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About gwhy

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    Advanced Member
  • Birthday 07/31/1964

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    E-sherco E-bmx

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  1. there is no need for flywheels as a Electric motor can produce as much torque as you need ( unlike a ICE motor which has a peak torque plato ) as a instant hit ( within reason ) it will have to be limited pretty quick afterwards though for the motor to survive .. and the controller would also be able to handle the phase current from the motor. it should be fine for a trials application because there will be quite long periods where itsl not be needed..
  2. This is still not a truely progressive torque clutch as it has no torque feed because its only connected between the throttle and throttle input to the controller.. maybe one day someone will do it correctly :-). i.e throttle for speed and clutch for torque.
  3. yes 2x 6s 20000mah lipo's will be enough to run a oset 20.0 . a bms normally is fitted permently to the battery and protects ( prevents cells from overcharging 4.2v ) and balances the battery when charging AND it also prevents any cells from dropping below the safe level when discharging ( when in use ) a bms will also prevent the battery from charging if any cells are below the safe level (3v). if you have 12cell battery then you would need a 12cell BMS and you would treat and charge this 12cell battery as 1 battery ( 1x 50.4v li-ion charger ). so if the battery is fitted with a bms and wired correctly and using the correct charger there is no need for low voltage alarms or a balance charger as it becomes a Plug 'n' Play system that is 100% protected 100% of the time. when selecting a bms you need to make sure it covers the max charge current that you will be charging your battery with and that its for the correct chemistry of your batterys ... lipo is 3v - 4.2v the bms also needs to be correct for the amount of cells that make up your battery. 12s lipo bms's are quite hard to get hold of ( expensive a 12s bms's bms start @ around $50) 13s are more common ( cheaper ) .. normally the higher the discharge rating of a bms then the more expensive it is , it is possible to bypass the max discharge current limit of a bms.. i.e a cheap 13s bms @ $10.00 - $15.00 will do the job but it will only be rated for a max discharge of around 30A so the the max discharge will have to be bypassed .. but you can still have the bms protecting the cells within the battery by using the bms to turn off the bike should any cell drop below the safe level.
  4. this is one of the main problems with electric bikes... there is not a lot of room on a bike to put batterys. ebike batterys ( legal ebikes ) are only rated for a max of around (average) 500w ( these depends where in the world you are ) and all legal ebikes should do no more than a average of 15mph ( again depend where you are in the world ) now those batterys in the link will be fine for this sort of spec but once you start getting into higher power or higher speeds the choices are few... higher voltage runs a motor faster and the plus side to this that less discharge current ( from the batterys ) is needed for the same power .. . the big down side to this is that small motors ( the ones on bikes ) run way to fast to gear it down to a sensible speed if a high voltage is used so there is always a compromise between voltage and current. i.e the telsa indeed do run on laptop batterys ( well the very yealy models ) but they ran on about 350v so to get the power needed the discharge current will not have to be so much.. if you run a small bike (oset 16 ) on 350v (dont try it as the motor is not designed for that sort of voltage :-) ) then the speed will just be way to high and if the discharge current was adjusted down to i.e 10A max ( thats still a wopping 3.5kw) but the motor will not have enough torque to get you moving as it will be geared for around 200mph @350V .. i think the ktm runs around 350V but this is a motor designed for that bike ... personally 350v on a bike is way to high ( especially a off road bike ) and a bit dangerous . normally the bigger the motor the slower it will run per volt ( kv of the motor ) .. thats why cars can get away with it as they have much more room for the motor and batterys.. but bikes you are always struggling for space.
  5. just looked up the spec for these cells: ( as long as they are genuine cells then ) 10A max discharge for a single cell (3-4C) found some discharge graphs discharge @ 2C capacity drops to around 2000mah per cell so that then becomes a 8000mah pack is discharging @ 2C and from what i can tell in do not include a bms with that listing ... it should be ok for a small 36v bike that dont get taxed to hard ( much better with 2 packs) as long as a suitable bms is also installed, then the cost dont look so good . you would need a CC-CV charger to charge these batterys so the standard sla charger will not do the job.
  6. you connect the source side of the meter to the battery and the load side to the controller so basically it goes in between the battery and controller ( rest of the bike ) . because it requires full battery volts and current then its not ideal to run it upto the handle bars as this will involve quite long power cables, so i would try to mount it as close to the controller input as possible and as high up on the bike as possible ( as they are not very water proof ).. if you fit xt60's on the meter it can be easly taken out or put back in as it will only be really used to check stuff, as you will have your LV alarms on the battery to monitor the battery. if you want a perminant tank mounted voltmeter then get something like this .. that meter only reads up to 33v so keep that in mind if you go higher voltage on the bike.. but if you want a future proof voltmeter then this one reads upto 80v ..
  7. 8awg is way to thick for xt60's, you can get away with 10awg (just) but xt60's are designed for 12awg. the best way to make adaptors is using thick copper wire, hot glue and heat shrink. for a 3 way xt60 P adaptor set it up like this .... solder well ( no shorts!! )... then completely fill the gap with hot glue then cover with heat shrink.. the hot glue will make the whole thing rigid and insultat the connection from the elements then use heatshrink to make it look nice :-)..
  8. 8awg is way to thick for xt60's, you can get away with 10awg (just) but xt60's are designed for 12awg.
  9. charger looks ok, i have never came across one of those before... for 6s it will have a max charge current of around ~ 3.5A ( it says that it is a 90W charger )
  10. nope looks like you have it all covered . one very useful bit of kit to have is a watt meter, its great for a number of things ( fault finding ... motor , batterys, controller ) and it can be used as a fuel gauge : also get your self a 5 pack of xt60 plugs and sockets and some 8mm heat shrink .. they are always handy to have..
  11. yes very lucky.. but now you no that its the shops fault so should be able to get a new set of batterys and charger ... for peace of mind sla's very very rarely catch fire .... but can split and get acid gell evey where. also if the 36v charger is also 3A then you are looking at around a 3-4 hour charge time.. ( flat to fully charged ) hope this helps you get it sorted out ...
  12. if you only have 3 batterys then this is not the correct charger for 36v ( 3 batterys ) and that would explain why the batterys have swollen
  13. has trhe charger got any specs on it ? i.e output voltage output Amps ... just wondering if they have given you a 48v charger instead of a 36v charger?
  14. just take the batterys and charger back and tell them what happened, also get them to test the charger. the fact that you left them on over night should not come into it as something, either the charger or batterys are at fault and this should not happen. If everything was working as it should then the voltage of the batterys should have come up as they were charging and this should in turn reduce the curretn from the charger until the battery voltage is the same as the charger voltage ( fully charged ) then no current would be flowing so no heat. ( but something went wrong ) the charger voltage may be to high so this will need to be checked.
  15. faulty battery . if its a standard sla charger, no they dont cut out they only reduce the current as the battery voltage comes up so if a battery is not taking a charge then the charger will still be pumping max current into it making it hot. you can measure the output voltage of the charger to test it. I have seen car batterys do the same. as with any battery its aways best to know approx how long it should take to charge then unplug them from the charger.. never leave any battery connected to a charger after they are fully charged . even small AA batterys ( i have even seen these go bad )