Hi Everybody, I've been pointed over here after looking on the Elmoto forum. I’m here because I’m seriously looking into the feasibility of building my first EV. I’m a competent mechanical engineer, I’ve built my own bikes from scratch, and I know enough to build a 12v wiring system, but I know absolutely zilch about electronics, and the last time I had anything electric powered was when I was building slot cars as a child. So I’ve spent the last few days going through as many relevant build threads as I can find, and trying to make sense of it all. I’ve sussed a few things out, but there’s loads of terminology I can’t even begin to understand – you guys are all pretty darn smart eh?
So here’s my thinking so far. I race flat track in the UK on ICE, but I’m massively inspired by the Alta Red Shift in flat track trim, and also what Preston Petty is doing with the Zero as a base. Both those bikes are way beyond my budget, plus at heart I’m a builder anyway, like I have been for my whole life. So I’m investigating whether I can possibly build it myself rather than ride a bought one.
I can put a rolling chassis together no problem, and I can fabricate and mount, but at the moment I’ve no real idea what I should be mounting. I need a set-up that will see me through a fairly precise fixed routine - six two-minute races (six laps of a quarter mile oval) in a day’s racing, plus a bit left over for restarts etc. I need around 30-35kw of peak power, and I’ll be running at around 45mph or so max, and I’d like the overall weight to be the right side of 250lbs, ideally around 220-230lbs. A good controller (with ‘feel’...?) is essential in terms of sensitivity to throttle response – I’ll be racing on loose dirt after all.
So far I've been looking at the Golden Motor 10kw, and the VEC500 controller to go with it. I'm thinking of running it at 48v, although I realise this will mean I need to draw more amps (around 280A?) to achieve peak power. Would I be better with a higher voltage to reduce the amperage requirements? It is essential to get good acceleration off the line. With an 18" rear wheel then 6:1 gearing would put me right in the max power at 3,400rpm at 45mph (if my calculations are good, it's many a long year since I did maths at school..), so I'd probably need a countershaft to avoid a huge discrepancy in sprocket size.
If anyone feels kind enough to help please, my initial questions are: Does anyone have any experience of that motor/controller combination? And what sort of battery system would I need to provide enough supply? I'm already aware of the dangers and risks of using Lipo, and although I know they are ideal for high discharge rather than duration, which is what I'm looking for, I don't feel confident enough to build my own system safely. Are there any alternatives that won't break the budget too much and not weigh me down with massive kgs?
I know I’m very much lacking in knowledge, and at 63 years old I’m not desperately keen to understand every little nitty gritty about flux reducers or all the other things I’ve no idea what they are. But I am keen if possible to put together a competitive EV race bike. So if there’s a combination of parts that work well together, and can be assembled and wired by someone who has a desire to make it work and isn’t afraid to ask about what he doesn’t know, I’d appreciate any help or advice please. Thanks in advance.
It will be alright in the end. And if it isn't alright, it isn't the end yet...