Panasonic Li-ion Packs

[micart671]

G'day,

I have a request from a customer specifically for battery packs using Panasonic Li-ion cells. (36V 10ah)
Can anyone help me?

Cheers,

[Kin]

Hey, you might want to ask the question. People are probably going to be able to answer best if they know the question. ^_^.


Trying to provide as much detail as possible, usually helps.

[micart671]

Ta,

I thought it was obvious? I wanted to know where i can source them from?
Simple really.

Thanks for your advice nonetheless.

[boppinbob]

http://www.amazon.com/Electric-Bicycle-Capacity-Lithium-Battery/dp/B0064OVD9S

[Kin]

In retrospect, you might be right that your question was more obvious than I thought.

The thing is, there are many different types of panasonic li-ion packs.

Is your customer looking for a very low discharge high density pack? Because the highest density Li-Ion cells (3.4Ah 18650) would typically not be good for ebikes, because it's designed for 0.5C-1C usage. It's also hard to source the 3.4Ah version, and even the 3.1Ah (previous highest) are tricky to source.

For quality cells, a lower density (2.6Ah-3Ah) can mean that they're more capable of discharge. The extra space offers more room for electrodes and things necessary for the kinetics. Some sony/samsung/panasonic cells are spec'ed for 2-4C, which is much better for bikes. They can't be as high density as the most energy dense batteries of lower discharge capability.

I'm curious about the battery that was linked, and if we can be sure it's actually made from panasonic cells.
So, it's rated at 36v/300watt.
That means it's 10S, 37v nominal. I'm going to assume that means it is 300/37 = 8.108Ah. In that case it would make sense it's made of 10S3P cells, which are 2.7Ah each. If these are panasonics, they are not the high density 3.4Ah panasonics. But that makes sense, in so far as the seller also claims,
Continous 460watts output, bursts of 1000W. That means it's 1.5C continous 3C burst.

SO if these are actually quality cells, it's within what's technically possible. However, it is also possible that if these are made from bad cells, it will perform nothing like promised. Maybe you can ask the seller for a spec-sheet on the cells used?

EDIT: I've realized they actually include more info, part of which claims 10s4P, so my estimates may have been wrong.

Edit2:

So let's say that's 10s4p with nominal 36v. 300watt hours/36v = 8.3Ah. 8.3Ah/4p = 2.03Ah per cell....I don't think those are panasonic cells. I am not an expert, but I have not heard of a low density high discharge panasonic cell that is as low as 2Ah, because that's pretty low for a quality cell.

Out of curiousity, I tried googling for "18650 Panasonic 2000mAh" and got an alibi seller "http://ewtbattery.en.alibaba.com/product/473900093-209729633/Panasonic_ICR_18650_3_7V_2000mAh_Li_ion_battery.html" who goes by "Mr.Jack Sparrow" <-- which made me laugh.

[micart671]

Hey Kin,

Thanks for the info. You certainly know your stuff. It's been a while since checking the forum out and didn't realise you had replied in detail.
I will follow up Mr Jack Sparrow

Cheers,

[Kin]

Hey, just to clarify, I want to think that I read around here a lot and know a little bit from life, but I'm not a battery expert- don't get me wrong. I want to offer that disclaimer.


There is some more information on the thread I started a while ago: viewtopic.php?f=14&t=37710&hilit=panasonic+magic


One thing to consider, if your client is reasonable, is if you can get your hands on genuine dow kokam NMC cells, or EIG 20Ah NMC cells, or LG Chem NMC cells. All three of them have very good LiNMC batteries, which are most likely better for an ebike application.


While i mentioned that seller on Alibi, i would be very cautious verifying what you're buying. There are a lot of disgenuine sellers on ALibi and Ebay, who might be selling fakes.