gwhy

Also on a side note.. always put at least some charge back into a battery fitted with a bms after use especially if you don't intend to use it for a good few days, no need to fully recharge it .. charge for maybe a hour before storing it. and always disconnect the battery from the bike never rely on the key switch you fully turn the bike off especially if the bike has a pre-charge circuit fitted as this will drain the battery.

li-ion and lipo cells have the same voltage so can be charged the same , to a absolute max of 4.2v per cell , lifpo4 is different and has a max absolute charged voltage of 3.7v per cell. the chargers are the same and the only difference is the total charge voltage need to be set at the correct output voltage for how many cells you are charging. if the charger states 54.6v and you have counted 13 cells then this is correct for lipo/liion 48v battery. ok now from what you have described my best guess is that you have a faulty cell which is bad news and the bms is shutting the battery down but it could be a faulty bms draining a cell down. can you get access to the bms ? there is a long connector with 14 or 15 thin wires on it .. unplug that connector from the bms then very carefully ( dont short any thing out !! ) measure each cell voltage, this can be done on the long bms connector . connect the neg meter lead to the main neg of the battery then start at one end of the bms connector plug measure each wire using the positive probe of the meter ( use a pin that fits into the hole on th econnector ) as you move along the connector measuring each cell they should all be the same difference between each one i.e a fully charged battery will be hole 1= 4.2v, hole 2=8.4, hole 3= 12.6 ect, and if you start from the other end it will be 54.6, 50.4, 46.2 ect a difference of 4.2v per cell. I think you have a very bad cell in the battery and this will show up if you test this way, as a good battery all the cells will be the same voltage. if there is a low cell then leave the bms connector off for 24 hours then measure again to see if the bad cells voltage comes back up and this will indicate that it is a possible bms fault. I have no idea what it would say 20s super charged on the battery if you counted 13cells ? ... any chance of posting up a pic? the charger will show a error because there is a fault with the battery. One thing you can test though with the charger is measure the output voltage as it should be 54.6v if its lower then this is what have dragged the battery voltage down.. post up results edit: if all the cells are the same voltage then you need to also disconnect the main neg wire that comes from the cells to the bms to stop the bms from doing any more damage.

what battery is it ? .. I know you said its lipo but how many cells do it have ? ... normally a lipo 48v battery has 12 cells and this should be a max of 50.4v . if it is a battery with a bms then it may be 13 cells as this is the more nearer a true 48v battery but the voltage would then be 54.6v fully charged ... or is it a li-ion battery with bms .. basically what im getting at is do it have a bms and if so then there are 2 possible problems ( dependent on how many cells it has ) it is a faulty bms or the battery has a bad cell. what charger are you using for your lipo's ? a bms would turn the battery off if there is a fault with the battery or the rest of the wiring on the bike as soon as you put a load on to it. if there is no bms fitted then you defo need to know how many cells it has as 51v is way over the top for a 12cell lipo battery and could be dangerous on the other hand if its 13cell then its not charging at all and you still need to work out what is going on. you can test to see if its a bms problem just by connecting the battery directly to the motor wires ( wheel off the ground ! ) it will either spin the motor up full speed or not. edit: on the charger is should say the exact voltage output... is it the correct charger for the battery you are using i.e was it supplied with the battery .. common output voltages of (48v) Li chargers are 50.4v, 54.0, 54.6v, 57.6v this is the fully charged voltage of the battery that you are charging and should never ever be any higher thats why its important to know how many cells you have and what chemistry .. lipo4 is another common chemistry used for batterys but the cell voltage is lower than lipo. also if there is a bms fitted it could be that the battery is being turned off because there is a low ( bad ) cell in the battery.

don't charge 3 batteries with a 48v charger , this will damage the batteries and may also over heat them and they may spit... you can charge each battery individually with a normal 12v car battery charger as long as its a slowish charger around 1A. The bike may work on 3 batteries but im not sure what the lvc is on the controller so it may not, but will do no damage to try.

If you are carrying a spare battery on your bike then you just as well have it connected, no point in carrying it without making use of it.. :-) Just measuring the mileage and time is not a good indicator of how long a battery will last unless you are on flat ground and at a constant speed until the battery is run down to a set level, what is really needed for a more accurate reading would be a watt meter, as this will tell you how many AH's have been used on the discharge and also how many AH's the battery required to fully recharge with the information from a watt meter you can then also get the WH's for the battery, this will also give you a much better indication of how the battery is aging i.e if you are putting in 10ah and only getting 6 or 5ah out then you can safely say that that battery is getting a bit old and past it or the battery is not very good for a high drain application as this is what you will find if using sla batterys. I have a mechanical mod that I have developed that replaces a pure e-bike throttle with a cable throttle of choice and can also fit stiffer or softer springs to the mech so the feel can be customised so that it behaves 100% like that of a gas bike but also puts the sensor for the throttle well away of any possibility of getting damaged , I have never found a good ebike throttle that I have been 100% happy with thats why I designed my own :-) . This is v2 , and still being tested for reliability.

Yes water can effect all the lower power side of things but the fault that is described with the startng to spin up then stop it is very unlikly to be caused by water, more like a diry/bad connection somewhere. And has already been said the fuse holder is a very good place to start. Sticking or worn brushes can cause these symptoms but that would not be the first place to look .

water should not really effect the operation of a motor as water is conductive.. my best guess is that you may have a sticking brush in the motor or a bad connection to the motor ( from controller ) or a faulty throttle ... do it still cut out if you only twist the throttle less than half way ?. test the motor by directly connecting a 12v battery to the motor leads ( keep rear wheel off the ground )..

There will be better traction for two reasons, bigger foot print ( tyre ) and less torque (to the ground due to larger wheel circumference ) so less likely to break traction. The battery, controller and motor will have a harder time with a larger rear tyre , so just keep a eye on the temperature of the motor that it do not start getting to hot..

As it looks like the rear tyre makes the circumference a lot bigger you should also increase the gearing as this will put a lot more strain on the motor and controller. It will also give it better climbing ability. Out of intrest what was the size of the original tyre and what size have you replaced it with ?.

I used to have the same problem with people grabbing the throttle .. I over come this by using a very short lanyard around my wrist ( throttle side ) so basically when my hand is not on the throttle then the bike is disabled. I have been thinking about doing it electronically with a proximity detector and a small magnet sewn onto a glove.

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..

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.

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.

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.

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.

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 http://www.ebay.co.uk/itm/12V-24V-Car-Motorcycle-LED-DC-Digital-Display-Voltmeter-Waterproof-Meter-new-WaT-/371844206229?hash=item5693a44e95:g:2y4AAOSwHoFXrDDR .. 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 .. http://www.ebay.co.uk/itm/Mini-DC-4-80V-Voltmeter-Panel-3-Digital-LED-Voltage-Tester-Meter-Waterproof-F3L5-/391415886169?var=&hash=item5b22347159:m:mklw-JoKdR_66GSIw-B2Qng

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 :-)..

8awg is way to thick for xt60's, you can get away with 10awg (just) but xt60's are designed for 12awg.

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 )

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 : https://hobbyking.com/en_us/turnigy-180a-watt-meter-and-power-analyzer.html also get your self a 5 pack of xt60 plugs and sockets and some 8mm heat shrink .. they are always handy to have..

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 ...

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

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?

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.

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 )