Hobby Charger VS Cheap Chinese Charger [ charger behavior ] some thoughts

I agree , chargers are tools and as such need to be used correctly ..

Unfortunately - while many express the virtue of hobby chargers , they seem to ignore the pitfalls , and give bad advise on there use .

I honestly dont understand how people can knock the 18650 chargers [ Trustfire TR-001 etc ] since the majority do a great job .

But then there are some seriously good hobby chargers out there if you want to pay the price ...

That is the methode the LiIon cell manufacturers recommend.

A typical charge specification has a maximum voltage (4.2 volt) and maximum charge current (Like 0.5C) and a minimum charge / cutoff current (like 80 mA). The hobby charger follows this, except the cutoff current is usual defined as charge current/10. I.e. when charging with 1 A, the cutoff current will be 0.1 A.

This charge methode will not force a high voltage on an old cell (This is damaging to the cell), but will stop charging when the cell cannot accept more current (Defined with the cutoff current).

And many dedicated 18650 chargers do exactly the same thing ... [ Sensitive to the internal resistance of batteries - therefore terminating early ]

And yes there are some chargers that force batteries to a higher voltage state , but depending on the school of thought ?

There are those who believe in conditioning batteries , even Li-ion ..

And some Li-ion get better after some use ? If you cant condition Li-ion, this should not happen .

Can you bring back degraded cells ?

One of these days , Im going to look into it , probably when school finishes , I will run some experiments , to see , condition new cells , or recondition old cells in any shape or form

Imho chinese cheap chargers are great if you use protected litio battery, because the only cons is that them usually over-volt or can broke keep charging and making burn/explode the battery(very remote case).

Litio are very solid but can be dangerous, on the other hand for nimh you need more care and a good smart charger to keep them healthy.

Can somebody also tell me how to recognize bad cells, by looking at there resting voltage?

I have some batteries, from a dead laptop....(not dead batterypack!) and would like to know if they are usable or not..
my TR001 only charged them up to 4.16-4.17V. (i dont know if my DMM is correct either)

If someone can give a link, then people dont have to explain it twice..

thanks

I noticed that my cheap charger charges at or outputs 600ma.

IF I get a charger that outputs 1 Amp- will this charge the batteries more quickly, and if so will it be 30 to 40% quicker?

Noticed an Ultrafire cheap dual charger that indicates 1 Amp.

High charger current will charge faster, but there are a couple of not as much faster as the current is higher.

With a CC/CV charger the charge phase is in two parts, first a CC (constant current), this part will be considerable faster. If you double the current, this phase will take less than half time.

The you have the CV (constant voltage), this is longer at higher charge current (because you reach the CV phase faster). How long it takes is also very much depend on the cutoff current, i.e. a charger that stops at 300mA will have a shorter CV phase, than one that stops at 100mA.

The above is only valid for chargers following a CC/CV charger curve, but very few chargers does that and on many cheap chargers you can not thrust the specified current either. You best bet is to find some reviews that uses comparable cells and see the actual charge time measured.

You could use the charger reviews on my website for that , the AW18650-22 cell I use has nearly the same capacity in all my measurements (albeit a low capacity).

Its very hard to determine that .. [ Cell condition ]

There are signs to watch for . but after charging and then discharging a bunch of 16340 ...

What to watch for =

Wont hold a charge , voltage drops faster than other batteries [ still not a sure sign ]

Sag after charging [ again not in any way 100% ]

To really sort out the crap from the crop so to speak , you need to discharge the cell , this is the only true way to tell ..

An example ..

I had a 16340 that charged to 4.2v and held it , voltage sagged very slowly over time [ as it should ]

There were no real warning signs that the cell had degraded , until discharged and the cell returned less than 200mAh capacity .

