UPDATE : so-called protected 18650 cells from All-Battery.com

[vortechs]

The thought did occur to me that the all-battery web site might be talking about a group of four 18650's with a single protection PCB, however the picture didn't show that and the description says "internal PCB", furthermore all of the statistics given, such as dimensions and capacity, are all obviously for a single 18650 rather than a group of four wired together.

However, the listing and description on the Battery Junction website (http://www.batteryjunction.com/186502200pcb.html), is more clearly a single 18650, since at Battery Junction you can order any quantity you want, rather than groups of four. Below is the Battery Junction listing for them (the formatting doesn't show up as well here as it does on the actual website). Note that this description is virtually identical to the one at all-battery, so it seems likely that they were both copied from the same source, probably data from the manufacturer. At least one thing in the description is incorrect, since the length of the cells is 65mm rather than 68+/- 0.2mm. This does raise the question of whether the missing 3mm is where the internal protection PCB is supposed to be and they somehow got left off of this batch, or perhaps the manufacturer shipped the wrong item. MattK (from Battery Junction) has been pretty good on the forums, so I'm sure he'll get things sorted out eventually.

Here is the description of the item on the Battery Junction website:

Li-Ion 18650 3.7V 2200 mAh rechargeable battery with protection PCB

Li-Ion 18650 3.7V 2200 mAh rechargeable battery with protection PCB
Item#: 186502200pcb
Availability: Usually ships the next business day.
Price: $5.95
Enter Quantity:
Quantity Discounts![font=arial, helvetica]
1[/font][font=arial, helvetica] - 4[/font]

[font=arial, helvetica]$5.95 ea.[/font]

[font=arial, helvetica]
5[/font][font=arial, helvetica] - 19[/font]

[font=arial, helvetica]$5.65 ea.[/font][font=arial, helvetica]
20[/font][font=arial, helvetica] - 49[/font]

[font=arial, helvetica]$5.35 ea.[/font][font=arial, helvetica]
50[/font][font=arial, helvetica] +[/font]

[font=arial, helvetica]$5.05 ea.[/font]
[font=arial, helvetica]
FEATURES AND BENEFITS
Lithium Ion 18650 cylindrical rechargeable batteries
- 3.7V 2200mAh high capacity
- Higher energy density and lower weight than other types rechargeable batteries
- Manufactured under ISO9001-2000 to assure quality
- Internal PCB protects against under and over charging- low voltage 2.8, high voltage 4.2.
- Battery tested based on International Electrotechnical Commission (IEC) standard to ensure capacity, quality and life time

Applications:
- Building Laptop Battery
- Building portable power device needing high energy density and low wieght

Cautions:
- Use special caution when working with Li-ion cells, they are very sensitive to charging characteristics and may explode if mis-handled.
- Make sure user has enough knowledge on Li-Ion rechargeable batteries in charging, discharging and assembly before use.
- We are not resposible for any damage caused by misuse or mishandling of thses Li-Ion batteries

Product Specifications:
- Capacity* Nominal 2200 mAh, Minimum 2150 mAh
- Dimensions:
Diameter 18+/- 0.2 mm
Height 68+/- 0.2mm
- Weight (Typical) Approx. 46 g yes
- Nominal Voltage: Average 3.7V
- Cut-off Voltage: 3.0V
- Internal Impedance: less or equal to 180 milliohm (with PTC)
- Cycle Performance: 90% of initial capacity at 400 cycles
- Cycle life: > 500 cycles
- Charge: Current = 0.5C mA Voltage = 4.2 V End Current = 0.01 mA
- Discharge: Current = 0.5C mA End Voltage = 3.0V
- Max. Charging current: 1.5C ma
- Max. Discharging current 1.5C ma (for continuous discharge)[/font]

 

[vortechs]

Has there been any new news on the protected TENERGY 18650 cells from All-Battery.com?

 

[TinderBox (UK)]

I e-mailed them yesterday and they said it would be 1 to 2 weeks before the new battery`s are in stock.

regards.

 

[Paul_in_Maryland]

So, who has the best price for protected 18650s where the circuit functionality has been verified?

Possibly CPF's Mark of e-lectronics.

 

[vortechs]

I've decided to test the protection circuit in my 18650's from BatteryJunction, to see if they have the same issues as the ones from All-Battery or if they are the "2nd generation" cells.

I plan to run one in a MicroFire M2L and check the battery voltage periodically. The MicroFire M2L has a 5W LED module regulated to take 3.6-6V input but I'm not sure how it will respond to voltages lower than 3.6V.

1) Can somebody who is knowledgable about Li-Ion's let me know what the lowest voltage I can safely go to without damaging the cell? The protection circuit is supposed to cut off at 2.8V, so I don't have to go much below that, but I'd like to know where the lower safe boundary is. I noticed that TinderBox (UK) took one of the All-Battery cells all the way down to 1.4 volts.

