3 batteries from flashlight reading widely different voltage

So, I removed my AWT IMR18650 3000mAh batteries from my Eagletac MX25L3 flashlight.
Upon loading them into my Liitokala 500 charger, I got the following voltage readings.
3.04
3.44
4.08

Wondering if my charger was giving me bad readings, I loaded them into my Gyrfalcon All-88 and got the same readings.

These batteries are about a year old and have been used occasionally for short periods of time. I regularly remove the batteries from all my flashlights about once every two months to recharge them, even if they haven't been used much. I've never seen this behavior in these batteries. I do have a few other of the exact same battery that have not exhibited any problems.

By the way, the batteries were all purchased as a set from a reputable dealer. Then labeled with the flashlight name and used only in that flashlight. They have been charged together, on the same charger ever since.

Should I toss these batteries? Can they be used in single cell lights with no worry?
(they are definitely not going back into a flashlight as a set).

Thanks for your advice!! :hairpull:

Hello MAD777,

As a check charge all your cells then let them sit out of the charger for 24 hours. Then measure the voltage of each cell.

This may give you an idea of what is going on.

Tom

Will do SilverFox. I'll let you know.

Also do you actively rotate their position in the flashlight after each discharge-charge cycle? If in series the battery at positive end will take a battering and if one has been in this position more than others then thy explains the huge variation. If they are in parallel there may be some added resistance to one or two of the sleds which would mean the battery with least resistance associated to it would be discharged faster.

Thom2202, I believe they are in series, as two batteries are pointed to the head & one toward the tail. I've never kept track of their order. Just replaced them randomly in the flashlight. I'll pay attention from now on.

each battery is dictated by its internal resistance. If improperly matched they discharge at different rates. Over the years testing lithium primaries going through 3-Cell surefires have yielded similar results. Especially when the light is dimming as to suggest batteries are depleting.... then with the ZTS lo and behold my lithium primaries read 100%, 20%, <20% [no light]

Hey MAD, the batteries in series response is right on. I actually mark my battery carrier or the drop in slots and pay attention to where I put the cells. I had two cells come out of my T6vn at 3.44 and the other two at 3.9 or so once. It pays to keep a closer eye on multi-cell lights a little more carefully.

Thanks for the insight Illum & brighterthanthesun. I feel better now that I know the phenomenon wasn't completely out of reason.

I will definitely be marking the order that batteries are placed in the flashlight.

Actually, I'm halfway there as each battery has the light's name, plus 1/3, 2/3, & 3/3 labeled with a Sharpie. I just need to pay attention to the order & rotate that order with each charge.

I'll let you know the outcome of my recharging. Thanks a bunch guys!

brighterthanthesun said:

Hey MAD, the batteries in series response is right on. I actually mark my battery carrier or the drop in slots and pay attention to where I put the cells. I had two cells come out of my T6vn at 3.44 and the other two at 3.9 or so once. It pays to keep a closer eye on multi-cell lights a little more carefully.

Click to expand...

I actually started a thread today, http://www.candlepowerforums.com/vb/showthread.php?433000-4-married-18650-s-not-same-voltage-reading

This thread might actually provide some answers to my question.

Thanks guys for the helpful replies here.

I'm a bit confused by the whole battery matching thing as well. I have purchased (8) 18650 in batches of 4. They have quite different internal resistance as measured with a Liitokala Lii-500 charger. I use four in one light and the other four go in single cell lights. Should the four that are paired into one light be matched based on the internal resistance or is there a better criteria?

Hello Bwalker,

There seems to be some variability in measuring internal resistance. The traditional way to match cells is to match them on capacity. If you want to go further you can look at the discharge curve and also match on voltage under load.

I would look at discharge capacity and go with that.

Tom

SilverFox said:

There seems to be some variability in measuring internal resistance. The traditional way to match cells is to match them on capacity. If you want to go further you can look at the discharge curve and also match on voltage under load. I would look at discharge capacity and go with that.

Click to expand...

If your deployed app doesn't include undervoltage protection on each cell, then it is important to match on both capacity and IR (or, equivalently, matching discharge curves at the intended rates), else you could end up seriously overdischarging some cells.

Okay, so I need to test their capacity and also their IR. Presumably the lowest IR will have the highest capacity, right? At any rate, I'll take the four highest capacity and see how they compare as far as IR. Thanks for the input.

bwalker said:

Okay, so I need to test their capacity and also their IR. Presumably the lowest IR will have the highest capacity, right? At any rate, I'll take the four highest capacity and see how they compare as far as IR. Thanks for the input.

Click to expand...

Just keep an eye on the voltage of each cell before or when you are recharging them. Each of my batteries are numbered so I can keep track of them better. If I notice a cell that starts coming out of a three or four cell light lower than the rest I use that one in a single cell light and find a better matched cell for the big light. I have 10 to 16 of each cell type that I use so I can always find a cell from the same batch that I can throw into the four battery set.

Today I put the three wacky batteries on my LiitoKala 500 charger /analyzer. They were at about 3, 3.5 & 4 volts. I charged the 3 volt up to 3.5 and added the second battery. When both those made it to 4 volts, I added the third battery. All charged to 4.20 volts without any suspicious activity.

Then I put the charger in test mode and discharged all the batteries to 3.14 volts. All three took the same time to get there and all three showed the same capacity.

I then charged them back to 4.20 volts tonight, and everything behaved normally. Finally, I replaced them into the flashlight and it operated as it should.

I will check those batteries every day for a good while. If I see any anomalies, I'll report back.

Thanks for all the advice received. And I did rotate the order of the batteries and will continue that practice.

Hey Mad-
It sounds to me like one of the slots in the carrier isn't making good contact with the cell - the one that was 4volts.
I'd tug on the springs etc n make sure it's a snug fit.

I'll check the carrier contacts when I get home tonight, while I'm checking the batteries. Thanks psychbeat!

i doubt its anything wrong with the light.its either different self discharge in the cells or the protection boards in each cell have different parasitic drain.
awt cells could be anything from cheap chinese to decent major brand cells.
if you dont need the light for a while leave the cells out a few weeks and see if any drop more than others.

Just a quick check tonight and all voltages are at 4.20. The light's contacts looked good.
I'll remove the batteries and then check them after some time has passed. (I think I can find another light to use in the mean time.)