Understanding battery voltages?? Danger close?

Batteries and Chargers Rechargeable Batteries
1

So I picked up a Innova 3320 multimeter today and went to work checking my voltages off of my Ultrafire WF139. The AW 14500 battery read 4.30??? Isn't that danger close for something bad to happen? This took the pcb off of the battery a long time ago so that I can operate it in my Nitecore D11. I ran the AW 14500 in my light for a few minutes and checked the voltage again, it's down to 4.22. I decided that should be ok.

Is a reading of 4.30 overcharged? On another note I recharged my AW RCR123 and it read 4.13 off of the charger. Is the Ultrafire W139 doing a bad job?

Thank you. As you can tell, I'm still a noob.

2

Maybe taking the wrapper off of the battery was a no no. I have since covered with electrical tape. With this multi-meter, I have come to the conclusion that Ultrafire batteries suck. Perhaps I shouldn't use an ultrafire charger.

3

4,3v is overcharged should stop at 4,10/4,25 MAX, test your DMM on other, check if it is repeated

charge few times to 4,30v(no more) will just low the battery life, repeat that can be dangerous

Isolate the battery with electrical, better kapton, tape to avoid shortcuts and use protected batteries on cheap chargers

ultrafire have inconstant quality many fakes, go on trustfire flames for budget batteries

4

That meter is completely useless for measuring LI-Ion battery voltage. Well, maybe "completely" is a bit strongly worded, but I sure as hell wouldn't trust that my flashlight is a flashlight and not a pipe-bomb by testing it with that.. thing...

20.00V 10mV ±(0.8% of rdg + 5 digits)

At the range you're measuring (4.20 ish), you've got 10mv Resolution (2 digits after the decimal point).

0.8% inaccuracy AND +/- 5 digits..

worst case.. 4.20 (actual) * 1.008 = 4.23V PLUS 5 Digits, 4.28V (measured)

As you can see.. that battery could be as low as 4.22V and read as 4.30.

The even scarier situation is the opposite..

4.29V (actual) * .992 = 4.25 MINUS 5 COUNTS = 4.20V

So now, you have a (quite) overcharged battery that looks perfect on your meter...

Personally, I swear by my Hioki 3801-50

4.2000V (actual) * 1.00025 = 4.2011 + 5 COUNTS = 4.2016V (measured worst case)

http://www.hioki.com/product/pdf/DMMsE3-1XE.pdf

PPtk

5

Hrm, I heard it was a decent multi meter to use. I will look into yours and perhaps return it.

6

Woah. Yeah....that's a bit out of my budget. I'm still trying to understand the formula you laid out above. Thanks for your input.

7

Good meters aren't cheap.. That is the unfortunate part.. but if you value safety (not just in batteries, but in other things electronic as well), think of it like life insurance...

The formula for most DMMs is a percentage of error plus a number of counts of error. counts are (pretty much) always the number of least-significant-digits.

So, a meter with 1mv resolution, 1% error and 5 counts would be calculated as such...

Actual voltage.. 4.200V

1% error = 4.158V or 4.242V (worst case in each direction)

add/subtract 5 counts

4.153V or 4.247V worst case displayed.

A meter with 10mv resolution, 1% error and 5 counts would be calculated as such...

Actual voltage.. 4.20V

1% error = 4.16V or 4.24V (worst case in each direction)

add/subtract 5 counts

4.11V or 4.29V worst case displayed.

These are all worst case possibilities. Even a 'cheap' meter COULD be 100% accurate, but there's no guarantee. Cheaper meters tend to vary much more with temperature as well.

8

For something more affordable, try an oldie but goodie like this..

http://www.ebay.com/itm/FLUKE-8810A-5-1-2-DIGIT-DIGITAL-MULTIMETER-/110795941568?pt=LH_DefaultDomain_0&hash=item19cbf3e6c0#ht_624wt_1396

Basic Vdc Accuracy ±0.005% of input + 2 digit

Fancy? nope. Highly Accurate? Yep. Without spending hundreds (or thousands) of dollars, you can't get much better than this.

9

I noticed my 17670 ultrafire (grey) batteries refuse to fully charge in my WF139. I get a reading of about 3.8 volts on both of them. The charger continues to flash green and then red slowly. It only seems to do it on these batteries. Why would that be?

10

Yeah, no offense. But that's beyond me. I only need the MM as a general rule of thumb. Not for drop dead accuracy.

11

No offence taken. Like anyone in the world, you're free to do as you wish.

Hope I helped you understand the accuracy specifications of meters so that you can knowledgeably compare.

PPtk

12

Tons of possible reasons. High internal resistance would be my 'off the top of my head' answer... If a charger like the WF139 sees these as 'bad' cells, I would be very wary of them. Its a cheapie charger that doesn't do much monitoring of the cells being charged, so if even it thinks they're bad - they probably are.

PPtk

13

Yes thanks. I did some reading and apparently most of the ultrafire stuff are recycled batteries. So they're probably old. I just purchased them from batteryjunction a few months ago.

14

Most of the fake "Ultrafire" batteries cheap people buy from ebay you mean. Should be better if you bought real ones from BJ.

15

I bought them from Batteryjunction. And after looking at battery junction's policies. I will never shop there again. They play ignorant as to what they are selling. In all actuality they should only sell quality products and stand behind them. If they're going to call themselves, "BatteryJunction". Otherwise call yourself, "the import junction", if you're going to have policies like this;

"No, BatteryJunction.com does not pay the return shipping cost for defective merchandise. We are not responsible for product defects, because we do not manufacture the products we carry."

16

Candlepower is ridiculous, I posted about the same issue concerning the 17670 batteries purchased through Batteryjunction and they removed my thread. Always looking out for their revenue producing dealers.......

17

I'll never shop there again, either. Seems like a good place to buy from until you have a problem and call their "customer service" which is unhelpful and arrogant.