Polpus Posted May 3, 2016 Share Posted May 3, 2016 Hi all , I needed to increase the really poor range of my generic chinese EUC so I decided for the cheapest way that was adding one more battery to it . It's a 350W motor and originally mounted a 132 w/h and I bought on Aliexpress an equal one -obviously with its BMS- , so now I'm having 264 w/h , still not too mutch but for my entry level EUC will be good. This is my first EUC so next will be a more powerfull one ! I wanted to share with you my mod , which consisted mainly in finding suitable space for the new battery . Firstly I was convinced I would have found place just over the original mounting one , but once I had the new battery in my hands I realized it was impossible . Original Side Covers could be used but one of the two did not stay perfectly closed so at the end I had to prepare and mount a new side cover . I think, after the tests , I will seal the Covers in order to avoid any possible rain/water infiltration . Link to comment Share on other sites More sharing options...
Polpus Posted May 3, 2016 Author Share Posted May 3, 2016 Link to comment Share on other sites More sharing options...
Chriull Posted May 3, 2016 Share Posted May 3, 2016 Wow - quite some work done with this mod! i hope you where carfull with the combination of the board electronics snd rhe batteries - if anything sharp cuts the battery insulation this could lead to nasty shortcuts! Unfortionately i have two further points, which hopefully won't be inflicting your wheel wirh this new design: Long(er) wires introduce quite some inductance and could hinder the big capacitors to fullfill one of their tasks - filter/stabilize the supply current. Could lead to nasty side effects like cpu "hick-ups", mosfets not beeing able to switch neatly, etc... Second are the mosfets itself - with the higher inductance of the wires they could start to oscillate, but will quite definitely have slower switching slopes - more power to dissipate... Link to comment Share on other sites More sharing options...
Keith Posted May 3, 2016 Share Posted May 3, 2016 42 minutes ago, Chriull said: Wow - quite some work done with this mod! i hope you where carfull with the combination of the board electronics snd rhe batteries - if anything sharp cuts the battery insulation this could lead to nasty shortcuts! Unfortionately i have two further points, which hopefully won't be inflicting your wheel wirh this new design: Long(er) wires introduce quite some inductance and could hinder the big capacitors to fullfill one of their tasks - filter/stabilize the supply current. Could lead to nasty side effects like cpu "hick-ups", mosfets not beeing able to switch neatly, etc... Second are the mosfets itself - with the higher inductance of the wires they could start to oscillate, but will quite definitely have slower switching slopes - more power to dissipate... +1 with @Chriull plus what looks like very thin wires from the FET's back to the board compared with the yellow/blue/green wires that take their power to the wheel. Brushless d.c. speed controllers are very sensitive to those capacitors, high voltage spikes can get through to the electronics and, particularly, the FET's if they don't have low enough impedance. Ironically the long thin wires to the FETs might just be a case of 2 wrongs making a right! Link to comment Share on other sites More sharing options...
esaj Posted May 3, 2016 Share Posted May 3, 2016 Don't know if and how well it will work or not (I too would be a bit suspicious at least of the effects on gate signals of those long wires), but I give it A+ for effort at least Link to comment Share on other sites More sharing options...
Polpus Posted May 3, 2016 Author Share Posted May 3, 2016 Peeps thanks for your comments. Capacitors wires are pretty large and not so long. I exlude inductive problems. Also MOSFET wires are the biggest could be soldered on PCB avoiding short circuit. Today 10 kms ride with often Speed max reached and no problems... Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted May 3, 2016 Share Posted May 3, 2016 Hey nicely done! I was wondering whether those MOSFETS could be moved to a distant location. Someone should hire you to do some EUC design consultation. Link to comment Share on other sites More sharing options...
Chriull Posted May 3, 2016 Share Posted May 3, 2016 2 hours ago, esaj said: Don't know if and how well it will work or not (I too would be a bit suspicious at least of the effects on gate signals of those long wires), Since the gate signals should be (at least imho) current driven this could give them enough "stability" to sustain longer wires... but hard to say without measurements for switching times in the range of some hundreds of nanoseconds... 2 hours ago, esaj said: but I give it A+ for effort at least From me too - i did not express my respect and how much i appreciate @Polpusinitiative for his mod while writing my concerns before while riding in the metro. I assumed that it works for his wheel, since he posted it as review of his mod - and imho should be a nice and inexpensive way to increase range with limited space while presumably reducing possible overheating problems. (if one has the skills to do this as neatly as here posted) I just wanted to post here my concerns to state, that it could maybe also lead to disaster/unwanted effects if one tries to adopt/repeat this ideas. Maybe "small" generic wheels (with the 350W motors) have enough safety margin by design, so my concerns are void for this - maybe it is absolutely a no go (or maybe also not?) to make such mods to high power wheels like a ?1500W? ACM Gotway's. It's also a bit an "esoteric" topic (switching high current with high frequencies has many side effects to consider) - longer wires imho mainly introduce new inductances but (can) also have capacitative effects. There also could be too much capacitance already from the pcb layout which gets compensated by the new inductance of the longer wires, etc. But overall the side effects of such mods should imho not tend to the positive side? So if one tries to follow this idea one should be prepared for some trial and error until reaching a neatly working layout. And tend to carefully test for the limits if some timing problems arise (maybe a H-bridge shoot-through in the worst case), or the already mentioned cpu reset in because of too much spikes and/or not enough filtering/decoupling by the capacitors. And hopefully my concerns never matter, because there are just more then enough safety margins... (And these are just concerns - i have no ideas of the real inductance/capacitance numbers of such mods and there effective influence in this practical enviroment) 1 hour ago, Polpus said: Peeps thanks for your comments. Capacitors wires are pretty large and not so long. Imho the bigger capacitors should be not as critical in regard to their position/wire length. The main filter capacitors are (should be) the small ones in direct neighbourhood to the critical components. 1 hour ago, Polpus said: I exlude inductive problems. Also MOSFET wires are the biggest could be soldered on PCB avoiding short circuit. Today 10 kms ride with often Vmax reached and no problems... Mabye some steeper inclines with low speed (should be imho one of the biggest burdens for e-wheels) to test and verify the worst case? Aside of this again congrats to your ideas and realisation! Imho one of the bigger and creative mods to maximize the efficiency of a wheel around here! Link to comment Share on other sites More sharing options...
Polpus Posted May 4, 2016 Author Share Posted May 4, 2016 @Chriull I agree with you , this Mod has to be performed on a low power cheap EUC , I did not stop myself to analyze which kind of mosfet is mounted , just cuz all in all I do not expect electronics of these industrial poor entry level machines to be so sophisticated to be affected by a bunch of cms of cables . The same copper used for electrical net/pads is a very bad quality one . . . Anyway my EUC actually has the same behaviour BEFORE the mod , so it is functioning GOOOD ! (If something happens I'll post here..) Link to comment Share on other sites More sharing options...
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