I am, as stated, naturally suspicious. Especially when i get conflicting information.
I am relatively new so I wont add links but i will copy and paste any requested info. I am looking at esc’s for the board I am planning and will upload each step as I go with that but right now I am doing the math and making sure everything is correct on paper first.
The esc I am looking at is a Flipsky FT60BD Dual ESC 60V 120A with heatsink | For DIY Eboard. I will need 2 of these. But the picture with information printed on doesn’t match the information on the page. On the esc its self it says it is rated for 12s lipos if my math is correct (which honestly it may be wrong, I’m not great with numbers) that is only around 43V not the advertised 60V. this is a big concern as the battery I had planned for is a 14s8p battery from mboards, with a volltage of 50.3V. Am i correct to assume the lower numbers are true or will i have the headroom to run the board like i want?
the motor i want to run is the 2700w motor on the flipsky site. Running that at 50.3V gives it an amperage of 54Ah x 4 is 212Ah which is why i think I will need 2 one for back one for front. learning cable management will be next.
A good example is ebike manufacturers will say 48v battery, which is 48v nominal, 50.4v charged
14x3.5v is 49v
14x4.2 is 58.8
If the controller says 60V then you will be able to get away with it, but stepping up to a higher voltage controller would lead to higher reliability/longevity.
Your battery won’t spike up in voltage unless you brake hard/long on a full battery.
batteries don’t like going over voltage especially if they are lipos, and if they do go over then you get into the danger zone
If you are using lipos, then your bms should be set to finish charging at 4.13v a cell. You will get longer life out of the batteries, and you will never have to worry about overcharging
12S lipo is 12*4.2 or 50.4V — do not pay attention to the “nominal voltages” which are essentially lies, but more specifically, just names.
60V is the absolute limit and you cannot operate at 60V because driving the motors causes inductive voltage spikes and you won’t have any margin of safety.
These numbers mean very little — if anything at all. The higher they type them, the more shit they sell. What do you think they’re going to do?
Also, motor parts aren’t necessarily limited by power. They are limited by temperature. The maximum temperatures could be achieved at low or high power levels…
I really, really hope you already completed steps 1 - 3
Flipsky has little to no quality control, and you get what you pay for. When you buy cheap, you buy twice.
We have a thing we call the ‘Flipsky lottery’ for a reason.
Sometimes, you get something that will die for no discernable reason. But if you’re lucky, you get something that will outlast everything else. The question is, are you feeling lucky?
Voltage spikes–the short answer is the real world is chaotic and filled with noise. Equations you can compute mentally are simplified and usually do not account for this chaos.
so flipsky suck, got you. do you have any suggestions for better site to order from?
I do intend to get a helmet, but before I physically do anything I want to get everything down on paper first. Once I know what parts I want then I will know what enclosures I need. I know someone with a 3D printer so I should be able to get the right enclosure for the parts I end up picking.
what I dont want is the cartoonish eventuality where I buy 6-7 random parts spending 2k and have parts fizzel out and the battery go up in flames.
this is the first time I have done anything like this before so I want to do it right, which is another reason I’m very suspicious of conflicting data.
I’d probably try and find a deck and enclosure system that’s already out there in the wild instead of relying on a 3DP enclosure. Results are typically not great, especially compared to nice fiberglass ones out there from makers like EBoosted, or Kydex ones from Tomiboi.
the battery is made of 21700 cells that are supposed to run at 3.65V x 14 is 51.1. I believe I need a minimum of about 10% of headroom for spikes and longevity, which is why i thought a 60V would be fine but I’m now looking at 75V esc’s. need everything to work on paper before i start sinking money into it.
Not every Flipsky product is as bad as they are made out to be. I’m running my first two ever, but I’ve lost count how many times I’ve repaired them. They’re going great now though.
For 12S, I feel comfortable with their dual V6.7 and have recently used one. All the design faults I’ve dealt with on my V6.6’s have been attended to, and I’m currently running a repaired V6.6 at 90A motor current without fault.
3D printing enclosures doesn’t sound flash. I use fibreglass for mine. Urethane insulation foam is easy to shape manually for making the plug. I cut slots into the mould when that’s done and add dividers because I believe some flex and compliancy is essential. Polyester resins fine for the enclosures and moulds, and black gelcoat makes it easy to spot and deal to the air bubbles.
Lots of effort but well worth it. If you’re good at modelling and printing I’d suggest printing a plug to make a mould off. Too hard for my little brain though doing that.
Voltage spikes happen with every motor and every controller setup, there’s no way to avoid them and no way to calculate it. Some setups have smaller, some have bigger spikes. It’s always a good idea to allow at a bare minimum 10%, ideally more like 15% headroom, 20% if the hardware doesn’t have good reputation. The more stable and well made the hardware is the closer you can get to that 10% mark, but going for too low headroom is risky even on the best hardware.
well that’s kinda the thing, I am learning this as I go so getting on a forum and asking about it and taking peoples advice and looking for more information is how i am having to learn. I don’t have any datasheets I am taking numbers applying year10 maths and figuring things out. I had no idea that flipsky were not good but they seem to have the widest range of parts.
Although I’m a bit upset because its not as easy as buy a bunch of parts stick it together and go, I’m having fun doing math of all things (something i never thought possible as a kid/teen) finding that the written numbers are not what they will actually be and so on.
So if you have a book I should look at getting, to know better how it will all work then please enlighten me, its what I am here for.
the biggest thing i have learnt is that if i had decided on just 2 motors it would have been a much easier build. Less numbers to crunch, more parts to choose from, less complications.
Why not run 2 motors? 2 motors can be stupid strong already if you build it well with good parts. On some tires I accelerate as well as a decent 1000cc bike on my 2WD board.
Also just so you know W ratings are meaningless. For everyday riding 2 motors are much more practical. 4WD has it’s place sometimes, but as a beginner definitely don’t start with a 4WD build. And don’t get 4WD if it’s going to be your only board.