Nitecore D2 not really charging to 4.2v??

[Monotremata]

Just got a new hcigar with the DNA75C chipset in it on Friday. Before this, all my mods just showed me a pic of a battery and the little bar showing the charge and it was always full with a fresh battery (the one I replaced was an HCigar with the DNA75). Now with the 75C I actually have a percentage on screen. Using my trusty 3 year old Nitecore D2 as always, the last 2 or 3 batteries I put in are showing at 95%, when the charger says they're charged to 4.2v. The Samsung 30Q (which is only about a year old) I just put in about 20 minutes ago was just taken off the charger 2-3 hours ago that said it was fully charged, yet it was at 4.09v when I put it in according to the mod.

Is my Nitecore not doing its job? Is the mod lying? Is this yet another calibration thing I need to do to the dna chip? Is it time to get a real Xtar (I have an MC2, just no fancy display or higher charging rate)?

 

[txtard]

My Nitecore D4 is the same way. It shows 4.2 and the Fluke meter shows 4.17 or 18. I think it's just the Nitecore's doing it.

 

[Heartsdelight]

My old Nitecore D4 & now my Nitecore I8 does the same thing. Although it does charge to about 98-99% but never to 100%. So I agree, I thinks it’s Nitecore.

I have the Hohmtech Charger that has the battery refresh thing, forgot what it’s called but I think for batteries that are 1-2 years of heavy usage should probably be refreshed. Haven’t done mind yet. There’s a thread on the Hohmtech Charger that @mjag has done over at the other place. @mjag can explain it better than I.

 

[SteveS45]

Slide the battery down until it disconnects and reconnects so reads the voltage again and it will continue to charge to 100%. Some charges time out and stop charging. Just my opinion but try it.

 

[AzPlumber]

Common for batteries to drop a few hundredths of a volt as they cool down after being charged. Older batteries will typically drop a bit more than new ones. The best way to test a charger's cutoff is to check the batteries voltage as soon as fully charged with a digital volt meter.

 

[the wind]

sounds like its working right to me but backups include chargers.

 

[puffon]

I'd like to find a reasonably priced charger, that can be set to only charge up to 4.1v
It increases battery life by a lot.
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
"Most Li-ions charge to 4.20V/cell, and every reduction in peak charge voltage of 0.10V/cell is said to double the cycle life. For example, a lithium-ion cell charged to 4.20V/cell typically delivers 300–500 cycles. If charged to only 4.10V/cell, the life can be prolonged to 600–1,000 cycles; 4.0V/cell should deliver 1,200–2,000 and 3.90V/cell should provide 2,400–4,000 cycles."

 

[DaveP]

I'd like to find a reasonably priced charger, that can be set to only charge up to 4.1v
It increases battery life by a lot.
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
"Most Li-ions charge to 4.20V/cell, and every reduction in peak charge voltage of 0.10V/cell is said to double the cycle life. For example, a lithium-ion cell charged to 4.20V/cell typically delivers 300–500 cycles. If charged to only 4.10V/cell, the life can be prolonged to 600–1,000 cycles; 4.0V/cell should deliver 1,200–2,000 and 3.90V/cell should provide 2,400–4,000 cycles."

That's interesting info, PuffOn. We'd all benefit from a charger with adjustable cutoff points. My Xtar VC4 shows a virtual dial with voltage readings for each bay instead of bars. Maybe I'll start pulling cells when it gets to 4.1v. Double cycle time is worth losing a tenth or so. Every battery drops a tenth with the first few vape hits anyway.

 

[r77r7r]

Yes, I think that Mooch addressed the benefits of a slightly undercharged finishing point recently.

 

[stols001]

In that case, I guess I will just enjoy my nitcore undercharger quite happily

Anna

 

[Evi|grin]

Mine also...all batteries come off at 4.17-4.18 according to the Fluke.

 

[Monotremata]

Guess thats just the way it goes heh. Never thought to use my meter on them, all my previous mods just showed a full battery meter. Oh well, if it means more cycles, its fine by me.

Like @SteveS45 said, I have actually seen that behavior before. Theres been a few times while sliding the battery out Ive slipped and let it go and when it reconnects, the fully charged batteries were never at 4.2.

 

[Heartsdelight]

In that case, I guess I will just enjoy my nitcore undercharger quite happily

Anna

Me too then

 

[DaveP]

All 18650's spend most of their time in the part of the discharge curve on either side of 3.7v. If it drops from 4.x volts to get into the mainstream power range that's OK with me. I'm more concerned about total discharge time before cutoff.

In the graph below the voltage drops more rapidly from max to about 3.8v, then decreases more slowly until the rapid drop begins around 3.5v.