RC lipo for my dirt bike build

[Jan]

Hello from Sweden! This is my first post here. I found this thread: https://elmoto.net/showthread.php?t=3775 where DRZ400 wrote: "Gear your bike for a top speed of 50, at 3600 rpm. Use Turnigy RC packs. 5S, 5ah. 4S,5P would give you a 74V 25AH pack. Should get you there."
Because of custom regulations and trade treaties it is better to buy something in europe than importing from US so I found these: https://www.gensace.de/tattu-10000ma...tery-pack.html. What do you think, are they a good alternative?
I am building a dirtbike with an 8000 kW QS motor but I have to start small. Probably only 36V for a start and then successively add modules.

[Stevo]

Be sure to use a BMS and maybe charge outside your home just in case they go up in flames.

Sent from my Pixel 3 using Tapatalk

[Jan]

Thank you. Yes, I will do that.

[flo]

Hi,
i do believe that this is actually quite an expensive solution..
22s90Ah would run to near 3000 euro, while my homebuild pack exatly that size was 2200.
Just as an example..
On top a big pack of those would give you quite a headache ballancing in my opinion,

For ballancing always connect P first than S, which is impossible with those ready made packs.

That said my alibaba cells surely were not better at all. That is why i used quality cells with my next build.
In the end its is cheaper to source a better quality pack right from the start.
Second life-evbatteries dot com might have something suitable for you..
Good luck and keep us updated

Flo

[Jan]

I understand, but I need a pack with CE-marking or a CoC for my build to be street-legal. Therefor I can not build it myself (or letting someone else build it). I would really like to have a LiFePO4 pack instead but that is more expensive if I want a higher C-value than 1 or 2, at least what I have found.
If I understand it correctly a high value, this pack is C15, is good for performance?
Is balancing each module individually impossible? Each one comes with a balancer connection.

[flo]

Hi,
not sure if you really need the cells to have been CE approved in sweden. Anyway, i do strongly believe also, that with all those chinese brand cells the CE label is just printed on for show.. not that they actually comply to any rules in EU.
Hobbyking and so on cells are known to be notorious overrated so your 15c cells will be good for 10c if you are lucky. And yes 10 or 15c burst will give you more power than a 2c burst cell. On the other hand -most likely- the cheap hobbyking packs will sag so much while doing so, that you are on the edge of damaging them. Starting with a 10000mah pack will give you barely any range and a heap of voltage drop, so best to start with 40Ah ... which will going to cost a lot. Fun fact: by then you do not need the high C rate anymore.
So I personally would rather start at 60 Volt for saving money on batts. And upgrade the pack to higher voltage later, than starting on a 10 or 20Ah pack, likely damaging that already before upgrading to it to a higher Ah pack.
That said buying nissan leaf or bmw i3 cells used - how could these not comply to eu rules? Being taken from road legal cars that is. Most of them come in pre-assembled packs anyway. Nissan leaf gen4 in 4s2p nowadays or the bmw cells i have seen then were like 12s packs... just connect 2 of those .. secondlife-evbatteries sometimes gets VW e-golf packs... just snoop around the net what cells would suit you best and go from there.
Just my take on it.
greets
flo

[Jan]

Thank you! I saw Honda Jazz battery quite cheap.Could that be something? Dint know specs for single cells.

[Jan]

I found half a Leaf 24kW battery for 1000€ SoH 72%. Seems low but is it too low. I will need 10 modules, at least, and that's a lot of weight. 3,8 kg/module!

[Stevo]

I completely agree with Flo.... stick with a used automotive batt pack, they must be available somewhere in Europe.
The batteries are always going to be the heaviest part of these projects. Good luck with your search and let us know what you end up with!

[Jan]

I will have to solve how to keep the balance of the bike because of the heavy batteries. If I mount them all where the engine was mounted I will have a bad center of gravity. Is it possible to have packs where the exhaust was mounted, instead of the fuel tank and where the engine was mounted?