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BAD Version 7.1 (HKJ test/review)
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#21 (permalink)      3/1/2015 2:22:13 PM US Central   quote/reply + tips
JPBel
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Ghost.of.Fast.Tech wrote:

Do not intentionally overcharge a battery just to take a picture for FT. Batteries are internally damaged from such abuse and will no longer be safe. Either right away or at any random time later it can vent with flame from the hidden damage it sustained. If it vents inside a sealed pipe (like a flashlight) it can violently explode. People have been badly injured. JPBel, you should never advise people to intentionally overcharge a li-ion!

For anyone who already has one, only use it if you can keep an eye on it. You must not leave the battery in the charger too long after the light turns green. A 3400 mAh battery (highest common real capacity) should be fully charged from empty in 4 hours. Lower capacity or partially discharged batteries will be done sooner. Set an alarm to remember to remove the batttery or plug it into an outlet timer.Do not ever leave it charging overnight or when you are not home.I would encourage people to contact fasttech and link to HKJ's test. Fasttech specs are entirely wrong, most importantly it does not have overcharge protection as FT claims.


I agree with you, it should not be done in an uncontrolled way by someone who have no ideas about the risks it involve.

Since we are on batteries safety discussion.

What will happen to the battery are greater capacity loss than normal and greater potential for overheating during that specific charge.
It will not render the battery useless if it does'nt overheat and vent.
But subsequent charges might require that the CC be adjusted down for that battery, so that the CC stay within the C charge rating of that battery base on its actual capacity.

Even with normal wears and tears the capacity should be monitored, and the CC be keept within the battery C charge rating according to the battery actual capacity.
Batteries should be discarded as unsafe to be charged in that charger if it can't adjust the CC suitably.
Failure to do so pose more risks than trickle overcharge do as more current = more heat generated.

No matter the charger used, never leave the batteries in a charger for long period of time after the charge is completed, and monitor your batteries capacity.

What is the CV open voltage at the battery terminals of the charger, without a battery in it ?

There are lots of chances that it is the trickle circuit itself that is causing the problem, due to inrush current.
But If CV can be measured and the open voltage is > 4.35V you will have the proof you need.

#22 (permalink)      3/1/2015 7:03:02 PM US Central   quote/reply + tips
Ghost.of.Fast.Tech
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JPBel, either there is too much of a language barrier or you need to learn a lot more about li-ions & chargers. Either way, you really should not be advising people about them.


I agree with you, it should not be done in an uncontrolled way by someone who have no ideas about the risks it involve.


You don't mention any risks. Don't provide a "controlled way" to do it. Don't mention that the battery should be disposed of after. You just tell a random person on the internet to overcharge any random li-ion they have to more than 4.35v just to take a picture for FT.


Since we are on batteries safety discussion.

What will happen to the battery are greater capacity loss than normal and greater potential for overheating during that specific charge.
It will not render the battery useless if it does'nt overheat and vent.


Overcharging does not just cause capacity loss and danger "during that specific charge".
Li-ion cannot absorb overcharge, it causes plating of metallic lithium. The battery is at risk for an internal short & venting with flame. Not just "during that specific charge" but at any random time.

Also, while overcharging is a risk with all li-ions (even quality cells) you always need to be aware that people may be using horrid junk batteries. Trustfire, ultrafire, ***fire, other random chinese names. Overcharging is especially dangerous with junk batteries.

Other things you've said are also either plain wrong, disconnected enough from the truth to become wrong as you've said it or so unclear that it will just confuse most people.

I'm sorry, I don't mean to be harsh but I need to be clear.


Edited on 3/1/2015 at 9:29 PM. Reason:
I am Not a FastTech staff member.
#23 (permalink)      3/2/2015 5:09:58 PM US Central   quote/reply + tips
JPBel
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@Ghost.of.Fast.Tech

You are not harsh on me, not at all.


You seem to know a lot about lithium batteries, please educate me.

In how many ways can a lithium battery be overcharged ?
Yes, there are more than one way and many peoples get that part a bit wrong, maybe i am one of them...
Hint: Constant Current / Constant Voltage / phase 1 and phase 2 of the charging process.

