Keeppower 18650 3500mah Teardown (P1835J)

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Big_Sam
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Keeppower 18650 3500mah Teardown (P1835J)

Well, I had this Keeppower that had got a crushed button top and slightly damaged wrap so fancied having a look under the wrapper!

The wrapper is single layer, black, seems quite rubbery and not as brittle as the cheap wraps. Under the wrap is the circuit board, +ve strip with kapton tape, and a spot welded button top.

Protection circuit seems to have 3 x MOSFET in parallel which would help to reduce voltage drop across the protection circuit.

MOSFET: AO8814

http://www.aosmd.com/res/data_sheets/ao8814.pdf

Can’t find any info about the control chip yet, I will update if I do.

Wrapper removed and label

Button spot welded, couldn’t get it off, the dent doesn’t seem to have damaged it.

Protection Circuit

MOSFETS cut and bent up to see the tracks.

All parts

I would like to identify the cell, markings are similar to ones I have seen on Sanyo NCR18650GA (edit Jan 2020, the supplier confirms it is that cell Keeppower are using)

My dodgy attempt to draw out the circuit, no guarantees its rights!

I bought this from 18650.uk earlier this year, so it should be the 2019 edition.

Thanks, Sam

Edited by: Big_Sam on 01/08/2020 - 17:51
mattlward
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That is a good looking protected cell. No wonder they do work so well. I only have a couple and they are older versions, but have not given me any troubles.

EDC rotation:
FW1A, LH351D 4000k (second favorite)
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Nichia 4000k sw40 r9080 (favorite light!)
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
S2+, XM-L2 T6 4C

Big_Sam
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I’ve been running it in the FT03 XHP 50 and not managed to trip the protection yet, I think it must step down before it trips. HKJ reviews has trip about 7A – 8A.

18650UK
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Hello!

I can confirm the cell under the wrap is a Sanyo NCR18650GA. I tore one down to check them against their datasheet (which pulls a large amount from the Sanyo one) ran them back to back in testing to see if it was possible to determine whether or not they were using the same direct from factory quality that we purchase, or whether they were using factory seconds/ B Bin cells. They performed only marginally worse than what we know to be direct from factory cells, indicating that they might perhaps just be old (>1year from manufacturer) or just stored incorrectly at some point.

I’ve just released it as an “Unbranded” version. Same cell, SLIGHTLY different protection circuit but without the Keeppower brand, so cheaper Winkhttps://18650.uk/product/sanyo-ncr18650ga-18650-battery-protected/

If you would like the datasheet for it, just pop me an email to wholesale@18650.uk

mattlward
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To bad sales to the US would be to expensive to ship…

EDC rotation:
FW1A, LH351D 4000k (second favorite)
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Nichia 4000k sw40 r9080 (favorite light!)
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
S2+, XM-L2 T6 4C

18650UK
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Its an unfortunate issue, yes. Im surprised that some of the larger wholesale businesses in the US haven’t already spotted and jumped on this. There’s a huge amount of room to be able to provide people with properly obtained, tested, verified and built cells at a fraction of the cost of the currently available ones. I’ve specifically used plain clear wraps from design stage so that customers can see exactly what they’re getting rather than coming up with some kind of “brand” for them.

ggf31416
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Liionwholesale has its own brand (MJ1, GA and others) of protected cells and Illumn has a low cost protected MJ1 made by Keeppowers (but from Zeroair testing the protection circuit seems less performing than the more expensive counterparts)

Big_Sam
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Hello, that’s interesting thanks for confirming that

I’ll be getting one of the new ones to take apart, do they have welded button tops?

Photonica
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G2Jk – appears to be a Seiko Battery Management IC, or a clone. There is no “G2JK” entry, but Google shows G2JK, G2JS, etc. So the last character code be a variant or temperature qualification code (Consumer, Industrial, Automotive, etc).

SMDCodeSearch

G2J S-8261AAJBD SEIKO 6-Pin SNB/BD006-A 电源管理ICPower Management IC/PMIC 电池管理Battery Management

AllDatasheet Search: Result

More Photons!

Big_Sam
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Thanks for the info on the chip, very handy to know!

18650UK
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Big_Sam wrote:
Hello, that’s interesting thanks for confirming that

I’ll be getting one of the new ones to take apart, do they have welded button tops?

They do indeed. All cell attachments are welded. No stick on stuff here Wink