Charging Battery Pairs

[JimmyJet]

Hey Folks,

I have 4 pairs of TrustFire protected 18650's which I charge on a TrustFire WF-188 charger. The batteries are always charged in a pair, used in a pair, never mixed, and always rotated. The mod is a dual-18650 VV box.

Lately I am seeing an odd trend. One battery takes much longer to charge than the other. Doesn't matter which channel on the charger, the result is the same. The batteries are 6 months old or less.

Has anyone seen this before? Should I be concerned?

Thanks, JJ

 

[six]

When you pull the batts out of your mod, check them with your multimeter and see if one is drained more than the other. I think you'll discover that to be the case. That's fairly normal.

I don't think it's anything to worry about, but it could be time to get a back up pair of batts or another pair to start cycling in your roation.

 

[oldsoldier]

This is very common and can easily be verified by using a multimeter on the batteries before charging. It also doesn't hurt to check the batteries after charging either...

 

[JimmyJet]

Thank you, guys. Good advice. I did just that. Metered one pair of batteries before going on the charger. One was 3.89V, the other was near zero. That surprised me. I fiddled with the multimeter to make sure I was getting an accurate reading. Definitely, one battery was reading near zero.

Is that battery dead?

 

[Rocketman]

You stated pairs of 18650 cells. A cell with a voltage indication of ZERO has cut off (the protection circuit cut the cell off).
Something is wrong with your mod or the cell/protection circuit is bad. Are you using the cells in a series or parallel mod?

The pair with unmatched voltages are not matched. Maybe caused by the mod. Time to troubleshoot before something bad happens. Slight mismatching is common, but a cell at 3.89 volts and one that has cut off is NOT COMMON or SAFE.

 

[KeithB]

I haven;t seen it myself, but I think at least two of the recent exploding mod stories began with the user noticing their batteries were taking longer to charge. I'd be careful with them.

It seems like when using batteries in series, one will always reach cutoff before the other, but 3.89V vs cutoff seems like a pretty big difference. My "live" battery is usually around 3.4V or so when I let them get that far which I don't usually do any more.

 

[SammyT]

When you say pairs do you mean that you have used them in a series since they came from the vendor? I ask because I am going to be using a dual 18650 mod, and I have 2 aw imr 18650s that have been used approximately equally amounts of time in a 3.7v device (one at a time.) I don't have the scrilla to buy 2 more batts right now. sorry to hijack your thread I just didnt want to start a new one for a similar question.

 

[Rocketman]

\ My "live" battery is usually around 3.4V or so when I let them get that far which I don't usually do any more.

It's likely that your live battery was dropping to about 2.8 volts under vaping load, and the other was dropping to cut off (about 2.5 volts), stopping you from vaping any more. Not a good thing to vape to cutoff, but sometimes it just happens
In your case, the mismatch wasn't that much. It really wasn't 3.4 Vs zero.

 

[JimmyJet]

You stated pairs of 18650 cells. A cell with a voltage indication of ZERO has cut off (the protection circuit cut the cell off). Something is wrong with your mod or the cell/protection circuit is bad. Are you using the cells in a series or parallel mod?

Thanks for the input, guys. I am still troubleshooting and frankly I'm more confused. But I am starting to think my charger is the problem.

I say this because I am now seeing the same issue with pairs of 14500's that I am using. I am using pairs of 18650's in this mod and pairs of 14500's in this mod.

All of my batteries have been used in pairs since the day I bought them. Never mixed. I mark all my batteries so there is no confusion about pairs. Always used in pairs, always charged in pairs.

Today I will go buy a new TR-001. If the problem goes away, I'll have the answer. If not, back to troubleshooting.

Thanks again, guys.

JJ

 

[KeithB]

It's likely that your live battery was dropping to about 2.8 volts under vaping load, and the other was dropping to cut off (about 2.5 volts), stopping you from vaping any more. Not a good thing to vape to cutoff, but sometimes it just happens
In your case, the mismatch wasn't that much. It really wasn't 3.4 Vs zero.

That what I had figured; that they weren't that far off in voltage so it wasn't too bad. It was really only a problem with the 14500s I was using in a 5V regulated mod. The good thing about a regulated mod is you get the same vape as long as your batteries hold out; the bad thing is you get no warning in the vape before your batteries die. The 14500s were not enough to get me through a whole day.

Two 18650s in series in a regulated mod (VV this time) not only last me all day, they last me two full days of fairly heavy vaping with two or three hours to spare. I did run them all the way down a couple of time just to see how long they'd last and got similar results; now I just use them for two days and swap them out for another pair while they charge.

Anyway, they point I really wanted to make is that the whole point of keeping batteries in pairs; buying them in pairs, using them in pairs, charging them in pairs, storing them in pairs and not mixing batteries in pairs; is to try and have your two batteries in as near identical condition as possible. Two batteries that age together should keep close to the same internal resistance as they age. When one of the batteries starts to behave differently than the other, say taking longer to charge, then they may be starting to differ from one another enough to where it may be cause for concern. I feel that any time your batteries start to change in performance, either longer charge time, shorter vape time, getting warmer than they used to, then it's time to start thinking about new batteries.

Having said all that, it could be the charger. There's a good thread on using your multi-meter over on the CandlePower forum that also discusses how to check your charger. I just prefer to err on the side of caution when it comes to Li-Ion bateries.

 

[JimmyJet]

I feel that any time your batteries start to change in performance, either longer charge time, shorter vape time, getting warmer than they used to, then it's time to start thinking about new batteries.

Having said all that, it could be the charger. There's a good thread on using your multi-meter over on the CandlePower forum that also discusses how to check your charger. I just prefer to err on the side of caution when it comes to Li-Ion bateries.

Well said Keith. As someone said in another thread, is saving a few dollars worth risking an explosion in your face?

As of right now I have a brand new TR-001 charger. I will report back later when I see some results.

JJ

 

[JimmyJet]

Hey folks, just a brief update. After several days of using a new charger, I believe my old charger was the problem. I started using the multi-meter before and after every charge, which I should have been doing in the first place. Battery pairs are going on the charger around 3.8V, charging evenly, and coming off the charger at around 4.2V consistently.

The important lesson here, use the multi-meter. It only takes a few seconds to test voltage before and after a charge.

Thanks for all the help,

JJ

 

[DaveP]

I use a TR-001 charger. It's not a bad charger for the money and it's dual channel. I suspect your other charger was dual channel also since you said one charged before the other.

FWIW, I fired up my cheapo box mod that uses two 14500 batteries today. It's been sitting in a box unused for a couple of months. One battery read 4.06 and the other read 4.08. You should have similar performance from two good batteries and a good charger. I don't use my box mod (after it's sat unused for a time) or charge my batteries without checking voltages first.

Using the on-off switch to break the circuit on a mod when it's out of sight is also a good idea.