4.3v charger options for multiple cells ???

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FmC
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4.3v charger options for multiple cells ???

I have ended up with a bunch of Samsung 28A’s from laptop pulls, & have a few multi-cell lights, & another on the way….

So I’m in the market for a charger capable of charging them reliably & properly, preferably up to 4 cells at once.

I’m leaning towards the new Opus in the pending group-buy, but have been wondering what my other options are.

The ConttonPickers Dual 4.2V-4.35V looked enticing, but would end up being rather expensive after getting an appropriate wall-wart, leads, & cradle, not to mention a little cumbersome.

A pair of Heseny HXY-18650-2A’s that don’t come recommended is not appealing, nor is the Polar which looks as though it’s a clone.

Any other recommendations?

Thanks Beer

Edited by: FmC on 04/18/2014 - 05:04
WarHawk-AVG
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For the money on a good charger that can do 4.2v AND 4.35v…I say jump on that group buy

But you really don’t need to charge them to 4.35vdc, 4.20 is fine but “undercharged” is all which might actually make them last longer (more recharge cycles in it’s lifetime)

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_...

FmC
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I’m currently charging them @ ~4.2v, but I’m not really concerned about longevity when I’m getting 8 for $15 :bigsmile:

Gj
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Samsung 28A's are not 4.35V cells, they are properly charged to 4.30V.

 

The XTAR SP1 charger I bought from RMM happens to terminate at exactly 4.30V when on the 4.35V setting. I guess I got lucky. Who knows what the next one will terminate at? My Efest LUC V4  terminates at 4.16V instead of 4.20V.

http://www.mtnelectronics.com/opencart/index.php?route=product/product&path=79&product_id=187

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Thanks for clarifying that, Gj. Title edited for correctness.

With the variances/tolerances typical with these type of things (as per your example), I’m thinking that 0.05v over will be acceptable.

Thanks.

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Chargers usually list +/- 0.05V in the specs.

ImA4Wheelr
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Shouldn't properly designed 4.35v chargers terminate when the cell "signals" it is full?  Meaning it should terminate a cell at 4.2 or 4.3 for those types of cells.  Is that a valid assumption?

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ImA4Wheelr wrote:

Shouldn't properly designed 4.35v chargers terminate when the cell "signals" it is full?  Meaning it should terminate a cell at 4.2 or 4.3 for those types of cells.  Is that a valid assumption?

A cell does not signal it is full, the charger has to know the correct voltage.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

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Thanks HKJ.  For some reason, I though the CC/CV algorithm terminated when cell voltage dropped or something like that.  Appreciate the quick answer.  Smile

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ImA4Wheelr wrote:
For some reason, I though the CC/CV algorithm terminated when cell voltage dropped or something like that.  Appreciate the quick answer.  Smile

That only works with NiCd and NiMH, for a CC/CV the charger picks the correct voltage and wait until the charge current has dropped to minimum value.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

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ImA4Wheelr wrote:

Thanks HKJ.  For some reason, I though the CC/CV algorithm terminated when cell voltage dropped or something like that.  Appreciate the quick answer.  Smile


HKJ wrote:

A cell does not signal it is full, the charger has to know the correct voltage.


Actually it does HKJ

Its CC/CV, it pushes constant voltage (4.20vdc per cell for Li Ion), it monitors the current being drawn by the battery, the CC part is the ability of the chip to regulate said current (mainly because without the regulation initial absorption of a depleted battery cell can be VERY high)…when the battery stops soaking up that current (at a pre-determined level [approx 30-60mA] it terminates the charge

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

The stage 1 current level (at 1 amp fixed/regulated) is controlled by the chip, stage 2 the current taper is controlled by the internal chemistry of the battery, as it soaks up the power it naturally pulls less and less the chip doesn’t change it’s current supply capability, the battery just “absorbs less”, at termination/saturation point where the ≤ 3% of rated cell capacity current draw does the chip terminate the charge, in the picture when the cell drops below 4vdc does the chip kick in a “topping off” charge

You could literally manually charge your Li Ion batteries, if you had a linear regulator set for 4.2vdc per cell and that had a fixed current capability, you could hook it to a Li Ion cell, monitor current flow and when it reached the ≤ 3% of rated cell capacity it would be full…the charging chips just do it “automatically”

Coincidentally the charge pattern looks alot like Li Ion on Lead acid (all beit the cell voltage is 2.3v~ vs 4.2v~ per cell [notice that long slow swooping current draw in the cell during stage 2 charging])
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

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It seems your overlooking the context.

