Evva vs. Keeppower NCR18650B Protection PCB Visual Comparison

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RMM
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Evva vs. Keeppower NCR18650B Protection PCB Visual Comparison

Due to the many questions about some of the protection circuits in some of the batteries I am selling (mfg. by Evva-Tech), I decided that a teardown was in order. Although it pained me to do this to two brand new batteries, I had to see what we had inside of these cells. I decided to do a comparison to the admittedly similar looking Keeppower. I have no way of doing any fine testing of these circuits the way that HKJ does, so this is more of a visual comparison.

The two cells to be torn down


Slicing it open

Rear end – Evva left, KP right. The material appears to be similar, if not identical.

Button tops

With wrappers removed. Note that the Evva circuit has a larger OD.

First look at the KP circuit. Looks like AO8814 MOSFET with Seiko S-8261 IC. This comes in various configurations: datasheet.
Looks like this one has a “G2JA” which isn’t found in the datasheet.

First look at the Evva circuit. It looks like the same major components except that there are (3) MOSFETs vs. (2).

Big view of the two together. Looks like they even share the same value resistors.

While I do not have any quantitative evidence to prove it at this point, the Evva looks like a good protection circuit that uses a Seiko IC as specified as well as good MOSFETs. The KP circuit is obviously well made and is held in high regard and is often said to be the “gold standard” of protected 18650s. I am not sure how much difference the third MOSFET makes, if any at all. It could potentially lower resistance in high drain scenarios but I am not sure of that.

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Edited by: RMM on 11/09/2013 - 02:28
InfinitusEquitas
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Thanks for doing that teardown!  I can certainly appreciate how unpleasant it must have been to slice into the batteries.

It looks like the Evva battery is 1,  maybe 1.5mm longer?

NightCrawl
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Can you show how the positive poles are attached? 

Interesting that the KP cell has 2 Mosfets. Per HKJs test, protection kicks in at 11.5A which would require 3. Not the first time I notice discrepancy in data with Keeppower cells. 

ryansoh3
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Thanks for the teardown and comparison! Smile

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Werner
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Thanks, no we need anyone rip one of the cheap Unbranded protected Sanyo or panasonics…

Helios-
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Someone did a clear wrapped panasonic NCR18650B from FT.
Protection chip was marked DW01. Its made by a Taiwanese company, fortune semiconductor, google brought up a datasheet.
Thread


Counterfeit 18650s, 2,<a href=“http://

Werner
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Were have you found the info about the FT Panasonic cell?

RMM
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Werner wrote:
Thanks, no we need anyone rip one of the cheap Unbranded protected Sanyo or panasonics…

Don’t tempt me! I’ve got some of those too from Fasttech and Wallbuys.

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You may be able to do it without irreversibly removing the protection. Lift it & desolder one wire from the pcb.


Counterfeit 18650s, 2,<a href=“http://

RMM
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NightCrawl wrote:

Can you show how the positive poles are attached? 

Interesting that the KP cell has 2 Mosfets. Per HKJs test, protection kicks in at 11.5A which would require 3. Not the first time I notice discrepancy in data with Keeppower cells. 

Here you go:
Evva Left, KP Right. The KP is spot welded directly to the positive pole, it looks very secure to me.

The Evva has a tab spot welded to the positive pole which then connects to the button top.

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NightCrawl
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Thank you. Smile

xmldriver
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Great thread, not all protection circuits are equal! Are the NCR18650PF circuits Seiko?

RMM
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xmldriver wrote:
Great thread, not all protection circuits are equal! Are the NCR18650PF circuits Seiko?

Yes, they are also Seiko.

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