Nitecore TM26 Charging problems?

Just received my TM26 the other day....love it! I have noticed that the flashlight's internal charger will not charge the batteries to their full capacity. I have tried 3 different sets of "new" batteries (Nitecore 2600's, Orbtronic 3400's and Trustfire 2400). During charge, the display never exceeds 4.07 volts. After a few hours...the oled will display charge finished/4.2v. As soon as I unplug the charger, the flashlight displays 4.07. I've tried it twice now, the first time, checking within minutes of the light saying Charge Finished, the second time after leaving the charge cord plugged in for an extra 3-4 hours after it said Finished Charging. I checked all batteries with a multimeter and they read 4.05-4.07 volts. It appears that my TM26 will not deliver a full charge to the batteries. From reading other posts it appears this is not an isolated case. If there has been a resolution to this....please advise. I am getting ready to return light.

Mike

Personally, I wouldn't even consider returning the light over just that. Most users I've read agree it charges to around 4.1v. If you think about it, it likely is a good idea they don't push to the full 4.2 given there is not independent cell chargers. One cell is a little weak, or someone mixes cell capacity, or they are not balanced to begin with, will all provide the perfect storm for failure and safety issues when pushed to the max charging limit.
I personally think that was a smart move on their part, and the difference in capacity from 4.1 to 4.2 is not worth making a big deal over IMO.

I remove my batteries and charge them with the Nitecore i4 charger.

Your comment of self charging to 4.1 volts is common.

Charging to 4.1 instead of 4.2 only loses just under 10% of capacity. And the bonus is, this will noticeably increase the number of charges you get from your $60.00 worth of batteries. Some studies show up to double the life charging to 4.0v.

Thank you for your input....I am new to this flashlight hobby and thought I had a problem. I still am curious why the OLED displays charge complete/4.20 volts....when it never exceeds 4.07. Even in a picture on their website, they show the flashlight charging with a display of 4.17 volts.....then finishing charge at 4.20 volts. You will never see 4.17 volts while charging from flashlight. Is that not misleading?

http://www.j2ledflashlight.com/wpimages/nitecore-tm26-charging-finished.jpg

When I charge my batteries with a cottonpicker charger, I typically charge to 4.2V, and when I unplug the charger and just check the voltage, it usually sits at around 4.12 on my 16340. On my 18650, it sits at around 4.17V after charging to 4.2V. I don't think it's a big deal though.

Mike Sloan said:

Thank you for your input....I am new to this flashlight hobby and thought I had a problem. I still am curious why the OLED displays charge complete/4.20 volts....when it never exceeds 4.07. Even in a picture on their website, they show the flashlight charging with a display of 4.17 volts.....then finishing charge at 4.20 volts. You will never see 4.17 volts while charging from flashlight. Is that not misleading?

http://www.j2ledflashlight.com/wpimages/nitecore-tm26-charging-finished.jpg

Click to expand...

They may not be using the CC/CV profile for charging. When you apply a charge to a battery, it will have a higher voltage then it will after you let it sit for a while. So CC/CV goes to 4.2v, then drops back the amperage maintaining the 4.2v until there is such a small amperage that it's no longer adding anything. That is why your battery sits, @ 4.2v so long if you watch it on a charger with display. Possibly Nitecore hits 4.2v then shuts off leaving it a bit short of full.

Verndog said:

They may not be using the CC/CV profile for charging. When you apply a charge to a battery, it will have a higher voltage then it will after you let it sit for a while. So CC/CV goes to 4.2v, then drops back the amperage maintaining the 4.2v until there is such a small amperage that it's no longer adding anything. That is why your battery sits, @ 4.2v so long if you watch it on a charger with display. Possibly Nitecore hits 4.2v then shuts off leaving it a bit short of full.

Click to expand...

Don't want to beat this to death....but

If that's the case...why do I not see anything higher than 4.07 during charge? I should see what they advertise. I would have no problem if I saw upwards of 4.17 during charge and then settle out to 4.07 when charge is removed. I actually think it is only approaching 4.07 until it terminates charge....and then settles back to 4.03 as shown on display and confirmed externally with a fluke meter. I am using Orbtronic 3400's and they only settle out by .03 when they come off my Intellicharger I4. So still not convinced that there is not an issue here? Thinking about ordering another TM26 and comparing the termination voltage....if they both agree....have to live with it.
To not use CC/CV profile in their charge circuit would be troubling, as well.

I have a Jetbeam DDR30 that has internal charge capability and when it indicates charge complete...the batteries are actually around 4.17-4.19 volts.

Mike Sloan said:

… After a few hours...the oled will display charge finished/4.2v. As soon as I unplug the charger, the flashlight displays 4.07. I checked all batteries with a multimeter and they read 4.05-4.07 volts.

Mike

Click to expand...

Mike Sloan said:

... I actually think it is only approaching 4.07 until it terminates charge....and then settles back to 4.03 as shown on display and confirmed externally with a fluke meter.

Click to expand...

You said in post 1 display read 4.2 and multimeter check was 4.05-4.07. If not running CC/CV then it had to have reached clearly past 4.07 during charge. Whether it displayed that, or the interval it refreshes is another story or question.