What happen , in the second phase of the charging process, if you increase the charging voltage above the recommended CV ?
What would you call that ?
Me, i call that first and second phase overcharging.

What exactly is causing the lithium plating on the anode ?
Please don't tell me "overcharging" because batteries can technically be overcharged in more than one way, and there is only one reason for the plating.

What is the difference between normal and trickle charging ?
Yes, there is a big difference.

What are the result and effect induce by the lithium plating of the anode ?
When is the plating become a serious problem ?

Why lithium batteries lose capacity when aging, at every cycles, even during "normal" charge/discharge ?
Because there are less and less free lithium ions at each cycle, but where did they go and how does it affect the batteries charge/discharge capabilities ?

Why some manufacturers are only stating the C rating instead of amps for their batteries ?
What does C mean and why is it more important than mA ?



Random chinese names batteries are not the problem.
The real problem is how peoples charge/discharge them.

Unknown batteries should always be capacity tested first, at very low CC (Constant Current) discharge/charge, to determine theirs amps capability before using them in a real application.
The capacity of a battery tell at what CC to charge it, and how many amps can safely be draw out of it.
Never assume you can go above 1C discharge with those batteries and the charging CC should be keept below 0.7C.

What do you think would happend if you charge a 280mAh lithium battery with a charging CC of 1000mA if the battery can only safely do 0.7C ?
How would you call that ?
Me, i call that first phase overcharging...


That is the answers for the above questions.

Over-Voltage
If the charging voltage is increased beyond the recommended upper cell voltage, typically 4.2 Volts, excessive current flows giving rise to two problems.

-Lithium Plating
With excessive currents the Lithium ions can not be accommodated quickly enough between the intercalation layers of the anode and Lithium ions accumulate on the surface of the anode where they are deposited as metallic Lithium. This is known as Lithium plating. The consequence is a reduction in the free Lithium ions and hence an irreversible capacity loss and since the plating is not necessarily homogeneous, but dendritic in form, it can ultimately result in a short circuit between the electrodes. Lithium plating can also be caused by low temperature operation.
Overheating
-Excessive current also causes increased Joule heating of the cell, accompanied by an increase in temperature. See next section below.



It does'nt mean charging pass 4.35V is safe, even tho trickle charging is a bit far from excessive current, it still can not be considered safe.
The lithium plating might not be as much with trickle charge but it is still producing more than during a normal charge.


Edited on 3/4/2015 at 2:42 PM. Reason:
#24 (permalink)      3/2/2015 9:56:42 PM US Central   quote/reply + tips
JPBel
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I forgot to address 2 points.

Are you familiar with metals electroplating ?
The dendritic form of plating only appear when the current used for electroplating is too high for the plating surface area.


The other one is about capacity losses and plating.

Unlike you might think, some plating also occure during normal charging.
If you plate lithium on the anode, it reduce the number of free ions.
Not only will it affect the capacity, it will also be affecting the safe max amps limit for charging and discharging.
Less ions = can't absorb/realease as much as before compair to same period of time, once they are plated they can not be used for the exchanges.
If you keep charging it at same CC rate as before the plating, it can become problematic, more problematic than the plating itself.

Edited on 3/3/2015 at 4:48 PM. Reason:
#25 (permalink)      3/2/2015 10:48:38 PM US Central   quote/reply + tips
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yorgen
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I have a nitecore d4, and this miller. I got the miller for its small form when travelling. I also wanted to test a cheap charger, to determine if I could recommend it to new vapers.

Now some issues have come to light about the trickle charging, I won't recommend this charger to new vapers.

@Ghost.of.Fasttech; do you have any suggestions on a replacement for the miller, that is; cheap, won't trickle charge, and preferably usb/micro usb input ???

I'll still use mine when traveling, as I tend to recharge my cells when they get down to 3.5-3.6V, and take them off charger as soon as the light turns green, usually an hour or so.