Originally it was maybe 530mAh , but after some 2 + years of light use , had degraded to under 200mAh

So if your hanging onto your batteries or trying to reclaim older batteries [ from laptops ] a hobby charger might be a invaluable tool to really know whats going on . [ running discharges ]

You dont need the most expensive , you just need one thats going to tell you what you need to know .

resting voltage will not always tell if you have a bad cell, discharging will, you can put them in a torch and gun them on high for a while then use a DMM but the best way would be to cycle them on a hobby charger, discharge and charge them a few times see how much mAh it give,s and takes and watch for voltage sag a bad cell will drop voltage quick once a load is put on it and maintained, the hobby charger will cutoff and stop if the cell,s voltage drops to low so there is no risk of over discharging.

the internal resistance of batteries play,s a big part in charging dishcarging and when people do current draw test on torches, imo cheap dedicated chargers would be affected by this more but thats mo.

ive tryed to bring back a couple of bad li-ion,s and li-po,s they dont realy come back i must admit i didnt spend much time on it but the mAh never improved and the the internal resistance only whent up and the li-po,s puffed, but ive been able to bring nimh back to life as my hobby charger has some good modes for that.

a good test to do is c rate,s over time say have 4 batteries with the same or close to internal resistance of each other and charge one at 0.2 amp one at 0.5amp one at 1 amp and the last one at 2 amp and then over time record the internal resistance and the amount of mAh they take.

ive noticed the battery charged at 0.2 amp will take more mAh and have a lower internal resistance then the one charged at 2 amp over time.

this is why parrallel charging in my mind is not the best as the cells spike quickly and dishcarge and charge each other at upto 2c + for li-ions even though its only for a short period i belive this will raise the internal resistance of the battery sorten its life and over time it will be able to give less current.

this is why i belive balance charging in series is better, but people want faster charge methods they want to charge one or two batteries at 1 + amps each unless they are top self batteries it will raise internal resistance of the batteries, i think your better off charging at lower charge rates like 0.5 amps yes it will take a little bit longer then charging at 1 amp but if you charge 6 at a time then its much quicker.

just my thoughts im half asleep

I would just like to confirm your results, I have noticed the same thing when testing batteries. I get them topped off completely with my TR-001 ~4.2v were my Accucell hobby charger leaves them a little off ~4.1v. I also get higher amperage readings from a battery that comes off the TR-001 compared to one that comes off the Accucell hobby charger. Thanks for confirming my suspicion.

E1320 i would do a test use the same charge rate on the Accucell hobby charger as the TR-001 and see how that turns out as i asume your using a higher charge rate on your hobby charger then your TR-001

i would also test your Accucell hobby charger as i found them like the imax,s to be off .04 volt + or - per cell and the voltage on the main charge leads to be the same.

if your Accucell hobby charger is saying the battery is 4.2v and it stops charging but you check it with your dmm and its 4.1 there is a good chance its not charging them to full and your TR-001 could be charging them to full or slightly over charging them.

this could also be why people are questioning there rested voltage of the cells after comming of there cheap hobby charger over charging (using to high amps) or inaccuracy or both

Thanks for the info!

To test your hobby charger !

Verify battery voltage first , let it rest for a while [ like 24 hours ] , then verify with MM ..

Now place in Hobby charger , what ever function you chose , it should test battery state [ voltage ] first and give a read out , before continuing with the function .

If the read out = MM then its calibrated correctly , if not , say its a little out , then you should be able to adjust the calibration [ iMax B6 can be adjusted ]

Unfortunately one cant program the charge cycle behavior . [ B6 ]

hey old is the imax b6 still a one shot deal with calibration

If mem serves , its a one shot thing for balance charging , for voltage calibration , as many times as it takes ...

I haven't fully read the following posts, but I Disagree with the OP on several points

  1. How Resting Voltage works, vs the way a cell is treated
  2. The overall concept of why true (CC/CV) vs emulated CC/CV is better
Lets start with some battery stuff.

Termination voltage. All chargers should be trying to aim for 4.20V finish, without Ever exceeding this voltage (we all agree here). A true CC/CV charger will have voltage measurement systems in place to monitor this voltage, and will always stay below this. Consequently, achieving a cell resting voltage of 4.20V is very difficult when you cannot exceed this. This is because the cell has an internal resistance (which as the old points out, applies in both charging and discharging states).

Charging - CC/CV technique.
The CC part is where a cell can be charged at its recommended charging current, without exceeding the max charge current. In this part of the cycle, the voltage rises. Until which time it reaches 4.20V per cell, then the charger will reduce current to the cell to maintain 4.20V. This is all governed by the internal resistance of the battery.