2) Are there any problems with this plan or things I should be careful about?

Thanks for any help.

 

[LumenHound]

Different manufacturers give different low voltage cut-off points for their cells.

Panasonic doesn't want users to discharge their cells below 3.0 volts but actually show 2.3 volts as the point where overdischarge protection kicks in.
Panasonic Overcharge/Overdischarge/Overcurrent Safety Circuits

Molicel states a discharge voltage cut-off of 2.5 volts.
Molicel 18650 datasheet

Varta lists their low voltage cut-off as 2.75 volts.
Varta 18650 datasheet

I would think that if the overdischarge protection doesn't kick in on your Battery Station cells by the time they discharge down to 2.5 volts then your cells don't have any protection circuitry in them.

 

[SilverFox]

Hello Vortechs,

The safe low voltage for a Li-Ion cell depends on the current draw. At higher current levels, you can go a bit lower in voltage. Damage to the cell chemistry is done when you go below 3 volts, but the real damage occurs at around 2 volts. If the cell is left at low voltages for any length of time, there is risk in re-charging it.

I always encourage people to charge often and run down to the low voltage cut off. That way the cut off is available in case you forget, but you aren't using it every cycle.

A point of reference...

AW cells, Pila cells, and Wolf Eyes cells, that I have tested, have a low voltage cut off of 2.3 volts under a 3 amp load.

Tom

 

[vortechs]

I have experimented with one of my protected 18650 cells from BatteryJunction. The cell has a plain blue plastic outer case marked "TENERGY Li-ion 18650 3.6V 2200 mAh".

I used a Fluke 79 series II multimeter to take voltage measurements. Fresh out of the manufacturer's wrapping the cell measured 3.914 Volts. I put the cell in a MicroFire M2L (5W LED light) and ran it at full brightness, turning it off every 6 minutes to remove the battery and check the voltage. After 30 minutes the cell voltage was down to 3.620V (although it came up to 3.683V after 5 minutes of rest). After 33 minutes of runtime the LED started strobing on the high brightness setting. I turned it off and checked the cell voltage and measured 3.550V (it came up to 3.598V after 5 minutes of rest). I changed the light to the low brightness setting (the M2L is a two stage light) and continued the test. At about 60 minutes of runtime (33 on high, 28 on low) the light went off. I immediately removed the cell and the voltage measured 2.799V (it came up to 2.880V after 5 minutes of rest). I put the cell back in and turned it on. It ran (on low) for 1 minute and 47 seconds before the light went off again. This time the cell voltage measured 2.684V (it come up to 2.828V after 5 minutes). I tried this 4 more times, each time the light only ran for less than a minute (on low) then turned off. The cell voltage measured immediately after each time the light turned off was: 2.741V, 2.784V, 2.707V, 2.720V, although each time the voltage would recover to a little over 2.8V (typically 2.828V) after a rest period.

After the last rest period, I decided to check the current the LED was drawing on low. It read 0.27 amps at the tail (tailcap removed, measuring current from battery terminal to flashlight body).

Conclusion: the low voltage protection on this cell seems to be functioning at 2.8V as per the advertised specification (or the MicroFire M2L itself is cutting out at 2.8V). [see Corrected Conclusion below]

If anyone has any additional tests they would suggest, please let me know.

Note that I have not attempted to test for high voltage (overcharge) protection or protection against excessive current draw; I would prefer to leave that sort of testing to somebody who is more experienced.


[edit:
Corrected Conclusion:
1) The regulator in the MicroFire M2L light assembly cuts out at 2.8V in the low brightness setting.
2) The 18650's from BatteryJunction are NOT protected against low voltage.]

 

[vortechs]

P.S. Thanks to LumenHound and SilverFox for their advice.

 

[LumenHound]

The MicroFire M2L 5 watt led/reflector module has a built in regulator that works with any voltage between 3.7V to 6.0V. If the led strobed on high then the regulator may be what's cutting the flow of current from the battery and not any overdischarge circuitry built into the battery.

Can you test the battery again using an ordinary resistor or a plain old bulb from a 3D or 3C flashlight as the load?

 

[vortechs]

The MicroFire M2L 5 watt led/reflector module has a built in regulator that works with any voltage between 3.7V to 6.0V. If the led strobed on high then the regulator may be what's cutting the flow of current from the battery and not any overdischarge circuitry built into the battery.

Can you test the battery again using an ordinary resistor or a plain old bulb from a 3D or 3C flashlight as the load?

Yes, I knew about the built in regulator in the M2L, that was one of the reasons I mentioned the light I was using for the test. It happens to be the only light I have that will work with a 18650. I thought it was interesting that the high setting started strobing at about 3.6V but the low setting worked fine down to 2.8V.

Thanks for recommending I try a different load. I searched in my pockets and came up with a JIL Intelli, so I removed the head, taped some contact wires to the nearly depleted 18650 battery and ran the JIL with it (with the multimeter in parallel). At the start of the test the 18650 was at 2.956V. It ran the JIL dimly for a little while but by the time the battery voltage was down to 2.7V, it wasn't working very well.

