Great, no problem. I really appreciate your help.
I recently purchased two yuneec e-go from ebay. One was in perfect working order and the other one had “connectivity issues” according to the ebay listing. Well I finally had a chance to open up the defective e-go to see what was the issue.
The connectivity issue was actually a defective battery. The board didn’t turn on. The remote control that came with the board worked perfectly with my first board.
I opened up the battery and here is what I found. The BMS had some of the FETs (or diodes?) melted of from the solder from their base. They had also melted off the blue plastic shrink wrap that held the battery together. I soldered the FETs back on but that did not fix the battery. Next I tried to charge the battery but it had no effect.
I checked the battery voltage and it was 6.2 volts on the blue EC3 connector. This is waaaaay too low for a 7S lipo, it comes out at less than 1V per cell. This means that the cells themselves are completely discharged and, I’m afraid, beyond salvageable (I think?).
I also checked the fuse in the battery. Its a 30Amp fuse. The fuse was in good condition and had continuity as confirmed by the cell voltages. The 30 Amps was as high as Yuneec designed the battery to output and I can assume the ESC should be capable up to 30 Amps.
I checked the ESC and motor by unplugging the battery from the working unit and they work perfectly.
Therefore, I’m left with a Yuneec E-GO that only had a bad battery/BMS.
I’m thinking of getting three (3) lipos with 3000mah to 5000 mah and a cheap lipo balancer to function as my bms. That way I can build a lightweight 9S1P battery and be over the original 7S but below the 10S people say burns the ESC. Hobby king sells a balancer board where you can plug in up to 6 batteries and they will all charge while balanced. I plan on getting a super cheap balance charger from turnigy for battery management.
I’m planning on using the original switch and the VDC input jack to power the lipo balancer to charge the battery. I’d need a new 12 VDC wall adapter as the cheap turnigy balancer will not take the 29 volts coming from the original yuneec wall adapter.
Also, the drive wheel is overmolded onto the gear itself so there is no way of removing it. The wheels themselves are not particularly heavy or bad. I may end up keeping them.
I may change the bearings for biltins.
The deck is actually flexible once the battery is removed. It is also not particularly heavy. I think I can reuse it, but I would attach the batteries and cover in a way that does not hinder the flex. Otherwise I may get a Never Summer Heist board which is super flexible and really light.
Any ideas suggestions are welcome.
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Hiya!
Did you notice how the Yuneec BMS has an open balance port on the BMS? I’m building a BMS based on their slim, pretty board using the higher voltage version of the Texas Instruments; BQ77908A Multi-Cell Lithium-Ion/Polymer Precision Protector (http://www.ti.com/lit/ds/slusav5a/slusav5a.pdf). To be honest, 7-8s is the safe range to keep using your Yuneec hardware.
To reuse the battery pack case (power switch and jack), you should make sure to really fill in the area around the switches/ports with hot glue or waterproof kitchen caulk (to prevent water damage). The switch CANNOT BE USED DIRECTLY TO CONTROL POWERFLOW. To use it, you connect it to an antispark switch/circuit that acts as a relay (otherwise your switch will be a instant flash fire hazard). You can disassemble a LiPo pack and fit it into the Yunneec’s cabin, but you’ll have to make sure its safe from puncture and water and that all of the parts fit.
In your position, I would suggest you ask someone to vacuum form you a box for just the batteries and antispark switch and run battery wires over/under the board. I have one working yunnec battery, a battery shell, and a 10S I’m using with my fully modded Yuneec. If you end up deciding you don’t want the Yuneec battery shell, I’d be happy to take it off your hands - they’re flexy enough to fit some firmer boards.
Swapping the bearings is a good idea - but you should remember that some cheap bearings can be pretty effective.
While you have the yuneecs as they are, put ducttape under the ESC and cover up points where water can leak in (Bottom, LED side, and switch side). Yuneec should not be able to say that you can ride through puddles/rain.
Hi, I’m a bit confused here sorry!
What kind of speed were you able to achieve with the stock battery + a VESC?
Thanks!
I weigh 128-130 lbs, so my speeds were more or less 15mph.
With the VESC using FOC Sensorless I could power the motor up to 20Amp (which is 2/3rd the Batteries 30Amp fuse). That took me like more or less 17-18 mph and infinitely better hill climbing.
With VESC using BLDC sensorless I would power the motor up to 30Amp (100% of the 30Amp battery) and that still only got me to about 18mph (hill climbing was killer).
Increased amperage helps if you need more torque, however it’s not going to increase your speed as much as increased voltage would.
It works!
The yuneec deck that came with this board was delaminating on the bottom ply. I’m going to remove that to see if I re-use it as a standard “flex” deck.
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The trucks are machined from a regular skateboard truck, not unlike the dyi trucks. The rear truck weights a hefty 494.8g. I’ll see if I can replace it with a lighter truck such paris or caliber.
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The original bearings are shot. I recommend replacing them with reds or biltins.
Here is a pic of my three longboards. The modded 8s lightweight yuneec , along with a stock yuneec and finally my trusty old sector 9 woody.
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I got rid of all the heavy unnecessary hardware bloat. Tomorrow once the shoogoo is dry ill check the weight as compared to the original yuneec. I have to be careful and check the motor temps consistently because i removed the mechanical fan which caused unnecessary drag on the motor. Hopefully it doesnt burn up with an 8s setup and I"ll get a few more mph.
The weight reduction is around 1.6lb +- 0.2. I’m using thr bathroom scale so its not as precise as I would like. However the 1.6lb +- 0.2 and new weight distribution make the board feel much better and certainly noticeable. They advertise the yuneec as a 13.9 lb but Its actually a bit heavier. Starting weight was 14.4 lband final weight was 12.8 lb.
With the arbor wanut dropthrought deck the board is now longer and lower to the ground. Ill get more precise measurements later.
I may move the esc back towards the motor in the near future but I need to make an extension for the battery cables.
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Dude this build looks great and has finally inspired me to do some real mods on mine. i got 2 turnigy 4s packs at home and a bustin shrike that i currently have the Yuneec setup on. I even have the EC3 connectors for the batteries while im waiting on the VESC for the new build. This is more than do-able, looking forward to that ride review.
Its certainly doable. I’ll post more details of the materials and the build later on along with a ride comparison.
How are doing for clearance on the motor with the drop-thru and the cover removed?
So i had a chance to ride it briefly. It is certainly faster. I have to measure it but at least 1-2mph more. There seems to be an issue because the breaks work intermittedly and the motor too. It may be on the controller side since i belive the slider is dirty. One thing of note, with the bear trucks I got speed wobbles very quickly. I tightened them down a bit.
The motor clearance without the housing is as shown on the photo:
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