Edited on 3/2/2015 at 10:49 PM. Reason:
#26 (permalink)      3/2/2015 10:52:27 PM US Central   quote/reply + tips
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Thanks for the thread, GhostofFT. I ordered this in mid December as a travel/emergency charger, I've only used it a handful of times. After reading this thread I opened it to see the dreaded "7.1" on the board. I will continue to use it as I have previously, pulling the cell off as soon as the light is green. Bummer about the overcharging, good to know but it won't really change anything in my case.
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#27 (permalink)      3/2/2015 11:27:57 PM US Central   quote/reply + tips
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I had one of the early tp4056 versions of the miller and it was great till some fuck stole it. These days, I can often be seen recommending XTAR chargers. VP1 for home use (as it is the best, and can now be found for not much more cash than an i4 which i also own, like, and use) and the MC0/MC1 for tiny pocketable usb chargers

The MC1 isn't perfect, but it's very good at charging batteries, it's very small, and it's very cheap. Nearly as cheap as a Miller.

review of xtar mc1

i have a love hate relationship with Xtar:- that is, i love their chargers, and hate xtar for trying so hard to take my money every time a new VP series charger is released lol
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#28 (permalink)      3/3/2015 12:11:37 AM US Central   quote/reply + tips
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yorgen
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Thanks Hiko9. I was just researching xtar chargers when you posted. mc1 looks like a great alternative to the miller. Shame fasttech doesn't deal with xtar anymore.
#29 (permalink)      3/4/2015 2:58:19 PM US Central   quote/reply + tips
JPBel
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Schnarph wrote:

Thanks for the thread, GhostofFT. I ordered this in mid December as a travel/emergency charger, I've only used it a handful of times. After reading this thread I opened it to see the dreaded "7.1" on the board. I will continue to use it as I have previously, pulling the cell off as soon as the light is green. Bummer about the overcharging, good to know but it won't really change anything in my case.


I would not recommand buying or using this charger if you measure more than 4.35V on its terminals, when the battery is not inserted.

If you measure more than 4.35V, then the problem is not a trickle charge problem, it is a more serious one.

#30 (permalink)      3/5/2015 10:46:23 AM US Central   quote/reply + tips
Hiko9
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some cells state 4.25 as max voltage. I would say anything above 4.25v is a serious problem

in fact, i wouldnt use a charger that charged above 4.22v. A digital charger like the VP1s charge termination current is so low (0.5ma) that the cell voltage will actually drop if you leave the cell in overnight after charging. Not even enough to counter the self discharge of the li-ion.

The old millers with the TP ic used to work like that too. Shame if they're not as good as they used to be :(
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#31 (permalink)      3/5/2015 6:29:23 PM US Central   quote/reply + tips
JPBel
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Hiko9 wrote:

some cells state 4.25 as max voltage. I would say anything above 4.25v is a serious problem


And you would be right for many of lithium batteries.
The 3.6V nominal ones for sure.

The Constant Voltage(CV) use for charging and the voltage the batteries will reach are 2 different things tho.

With good chargers, battery is considered full when the charging current drop below CC/10(1%~3%) of the programmed charging Constant Current(CC).
Ex: Some batteries will only charge to 4.09V while other to 4.21V, on the exact same charger.

Terminating the charging process based on voltage should only be done as a failsafe, in case the current never drop low enough.

Some peoples think it is the voltage that is dangerous, it is not per say.
It is the "not absorbed mW/s" over what the battery is capable of that is the problem.

Ex: Charging a 2000mAh battery with a CV of 4.35V and a CC of 1000mA will cause no problems, as a 2000mAh can safely be charged with a CC of 1600mA at 4.25V.

1000*4.35=4350mW vs 1600*4.25=6800mW, the first is 0.5C of 2000mAh and the second the recommended 0.8C for charging 18650.

At very low mW/s over, only premature aging will occure.
At high mW/s over, overheating will occure, and there will be greater risks of the battery short circuiting itself.

While a CV of 4.35V is safe for high capacity batteries with most charger, it won't be the same for low capacity ones unless the CC is limited much lower.


Edited on 3/5/2015 at 7:56 PM. Reason: