2x18650 vs. MN16....a charger warning

[Owen]

Please see post #16 regarding an issue with my UltraFire charger overcharging my cells.

A little warning for others running the MN16 LA on 2x18650(I suppose this would apply to the MN11 and P91, as well).

Last night I burned out a MN16 LA for the second time in a week.
The first time was using LG 2600mAh unprotected 18650s on a Leef C-C body with a KT2, and a SF Z58 tailcap. The MN16 had 1-2 hours of runtime, though it's impossible to know exactly. Used it, put it down, picked up to use again, dim sick yellow output. Dang.
I'm sure we all know that the MN16 is overdriven with this setup, and that's probably why some of us are using it(me, for example), since it's so bright and white.
Some of us have commented that our high draw lights are brighter with the clickies, and I thought that might have contributed. Also the 2600mAh cells not dropping much voltage into a less than 1C load could have been a factor.
So...I got all smart and stuff before putting in another MN16, and swapped the tailcap for a Z41(the standard SF lockout tailcap), and the LG batteries for AW's 2200mAh protected 18650s. Minimizing the risks, to my way of thinking.
My second MN16 didn't even last 10 minutes total. Same as before. I had used the light several times throughout a evening/night double shift, left it sitting on a table, picked it up to use again, and got dim yellow output.
Both MN16s have a black spot, and the inside of the globes are smoked.

The only other contributing factor I can think of is that I've been using an Ultrafire charger that sometimes charges the cells to 4.25-4.3V, and that little bit of extra voltage may have been the straw that broke the camel's back.

I'm tempted to get another MN16 and try using my old Pila charger for the AW cells, but really don't want to chance frying another lamp "just to see", and will probably just switch to the MN20 for this setup.
Good luck.

oh, and here's a pic

 

[defusion]

Re: 2x18650 vs. MN16....a warning

the MN20 is a good idea, less overdrive.
another option you might want to consider is a lumens factory bulb.
though i'm not sure if they will, you should call surefire and explain your situation. they might replace your bulbs for free.

 

[pete7226]

Re: 2x18650 vs. MN16....a warning

Interesting outcome. I've been using my 2x18650 setup with both p91 and mn16 for the last 6 months or so with probably 15 hours of use between 2 p91's and 2-3 hours on a mn16 with no problems. I've used mostly the ultrafire charger for charging and the pila occasionally.

 

[Owen]

Re: 2x18650 vs. MN16....a warning

Yeah, this was a nasty surprise. I'm going to PM you a question about another light...

defusion, I won't ask SF about to replace them. Since I'm not running a SF-approved or recommended battery configuration, I would not expect them to warranty the lamps.

 

[c0t0d0s0]

Re: 2x18650 vs. MN16....a warning

Here's a comparative runtime/brightness plot of several incandescent bulbs, including the MN16 running of a pair of AW 17670 cells, initially charged to 4.2V.

Note the shape of the graph: it's not nearly as flat as that of the other 2 bulbs running on li-ions, and with a huge initial peak... in other words, brightness with this bulb seems a lot more voltage-dependent than one would expect. It certainly looks overdriven the first few minutes, and is bright as hell (i guesstimate 400-425 lumens), and very white. I can see how it can be blown if the cells were bigger and slightly overcharged! It might not be the best bulb for this kind of a rechargeable setup. I think I'm gonna order a LF EO-M3T just to see how it compares!

 

[leukos]

Re: 2x18650 vs. MN16....a warning

I still think that SF's LOLA's are better suited for use with Li-ions than their HOLA's. Years ago quite a few folks on CPF reported HOLA's burning out frequently (even some bulb explosions) when used with Li-ions.

 

[mdocod]

Re: 2x18650 vs. MN16....a warning

I think you already found your problem, the charging up to 4.3V.

not only is that gong to wear out those cells a lot faster, but that could be the difference between a 5-15 hour life and a 1 hour or less life on the bulb.

 

[trouble]

Re: 2x18650 vs. MN16....a warning

Interesting I've run an MN16 on 2x17670's with no issues so far, I'm getting ready to put that same combo in my new M4. Should I go through with this combo or should I reconsider? Maybe a Lumens factory LA instead?

