Xtar V4 mAh question

21 posts / 0 new
Last post
Coscar
Coscar's picture
Offline
Last seen: 3 hours 46 min ago
Joined: 01/03/2016 - 20:16
Posts: 797
Location: Gulf Coast
Xtar V4 mAh question

I just got an Xtar V4 charger and I dont quite understand the mAh in the display. I just charged 2 brand new NCR18650B 3.7V 3400mAh 18650 batteries – supposedly Panasonic – but they only show 1835/1850 mAh on the display when full.

Does this mean the batteries are NOT 3400mAh and are counterfeit. Reviews seem generally good on the site.

The batteries came from GearBest and I wanted to make sure I understood before contacting them.

Im not a Pessimist …. just an Optimist with a lot of experience


A little John Prine

Edited by: Coscar on 02/04/2016 - 15:45
CRX
CRX's picture
Offline
Last seen: 1 week 5 days ago
Joined: 04/02/2013 - 15:27
Posts: 4243
Location: Scotland

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.

djburkes
djburkes's picture
Offline
Last seen: 4 years 1 week ago
Joined: 03/16/2015 - 11:00
Posts: 1829
Location: Arkansas
Coscar wrote:

I just got an Xtar V4 charger and I dont quite understand the mAh in the display. I just charged 2 brand new NCR18650B 3.7V 3400mAh 18650 batteries – supposedly Panasonic – but they only show 1835/1850 mAh on the display when full.

Does this mean the batteries are NOT 3400mAh and are counterfeit. Reviews seem generally good on the site.

The batteries came from GearBest and I wanted to make sure I understood before contacting them.

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

Coscar
Coscar's picture
Offline
Last seen: 3 hours 46 min ago
Joined: 01/03/2016 - 20:16
Posts: 797
Location: Gulf Coast

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

Im not a Pessimist …. just an Optimist with a lot of experience


A little John Prine

Coscar
Coscar's picture
Offline
Last seen: 3 hours 46 min ago
Joined: 01/03/2016 - 20:16
Posts: 797
Location: Gulf Coast
CRX wrote:
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.

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.

Im not a Pessimist …. just an Optimist with a lot of experience


A little John Prine

mongoose
Offline
Last seen: 16 hours 13 min ago
Joined: 05/12/2015 - 10:17
Posts: 327
Location: uk

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.

homer

hank
hank's picture
Offline
Last seen: 6 days 21 hours ago
Joined: 09/04/2011 - 21:52
Posts: 9634
Location: Berkeley, California
Quote:
vc4 charger … shows the mah put into the battery on that charge cycle

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.

CRX
CRX's picture
Offline
Last seen: 1 week 5 days ago
Joined: 04/02/2013 - 15:27
Posts: 4243
Location: Scotland
Coscar wrote:
CRX wrote:
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.

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.

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

Coscar
Coscar's picture
Offline
Last seen: 3 hours 46 min ago
Joined: 01/03/2016 - 20:16
Posts: 797
Location: Gulf Coast
mongoose wrote:
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.

Yes…. VC4. Sorry bout that

Im not a Pessimist …. just an Optimist with a lot of experience


A little John Prine

Coscar
Coscar's picture
Offline
Last seen: 3 hours 46 min ago
Joined: 01/03/2016 - 20:16
Posts: 797
Location: Gulf Coast
hank wrote:
Quote:
vc4 charger … shows the mah put into the battery on that charge cycle

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

Im not a Pessimist …. just an Optimist with a lot of experience


A little John Prine

CRX
CRX's picture
Offline
Last seen: 1 week 5 days ago
Joined: 04/02/2013 - 15:27
Posts: 4243
Location: Scotland

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

hank
hank's picture
Offline
Last seen: 6 days 21 hours ago
Joined: 09/04/2011 - 21:52
Posts: 9634
Location: Berkeley, California

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.

Lazy-R-us
Offline
Last seen: 8 months 2 weeks ago
Joined: 09/13/2015 - 00:30
Posts: 685
Location: Carolinas, USA

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

Lazy-R-us

jhalb
jhalb's picture
Offline
Last seen: 4 years 9 months ago
Joined: 03/23/2015 - 21:24
Posts: 1350
Location: California

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?

Coscar
Coscar's picture
Offline
Last seen: 3 hours 46 min ago
Joined: 01/03/2016 - 20:16
Posts: 797
Location: Gulf Coast

Lazy-R-us wrote:
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

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

Im not a Pessimist …. just an Optimist with a lot of experience


A little John Prine

Coscar
Coscar's picture
Offline
Last seen: 3 hours 46 min ago
Joined: 01/03/2016 - 20:16
Posts: 797
Location: Gulf Coast

jhalb wrote:

Does that make sense I hope?


Yes it does. Thanks
C~

Im not a Pessimist …. just an Optimist with a lot of experience


A little John Prine

brad
brad's picture
Offline
Last seen: 4 hours 31 min ago
Joined: 12/04/2012 - 02:07
Posts: 2412
Location: USA

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

Not what we have but what we enjoy, constitutes our abundance.

flydiver
Offline
Last seen: 1 hour 1 min ago
Joined: 06/19/2013 - 19:16
Posts: 1321
Location: Seattle, WA
hank wrote:
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.

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.

To Air is Human, to Respire….Divine.

chuckhov
Offline
Last seen: 3 years 4 months ago
Joined: 12/24/2014 - 02:57
Posts: 1178
Location: Florida, AKA God's Waiting Room

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

piasca
Offline
Last seen: 13 hours 16 min ago
Joined: 01/15/2015 - 19:51
Posts: 173
Location: Portugal

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

lightme
lightme's picture
Offline
Last seen: 5 years 10 months ago
Joined: 11/12/2012 - 19:51
Posts: 615
Location: WV

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.