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About gwhy

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    E-sherco E-bmx

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  1. Do a search on ebay for a 2-wire Mini DC5V-120V Voltmeter LED Panel 3-Digital Display Voltage Meter UK, they are small but you will have to mount it somewhere where water can not get in the back of it ( good idea to fill the back up with hot glue after plug has been connected ), also always have a small fuse inline with the red lead ( just in case). A 2 mode switch idea will defo be possible but may require a bit of experimentation to get it to the values you want, it will involve setting the dials to the settings you require then disconnecting the pots and measuring the resistance of each pot/dial, this information can then be use to use fixed resistors and a switch. If each pot only has 2 wires then this will be straight forward but if they have 3 wires it may be more trouble than its worth.
  2. with 24v battery and the same controller and ratio then nothing will change, To get more acceleration you will either have to lose a bit off the top end via ratio ( but this will also increase the torque and may not be very desirable/controllable ), or increase the voltage to 36v , this will also increase the top speed and you can then charge the ratio to slow it down again but this can cause the same problems as above, you will prod also have to replace the controller to a 36v one so you will need to know what is the current limit on the 24v contoller so you can either match it or have a higher current limit . Or the last option is to increase the current limit on your exsiting controller and change the ratio to make it a bit faster , but im not totally sure if this can be done on the older oset controllers. but no matter what way you go you may have more problems with the motor over heating
  3. yes a 8 amp charger will reduce the charge time.... I think you have a few cells with in the battery that have got very out balance and thats why it is cutting out at 51 volts it should cut out at around 44v for a 14s and around 41v for a 13s. Worst case scenario is that there a few duff cells in the battery. this can be repaired, but you do need to check the voltage output of your charger it should be 58.8v if its lower then you battery will never charge to full capacity anyway.
  4. ok so if your battery is only getting to 56v then this is way to low, the only thing I can suggest is to leave the battery on charge for at least 24hours then measure the output to see if this increases the battery voltage... i advise charge in a fire safe area i.e outside some where, dont charge indoors for this long!!. final fully charged voltage should be 58.8v
  5. It sounds like you have a battery bms problem. out of interest what do your charger say is the output voltage is?, as 56v is to high for a 13s battery and to low for a 14s battery, this can also be caused by the battery bms ( not fully charging the battery ) but it may be the wrong charger.
  6. the OP said he had little electrical knowledge, yes load test charger would be the next step if it was the correct voltage coming out of it. personally I would just monitor the charge current and charge voltage over time then discharge the battery with a know load and measure the capacity and C rate. IR can change so much with temperature so it not always a good way to go with sla but good enough if you had them from new and knew what the IR was from new and at a specific temp.
  7. 1: you need to measure the voltage at the batterys , when charging and when not charging, full battery should read around 39v ( without charger connected ), a flat battery will read around 36v or even lower 2: measure voltage out of the charger when not connected to battery should be around 39v, for 3 sla batterys this is a starting point to get to the bottom of the problem
  8. remove the cover clean hole and fill the hole with jb weld dont worry about trying to fit the bolt back on as it serves no purpose. just make sure that when the cover is back on that the coils dont rub or hit any jb weld on the inside
  9. yes there is but i dont know if this will help and i dont know if the cost of a gamble would be worth it, Im not sure what controller is on that model oset but some controller you can turn down the current, if you can only turn down the speed this will not do the trick. if someone can post up the peak current of these bikes it would then be easy to source a battery for them. you can have a look at power tool batterys these tend to be high drain and a cheaper option to boost-bike battery's , this is acually a good option on the smaller bikes, but not so good on the bigger bikes.
  10. looking at the specs for the battery I would say that this may be the problem , 7.2A peak/burst is very low for this application with a over current shut down of 24-36A , if it is a cell problem within 1 of the battery's this can also have the same symptoms as your seeing. if you have a volt meter you can confirm this by seeing if there is any voltage on the battery when the fault happens ( measured without disconnecting or turning off the bikes battery ).. basic things to check are is the back wheel nice and free to rotate ( with chain disconnected ), or if there is any grinding noise from the motor when rotated by hand , both these things can increase the current of the system and in turn trip the battery, if you have a current meter you can also check the no-load current of the bike i.e full throttle with back wheel lifted off the ground, I guestimate that the noload current should be no more than around 2.5-4.5A ( maybe someone with the same bike could measure this and post it up on here for future ref. edit: is should have also said if you measure for voltage as above but do still see the 24v but bike still do not work then it could be the controller shutting down due to the low voltage cut off of the controller, which may point to a faulty battery cell.
  11. It Sounds like your lithum battery may not be able to deliver the current demand and the battery is shutting down ( bms built into the battery ) this could also be a cell problem within the battery itself, do you have a link to the battery that you bought or do you know the specs of the battery ?.
  12. 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
  13. 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)
  14. 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.
  15. 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.
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