Review: Sony US18650GR 2550mAh laptop cell

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Stephen Wallace
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Review: Sony US18650GR 2550mAh laptop cell

This is the last of the single 18650 cells sent to me for testing by Jim - ebay UK member big_f_d_d.

I have recently purchased some 16340 cells from him, and he sent me another couple of loose 16340s to test, but hopefully I'll be able to test all the 16340 cells one after another, so that we can start seeing some 'like for like' comparisons, whereas currently my testing schedule has been somewhat random, due to jumping cells I have been sent to test to the front of the queue.

This Sony cell is a bit of a departure for me - IMR cells aside - as it is obviously a bare laptop cell, or possibly for power tool use, and has not been converted in any way for use in lights. So no protection circuit, no button, no aftermarket wrapping, and the stock wrap does not extend to the bottom of the cell. It is common for cells that are intended for use in packs to have an entirely bare base in order to make welding/soldering the cells together easier to do.

Testing equipment

A quick re-cap of the equipment used for testing: -

I will be charging cells with an iCharger 106B+, and discharging and testing internal resistance with an iCharger 208B. Two chargers are used for speed and convenience – one cell can be charging while a second is being discharged (not relevant in this instance). I use the same charger for each step to ensure consistency in conditions between tests, so that results are comparable.

Voltage is measured with a Precision Gold WG 020 multi-meter, dimensions with a Precision Gold digital calliper, and weight with a Neva digital scale stated to be accurate to 1/100th of a gram.

The base of the cell is attached to the charger via a 12” 16AWG cable with a large, strong magnet soldered to it. The positive button is attached via a magnet (if it adheres well) or via a crocodile clip. The positive contact on this cell appeared to be aluminium, with the high strength magnet wanting to pull to the shoulder of the cell. A smaller, weaker magnet was attached to the contact, and then the strong magnet was attached over that. Internal Resistance did not appear to suffer as a result.

Results at a glance

Sony US18650GR 2550mAh unprotected

Provided for testing by Ebay UK member ‘big_f_d_d’

Big_f_d_d does not currently have this cell listed on his ebay page, so I cannot comment on pricing.

 

Cell 1 (1)

Initial voltage on receipt

3.79V

Measured length

65.01mm

Measured width (max)

18.30mm

Weight

46.42grams

Internal resistance at initial voltage

93mOhm

Capacity from initial voltage down to 3.00V @ 0.5A

1148mAh

Internal resistance after storage charge

99mOhm

Capacity from 4.2V down to 3V @ 0.5A

2421mAh

Capacity from 4.2V down to 3V @ 1.0A

2346mAh

Capacity from 4.2V down to 3V @ 3.0A

2345mAh

Capacity from 4.2V down to 3V @ 5.0A

2291mAh

(1) This is a single cell provided to me for testing, rather than a purchase that I have made.

Construction

As has been stated, this is a bare cell intended for the construction of laptop or power tool battery packs. As such, there is no protection circuit, and no button. The positive contact is an aluminium plate, pretty much flush with the shoulder of the cell. It is about the same size as the positive contacts on an AW 2600, 2900 or 3100mAh cell.

There should be issues using this cell in a light with a raised or spring contact at the head, but with a flat contact or a light with physical reverse polarity protection, this may not be suitable.

The wrap is thin, and with a tape like consistency, but does not appear brittle. The cover does not wrap around the base, so you need to ensure that the inner diameter of your battery tube is anodised, or other wise lined to protect contact, and that the anodising isn't worn.

With no protection circuit, the negative contact of the cell is the case of the cell's canister, and as such is steel - there should be little concern about wear and tear.

Light compatibility 

Light

Characteristics

Fits

Functions

Olight M20

Wide tube, spring at head, sprung plunger at tail cap

Yes

Yes

SWM T20CS

Short tube, dual springs

Yes

Yes

Jet IIIM

Wide tube, raised contact at head, tail spring

Yes

Yes

Fenix TK15

Two-piece tube – narrow at head. Short tube, short spring at head.

Yes

Yes

Fenix TK11

Narrow tube, tail spring only

Yes

Yes

Eagletac G25C2

Wide tube, sprung plunger at head and tail (minimal travel at the head end), physical reverse polarity protection

Yes

Yes (2)

Nitecore IFE2

Narrow tube, physical reverse

Polarity protection

Yes

No (2)

(2) Despite the cell's flat contact, and the Eagletac's physical reverse polarity protection, this cell did work in the G25C2, and allowed all modes to be accessed. However, the cell was not compatible with the Nitecore IFE2's physical reverse polarity protection. 