SO, if we applied 1.0A charging current to a cell at 3.00V, its internal resistance of 500mOhms will result in the voltage of the cell to Rise under charging load. Based on Ohms Law, this setup will result in a 0.5V increase, and the cell voltage rises to (3.00 + 0.50 = 3.50V). Once we remove the charge current the voltage will drop back down.

Lets say this cell now reaches a resting voltage of 3.70V. The same 1.0A charging current, will give the same 0.50V increase, so the voltage of the cell under the charging current will now reach (3.70 + 0.50 = 4.20V)

Beyond this, the resting voltage of the cell will continue to increase past 3.70V, but the actual voltage at the cell due to the charging current will continue to rise past 4.20V. So we must now Reduce the current to maintain a maximum cell voltage of 4.20V. At this point, we say the charger transitions from the CC mode to the CV mode.

If the cell now has a resting voltage of 4.00V, there is a certain amount of current that we can apply that will not exceed the charging voltage of 4.20V. A charge current of 0.40A will cause a voltage increase of 0.20V, and so at this instant, we can only be applying 0.40A charge. Our charger is slowing down so as to not exceed 4.20V, but accordingly will be give the cell less and less energy.
The key to this is --> as the charging current drops, the difference between cell resting voltage and cell charging voltage will get closer and closer, but will take longer and longer because were giving the cell less charging power.

SO... To achieve a resting voltage of 4.20V, if we extrapolated the graphs, we will see that as voltage difference tends to 0, charging current also tends to 0. What does this mean? - to get a resting voltage of 4.20V, we need our charger to charge for an infinite amount of time.

So again, lets put this down simply.
Because of the Internal Resistance of the battery, The ONLY way to achieve a resting voltage of 4.20V is to
a) While holding a charge voltage of 4.20V, apply a current that tends to 0mA, i.e. charge for an infinitely long time
b) Allow the charge voltage to go ABOVE 4.20V and terminate charge at a given current so that the cell resting voltage drops down to 4.20V

The number one rule of a True CC/CV charger is that it Never exceeds 4.20V, and because it usually terminates at a current above 0mA, (usually 1/10 charge rate), it CANNOT EVER give you a resting voltage of 4.20V.

So how does our budget a charger achieve a resting voltage of 4.20V??? Simple - It either charges for infinite amount of time, or it has allowed the cell voltage to exceed 4.20V
(remember, our cell protection circuits protect for over-voltage between 4.25 to 4.35V. It can stop huge over charging due to wrong chargers etc.. but it won't stop regular insidious overcharging with less accurately regulated chargers)

2) CC/CV charging profiles are the Ideal charging profile for lithium. Lithium cells that we commonly use, charge to a fully charged voltage of 4.20V. A cell at this voltage is safe, and this voltage Must not be exceeded at any time.

The CC part is where a cell can be charged at its recommended charging current, without exceeding the max charge current. In this part of the cycle, the voltage rises. Until which time it reaches 4.20V per cell, then the charger will reduce current to the cell to maintain 4.20V. This is all governed by the internal resistance of the battery.

*A budget charger doesn't have a true CC/CV profile, it only roughly emulates it, reducing current much earlier than necessary before the cell has even reached 4.20V. This is effectively means during the time in which a charger Can be very safely delivering charge power, the budget charger is already backing off. This period is also where charging time could be significantly reduced.
At the last part of charging, the CV phase, where the overcharging is done, the budget charger keeps going and as demonstrated above, Must be allowing a slight over-charge to achieve a 4.20V resting voltage.

So what does the budget charger give us? A Slower charge because its backing off too early, but an over-charged cell because its not truly regulating to a maximum 4.20V.

A resting voltage of 4.17 is therefor MUCH healthier than a resting voltage of 4.20V.

Lets have another example,
It is true that this voltage differential (and voltage settling) will occur with hobby chargers, simply because they usually terminate charge at 1/10 charge rate. A 0.5A charge will terminate at 50mA, and accordingly with a internal resistance of 500mOhms, this equates to a voltage increase of 0.02V.Therefore a charge that terminates at 4.20V, 0.05mA, will give a resting voltage of 4.18V.
If your budget charger that terminates at 50mA, gives a resting voltage of 4.20V, it must have terminated at 4.22V.

