Got it from GB for 3 bucks. Thought I’d check it out this morning, so I put a 25R in it and let it do its stuff. It was still charging when I thought I’d pull the battery out and meter it. 4.24 volts. Oops, sometimes you get what you pay for.
It is just 0.01V outside specification and probably your meter accuracy.
It was still charging.
It was not fully charged, that’s why.
I have same charger, but bought for 1.24$, will check.
Mike
But you don’t know where it was on the charging cycle and measuring the current at that point would have provided useful information. How long was it charging for? And as sp5it mentioned it could be that your DMM isn’t precise enough to get an accurate reading.
Nearly all DMMs are at least + or - one count. Inexpensive ones are often + or - 3 or more counts and a + - a few percent.
I haven’t checked recently — Meters accurate to better than .005 Volts used to be very expensive. Even then you needed to get them calibrated every year or two.
Maybe possible to get an old high precision HP or Racal cheap on eBay and then pay to have it calibrated. Dunno I haven’t looked at the auctions.
Modern DMM’s usually have good precision, even cheap ones, for best precision with LiIon get a 6000 count meter.
Calibration do not adjust anything, it is just done to confirm and document that the meter shows correctly.
If you are in the US, you can get lots of fairly cheap and good equipment on Ebay, outside US it is much more difficult.
I use my meter pretty much daily. My Xtar VC2 charges my 18650’s to 4.18 or 4.19 consistently. I’m quite confident that the new charger is over-charging when the same meter reads 4.24 (and still charging).
4.24V is not overcharging and the charger may stay at that voltage for some time, before the charge is finished.
I haven’t paid any attention to the cheap meters on Gearbest / BAngood. How good are they?
I’ve been using my ancient Beckman and a made in China Digimess (Grundig) DM-200 I got very cheap on eBay. The Beckman is very old, but nearly industructable.
The Chinese Fluke 17B+ is about £100* for a real one. Acuracy is 0.5% + 3. counts
If my math is right, 4.200VDC could read anywhere between 4.175 and 4.224
Not bad at all for the price.
A Fluke 177 is /- (0.09% 2)
4.200 VDC could read anywhere between, 4.194 and 4.205 or 6.
Better, but the 177 is just over twice the price of the 17B+.
*prices are lower in the US or direct from china.
I bought two 100s and two 202s earlier in the year and both of my 100s slightly overcharge to the tune of 4.22v-4.23v, which is still within spec.
My two 202s slightly undercharge to about 4.18v-4.19v.
They’re pretty consistent in that regard.
For ~$22 delivered, they’re a no brainer IMO.
Chris
Many of them are rather good.
I have started reviewing DMM’s, you can see my current list here:
http://www.lygte-info.dk/info/DMMReviews.html
For good DC volt precision check the Zeast 282
The Liitokala can be modded to charge to a lower charge voltage and/or current
Did the mod to one of my chargers and it worked fine.
With the renewed interest lately in the LiitoKala Lii-100 charger, I pulled mine out last night and put an 18350 that was at 3.92 into it. When it stopped charging the battery read 4.22 on both a Fluke and a B&K meter. Should I put a 10K 1/4 watt resistor across R5? I’m probably too lazy to do it unless I’m giving one away. So I just put it back into the A6 I took it from and turned the light on high for 20 seconds. I suspect that different batteries may come off at slightly different charged voltages due to the interaction between the charger circuitry and the battery chemistry, so maybe I’ll get around to testing this again with a big 18650 to see if the result is the same. But all of this from a guy (me) that puts his batteries away for storage fully charged rather than at 3.8, so my concern for cell longevity is somewhat questionable. I do think that it is a good idea when you first get a new charger of any manufacturer to test it at least once and not take anything for granted, and to be a little extra careful if you will be giving it away.
Change that to a 10meg resistor. Gettin’ old.
You have far more experience with modern test gear than I do.
My antique Beckman has a single multi turn pot. Hook the meter to a 250mV standard and adjust to read 250mV DC.
My Digimess DM200 has three multi turn pots. The DM200 is a very old design but they still sell it.
Digimess Instruments offer factory calibration for £65.00 or £75 with a UKAS certificate. I bought the meter from their eBay store with a fresh calibration for less than £100. I can’t see paying £65.00 to calibrate a 4000 count (0.3% + 2 d) meter.
I don’t think either meter has drifted much. They agree with each other to 2 or 3 counts.
I might buy a $28 2.500V 0.01% reference from VoltageStandard.com