brake on and open throttle) and read the battery level,
If this fails to show anything they said try the relay, so everything you said gwhy, thanks so much!!!
Out of intrest and information, did oset say what the lvc is on the controller ?
thanks, the low voltage cut off sounds like it could be the issue, would I just be looking for a connector or something more complicated?
I have two sets of batteries for it so i'll charge up both sets and take it to some hills to try and feel the connections when (or if) it does.
I've emailed Oset uk to see if they can help, no reply yet
Yes it can be more complicated than that, but unlikely. Check all connectors and make sure that they are clean and well connected tot he wire at the crimp ,even at the battery's, The relay is also inline to the controller so this is another place to look at the connections, but it could be the relay itself ( high resistance contacts in the relay).
ok, so no bms. one thing you could check is the lvc ( low voltage cutoff ) built into the controller, if the bikes voltage drops to below the lvc limit of the controller the bike will cut out. The battery voltage drops under load i.e going up hills Im not 100% sure what the lvc is on the oset controller but I think its around 38v, you will need away on logging the voltage under load to fault find this problem, or if you can borrow a set of batterys to see if the problem goes away. It may not be the batterys at fault but could be just a poor ( high resistance ) connection between the battery and the controller, you may be able to feel for this by feeling the temprature of the connections when this fault happens as if it is really bad then connections will be much hotter than normal.
Lead will normally not give such a surge as lipo can, this is just because lead has a higher internal resistance. With the bike rear wheel off the ground can you roll on the throttle with no surge ? ( can you make the rear wheel move at a very slow speed ). Nearly all electronic throttles have some initial play before they start driving the wheel, there are electronic devices that will allow you to map the throttle movement so this free play can be taken out. Its not advisable to use the rear brake to slow the control down as this will be putting more stress on the battery ( higher load and will run down the battery quicker than normal ) but I understand that it can be necessary for slow control but rear brake should be applied when rolling the throttle off ( if that makes sense )
After a little more "thinking", i have realised how daft the question was.a 1400w motor isnt gonna run at any less. Im just going to upgrade the battery. The Oset "48v" is actually 46v. Im sure the last one i had built was 54 fully charged. Anyhow, thanks for your input guys.
its not daft .. as you can run it at a lower wattage by using the power limit pot as this is what it does.. Battery voltages are listed as nominal voltage not fully charged voltage, so it all depends what chemistry is used in your cells and how many.
I don't see the problem? There are THREE adjustment knobs that go all the way from virtually nothing to the max power required.
SPEED - POWER - RESPONSE are the 3 knobs
What he said ^^^
But no matter what you do with the power it will never be no where near legal to ride on trails as it will have no tax and no mot and no registration ( well in the uk anyway )..
it would be very easy to set up a switch but you would need to measure the resistance of the dial at the limit you want then replace it with a fixed resistor.
yes, you will need 2 of these ... 1 for each P'ed set of batterys.
yes you will need to leave them connected to the batteries for charging And discharging, you can then also use the LV alarms, treating each block of 3 P'ed batteries as just 1 battery with 1 balance tap lead.
as long as the batterys physically fit in the space then larger capacity batterys would be fine as also as long as all the batterys are the same make and capacity. it the batterys are the same voltage and chemistry then the stock charger should also be fine ..
Sag is set depending on the weight of a rider . the manual is prob a generic factory setting for the shock. Mountain bike shocks dont have the same dynamics as a mc shock so things will be different.
sag should be setup with riders weight i.e with rider onboard and should be around 10-15mm for the rear and it normally higher for the front . bounce about a bit on the bike before taking any measurements..
Last week I received a reply from an Oset design engineer for a question I sent him. For my 24, I asked if you could replace the power dial and throttle with slide resistors connected to a cable quick throttle. He said the power setting can't be changed on the fly without coming fully off the throttle. He doesn't believe the hall throttle can be replaced with a resistor.
Yes it can be changed for a pot throttle.. but the throttle may need a bigger initial movement to start the motor also you may have to put a external resistor inline with the pot to give you the correct WOT voltage. The design engineer is correct about changing the power on the fly and can not be done.. but it can be done with some additional electronics that is totally separate from the controller.
if it is a hall throttle on the oset then you need to work out the +5v supply wire and the ground wire to the throttle and the signal wire ( in the wiring diagram it is not clear what wire is what and there is no color code ) with the domino pot throttle the wiper of the pot will connect to the signal wire and the +5v and the ground to either end of the pot ( if the signal wire is connected to the wrong point on a pot throttle this may damage the controller! )
Relays are very poor for use on trials bike in mud and water, they are open to elements, actual metal contacts exposed. After packing up twice i removed it and sealed it with tape inside old section of inner tube,but periodically check/wd40 inside.
A mechanical relay on anything is always a 98% bad design , when there are much better and more reliable switch options this day and age :-)
So I took the negative wire coming from the battery and disconnected it from the B- on the controller. Then I measured holding the negative probe to that wire and the positive probe on the relay. Now I get 36 volts on all four pins of the relay. Key switch on or off doesnt make any difference. The key switch is working when I measure the resistance through it.
Did I do it right gwhy?
there was no need to disconnect the neg at the controller , should have just clipped the neg meter lead to the neg of the battery then carefully check on each pin of the relay. With key switch on yes you should have full battery voltage on 3 of the pins and 0v on the 4th relay pin ( black wire ? ). The relay ground goes directly to the controller ( on the oset diagram that i have ) so now if you still have fully battery volts on all 4 pins then now connect the meter neg directly to the black (thin ) wire connection on the relay then measure the the other 3 pins they should have fully battery voltage on each pin with key switch on.... with the key switch off you should only have battery voltage on 2 of the relay pins ( 1 red thick wire and 1 red thin wire) ... the fact that you had 36v on all 4 pins from your tests I would check connections and wires ( black thin wire ) from the relay back to the controller ( it may not be a black wire because you have upgraded the controller).
edit: i just re-read my previous post and it should read with key switch OFF , I have just also thought that if you installed the resistor when you upgrade controller then if the back wire ( thin wire ) from the relay to controller is broken and that will give you 36v on all 4 pins of the relay with how you have measured it
connect the negative meter probe lead directly to the neg of the battery then the pos to each of the thicker wires on the relay, key switch on you should have full battery voltage on only 1 of the fatter wires on the relay (red wire), if you dont have any voltage then it could be the key switch itself , report back if you still have no voltage..
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in OSET Electric Trials Bikes
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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.