Ok the spaces have been lost in my post... (added spaces another way, formatting issue/quirk happened there due to a little glitch in the automatic spacing after playing around with dot points etc...)

Anyway, What I disagree with in particular are the arguments in the OP describing the "stressing" of a cell during charge, and "normalisation" of a cell.

Normalisation as I understand your description to mean, is describing how the resting voltage of the cell is able to stay at 4.20V following a charge. I.e. the difference between the charging voltage and the resting voltage is minimised. It was also mentioned that this will take an hour.

Your proof of "stressing" a cell argues that a cell that rests at 4.20V following a charge on the budget charger is proof that there is no voltage drop and therefore the lower charge current has been more gentle on the cell.

What the charger does to get the cell up into the 4.20V region does not influence the final resting voltage, simply because the hobby charger has a CV phase, which has the primary goal of allowing the cell to "normalise". Because of the high internal resistance of cells we normally use, even the hobby charger spends more than half its time in the CV phase, and it is during this time that current is reduced to the termination current. With a current that tends toward the same termination current, it will give no difference in settling time and the amount of settling off the charger. Cell health is a bigger determinant here, but thats another story.
So as demonstrated in my previous post, achieving a resting voltage of 4.20V is only possible if overcharged, or charged for an infinite about of time, and is additionally not relevant to the charging profile prior to the CV phase.
It was also mentioned was that a hobby charger charges too fast, 1A charging rate for a 16340 is too high for most cells, but at least with a hobby charger it can be set to any current, 100mA, 300mA, 500mA. 1A is not the only current that hobby chargers can charge at, it is up to the user to set the current.

Very informative and useful , okwchin . Thanks .

No time for a complete reply ,,, [ school ]

But several miss quotes , and errors to reply to as time permits ..

Ok the spaces have been lost in my post... (added spaces another way, formatting issue/quirk happened there due to a little glitch in the automatic spacing after playing around with dot points etc...)

Anyway, What I disagree with in particular are the arguments in the OP describing the "stressing" of a cell during charge, and "normalisation" of a cell.?? Discharging a cell imparts stress as does charging , this stress then manifests itself as cell degradation ,

as for normalization , think of it as the battery at rest , and at the voltage its going to maintain [ not accounting for self discharge ]

Normalisation as I understand your description to mean, is describing how the resting voltage of the cell is able to stay at 4.20V following a charge. I.e. the difference between the charging voltage and the resting voltage is minimised. It was also mentioned that this will take an hour.

Your proof of "stressing" a cell argues that a cell that rests at 4.20V following a charge on the budget charger is proof that there is no voltage drop and therefore the lower charge current has been more gentle on the cell.

What the charger does to get the cell up into the 4.20V region does not influence the final resting voltage, simply because the hobby charger has a CV phase, which has the primary goal of allowing the cell to "normalise". Because of the high internal resistance of cells we normally use, even the hobby charger spends more than half its time in the CV phase, and it is during this time that current is reduced to the termination current. With a current that tends toward the same termination current, it will give no difference in settling time and the amount of settling off the charger. Cell health is a bigger determinant here, but thats another story.
You did not understand !
Cheap charger , battery comes of at 4.2v and maintains 4.2v = I think of that as low stress ...
Battery comes of at 4.2v , and sags to 4.15 or worse , due to charge current being high = I call that more stress ...
This was all about Hobby chargers being used at 0.8A to 1A ,
Things change if you charge at 500mA or lower .
Many argue the hobby charger is better because it charges faster [ Higher current ] , my point is , there is a downside to this argument
Hobby charger is safer and causes less battery degradation , again , can you have your cake and eat it ?
So as demonstrated in my previous post, achieving a resting voltage of 4.20V is only possible if overcharged, or charged for an infinite about of time, and is additionally not relevant to the charging profile prior to the CV phase. I dis agree , I have several chargers that charge to 4.2 exactly , and with a good battery it will maintain 4.2v [ the worse the cell = higher internal resistance - well they tend to sag ]
It was also mentioned was that a hobby charger charges too fast, 1A charging rate for a 16340 is too high for most cells, but at least with a hobby charger it can be set to any current, 100mA, 300mA, 500mA. 1A is not the only current that hobby chargers can charge at, it is up to the user to set the current. 16340 ????? only mentioned them as a recent discharge test found several badly degraded cells that did not show from normal procedures [ MM ] .