 

[bagman]

Re: 2x18650 vs. MN16....a warning

I too have been running a MN16 on 2 x 17670 or 2 x 18650's for several months now without problems but I've stopped using my Ultrafire charger with them, they measure 4.23ish straight off the charger.

I bought another Li-ion charger recomended here (cant find the post but I've just lloked at the charger and it says Model YOHO-122 output DC 5v 1A and it always gives 4.2v or a bit less depending on the cells charged.

 

[senna94]

Re: 2x18650 vs. MN16....a warning

I too have been running a MN16 on 2 x 17670 or 2 x 18650's for several months now without problems but I've stopped using my Ultrafire charger with them, they measure 4.23ish straight off the charger.

I bought another Li-ion charger recomended here (cant find the post but I've just lloked at the charger and it says Model YOHO-122 output DC 5v 1A and it always gives 4.2v or a bit less depending on the cells charged.

I just purchased an M4 and have ordered the MN16 lamp to use with 2 17670. Even though the MN16 hasn't arrived yet I am now concerned about using this set up. In checking the cell voltages straight off of the YOHO-122 charger they measure 4.18 volts each. Dare I burn $31.00???? I am now wondering if I should have gotten an M6 and used an MN15 as an X-LOLA.

 

[defusion]

Re: 2x18650 vs. MN16....a warning

I just purchased an M4 and have ordered the MN16 lamp to use with 2 17670. Even though the MN16 hasn't arrived yet I am now concerned about using this set up. In checking the cell voltages straight off of the YOHO-122 charger they measure 4.18 volts each. Dare I burn $31.00???? I am now wondering if I should have gotten an M6 and used an MN15 as an X-LOLA.

the MN15 doesn't last too long in an M6 either
anyway, with 17670's you should see a lower voltage, which means it'll be safer.
but i highly recommend looking into lumens factory bulbs, the EO-M3T and HO-M3T. these were designed with rechargeable batteries in mind.

 

[trouble]

Re: 2x18650 vs. MN16....a warning

the MN15 doesn't last too long in an M6 either
anyway, with 17670's you should see a lower voltage, which means it'll be safer.
but i highly recommend looking into lumens factory bulbs, the EO-M3T and HO-M3T. these were designed with rechargeable batteries in mind.

Where can one find the above mentioned LA's? I googled them but came up with zip, I was directed to Pacific tactical's website but couldn't find either the EO or HO-M3T, any help is appreciated.

 

[senna94]

Re: 2x18650 vs. MN16....a warning

Where can one find the above mentioned LA's? I googled them but came up with zip, I was directed to Pacific tactical's website but couldn't find either the EO or HO-M3T, any help is appreciated.

I have also wanted to purchase some but have found that their current U.S.A. dealer Pacific Tactical only carries a few of their lamps. The only way to get them right now is to order direct from Asia on their website www.lumensfactory.com. I haven't felt comfortable giving my credit card info to a company in Asia. However, the good news is that hopefully lighthound.com will soon be an authorized distributor that will stock all of the goodies from lumens factory. I hope this helps.

Paul

 

[c0t0d0s0]

Re: 2x18650 vs. MN16....a warning

I haven't felt comfortable giving my credit card info to a company in Asia.

You can always pay with Paypal.

 

[trouble]

Re: 2x18650 vs. MN16....a warning

I have also wanted to purchase some but have found that their current U.S.A. dealer Pacific Tactical only carries a few of their lamps. The only way to get them right now is to order direct from Asia on their website www.lumensfactory.com. I haven't felt comfortable giving my credit card info to a company in Asia. However, the good news is that hopefully lighthound.com will soon be an authorized distributor that will stock all of the goodies from lumens factory. I hope this helps.

Paul

Yes that helps a bunch, and I agree I wouldn't give my CC info either, thank goodness they take PP!

 

[Owen]

Re: 2x18650 vs. MN16....a warning

I think you already found your problem, the charging up to 4.3V.

