It started with those YouTube videos of people on eSK8’s, it looked amazing! I watched almost all the DIY video’s i could find. Next, I ended up here, gathering even more and more information and inspiration! Today, I will present to you, my plan:
I want to keep my budget low, therefore I made some cheap choices. I live in the Netherlands which means high shipping and VAT costs, which is the reason why I will order a lot of these parts from Hobbyking, AliExpress or Banggood.
Hopefully I can get a good speed with nice hill climbing power out of this mono drive, especially with the FVT that can give me some nice power at 12S.
Next, I am considering 2 options for the battery:
Option 1: 12S1P by combining two 6S 8000MAH 30C ZOP LiPo - Link
To connect the balance leads of each 4S2P I will use these parallel connectors - Link
Advantages:
Higher C rating (20C+20C=40C)
Higher capacity (5Ah+5Ah=10Ah)
Less voltage drop
Hard case
Better quality (Turnigy)
Disadvantages:
Bit more expensive (~105 EUR)
A lot of wires!
The struggle
So, if you see my diagrams, am I building a or just an eSK8? Some feedback on circuits is always welcome! What is the best option for my batterie, the 12S2P or the 12S1P?
And if you have any further recommendations, please let me know! For instance about the cheap BMS and charger combination, or the ESC FTV.
Thank you for reading my topic, and even more thanks for some good advice!
Interesting choice with the chain drive, any specific reason?
Go with the bigger battery, saves you making a mistake with a smaller one and regretting it, besides it’s not that much more expensive and the 40C rating is complemented by the larger MaH capacity for less voltage sag.
Just checked that BMS though and i’m afraid that may make this a bomb, it’s for li-ion, not lipo, so the over discharge voltage goes too low. LiIons discharge at 2.8~3.0, LiPo’s are about 3.3~3.4. Taking a LiPo that low is asking for “exotic behaviour”.
Got a proper battery person to weigh in though, @Namasaki is my go-to LiPo hero
Yep he’s right about the bms, that is too low for lipo batteries. At the absolute minimum you want to have the cut off at 3v, 3.4-3.6 is preferred.
Go with the turnigy batteries they have much better quality than rebranded Chinese batteries. It will be more complex to wire but when done right will be much better
Lastly I would advise you against that esc if you have not already bought it. They seem to have bad brakes, overheat a lot or just don’t work very well. If you spend a bit more money and buy a Vesc you will be much better off
That gear ratio is not optimal at all… I calculated it for you, and you will have an estimated top speed of 60km/h… Not is this only freakin dangerous, but IT will result in a low torque, and your motor will run inefficient and produce a lot of heat…
@riva_00: I chose for the chain drive because of the short shaft of the motor. The chain drive does not take a lot of space + no slipping.
You are correct, I can better invest for some more mAh and some less voltage sag!
About the BMS, I’m only using it for charging. I will place the voltage meter in sight so I can keep track of it. Otherwise I need to buy a more expensive BMS which can handle more amps.
@pat.speed: The ESC has indeed some problems. They seemed to be updating the firmware, but that has brought also other problems. I will start looking for a VESC, that’s is a bit more safe.
@FredrikHems: Ajj, that is way to fast. I will change that! I probably go for just a belt drive instead, because
belt drive offers more gearing ratios.
Looks like that’ll charge to 4.3V, which’ll cause problems. if you want long lasting packs most people recommend charging to 4.1, or sometimes even less.
Please do not give wrong tips C will not change… A single cell will not start giving double current rating, the capacity increases which makes higher current. 20C * 5Ah = 100A; 20C * 10Ah = 200A
Dude please stop if you dont understand… The C rating mean that A single Li-Polymer Cell will be able to give out 100A At 5Ah capacity with 20C rating. If you connect them together the current parallelises not that cell willl be giving 40C rating
@riva_00, good tip, I will look more into that! For now on I only found BMS’s that goes up to 4.2V (Link), which is still too much. I’m gonna do some more research to find a BMS that fits the requirements of a 12S lipo.
@Youssless, @Kug3lis you guys are correct, I made a mistake there. The amps are not increased because of the C rating, but by higher amounts of Ah.
I think a good idea would be to think about what range you actually want from the board, so is it just for fun? Or are you going to use it for something more practical like commuting?
Once you have a range in mind, look at what other people get with similar setups and then you know what MaH and C rating you need to aim for. Also, don’t forget to aim a little higher than what you want, it sucks to spend money on something that almost does what you want (so if you want 10 miles aim for 12~14).
Now you know the range, what speed are you looking at? That’s purely up to you, but with a configurable ESC like the VESC or FOCBOX, you should again aim a tad higher and them limit the RPM of the motor, simply so if you wished you could go faster, you can without changing the pulley set-up.
Lastly regarding batteries, don’t cheap out on them, and certainly don’t connect anything before you’ve read up on every little thing. Keep reading the wealth of info on here, and then find the posters who give good, simple and concise answers, then ask them if your about to visit the burn ward in hospital
or just an eSK8? Some feedback on circuits is always welcome! What is the best option for my batterie, the 12S2P or the 12S1P?
