Has anyone looked at replacing the battery?

[bob2.0]

I posted a problem I have had today (https://www.elektroroller-forum.de/view ... 57&t=42707)

Now I wonder if I should look for a replacement battery because this one seems to be inaccessible and I cannot tell if the bike will let me down.

I have been looking on aliexpress. I think it is possible to find a replacement somewhere within £1000 that will fit, has a bit more capacity, and has a BMS that can be accessed to check of cells. It may consist of parallel packs.

Any thoughts on this?

[didithekid]

Hello,

You can order (1.) the original battery box, but in this advertisment the written dimensions of 360 mm x 85 mm x 185 mm and weight 12 kg may be wrong (it should be a bigger battery, near to 50kg): https://madatshop.com/dayi-lithium-ion- ... 47s_E6JhRQ
I remember, that it was reported connection to Plus and Minus will work with the ODIN.
https://www.youtube.com/shorts/mRvR2j0P2Ok

If You look for the real dimensions of the battery housing, You may find the size in china:
https://de.aliexpress.com/item/10050049 ... ry_from%3A

VG
Didi

[jeff-jordan]

Be aware of the size of the genuine battery inside our E-Odin.

[bob2.0]

Thanks I am aware.

I was looking at taking two packs that would fit side by side, but the numbers and sizes on 'Aliexpress' are a bit vague and probably wrong.

I think these suppliers just make batteries in any size you ask for. I think the more practical question would be what BMS current is ideal. Total of around 200A? Or more?

Anyway, I think my "current" issue [pun in English] is not the battery, but some other issue on the phase wires. So I will keep a watch on battery prices in case, but only that at the moment.

It is a bit infuriating that these packs are sealed without even a way to monitor the cells. So if I were to ever replace them, then better access and maintainability would be very desirable.

I was thinking that perhaps a half dozen smaller packs paralleled up would be better for 'hobbyists' like us? Then if a pack suffers bad cells, that pack can be replaced?

Most of these packs being made and sold on Aliexpress are from cylindrical cells in a package. So maybe one layer per pack, of 18650s at a time, all packed along the battery cavity.

[bob2.0]

For example;

https://www.aliexpress.com/item/1005007185197459.html

"72V 20S4P 40Ah 21700 Lithium Battery Pack 3000W"

At a cost of ~Euro 100.

This one gives a dimension of

245 * 177 * 73mm

I don't believe for a moment that they can cram 40Ah into that space at 72V, so some further enquiries would be needed.

It says " 4P x 21700 cells", and those are usually around 5Ah, so probably it is a 20Ah pack.

But if we are aiming within 280 high/wide and 340 long, then we could pack 4 of those longways and still have space for two more at 90 degrees.

Whatever they are in actual capacity, the sum total of 6 will likely be over 100Ah and cost ~Euro 600.

That was my initial thinking.

[bob2.0]

This supplier makes more sense;

https://www.aliexpress.com/item/1005008113831066.html

Is asking ~$300 for a 30Ah pack.

So 4 of those for ~$1200 from this supplier would fit.

[dominik]

Before thinking about buying batteries with unknown cells inside and without a Bluetooth BMS, i would open my battery and change the bms for one with Bluetooth.
Costs less then 100Euro

[bob2.0]

I'd like to 'anyway'.

Has someone done this already?

[bob2.0]

I'm even mad enough to consider making a new pack from scratch.

Can't say I have done such a thing before.

"How difficult could it be?!"

I was thinking about this before because if the pack was li iron phosphate, then the discharge curve flatter, and the power would not drop off so quick.

I get 40 good miles (OK, 'used to get', got to fix my small problem first) at top speed over 60mph, then at half discharged it goes to 55mph only.

If it was a flatter curve, would I get top speed for longer?

How about 256 of these?

I think these would cost ~£600 for 10 strings of 24 cells in each.

If the cells are packed in a 9 x 8 square, filling 285mm x 250mm, with each string 4 cells long, being ~300mm, then that is 9 x 8 x 4 = 284, or 12 strings of 24 cells each string. That's LFE / 24S, so at fully charged = 140Ah x 87V = 10kWh nominal.

Thoughts on the madness?

I can then service the battery cells, add bluetooth monitoring, longer life LFE, flatter curve.

Just thinking about the possibilities if it were to come to that.

[jeff-jordan]

@bob2.0
I once bought a similar battery pack (as in your first link) for my "spare can" project, look at this posting.

But it wasn't worth the shipping, so I ended up buying a proper eBike battery.
These chinese capacity and power readings, especially for lithium batteries, are often a fake.
You can buy 18650cells at AliExpress with 15000mAh, but if you're lucky, you'll get approx. 200mAh out of them.

Anyway, even a BMS (as in one of your links) with 3000W is a joke for our E-Odin.... it wouldn't stand the power for a minute.

With the genuine controller, the E-Odin draws about 125A when accelerating, so the minimum limit would be 11 kW.
Using the ND72530 (instead of the original one), my E-Odin draws a max. current of 150A. So the BMS needs to cope with 12.6 kW peak.
If I'd need to replace my battery, I wouldn't buy one with less than a 200A BMS (-> 16.8kW peak).

Furthermore (due to safety reasons) you need a pack/battery with a solid steel box, not styrofoam and shrink tube.
And, last but not least, you'll need to wire the battery (batteries) up with at least 16mm²/AWG6 silicon cable.