Having given it some thought, I believe that has only happened with unprotected cells being left on the charger overnight. I remember reading that you should remove the cells as soon as the light turns green(using the UltraFire charger).
Just to double check, I've got a pair of cells charging on the UltraFire, and another pair on my older Pila BC2 charger.

edit: the same AW 18650s that were in the light when I popped that last MN16 just came off the charger. I was looking at it when the lights simultaneously turned green. 4.26V ea. and the last time I use this charger.

editing again:with this discovery comes the realization that this charger has potentially damaged 20+ Li-ion cells of various sizes that I have used it on, as I have just been reading how overcharging them can cut their life in half. Thankfully the unprotected 18650s that I just sold to another member had only been charged on it a few times, but the protected 18650s and 17500s that I regularly use have been charged dozens of times with it. I am changing the thread title to reflect this.

and yet again: interestingly enough, the cells that were on the Pila charger also read 4.26V. Apparently, along with the "smart" UltraFire charger letting the voltage get too high, my protected cells from AW are not limiting the charge voltage. Didn't think of that before. This is turning into quite the debacle. Screw it, I'm about to order a Pila IBC charger from JSBurlys.

I notice that the Lumens Factory EO-M3T has the same specs as their EO-9L, which I've used without issue with the same batteries that fried my MN16s, so I will probably order a couple of EO-M3Ts in the near future.

 

[SilverFox]

Re: 2x18650 vs. MN16....a warning

Hello Owen,

The older Pila chargers were set at around 4.6 volts. The protection circuits limit the voltage to around 4.35 volts. The idea was to charge at a high rate and use a robust protection circuit. When the voltage tripped the protection circuit, the voltage would settle down to a more normal 4.2 volts.

If you watch the charge process on these older Pila chargers, you will see the green light come on, then after a while it will start charging again. This process continues until the protection circuit latches in a high voltage state.

Please understand that the protection circuit is supposed to be a back up safety, and not the main charge termination device. The charger is supposed to limit the charge to 4.2 volts, and if it malfunctions, then the protection circuit kicks in to keep things from getting explosive.

The new Pila charger has been redesigned. It limits the charge to 4.2 volts, and charges at a more reasonable rate. This makes it suitable for both protected and unprotected cells.

Interesting things happen when you charge Li-Ion cells above 4.2 volts. You get an increase in capacity for awhile, but the voltage under load drops. You loose cycle life, and under heavy loads, the cell will heat up more during the discharge. The electrolyte breaks down when the cell is overcharged causing these changes. Some brands or batches of cells seem to be more tolerant of overcharging than others. It depends on the chemical mix used for the electrolyte.

If you are sensitive to voltage under load, used cells that have been overcharged will give you less voltage. If you are running a lamp at the hairy edge with aged cells, changing to new cells will probably blow the lamp.

Cycle life is expected to drop from around 500 cycles charging to 4.2 volts to under 100 when charging to 4.3 volts. You enjoy an increase in performance for around 20 cycles, but then things drop off.

With Li-Po packs the RC people have discovered that the breakdown in electrolyte produces gas. This gas causes their packs to puff, at this point they consider the pack ruined and dispose of it.

The charging specification calls for charging to 4.2 volts plus or minus 0.05 volts. The RC people have found that it is risky to go above 4.200 volts, but undercharging is not a problem.

Tom

 

[Owen]

Thanks, Silverfox.
I charged another pair of AW cells on the BC2, and these came in at 4.19 and 4.20V, so I guess their protection circuits did their jobs.
I don't know why my other AW cells(6 of them) are allowing the higher voltage, but did order the new Pila charger already, and hopefully it will eliminate some of these concerns.

 

[DM51]

With the evidence of the blown bulbs, it almost certainly is the charger like you say, but it might just be worth checking your DMM to see if it is calibrated OK. If it is reading high, you would at least know those 20+ Li-Ion cells hadn't been damaged. Errors of ~0.05v are not uncommon in older instruments. Just a thought.

 

[mdocod]

Another possibility that would compound the problem....

are you the type that progolds and de-ox and stretches springs to minimize resistance? That can have a significant impact, which in combination with big new overcharged cells, could have been the death of the lamps.