Using old and new eneloops together?

[LuxClark]

I know this is a basic question I probably know the answer to but I could not find details searching the site.

I have 3rd gen eneloops that are probably a year old. I have 16 each of AA and AAA. But I find I could probably use more so I thought of doubling what I have.

If I but new 3rd or even 4th gen eneloops and they end up getting used together, how bad is that for either battery? I don't think the current ones have had extensive use because I don't find myself recharging them often. But when I need several right away (especially on camping trips for headlamps), none are available.

I assumed I would just end up marking them to know the difference (and get another battery rack) and just manage. But would I be doing more work than I should?

Thanks!

 

[Etsu]

I think you're likely to see more variation in capacity between cells of the same age, than you will just because of a 1 year difference in age (assuming you don't abuse your cells too much). So, probably no concerns with mixing them.

Just check their voltages when they're almost drained together, to see if they're reasonably matched in terms of capacity (when the lowest cell hits 1.0v, the others should be under 1.2v, otherwise the lowest cell is significantly weaker than the rest). As with any multi-cell device, don't drain them to zero, but take them out when your device indicates low battery. Then you won't have any concern about reverse-charging.

 

[oKtosiTe]

It's always better to avoid mixing if at all possible. Personally I mark lookalike cells with a permanent marker to be able to tell them apart easily.

 

[LuxClark]

Thanks for the advice. No matter what, I'll be marking them to know the difference from old to new.

 

[mcnair55]

I have been mixing cells for the last 8 years or so in all applications except my digicam as i use a designated set of 8,4 in cam and 4 spares in the case.It has never caused me a problem but only thing i do is never mix makes.

I am not into all this anorak wearing using a multi meter milarky prefer to enjoy it rather than become an obsessive geek.

 

[Norm]

I am not into all this anorak wearing using a multi meter milarky prefer to enjoy it rather than become an obsessive geek.

Mixing Ni-mh you will probably get away with but I wouldn't try the same with Li-ion cells.

Norm

 

[oKtosiTe]

Mixing Ni-mh you will probably get away with but I wouldn't try the same with Li-ion cells.

Norm

I agree. It's perfectly safe and unlikely to even cause harm to the Eneloops, but marking different sets and at trying to use matched cells can only benefit cell health in the long run.
Not that I've never mixed 'loops in a pinch myself.

 

[mcnair55]

Mixing Ni-mh you will probably get away with but I wouldn't try the same with Li-ion cells.

Norm

Quite agree Norm i would never mix Li-ion cells either.

 

[SuLyMaN]

I've been mixing eneloops 2nd and 3rd gen on a daily basis for about 1 year. The only difference I see is that the older gen one gets recharged one hour earlier than the newer one. Then again it really does not matter on my 5 dollar charger bought off eBay which takes 10 hours to charge depleted eneloops. The channels are individual though.
Edit: I guess the charge time has to do with the older one having less capacity.

Sent from my GT-S5660 using Tapatalk 2

 

[mcnair55]

I've been mixing eneloops 2nd and 3rd gen on a daily basis for about 1 year. The only difference I see is that the older gen one gets recharged one hour earlier than the newer one. Then again it really does not matter on my 5 dollar charger bought off eBay which takes 10 hours to charge depleted eneloops. The channels are individual though.
Edit: I guess the charge time has to do with the older one having less capacity.

Sent from my GT-S5660 using Tapatalk 2

I think i would have to agree,mine take perhaps an extra 30 minutes sometimes.I was eyeing up a charger in Tesco today,charges 2 or 4 cells at a time complete with 4 Tesco AA eneloop types for reasonable money.

 

[Dimt]

Should not be a problem as long as you recharge with a charger that independently charges each cell.

 

[Lampbeam]

I'm glad to hear it's alright to mix old and new NiMH. My batteries are four years old and not low self-discharge. They were neglected for over a year and allowed to discharge. Now I have a bunch of batteries with different mAh. Measuring mAh is not practical. So what I am doing with my 5D Maglite is running a quintet of D batteries until the light dims and then testing them in a battery tester. One of them tested questionable so I know that one probably has lower mAh. What I can do is replace it with a battery from my stash of old D NiMH until I get one that hangs in there with the rest of the quintet. One interesting thing about this observation is that four of the batteries tested good on the battery tester. Therefore I would hypothesize that the fifth battery that tested questionable held the other batteries back somehow causing the flashlight to dim prematurely.

