Why the VC4S doesn’t show number IR when batteries are fully charged?

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xtarflashlight
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Why the VC4S doesn’t show number IR when batteries are fully charged?

A customer told that he got some 18650 batteries fully charged on the VC4S, then tried on mode IR, but the charger didn’t test the batteries’ internal resistance, nor show the IR data on the screen. You may have the same question about the IR testing on VC4S charger before. Let’s figure it out.

Our chargers adopt the direct current load method to test battery internal resistance. It means to apply a little bit larger current to the battery for a short period of time. Based on the voltage’s change of the battery, also together with the applied current, it can calculate the DC internal resistance of the battery. If the battery gets fully charged, in case of over-charging, the charger won’t test internal resistance in order to protect the battery. Besides, when the adapter input current is lower than 700mA via the charger, which is insufficient for internal resistance testing, the charger doesn’t test IR either.

Any thoughts and opinions are welcome.

d_t_a
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Thanks for posting this explanation.

I notice that some other chargers also will not test IR (or will show a fixed IR value) when the battery is near or at full-charge (ie. near 4.20v)

For instance, the Nitecore SC4 will show a fixed IR value if the battery inserted is somewhere around 4.10v or higher.

The newer revision of Miboxer C4-12v2 also will not measure IR (no display) if the battery inserted is at 4.16v or higher.

maxchaos92
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Nice explanation,just today i was looking for the vc4s on Amazon,it’s in my cart,i don’t know if there is one with more charge current and same function at the same price,in your catalog?

d_t_a
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maxchaos92 wrote:
Nice explanation,just today i was looking for the vc4s on Amazon,it’s in my cart,i don’t know if there is one with more charge current and same function at the same price,in your catalog?

I’m not affiliated with Xtar… (although I’ve tried a number of different Xtar chargers).. when you mean “more charge current” — do you mean the charger can charge more batteries at a higher current?

Basically, USB-powered chargers like the VC4S are limited by the USB input power.

Previously, most USB-powered chargers use only around 5v/2Amps max (10-watts), which will result in 1× 2A or 2× 1A or 4× 0.5Amp charging speed.

Some newer USB-powered chargers can now use USB QuickCharge – usually 9v/2A (18-watts), this results in 1× 3A or 2× 2A or 4× 1A max charging speed. (the VC4S can do this if using a QC2.0-9v/2Amp USB power source). The Xtar VC8 also can make use of QuickCharge USB (which results in up to 8× 0.5Amp, in addition to the above-mentioned). I think some new Nitecore USB-powered chargers also have these similar charging current.

The next step up from USB-power will have to use the USB-C PD2.0/PD3.0, which can provide more power. Very few USB-powered chargers at this time use USB PD2.0/PD3.0.
Also, it will depend on the USB-PD’s power (some USB PD may just have a limit of 30-watts, 45-watts, 60-watts or as high as 100-watts).
For instance, the Xtar ST2 can be powered by USB-PD (15v/3Amps or 45-watts), this results in up to 2× 4Amps charging speed. (the Xtar ST2 is a 2-slot charger).

So until USB-powered chargers start to use USB-PD as power source, they just won’t be able to charge as fast as AC-outlet powered chargers (with more beefier power supply).

But note that USB-PD power supply doesn’t seem to be that common — and may also open up some issues — eg. the owner of the USB-PD charger may not have a USB-PD power supply, or may have one but that doesn’t have enough power (eg. USB-PD with 18-watts max power won’t be able to charge too fast either). The user will need to find a USB-PD 30-watt or USB-PD 45-watt or USB-PD 60-watt power source. Some ordinary users may not be able to identify if the USB-PD power supply they’re purchasing for the “USB-PD charger” is the correct wattage too, unless they’re well-versed in reading electronics labels..

maxchaos92
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Yes it’s exactly what I was asking,but if i need to buy a pricey USB PD i think I will go with the vc4s,4*1A it’s still plenty for me,as I have a nitecore d4 that can do max 4*0,375 and it’s very slow Crying