Charger compatibility 

Charger

Fits

Functions

4Sevens single bay

Yes

Yes

Trustfire TR-001

Yes

Yes

Ultrafire WF-139

Yes

Yes

Ultrafire WF-188

Yes

Yes

HXY-042V2000A

Yes

Yes

XTAR WP2 II

Yes

Yes

Pila IBC

Yes

Yes

Jetbeam/Sysmax Intellicharge i4

Yes

Yes

Internal resistance

Cell

Voltage

Internal resistance

Sony US18650GR

3.79V (as received)

 93mOhm

Sony US18650GR

3.74V (storage charge)

 99mOhm

FJD 2600mAh #1

3.72V (storage charge)

 143mOhm

FJD 2600mAh #2

3.72V (storage charge)

 138mOhm

Ridbatt 2600mAh #1

3.74V (storage charge)

129mOhm

Ridbatt 2600mAh #1

3.74V after initial capacity test (storage charge)

135mOhm

Ridbatt 2600mAh #1

3.74V after all testing complete (storage charge)

117mOhm

Xtar 2600mAh #1

3.85V (as received)

139mOhm

Xtar 2600mAh #2

3.79V (as received)

136mOhm

Keeppower 2600mAh #1

3.78V (as received)

123mOhm

Keeppower 2600mAh #2

3.78V (as received)

119mOhm

Hi-Max 2600mAh #1

3.79V (as received)

153mOhm

Hi-Max 2600mAh #2

3.80V (as received)

163mOhm

Conclusion

I like to see a cell for flashlight use to have a protection circuit, and the addition of a button assists with light and charger compatibility. On an entirely personal level, I have had encephalitis, leaving me with a poor memory, easily distracted, and I loose track of things at a drop of a hat, hence my reliance on protection circuits. That isn't to say that I wouldn't use this cell, but I would want to be using a light with a circuit board with a low voltage cut out, or at least some kind of low voltage warning. Having said that, this cell isn't being marketed for use in lights, so I can't really criticise it, but it is some thing to consider if you do decide to use bare cells in a light - do you trust yourself to keep track of how long the light has been on? Will the light grow obviously dim before the battery has overdischarged? Will the light cut off or warn you of low voltage.

I'm also not keen on the wrap not extending the full length of the cell, and hence representing a potential shorting risk, but again, that's just a consequence of using a laptop cell in a light. This could easily be resolved by the purchaser, by adding a second layer of wrapping.

Beyond that, you have my normal bug-bear - at 0.2C, the cell's capacity was a fair deal lower than stated, and in this instance, there is no protection circuit to blame for having used some of the power, or increased internal resistance.

Having mentioned internal resistance, this remains in two figures, but as mentioned above, this is most likely just due to the lack of a protection circuit.

Despite the somewhat reduced capacity - quite possibly indicating that this is not A grade stock, and hence why it is not in a laptop pack as we speak - this cell appears to perform well. The relatively low internal resistance is allowing it to maintain capacity well as discharge rate increases, with almost 2300mah of the original 2421mAh remaining at a 5A discharge rate. If you have a suitable light for this cell, with low voltage warning or cutout, and no ano wear in the battery tube, then this should perform well for you.

Edited by: sb56637 on 08/26/2014 - 17:46
kennethsross
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Location: Ayrshire

Good to read this review. I’ve just received a batch of Lenovo Thinkpad batteries, and opened up the first one.

4 of these batteries in it, and each one showing 3.73v (amazed they all read exactly the same.

One comment. I’ve only opened one of the laptop batteries up so far (eBay sale was a package of 10 of them), and the 4 batteries all have the plastic cover extending down and round on to the base of the cell.

Now to figure out what to do with them. I’m too big a coward to leave an unprotected 18650 – even a Sony one, in a device!

pajazzo
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Joined: 06/24/2013 - 04:46
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Howdy!

I opened a mac laptop battery and found six of theese dead inside. The voltage now is really low (0,549v) Is it possible for me to revive them somehow? I have a mac charger that gives 16,5V out and on the battery it says 10,5V. So as long as I have understood you regharge batteries with a slight overvoltage? Can I just attach the charcer directly to the batteries?

The batteries were located in three pairs of two. So two paraller making three serials, equal six batteries.

Thanks

Helios-
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Do Not connect the mac ‘charger’ directly to the batteries. Its not actually a full li-ion charger. Its just a power supply, laptops provide the charging circuit.
Voltage that low isn’t safe to try to charge anyway. When the voltage drops so low it can do internal damage to the cell.

Normal max li-ion voltage is 4.20. Lowest voltage when fully discharged should be 3.0 volts. Discard any below 2.5 volts.


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

Yosue
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Location: Maracaibo - Venezuela
Hi guys I just wanted to let you know that I found my old laptop and after watching several posts about opening the battery, I took the shot

When I opened I saw 4 18650 in green wraps. One of them was completely fried. Maybe the one that didn’t allow the laptop to work cordless. I thought immediately that were some samsungs 25r. Then I noticed the description in the label and says: SE US18650GR. As I didn’t know which brand was I Google it, and the first post that came up was this

I tossed them into my brand new xtar vc2 plus and had like 45% both of them (the pair. The third one will have to wait for a free slot)

I’m really looking forward they work perfect. They look pretty good from outside. Hope they look good inside

I will post some pics later

Greetings

Savydude
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I cut open an Hp battery and found a bunch of these, 8 too be exact, how have they been working out?

What kind of current draw do they allow?

Have light will flash :)

Zorzi
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Joined: 04/02/2014 - 08:49
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Location: Sao Paulo, Brazil

I just opened a Sony laptop pack and found 6 of these green batteries. 4 of them are above 3.5 volts and 2 were at 2.5 volts. I'm charging them to check if they can still be used, hopefully it will be a 100% harvest smile

 

Thanks for the nice review, Stephen!!

 

Zorzi