I haven't fully read the following posts, but I Disagree with the OP on several points Hmm didn't read it , but felt the need = Nice !

  1. How Resting Voltage works, vs the way a cell is treated
  2. The overall concept of why true (CC/CV) vs emulated CC/CV is better Is this gospel ? or merely the most accepted ?
Lets start with some battery stuff.

Termination voltage. All chargers should be trying to aim for 4.20V finish, without Ever exceeding this voltage (we all agree here). A true CC/CV charger will have voltage measurement systems in place to monitor this voltage, and will always stay below this. Consequently, achieving a cell resting voltage of 4.20V is very difficult when you cannot exceed this. This is because the cell has an internal resistance (which as the old points out, applies in both charging and discharging states).

Charging - CC/CV technique.
The CC part is where a cell can be charged at its recommended charging current, without exceeding the max charge current. In this part of the cycle, the voltage rises. Until which time it reaches 4.20V per cell, then the charger will reduce current to the cell to maintain 4.20V. This is all governed by the internal resistance of the battery.

SO, if we applied 1.0A charging current to a cell at 3.00V, its internal resistance of 500mOhms will result in the voltage of the cell to Rise under charging load. Based on Ohms Law, this setup will result in a 0.5V increase, and the cell voltage rises to (3.00 + 0.50 = 3.50V). Once we remove the charge current the voltage will drop back down.

Lets say this cell now reaches a resting voltage of 3.70V. The same 1.0A charging current, will give the same 0.50V increase, so the voltage of the cell under the charging current will now reach (3.70 + 0.50 = 4.20V)

Beyond this, the resting voltage of the cell will continue to increase past 3.70V, but the actual voltage at the cell due to the charging current will continue to rise past 4.20V. So we must now Reduce the current to maintain a maximum cell voltage of 4.20V. At this point, we say the charger transitions from the CC mode to the CV mode.

If the cell now has a resting voltage of 4.00V, there is a certain amount of current that we can apply that will not exceed the charging voltage of 4.20V. A charge current of 0.40A will cause a voltage increase of 0.20V, and so at this instant, we can only be applying 0.40A charge. Our charger is slowing down so as to not exceed 4.20V, but accordingly will be give the cell less and less energy.
The key to this is --> as the charging current drops, the difference between cell resting voltage and cell charging voltage will get closer and closer, but will take longer and longer because were giving the cell less charging power.

SO... To achieve a resting voltage of 4.20V, if we extrapolated the graphs, we will see that as voltage difference tends to 0, charging current also tends to 0. What does this mean? - to get a resting voltage of 4.20V, we need our charger to charge for an infinite amount of time.

So again, lets put this down simply.
Because of the Internal Resistance of the battery, The ONLY way to achieve a resting voltage of 4.20V is to
a) While holding a charge voltage of 4.20V, apply a current that tends to 0mA, i.e. charge for an infinitely long time
b) Allow the charge voltage to go ABOVE 4.20V and terminate charge at a given current so that the cell resting voltage drops down to 4.20V
Charge voltage yes - not necessarily battery voltage
The number one rule of a True CC/CV charger is that it Never exceeds 4.20V, and because it usually terminates at a current above 0mA, (usually 1/10 charge rate), it CANNOT EVER give you a resting voltage of 4.20V.

So how does our budget a charger achieve a resting voltage of 4.20V??? Simple - It either charges for infinite amount of time, or it has allowed the cell voltage to exceed 4.20V
(remember, our cell protection circuits protect for over-voltage between 4.25 to 4.35V. It can stop huge over charging due to wrong chargers etc.. but it won't stop regular insidious overcharging with less accurately regulated chargers)

2) CC/CV charging profiles are the Ideal charging profile for lithium. Lithium cells that we commonly use, charge to a fully charged voltage of 4.20V. A cell at this voltage is safe, and this voltage Must not be exceeded at any time.

