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    Travelling USA, Canada from Australia
  • EUC
    MCM5 previously IPS Lhotz, IPS 122, Puka, snail, generic

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  1. Hi OneLeg, If you are using the gotway app and gotway BMS to measure the power you should be aware that it tells lies. I have replaced my original generic bms with a new bluetooth bms so I can measure current from both the original battery and my new battery. The gotway app overstates the current output massively. I can't remember exactly the factor but it really isn't drawing anything like 4000w.
  2. I don't know what you are wanting to do with the mosfets? There is no need to touch the motherboard.
  3. The top pack cells don't need to stack on their diameter - they can be offset in a pyramid type stack on their 45 degree. Width would be 73mm and height whatever the space height is - 76 would be fine. The pack would just be a bit longer however there should be plenty of length. I just made a y joiner cable for both the battery charge (JST connectors) and discharge cables (xt60 connectors). I just charged one pack and then charged the other and then knowing they were both at the same voltage I could then join them with the "y" joiner. I am not concerned about my generic BMS as I also have the original manufacturers battery pack in parallel so if the generic bms shuts down then the manufacturers battery pack will take over. I have flattened the battery completely once and the tilt back worked at low voltage and there was no cut out. There is no real advantage to using higher than 10A rated cells if you are going to put in two packs of 2P16S. That will deliver 20 amps per pack continuously (40A) and bursts of probably up to 60A which is more than the motor can draw. Each 18650 cell can deliver 10A so in parallel two cells can deliver 20A and then two packs can deliver 40A. Note that a 60A burst x 60V is 3.6kW which is more than the 900w motor can draw. I was only adding one pack of 21700 cells in series to keep weight down so needed 20a capable cells - 20A plus existing 10A for 30A continuous rating with bursts say up to 45A or 45 x 60=2.7kW. If you want absolute maximum capacity then use 5000mah 20700 10A batteries in top bay in 2p16s = 576wh plus 3500mah 18650 10A batteries in side bay 2p16s =403wh grand total 979wh. Both packs will require their own BMS however you could use one from the original pack which won't have cut out. Some people will say that mixing 20700 and 18650 packs is not the greatest idea however as they are in parallel with their own BMS then personally I think it is ok. As others have stated earlier in this thread it is a lot of work and you are dealing with a lot of energy if you get it wrong. I am not a battery engineer and accept no liability. As you have stated you will be employing a qualified technician you probably don't really need to understand much more than what cells you want to use and then the technician should be capable of doing the rest for you.
  4. You might want to check out this previous post: https://forum.electricunicycle.org/topic/14748-new-mcm5-with-multiple-battery-options/?tab=comments#comment-251975
  5. I have just had another look at my photos of the battery compartment. https://imgur.com/a/udToFxs Looks like you could fit 2p 18650 in the top compartment and 2p 18650 in the side compartment. Gives you 800wh even in 16s if you use 3500maH 18650 cells.
  6. https://imgur.com/a/udToFxs Photos of the battery spaces on MCM5
  7. I think the motors are different in between the 1500w and 900w mcm5 so you wont need packs of 20 cells as you wont need 84v. You will need packs of 16 cells. I think there would be enough room in the top location for 20700 or 21700 cells as the spot is made for 20 cells and you will only be putting in 16. You will be able to recover the original bms of the original top pack of 130wh so you will only need one bms. I just purchased a generic 16s bms from AliExpress and have had no problems. As others have said it is a lot of work. I was aiming for about 400wh to keep weight down whilst ensuring maximum amps which is why I went for 21700s. For maximum battery size you would be better off with 18650s as you will be able to fit 2p in the side location where as with 21700s you can only fit 1p. Option 1 - total 2p 16s Sanyo 20700B 4250mah/20A batteries = 244.8wh x 2= 489.6wh total Option 2 - 3p 16s Sanyo NCR18650GA 3500mAh 10A = 201wh x 3 = 603wh Option 3 - Maybe somehow you can get 3p in the side pocket and 1p in top pocket as 1500w motor somehow gets 4p20s. This would give you max 804wh if you stick with all 18650 if you went with 20700 in the top bay you could get 850wh. If yours is 67v I can't see that it would be a 1500w motor. Even if it is the same motor then you would also need to change the control board to put in 80 cells as the voltage is different. Also board is not going from 600a theoretical. The cells are in series so 10A cells in theory put out max continuous 10A and 20A 20700s put out max continuous 20A. I have seen up to 50A from my modified battery pack through the AP instantaneously when doing pendulums or just starting out accelerating hard. After that settles way back to 10 amps or so.
  8. I am not a cop but simple google search came across this info from Vic Roads. Certainly Vic Roads don't think it's legal. https://www.vicroads.vic.gov.au/safety-and-road-rules/road-rules/a-to-z-of-road-rules/hoverboards-segways-and-other-motorised-devices
  9. Traveller


    Not the same but I have carried my daughter on my feet. She was 12 and her unicycle went flat. She rode on my feet and my son carried her unicycle. Not the most comfortable ride but we got to the end. I might add that it was a ride around Uluru. Might be the first family of five to complete the trip on EUC's.
  10. Just an update. I put 16 Lishen 4500mah 21700 13a cells in with their own standard off the shelf 16s bms as well as the original 170wh of 10a cells with their bms. So far have done 140kms with alarm set at 27km/h and tilt back at 30km/h. So far has performed flawlessly - really responsive, great hill climbing. Sides are too smooth to jump easily and it is heavy. I haven't done a range test as such but assuming 15wh/km as a guess should get about 28km range and this seems about right.
  11. Just bought this one - https://www.aliexpress.com/item/32862150354.html Same as above but bit higher capacity. Will give me 500wh total with a bit of modification and be less work. Take a month to get here though.
  12. Says maximum discharge 5c so that is 25 amps plus 15 amps from original battery gives 40amps peak or 2.4kw - this is more than the motor can deliver.
  13. Yes I know. This is for an electric unicycle. Could still switch off if current is over 18amps however as this is an additional battery added to original battery with its own bms - total current would need to exceed 30 amps which is 1800w so should be a safe bet. Just measured the space and I will need to relocate the bms off the battery however much easier than building the battery from scratch again. Just need to get it here now in a reasonable time frame. 5th October not an option.
  14. Just found this on Ali. 16s2p in the flat configuration for the side space. I am travelling around so if I can plan a place to be long enough in advance I might buy one of these for the other wheel and save 6 hours of labour. https://www.aliexpress.com/item/32829177989.html gives 480wh for $150 bucks. Have to check again that it will fit but I think it will.
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