Out of three chargers i have not yet hit the elusive 4.2V threshold.
I have not kept up on the new offerings in the last couple years so:
Perfect charger would charge at least two 18650 and 26650, 1A or selectable, have a voltage display for each battery, and also calculate capacity and internal resistance. One 18650/26650 is acceptable.
Basic requirements would charge at least one 18650/26650, have 1A or selectable, and voltage display would be nice.
Of course i am looking for lowest cost at good quality
Thanks for suggestions
I have 3 chargers that has a numeric display of terminal voltage, ie: 4.20V (iCharger, BT-C3100 and the VP-2)
While all three terminate at that voltage, when you take out the cell, seldom will you find the cell at that exact 4.20V. The cell usually and quickly goes down to 4.19, then will eventually stay at that specific cell’s resting voltage, depending on the cell’s ‘natural health’.
I have 3 Thrunite chargers (2 four cell and 1 two cell) and they terminate at 4.2 or 4.19 consistently. The 2 cell version takes 2 26650 cells easilyas do the 4 cell versions. I also have 2 AWT chargers and they also charge correctly. The one also has discharge function and measures internal cell resistance and you can select 500mA or 1A charging.
The 4.2 volt is only present when the charger is charging, when it stops charging or you remove the battery the voltage will be lower or you have overcharged the battery.
If you look at the voltage trace (red line) in any of my charge curves (Charger or battery) you will see the drop when the charger stops (at the yellow line).
I’ve noticed that too on my hobby charger, which has a 0.001V resolution on Data Log…. so what are you suggesting…keeping this way and saving some battery life or overcharging a bit?
Also would be of help of any kind to set the termination current very low? I mean this will fill the battery till the last drop, so I think it will sag less in the moment you remove it from the charger… Sadly my REAKTOR does not allow to set the termination current, and i think it is relative to the charging set current, but usually the less i’ve seen was 90mA
EDIT
to be honest in your discharging graphs, I’ve always seen the curve starting from 4.2. While in mine, even If i start immediately after charging @ 1A (so …relative slow) I always start from 4.14-4.17 et similar. Fresh new cells….
Battery manufacturer does sometimes list a recommended termination current for their cells, using a lower current will theoretically overcharge the battery.
Hobby chargers will usual use 10% of charge current as termination current.
I have made a test of what different termination currents means to capacity: http://lygte-info.dk/info/BatteryChargeVoltageCurrent%20UK.html
That table was the first job I did on my test stations, before starting the 2012 LiIon battery test (That is the tests that is still running).
It has always been the plan to do a larger test with more batteries, a few more currents and slightly better precision, but I have never had a free test station for it. This year I got some more test equipment and may get around to do it.
My situation is three crappy chargers, i have used a multitude of new and used calls that are sanyo, LG, and so on, the chargers simply suck, hence i want actual chargers that can fully charge batteries and meet the conditions ion the original post.
Sounds like a lot of back luck on your chargers. I have a Xtar WP2, Miller ML102 v1, Nitecore I2, and Accucel 6 that all have the batteries coming off at 4.20v or so. The batteries come off my Opus 3100 v2 at about 4.17v but that’s better than what you’re getting.
Maybe I missed it but what chargers do you have? To have that many charge to such a low level seems highly unusual. Are you sure your volt meter is accurate?
My Xtar VP-4, Opus BT-C3100 and Nitecore i2/i4 all consistently charge to 4.19-4.20v, that is if I check them immediately as I pull them out of the charger. They do drop a little down to ~4.15-4.17V after some time.
