Eneloops charging at 1A/2A?

Hi
I'm about to dive into the eneloop arena for my AA/AAA torches, and I'm currently deciding on kit.
I have a duracell 1hr Quick charger for AA's already, which shows a rating on the back for Ni-Cds of 1.4v @ 1A and Ni-mh of 1.4v @ 2A.
I have used some specific 1.2v Duracell 2hA batteries with this in the past and they didn't seem to last very long (lifetime wise not runtime wise).
Does anyone else charge eneloops at 2A and if so what kind of performance / life are you getting? If I charge them in Ni-Cd mode, I presume that my charger just provides less current (1A) and therefore they will charge slower/last longer? Can anyone advise on this point?
Also the charger has an auto cut out will this be affected if I run in the wrong mode? I can't see that it will from my own knowledge.
Thanks for any suggestions.
Scott.

Eneloops absolutely rock!.

They are much better than NiCads, and Much better than most NiMH for most applications.

However NiMH batteries, and eneloops for sure require a more intelligent charger. Their full charge status is harder for the older technology to detect, and a timer based solution is just going to burn your battery up over time ( I'm guessing that the charger you have IS a timer based NiCad charger, and that is why it ruined your batteries quickly, if you put a battery on a timed charger that still has alot of juice left in it, you end up overcharging it to the extent that it wasn't dead which just causes breakdown and heat..

You need to invest in a charger.

That is my recommendation.

There is no way to use the charger you are talking about and achieve good results over a long time, so if your worried about life of the battery as you mentioned, forget the NiCad charger.

Heres a tip (if I remember correctly), you can charge Nicads in a NiMH charger, but it's not good to try to charge a NiMH in a NiCad charger.

It's been a while since I read about that stuff, but if memory serves, your plan is not a great one.

Get a dedicated charger.

I charge my eneloops at 1Amp, but I think 2 would probably be ok, although, whats the hurry, 1 amp will probably make the life of your batt. longer, especially if your using the wrong charger!

I charge my Eneloops at 1 amp. They not only survive but thrive at this charge rate. You can charge them at 2 amp which is harder on the cells and does not give you as good of a charge. I have not noticed 2 amps damaging my Eneloops in real life but this does not mean it is not happening. I just think 2 hours is not that long to wait to protect my little buddies.

Timed chargers are not good for NiMH, I recommend that you look at getting a new one. I use the Duracell CEF23, which I found on Ebay for about $17 shipped (with two Duraloops included too). It charges at 550mA and seems to terminate pretty reliably for me.

scott2907 said:

Hi
I'm about to dive into the eneloop arena for my AA/AAA torches, and I'm currently deciding on kit.
I have a duracell 1hr Quick charger for AA's already, which shows a rating on the back for Ni-Cds of 1.4v @ 1A and Ni-mh of 1.4v @ 2A.
I have used some specific 1.2v Duracell 2hA batteries with this in the past and they didn't seem to last very long (lifetime wise not runtime wise).
Does anyone else charge eneloops at 2A and if so what kind of performance / life are you getting? If I charge them in Ni-Cd mode, I presume that my charger just provides less current (1A) and therefore they will charge slower/last longer? Can anyone advise on this point?
Also the charger has an auto cut out will this be affected if I run in the wrong mode? I can't see that it will from my own knowledge.
Thanks for any suggestions.
Scott.

Click to expand...

It's generally OK to charge Eneloops at a 1 hr/2 A rate, but they will probably get a little warm at the end of charge, and this will likely cause them to wear out a bit quicker than if charged at a lower rate.

The trouble with using the NiCd 1 A setting may be that the timer cut-out operates before the batteries are fully charged. This is what happens with my GP PowerBank 1 hr charger. It has the same NiCd/NiMH switch, but when on the NiCd setting the charge stops after 1.5 hours before the Eneloops reach a full charge.

The first post in this thread shows a charging graph for an Eneloop at 2 A on the PowerBank charger. It shows the classic charging profile for an NiMH cell including a strong end of charge signal where the voltage drops slightly. Bear in mind that this was for a single cell and with four cells in the charger they get a little warmer (but not too much).

I do not have direct experience of the Duracell charger, but many would say a charger like your Duracell 1 hr charger is a good choice for Eneloops.

Thanks for your answers. It looks like there are a few conflicting opinions there. What is the usual / speific mechanism for charging eneloops / Nimh batteries as opposed to NiCds?
I know that when I worked with NiCad technology in the 80's it was just a matter of waiting for the battery voltage to "top out". Is that the case with NiMh now?

scott2907 said:

Thanks for your answers. It looks like there are a few conflicting opinions there.

Click to expand...

My opinion is the correct one

What is the usual / speific mechanism for charging eneloops / Nimh batteries as opposed to NiCds?
I know that when I worked with NiCad technology in the 80's it was just a matter of waiting for the battery voltage to "top out". Is that the case with NiMh now?

Click to expand...

The mechanism for charging both NiMH (including Eneloops) and NiCd is the same. Two basic charging protocols are available:

1. Charge at a low rate, 0.1C or less, for a timed period of about 16 hours or until the voltage tops out;
2. Charge at a high rate, monitoring voltage and/or temperature, and stop charging either when the voltage starts to decrease (−∆V), or when the rate of temperature rise crosses a threshold (dT/dt), or some combination of these and similar factors.

