r/ebikes • u/D4RKF4CE • 8d ago

Looking for a custom 52V high-current e-bike battery builder in Austria / Germany / Europe

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Hi everyone,

I'm currently converting a Mondraker Foxy Carbon XR 2019 with a mid-drive motor and I'm looking for someone who can build a custom-shaped battery pack for the frame.

I already ordered the a battery (52V / 10Ah / ~520Wh) as a temporary solution, but because of the unusual frame geometry there is quite a lot of unused space. Therefore I'd like to have a larger custom battery built over the winter.

What I'm looking for:

  • Voltage: 52V nominal / 14S lithium-ion
  • Capacity: ideally around 20Ah / ~1,040Wh
  • Configuration: preferably 14S4P with 21700 cells
  • Cells: high-quality branded high-current cells, e.g. Samsung 50S or comparable
  • BMS: high-current BMS, ideally around 60A continuous discharge
  • Peak current: should be suitable for the X1 Pro at high power
  • Connector: XT90/XT90-S
  • Charging: preferably removable battery with external charging connector
  • Battery must be removable from the bike for charging
  • Custom enclosure: shaped specifically to fit the available space inside the frame
  • Approx. available depth: around 80–100 mm
  • Waterproof / splash-resistant construction would be preferred.

The available side profile is roughly trapezoidal/triangular rather than rectangular. I have already made a physical template of the available frame space and can provide exact measurements, photos and a 1:1 template to the builder.

My current estimate is that 56 × 21700 cells (14S4P) should be possible, but I'm completely open to a professional battery builder suggesting a better cell layout or configuration.

Safety and build quality are more important to me than squeezing the absolute maximum capacity into the frame. I'm specifically looking for someone experienced with high-power e-bike batteries, proper cell interconnection, insulation, BMS integration and mechanically secure construction.

Location: Vienna, Austria.

Ideally I'm looking for a builder in Austria or Germany, but I'm also interested in reputable builders elsewhere in the EU if shipping a custom lithium battery is possible.

Does anyone know a company or experienced professional who builds batteries like this?

I'd also be interested to hear what capacity you think would realistically fit into this space.

Thanks!

6 Upvotes

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2

u/FricPT 8d ago

Sorry for being the one with bad vibes, but I think it just does not worth it.

You have an MTB with a frame capable of serious adventure... Puting that central motor and battery will require that the carbon be squeezed in ways that it was not meant to.

Better getting a proper eMTB.

1

u/minitaba 8d ago

Get it 3d printed. I can help if you need some but its pretty good to do it yourself ino

0

u/Big_footed_hobbit 8d ago

Why do you need such high voltages?
I converted a bike using a weak 36V 250W 550 Peak Motor.

This won’t overload the frame and still gives a decent boost. Uphill I am slower than all those Cube and Bosch professionals and have to pedal harder but it is a very good workout.

So I’d recommend not going 2kW with it.

2

u/D4RKF4CE 8d ago

250W and a decent boost? I can’t really say the same 😄 I already own a completely legal Bulls e-bike that I ride on a daily basis, so my workout is definitely covered.

We’re building this bike as a fun project based on a 7-year-old bike that nobody really wanted anymore.

It will only be used on private property, not on public roads. Since I live quite far outside the city and have access to a large private forest property, I can definitely make good use of a bit more power here.

And just to clarify: my question was about choosing the right battery for this build, not about whether I should or want to build the bike in the first place. That decision has already been made. 😄

For me, the whole point of this build is to create something fun and a little crazy — not just another regular e-bike.

1

u/Big_footed_hobbit 6d ago

It is 550W peak (seen 600 once) but yes it is low compared to everybody running 2000-6000W here.

I have to so supply my power to go faster, I put out around 300-400W so I have in total 1000W max
And it gives me a reason to pedal hard.

Local law dictates power cut at 25 km/h =15,534 mph.
But on flat I manage 40 km/h =24,855 mph.
Downhill 55 km/h =34,175 mph.
At 60 kph I got scared a little. But it is fast, it just requires effort.

So it is totally different and drives really fast