 

[Norm]

I'm glad to hear it's alright to mix old and new NiMH.

I never said it was OK, only that you're unlikely to have any dramatic problems.

Norm

 

[Lampbeam]

So it's not OK? Am I going to have to put on my anorak and get my multimeter out?

 

[Mr Happy]

Therefore I would hypothesize that the fifth battery that tested questionable held the other batteries back somehow causing the flashlight to dim prematurely.

Yes indeed, of course, for sure, no doubt about it. The weakest battery will run out and stop contributing, so now the light will be running on four batteries instead of five. What's worse is that the dead battery will be getting in the way and stopping the other four from working effectively. Even worse than that, the dead battery will get current pushed through it in a way it doesn't like, so it will get damaged.

There's a golden rule about NiMH batteries: if you put two or more in a light and run the light until it dims, you will have damaged one of the batteries. For best battery care you always have to take the batteries out and recharge before the light dims out.

 

[Lampbeam]

Yes indeed, of course, for sure, no doubt about it. The weakest battery will run out and stop contributing, so now the light will be running on four batteries instead of five. What's worse is that the dead battery will be getting in the way and stopping the other four from working effectively. Even worse than that, the dead battery will get current pushed through it in a way it doesn't like, so it will get damaged.

There's a golden rule about NiMH batteries: if you put two or more in a light and run the light until it dims, you will have damaged one of the batteries. For best battery care you always have to take the batteries out and recharge before the light dims out.

OMG! I'm a battery abuser. I had no idea what I was doing was causing my batteries to suffer. I e-wasted two more of them just tonight. What have I done!? What have I become!?

 

[Mr Happy]

OMG! I'm a battery abuser. I had no idea what I was doing was causing my batteries to suffer. I e-wasted two more of them just tonight. What have I done!? What have I become!?

The first time you do it the damage caused will be small and survivable. But such damage is cumulative. If you do it over and over you will certainly cause the weaker cell to fail prematurely.

 

[Dimt]

The strong survive the weak get weaker.

 

[Swedpat]

There's a golden rule about NiMH batteries: if you put two or more in a light and run the light until it dims, you will have damaged one of the batteries. For best battery care you always have to take the batteries out and recharge before the light dims out.

That seems strange. It should mean I would never make use of the batteries true capacity(and how to find out the useful runtime of a light without damaging a cell?). If that is true it means likely the most flashlight users regularly damage their NiMh batteries. In most cases I just don't know how long time I have used the light after the latest recharge, neither how long remaining runtime I can use. What I use to do is to take out the batteries in the same time I see the brightness declines(how many don't do the same?). This is easy noticable with many regulated lights, but impossible to see with other lights(even some regulated) where the brightness slightly drops. Big problems here...

 

[Etsu]

That seems strange. It should mean I would never make use of the batteries true capacity(and how to find out the useful runtime of a light without damaging a cell?). If that is true it means likely the most flashlight users regularly damage their NiMh batteries. In most cases I just don't know how long time I have used the light after the latest recharge, neither how long remaining runtime I can use. What I use to do is to take out the batteries in the same time I see the brightness declines(how many don't do the same?). This is easy noticable with many regulated lights, but impossible to see with other lights(even some regulated) where the brightness slightly drops. Big problems here...

Yeah, it's only true in the extreme. That is, if you have a 2xAA flashlight and run it until you have nothing but moonlight mode left, you may be hurting one of the cells. But, I regularly leave my batteries in my flashlight until I can't get anything more than medium-mode out of it. When I measure the cells, they're generally around 0.9v-1.0v. They haven't been reverse-charged or damaged. The batteries just can't deliver much current when they get that low, which is what causes the flashlight to dim, not the voltage level.

If you've got very badly mismatched cells, then you might be causing some damage to one of them before the flashlight gets very dim. But if they're reasonably matched, you'll be okay.