HKJ wrote:

ImA4Wheelr wrote:

Shouldn’t properly designed 4.35v chargers terminate when the cell “signals” it is full?  Meaning it should terminate a cell at 4.2 or 4.3 for those types of cells.  Is that a valid assumption?

A cell does not signal it is full, the charger has to know the correct voltage.


Counterfeit 18650s, 2,<a href=“http://

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WarHawk-AVG wrote:
HKJ wrote:
A cell does not signal it is full, the charger has to know the correct voltage.
Actually it does HKJ

I do believe I know how it works.

The current into the battery will slowly drop, but it never drops to zero. Usual we set some arbitrary limit (Sometimes the limit defined by the cell manufacturer) and use that as the full limit.

If we use a 4.1, 4.2 or 4.3 volt charger, it will work exactly the same way on a 4.2 volt LiIon battery. There is no signal from the battery that "it is full", only our decision that the current is low enough.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

xv-750
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I have some 4.3v 18650's from laptop pulls, and I use a cheap ebay CC/CV module to charge them - carefully adjusted to 4.3 volts and 100mah charged indication.

These modules can easily handle a couple of cells in parallel.

see:  http://budgetlightforum.com/node/24794

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HKJ wrote:

WarHawk-AVG wrote:
HKJ wrote:
A cell does not signal it is full, the charger has to know the correct voltage.
Actually it does HKJ

I do believe I know how it works.

The current into the battery will slowly drop, but it never drops to zero. Usual we set some arbitrary limit (Sometimes the limit defined by the cell manufacturer) and use that as the full limit.

If we use a 4.1, 4.2 or 4.3 volt charger, it will work exactly the same way on a 4.2 volt LiIon battery. There is no signal from the battery that “it is full”, only our decision that the current is low enough.


If anybody does HKJ you do, I was trying to educate those that don’t

No offense meant if you took it that way

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Thank you HKJ and WarHawk.  Appreciate the input.  Sorry for my loose layman use of the term "signal".  I didn't think there was an intelligent device in each cell sending messages to the charger.  I was in my typical hurry and I don't know the lingo or understand the technical details of Li-ion charging.  I just figured that somehow my chargers are stopping at lower voltages on my older cells based on the behavior of the cells.  Otherwise, they would just keep trying to charge the older cells for longer periods of time then the newer cells charge up.

I know more now, but I admit I still don't understand as I thought the chargers were putting out higher voltage than 4.1, 4.2, or 4.3 or 4.35.  I thought I read 5v one time but I'm sure I misread or misremember.  So I'll just assume that a 4.35 charger should not be used for anything other than a 4.35 cell.

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ImA4Wheelr wrote:
So I’ll just assume that a 4.35 charger should not be used for anything other than a 4.35 cell.

Yup, that is correct. A 4.35V rated charger will keep pumping current until 4.35V is reached and the current drops, whether the cell is rated at 4.20, 4.30, or 4.35V.
As HKJ said, NiCd and NiMH cells do tell the charger when they’re full by dropping their voltage slightly (dV/dt), but li-ions do not and it’s important to set the charge voltage for safety and longevity.

BLF ≠ B-grade Flashlight Forum

 

FmC
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xv-750 wrote:

I have some 4.3v 18650’s from laptop pulls, and I use a cheap ebay CC/CV module to charge them – carefully adjusted to 4.3 volts and 100mah charged indication.

These modules can easily handle a couple of cells in parallel.

see:  http://budgetlightforum.com/node/24794

Thanks for pointing that thread out – definitely a good diy/budget option if you are going to be monitoring the cells.