Hey Im new here and I want to make a… kind of weird built as a prototype for a project in my university
Should I just make a new topic or post it like a whole thing into this noob thread?
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Hey Diverse and welcome to the forum.
If you want to create a topic to show us your progress and create a build log, then feel free to start a topic in the DIY builds category. If you want to ask a bunch of random questions first you might want to start here in the questions thread.
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Alright then 
Here some of my random current questions and the basic idea:
Im planning to build (/design?) some sort of “electric inline-skate” thing as a project for my university.
I would love to make the result or compromise as a “working prototype” and I got me some old Cross skates (skikes v07) as a base for the built as they have a lower center of gravity, larger wheels and come with air-filled tires (which might be more usable at higher-than-rollerblade speeds).
The skates would be two identical drive systems with each a motor, esc, receiver and batterypacks(cells/bms). Im still not shure how I will control them both, if I opt for handheld remotes in each hand for each skate or if I figure out a way to control them both with one remote… It might be difficult to steer with the latter 
I sadly have only about 70 days left to get it done completely and am currently in the process of finding the right parts and ordering them soon so the delivery times of maybe 30 days are within this period 
So far I got this list:
I plan on using 165mm hub motors as they seem to be quite powerful and slim (they could maybe even fit into the skikes without big modifications)
Someone recommended me to use 2 of these sv6 vesc6 (which are quite expensive but I guess I need to increase my budget a bit…)
As a remote I heard that this miniremote could be able to be bound to two receivers but I will get me two sets of them and figure stuff out (to maybe change it to one remote) when I get everything working with two of these in parallel (just testing the concept with each skate on one remote each)
2 of these BMS as they come with the important features and also a temp probe
I plan to make the battery packs removable as in power tools to reduce the weight on the skates/feet. This way it would be possible to take more battery packs in a backpack to get more range. The packs are planned to be 10s1p and these 21700 cells got recommendet to me:
That seller even offers to solder little tabs onto the cells for 0,55€ (each…) and I guess that is the best I can do as I dont know if they have a spotwelder for cells in my university and they didnt answer my mails about the workshops they have yet 
For the systems to turn on/off I heard people use antispark switches or bridges but I thought if it wouldnt be enough to simply unplug the battery to turn it on/off? (please tell me if Im overlooking something as I dont have much experience in e-skateboards yet 
just a tiny bit of quadcopterstuffs) Otherwise I would just make a xt90 plug thing and a neat housing for that
A goal would be to go slightly above bike-speed and I would try to get regen braking to work for these cells/motor/esc. For that I heard to just… use the bms for chaging only and simply solder the esc input directly to the cell-in/output so it doesnt destroy the bms if it isnt suited for that amount of current?
Anyway I just want to make this kind of stupid build and wanna see how it performs and feels ^^
Anyone who wants to give me Advice is welcome!
If someone has better solutions to the things I plan do some way please let me know!
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Used FOCBOX singles would be a lot more kind to the budget. Did you consider using equipment that isn’t new?
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u might want to look into LLT bms, sure they are more than whats on banggood, but bms is a device that u don’t want to cheap out on
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If you know someone that offers two of these (and import tax isnt that high) I would also take used, shure!
So far on a quick search I have only found this listing with two available on ebay:
And that ebay listing would result in about the same price as the ones that got recommended to me before ~300€ for two
Thank you for that compilation of quotes. Yeah then I will just add one of these on each skate and integrate the key into the housing (to be done) somehow.
Not sure if these are still available.
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Wow these are long! But for a reason as it seems to have more mosfets and stuff on it…
I will put them on my parts list thanks a lot!
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they do have smaller version that doesn’t have as much current capable and without ble module:
but i would prefer to have ble module to monitor cells if i can, that’s just me tho
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And the bluetooth is always on with these? I havent yet found information about standby power consumption or does it just consume power if I power it on? Like a switch somewhere? But they shure seem hq
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The idle drain of the bluetooth module is extremely low. It goes into a sleep mode when the app is closed on your phone
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some of them support a switch function, which would turn the bms on and off, also turning off the ble in off state, but ble module in general doesn’t consume that much energy anyway
Well… per-cell monitoring sounds interesting (totally overkill for a prototype xD) and i guess it helps to see if one of the cells starts failing and prevent risks of a full pack failure (if thats how its called)
But if my budget can be stretched a little bit more I will use the first ones you sent as they would be kinda cool…
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So its… bluetooth low energy (BLE) i guess so it should be fine
Do these work with bluetooth of laptops as well? or just phones because of the software (apk)
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I think you can order a module to connect to your pc as an extra, but i’ve only ever used the bluetooth and phone app.
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