Enerdel battery module max current?

[Zuikkis]

Hi,

I'm building an electric motorcycle with 12kW motor and about max 95V battery voltage, and looking for suitable batteries..

As you know I have a few Think Enerdel packs. I could build a 22S pack with these cells to get correct voltage. But I need about 150A current.

"Think City Enerdel Battery Service Manual.pdf" says maximum current for the pack is 140A. But this is for the entire pack, where there's two "chains" of modules in parallel! So for single module the current would be only 70A.

But then again the 140A limit might simple be because there's 170A fuse and the contactors have 200A limit if I remember correctly.. So 140A might not be the module limit but pack limit?

So, anyone know for sure, or do I just try it and after the explosion decide to get some other batteries? 

[Zuikkis]

While googling I found this:

https://www.greentecauto.com/hybrid-battery/repurposed-batteries/energy/enerdel-nmc-48v-50ah-2-2kwh-brand-new-battery-module

Looks exactly like Think battery except for the + and - terminals? Or is this actually a bit larger as it says 50Ah and Think cells only are like 35Ah?

But anyway even this page says 70A max current, maybe it really is that low.

[Zuikkis]

Heh, I'll continue my monologue.

https://www.elithion.com/pdf/enerdel/MP320-049.pdf

This is interesting, this pack has similar specs as Think pack, only 32Ah and the dimensions match exactly, except for the battery terminals. This datasheet shows 160A max and 480A pulse discharge (for 10 seconds).. That would be quite enough. The datasheet is from 2012 so even the time period would match Think batteries.

[worry]

Hi, very interesting.
Further into the Elithion site, I found this page.

https://liionbms.com/php/cells.php

It lists Enerdel cells as for energy or power. As our cells are for energy, they probably are not made for high current. Just a guess.

[Zuikkis]

I did some measurement. I measured the internal resistance of Think cells and also Nissan Leaf cells which I also happen to have.

My measurement procedure is simple; I measure the "idle" voltage of cell, then apply 3A charger and measure voltage again. Then we get R=Vdiff/3A

Think cells: 15mV --> 5.0 milliohms
Leaf cells:   5mV --> 1.7 milliohms

While 5mohm doesn't sound too bad, when I have 22 of cells in series it becomes 0.11 ohm. Even that doesn't sound bad, but if you calculate with 150A,  U=R*I = 16.5V.... So 90V battery would drop to 74V during load! And P=U*I so 16.5*150 = 2475 Watts lost as heat in the battery pack...

With Leaf cells, the drop would be only about 5V, and "only" 750W lost as heat in the pack.

The test was conducted in quite cold temperature (+13C). Battery internal resistance decreases when battery heats, and obviously it would heat quite a bit with 2kW internal heater. But I still assume Leaf cell would be 3* better in any temperature.

So, I think I'll use Leaf cells. It's just that those cells are in use and I now need to replace them with something else.

[worry]

Thank you for the math! I haven't thought of this as an issue. Except that charging amps need to go down in the end to reach full. Learning something new every day.

Now, let us see your motorcycle.