Next, I searched around and came up with a incandescent penlight bulb marked "PHILIPS 222 2.25V 0.25AHK". While this probably isn't the best bulb for the test, I figured it would suffice with the battery already as depleted as it is.

In just a couple minutes I took the battery down to below 2.2V under the load of this tiny incandescent bulb and there is no sign of the protection working. The voltage came back up to 2.680V after resting.

I tried it again and took the voltage all the way down to 1.5V under load. There was no sign of the protection circuit working. The voltage is currently recovering (2.450V and rising).

New conclusions:
1) The 18650's from BatteryJunction are NOT protected from undervoltage.
2) The voltage regulator in the MicroFire M2L LED assembley cuts out at 2.8V, so the light itself will protect against undervoltage.

 

[vortechs]

The voltage of the 18650 has currently recovered up to 2.610V.

Can anybody tell me if I should attempt to recharge this cell very carefully (e.g. use a long outdoor extension cord to place the cell connected to a Nano charger in the middle of the barren dirt of my backyard) or if I should simply dispose of it?

 

[LumenHound]

If you do decide to recharge it with a Nano charger outside you might want to run it through another low and slow drain to 3.0 volts in a safe area to see if it's capacity has been crippled. I'd draw a ring on it with permanent marker so it won't get mixed up with the other identical 18650 you have.

 

[LumenHound]

By the way vortechs, much thanks for doing the testing and posting your results. :goodjob:

There are quite a few 18650 users, myself included, who are curious about this particular cell.

For what it's worth, I got a report today from one of the sellers of this unprotected battery that the protected version of this 18650 is still on the way from the manufacturer in Asia. I don't know if that means they are currently making them or if they have been made and are enroute.

 

[SilverFox]

Hello Vortechs,

The longer the cell sits at low voltage the more damage is done.

Charge it immediately to at least 3.8 volts. Then you can stop the charge and contemplate your results...

Tom

 

[vortechs]

Thanks SilverFox.

I am currently charging it (on a long extension cord in my back yard).

 

[SilverFox]

Hello Vortechs,

You should pause now, measure the voltage, and check the cell to see if it is getting hot.

If it is normal temperature and the voltage is up, it is probably OK.

Tom

 

[vortechs]

Thanks again SilverFox,

I put on my safety glasses, went outside, unpluged the extension cord and checked the cell. It was cool to the touch.

I'm now using the very cheap analog multimeter I have at home so I don't trust the actual voltage measurements, but the voltage reading has definitely increased (by about 0.5V).

The "2200 mAh" 18650 will probably charge very slowly using the Nano charger, but that is probably a good thing for now. I'll check it again soon.

 

[TinderBox (UK)]

hello all

when i first got my 18650, I marked one cell as test, and took the voltage under load using a krypton torch bulb, all the way down to 1.4volts.

I then recharged the cell in my DSD charger without a problem.

Since i am waiting for my repacement 18650`s from All-Battery.com, I have just left cells alone.

I have just checked the voltage on my test cell using an DMM.

the test cell was at 4.06volts and the other two cells that i had not tested were also at 4.06volts as well.

and it`s been a few weeks since they were charged.

regards.

 

[MattK]

CPF members,

I'm sorry it took me so long to post here but I don't check here very frequently and only became aware of this issue when vortechs emailed me. I immediately emailed the factory but never had the time to do any of my own testing.

I finally got a reply from the factory and basically they made a mistake.

Our specification and contract for the cells clearly spelled out both PTC (over rate discharge)and PCB (under/over voltage cutoff) protection but the cells were not manufactured to spec and included only the PTC.

I'm truly sorry that the product was misrepresented to you - we did so in good faith, trusting in our manufacturer whom we believe made their error mistakenly - not maliciously.

For those wondering - BatteryJunction.com has a special relationship with All-Battery. Basically - we're seperate companies with seperate ownership but we do some co-operative buying where it makes sense. In some markets this is called a 'buying group'. This is one of those products that we buy together.

I have discussed this situation with the owner of All-Battery and we've agreed to handle this situation as follows:

If you want to keep the cells we're both willing to offer you $1 back per cell in the form of store credit or a refund.

If anyone wants a return or exchange for this product that they purchased from BatteryJunction.com please contact me directly via EMAIL - not PM to arrange a RMA. My email is linked from my account.

If you purchased the cells from All-Battery please contact [email protected] directly and she will arrange an RMA.

We already have a new order that's in production with the manufacturer. Now that the this issue has been clarified the product will be right and we're expecting stock on the PTC and PCB protected batteries in the near future.

My webmaster has already edited the product listing on my site and All-Battery is going to edit their descriptions as soon as possible.

We apologize again for any confusion and problems that may have arisen.