My point is they are leaning to the side of caution, which in comparison to carrying a potential hand cannon is likely a smart move. If you don't like it, then I suppose you should return it. But your light appears to act just like others reporting, so it's not defective, it's as designed.

Notice "while charging" display reads 4.17.....on the Nitecore website no less. I expect the same quality of circuitry in their internal charger as I get in their $20.00 Intellicharger. So if the "under charge" of 4.07 is by design....then this picture is misleading.

The notion that it is better to undershoot the termination voltage during parallel charging to account for cell imbalance is questionable. When you place all the batteries in parallel, they all become the same voltage. I am not speaking in metaphors here, they really all do become the same voltage. Not the average of the cells either. Current actually flows between the cells and they actually all adjust voltage until they all perfectly match each other. The charger only "sees" one larger pack and charges it as if it were a single pack.The charger then balances all the cells as if it was charging a single cell. Those in the RC airplane world have been parallel charging their Lipo packs this way forever. Take the Fenix RC40 flashlight and its giant pack. It is made up of "6" 18650's. They don't wory about the individual cell drifting during charge....because they don't.

Owners of TM26 will never see this while charging:

guys,
i am sure that future internal revisions of the TM26 will be improved.
it is a young product after all, a v1.0beta release

too bad that Nitecore intentionally does not print the version number anymore as was the case with TM11. well, most manufacturers don't do it. late adopters profit from the silent updates in matured products.

that's okay.
thanks nitecore.

The future revisions won't help those that have already purchased......however, woudn't it be cool if Nitcore had included a little mini port on the light that would allow you to download firmware updates and fix little bugs that pop up!

Mike Sloan said:

Owners of TM26 will never see this while charging:

Click to expand...

I would imagine that depends on how they setup their charging profile, and how closely the cells you are using match their profile...and also how well matched those said cells are.

I have tested the TM26's internal chargre with new Orbtronic NCR18650B's , Nitecore's very own 2600's, and KeepPower3400's. All new and at a resting voltage of 3.65 volts prior to charge. None of the charging cycles had a termination charge of over 4.07. Nor did the OLED display ever read a higher voltage than 4.07 during charge cycle. Subsequent charges with same batteries on the Intellicharger I4 all show termination voltage of 4.20 +/-.03. I don't know how to setup a charge profile, other than what I have already done. The TM26 does not allow for user adjustments to it's internal charge parameters.

Verndog...What voltages have you seen on your TM26 while charging? Are you getting different results? I have 2 more TM26's on order and will be able to better determine the consistency of charge between them. If they all have the same "soft" charge characteristic....then I will shut up and "get on" with enjoying this really cool flashlight.

Just finished a charge with the Jetbeam DDR30. Terminated charge voltage 4.17/4.17/4.18.....I like that!

Mike Sloan said:

Notice "while charging" display reads 4.17.....on the Nitecore website no less. I expect the same quality of circuitry in their internal charger as I get in their $20.00 Intellicharger. So if the "under charge" of 4.07 is by design....then this picture is misleading.

The notion that it is better to undershoot the termination voltage during parallel charging to account for cell imbalance is questionable. When you place all the batteries in parallel, they all become the same voltage. I am not speaking in metaphors here, they really all do become the same voltage. Not the average of the cells either. Current actually flows between the cells and they actually all adjust voltage until they all perfectly match each other. The charger only "sees" one larger pack and charges it as if it were a single pack.The charger then balances all the cells as if it was charging a single cell. Those in the RC airplane world have been parallel charging their Lipo packs this way forever. Take the Fenix RC40 flashlight and its giant pack. It is made up of "6" 18650's. They don't wory about the individual cell drifting during charge....because they don't.

Owners of TM26 will never see this while charging:

Click to expand...

This got me thinking so I charged it today...

it is what I saw.

SeamusORiley said:

This got me thinking so I charged it today...

it is what I saw.

Click to expand...

Ok....this is interesting! So to be precise....did you see voltages as high as 4.17 during the charging stage before the charge was terminated? Mine always says charge finished/4.20.....just never see higher than 4.07 during the charge cycle. Did you notice what voltage your display read when you disconnected the charger?

Thanks,
Mike

Hello to all. Thanks for a great forum. I just received my TM26 yesterday and charged it for the first time. I am using Eagletac 3400's and while it was charging, the OLED read 4.17 for quite a while. BTW this is a great light and I am now a very happy full fledged flashaholic.
Jack

JakMac said:

I am using Eagletac 3400's and while it was charging, the OLED read 4.17 for quite a while.

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lol

this thread is not about the OLED but about the real termination voltage. it does not matter if the OLED says 4.07, 4.17, 4.20, or FINISHED. what matters is what your multimeter measures when the charger says "FINISHED".

shelm said:

lol

this thread is not about the OLED but about the real termination voltage. it does not matter if the OLED says 4.07, 4.17, 4.20, or FINISHED. what matters is what your multimeter measures when the charger says "FINISHED".

Click to expand...

Actually, the thread has been made into that by the OP stating that Nitecores pic is misleading, and "you'll never see this".

^^^What Verndog said. I was just letting the OP know that my particular TM26 shows exactly what the Nightcore photo shows, 4.17 on the OLED while charging, not the 4.07 that his OLED shows.
Jack