The CC part is where a cell can be charged at its recommended charging current, without exceeding the max charge current. In this part of the cycle, the voltage rises. Until which time it reaches 4.20V per cell, then the charger will reduce current to the cell to maintain 4.20V. This is all governed by the internal resistance of the battery.

*A budget charger doesn't have a true CC/CV profile, it only roughly emulates it, reducing current much earlier than necessary before the cell has even reached 4.20V. This is effectively means during the time in which a charger Can be very safely delivering charge power, the budget charger is already backing off. This period is also where charging time could be significantly reduced. So it is less stressful , and gentler on the battery ...
At the last part of charging, the CV phase, where the overcharging is done, the budget charger keeps going and as demonstrated above, Must be allowing a slight over-charge to achieve a 4.20V resting voltage.



So what does the budget charger give us? A Slower charge because its backing off too early, but an over-charged cell because its not truly regulating to a maximum 4.20V.

A resting voltage of 4.17 is therefor MUCH healthier than a resting voltage of 4.20V.

Lets have another example,
It is true that this voltage differential (and voltage settling) will occur with hobby chargers, simply because they usually terminate charge at 1/10 charge rate. A 0.5A charge will terminate at 50mA, and accordingly with a internal resistance of 500mOhms, this equates to a voltage increase of 0.02V.Therefore a charge that terminates at 4.20V, 0.05mA, will give a resting voltage of 4.18V.= The issue was , folks buy hobby chargers to be safer , and to charge cells so as not to damage them , and then turn around and charge @ higher current rates that [ my opinion ] stress the batteries more than the cheap chargers they are avoiding , and at the worst time , closer to completion . [ This is up to the individual ]
And if you charge at a lower rate , then is it faster or better ? Me thinks not . [ Thats me ]
If your budget charger that terminates at 50mA, gives a resting voltage of 4.20V, it must have terminated at 4.22V. = Well the charger voltage may be 4.22 , this does not mean that the battery voltage is the same , as these chargers usually run 2 tenths above batt voltage . So if it terminates at 4.22 , then the actual charger voltage would have been more like 4.24 4.25v
Will get to this as time permits :

If your budget charger that terminates at 50mA, gives a resting voltage of 4.20V, it must have terminated at 4.22V. Lets start here ....

First , 4.22v is nothing , insignificant voltage to worry about , and is often touted as something for people to worry about . [ Why do people bring this up ? I dont know ]

If its something about stressing older cells , ?? . Most of the chargers I have are sensitive to the internal resistance of the battery , so when nearing completion , a cell with higher internal resistance will terminate at a lower voltage , [ Tr003 , WF-139 , WF-188 , Xtar to name a few ] and there are some charger that will try very hard to bring the battery to 4.2v such as the Soshine and TR-001 , but this is and will be about buyers knowing or educating themselves .

So rather than trying to scare people , we should be trying to educate them .

Also dont forget , @ 50mA , its a very gentle charge rate , gentle = low stress , and yes it takes a while .

[ Im out of time this morning - so maybe 8 hours from now ]

Cheap charger behavior , now most cheap chargers do the pulse charge method ..

What that is it , charges , stops charging to check the battery then continues to charge .

Now when it stops to check the batt , the charger than is able to adjust voltage [ of the charger and charge current ] ..

Now while the charger does indeed have a higher charge voltage [ lets say 4.22v near termination ] it does not mean that this is the voltage of the battery [ one needs to understand this ], and because it stops and starts , when the battery reaches 4.2v , it should [ should ] stop charging .

Now as to the termination voltage of the battery , two factors are involved , the charger [ obviously ] as well the battery ..

Depending on the internal resistance , and the sensitivity of the charger to such , can have a contributing effect on termination voltage ..

A battery in rerally good condition may terminate 4.22v or 4.21v and hold said voltage .. Because its a good quality battery ..

A battery in not so good shape may terminate 4.17v in the very same charger , and a cell on its last legs could very well go 4.2v ...and hold the voltage .

Its important to understand there are so many variables involved .