Xtar V4 mAh question

That’s probably a good sign as cells should arrive around 40-60% charged. Discharge then charge them again and you should see a reading closer to the stated capacity.

Are you sure that’s not showing how much mah was put into the batteries from the point that they were already charged?

No, I am not sure. These are my first Li-on batteries and charger and I am still learning
Thanks

Im confused, so are you saying that the mAh reading on the V4 display just indicates how much charge you are applying to the battery for that session, not the capacity.

I presume you mean the xtar vc4 charger, i’ve got one. It only shows the mah put into the battery on that charge cycle, not the batteries capacity.

That’s right. As CRX and mongoose said.

Check with your voltmeter (you should have one, to be using li-ions) right after, and a while later after, charging, and note the numbers as a baseline for that cell.

Yes, but that reading can still be a reasonable gauge of capacity on newer cells if charging from empty.

Yes…. VC4. Sorry bout that

Yes I have a volt meter. Is there a way to check the capacity besides draining the battery? I thought that was ‘not good’?

The only real way to determine capacity is by discharging.

HKJ’s Review might help

As to voltage

Estimating Remaining Capacity in Li-Ion Cells

You do not want to drain the battery, not ever. If you did, you’d recycle it, not try to charge it.
Use the light normally (assuming there’s low voltage protection on the cells, or the driver, or both) and recharge it when it’s needed.

The only way to determine the capacity of a battery is to measure how much charge you put in while charging, or measure how much charge you get out of it while discharging. I don’t think the VC4 has a discharge test mode, (and I looked for it quickly on HKJ’s review ). So what your charger told you is that it estimates that it put in 1835 mAH. Without knowing how much charge was there to start with, this does not tell you much. In order to know the capacity, you need to decide at what voltage you plan to remove the batteries from your lights (different cells have different curves, your tolerance for risk…). If you pick 3.0V as your threshold voltage, you would discharge the battery in your light or a test fixture to this level, then charge it. THEN you will know what approximate capacity this cell has in your use case.

The data sheet for cells should tell you what the minimum and maximum voltages are, and since everyone likes big numbers, marketing uses capacities based on using the full range. You may decide not to fully discharge to the minimum voltage, which means you wont get the full claimed capacity

When you got the battery it was supposed to be at the recommended resting/storage voltage which is ~3.7-3.8v, ~50-52% capacity. Had maybe around 1600mAh remaining.

Then when you put them into the charger at that voltage your charger added 1835/1850 mAh as you described. They are now probably at the full voltage 4.2v which will now probably have a capacity of discharging the full 3400mAh.

So in theory, you added 1850mAh to a battery that already had ~1600mAh in it. Add 1850 and 1600 and you get ~3400Mah. My numbers are not exact of course but I am trying to relay to you why you were only seeing 1835/1850mAh when you charged them to 4.2v.

Does that make sense I hope?

Okay, I think I understand. So if I decide that 3.3v is my ‘low voltage’. According to CRX’s table, the battery’s capacity should be at 0% at that point and when I charge it, “ideally” it should show 3400mAh on the display when charged. Is that correct?
I have a BLF A6(w/protection) and using high drain non-protected batteries(Panasonic NCR18650B 3.7V 3400mAh & Samsung 30Q).
Thanks

Yes it does. Thanks
C~

Wonderful thread Coscar, I had all of the same questions about my own VC4 and my batteries.

I think this needs some clarification. You don’t want to drain the battery to empty….ever. Occasionally, IF you have good reason like a capacity check, you can discharge to ~3.0v. Since that cut-off will be under draw the voltage will pop back up a bit when you remove the draw. I do not recommend doing this on a routine basis. It’s better to leave ~20% of the capacity (see that chart) for regular discharge cycles.

With that Xtar you can ESTIMATE charge capacity when you start with a discharged cell, which will (have to) be ‘good enough’. Discharge capacity tests are more accurate. But, even with discharge the capacity you measure will be somewhat different at different amp draw, AND with different (dis)chargers. I get different results from 3 of my units that will discharge when attempting to match the discharge in every respect.

The Xtrar VC2/VC4 is NOT an Analyzing charger, but many make the mistake that it is.

‘Charge In’ does Not equal Capacity, any more than filling up with 8 gallons of gas in a car with a 15 gallon tank tells you how big the tank actually is.

A Discharge to a standard level by something designed to measure ‘Discharge Capacity’ (Never Charge In) will tell you something.

I really think that Xtar should Dump this ‘feature’ along with their meaningless “time to completion” feature/guess on their upgraded VC2 + (or whatever it’s called).

Xtar makes some good chargers (I own 3 of their chargers, and 2 of their lights), but these gimmicks are pretty meaningless. - I wish that Xtar would make a true Analyzing charger, but they do not.

So - I bought a LlitoKala 500 and like it a lot.

Thanks,

-Chuck

In the vc4 the capacity is just function of time and charge current.

I bought a pair of Sanyo NCR 18650GA button tops from Gearbest and they seem to be genuine because they look and perform as they should. However, I never did get my Xtar charger so what seemed like a good deal really wouldn’t have been until I contacted my credit card company before 60 days ignoring Gearbest’s suggestion that I wait longer. For some reason they reimbursed me the full amount so the cells ended up being free.