The main difference between NiCd and NiMH is that NiMH exhibits a lower −∆V than NiCd and so must usually be charged at higher currents to get a good end of charge signal. Against this is that NiMH cells usually get hotter during charging at high currents than NiCd. But good cells like Eneloops are designed to last many charge cycles in spite of this.

Most of the time the method 2 fast charge is recommended, but the slow charge method 1 is useful from time to time for battery conditioning.

Thanks Mr Happy that sounds good to me. From what I've found on search, it would seem that most people chrage at <1A for Eneloops. Therefore I think I'll try out my charger in NiCd mode first and see if the end detection works ok, and just continue in 1A mode from there if it does. Since most (cheaper) chargers can spot a minute -dV at <1A this one should be able to. I'll check it with my multimeter first - it's been good to get a second opinion on it. Cheers.

scott2907 said:

Thanks for your answers. It looks like there are a few conflicting opinions there. What is the usual / speific mechanism for charging eneloops / Nimh batteries as opposed to NiCds?
I know that when I worked with NiCad technology in the 80's it was just a matter of waiting for the battery voltage to "top out". Is that the case with NiMh now?

Click to expand...

No, it works differently and the detection is alot more sensitive, generation of heat at full capacity is the one of the most reliable indicators, the voltage does differnt things than NiCad.

There are some good articles about this, Il post em if noone else does, but I gotta jump in the shower now or il be late, see yas.

Thanks Mike.
I've done a bit of reading and you guys/girls and Wiki suggests that charging is optimum at 1C/hr. So I guess its best to match the C to the charger. Since the hydride mode on my charger states that it runs at 2A some I'd be optimum if I chose 2000mAh batteries. There's some 2Ah eneloops on DX right now for a very reasonable price, so I'll get those. Then I wouldn't need to run in Ni-Cd mode.

For what it's worth, there are about 4AA eneloops I have which get used very regularly, these I charge at 1C (2000mA) in my Maha C9000.

I have had no problems at all, the cells are performing great, although the C9000 is an excellent charger, so I trust charging them at 1C with this thing

Nice thread! I usually just charge my eneloops at 1A but it would be interesting to see what capacity i get if i charge em at my chargers max (1.8A)... Ill give it a try!

scott2907 said:

There's some 2Ah eneloops on DX right now for a very reasonable price, so I'll get those.

Click to expand...

DX only sells fake eneloops, don't buy them there.

I charge all my ni-mh batterys at .5 C. It takes about 2 hrs for completely drained batterys. Mine are used in flash lights and are run till they go dim anyway. So 1a is what I use for AA eneloops.
Billy

Loads of good info in this thread: https://www.candlepowerforums.com/threads/178667 Silverfox appears to recommend charging at 0.1C for 16 hours or 0.5-1.0C with good end-of-charge detection.

Already got my new AA eneloops and I have just purchased a Powerex MH-C9000.
This is where I need some help.

Should I use the 'break in' function on my MH-C9000 on the eneloops first ?
Is 1A the best charging rate that I should charge my eneloops at ?

I am new to all of this and I want to start off ' doing the right thing ' , to prolong my batteries life and to get the best out of them.

Any help/tips/suggestions you can give me would be appreciated.

scott2907 said:

Thanks Mike.
I've done a bit of reading and you guys/girls and Wiki suggests that charging is optimum at 1C/hr. So I guess its best to match the C to the charger. Since the hydride mode on my charger states that it runs at 2A some I'd be optimum if I chose 2000mAh batteries. There's some 2Ah eneloops on DX right now for a very reasonable price, so I'll get those. Then I wouldn't need to run in Ni-Cd mode.

Click to expand...

2 A is fine for eneloops. As other say there's other issues choosing the NiCd setting. It might be fine or it might fry your cells. It's a matter of luck. If the charge current is 700 mA, 1 A, 1.5 A or 2 A I don't believe makes much of a difference - at least in a good charger.

The eneloops even can take much higher charging rates if it's required although you then wear them more. If in a hurry and I don't have other cells available I've sometimes charged my eneloops with 3.4 A and no fried cells.

K31th said:

Already got my new AA eneloops and I have just purchased a Powerex MH-C9000.
This is where I need some help.

Should I use the 'break in' function on my MH-C9000 on the eneloops first ?
Is 1A the best charging rate that I should charge my eneloops at ?

I am new to all of this and I want to start off ' doing the right thing ' , to prolong my batteries life and to get the best out of them.

Any help/tips/suggestions you can give me would be appreciated.

Click to expand...

It's a matter of taste. Your eneloops should should be up to full capacity in 2-3 cycles anyway. But I'd say it's a good idea to do a discharge to fully discharge them after the first few uses before charging them and then once in a while but not every time. More like every every 10-20 charges. Of course you can baby them even more but is it really worth all the trouble to get a handful more cycles more out of several hundred?

altis said:

Loads of good info in this thread: https://www.candlepowerforums.com/threads/178667 Silverfox appears to recommend charging at 0.1C for 16 hours or 0.5-1.0C with good end-of-charge detection.

Click to expand...

Nice referral, thanks. Loads of good information there. That thread should be sticky

It comes as a bit of a supprise to me that noone seems to have made the "perfect" charger. I know that each cell is different but a lot of threads seem to indicate that the specified or suggested termination methods just arn't working as indicated, or arn't suitable. It would seem that an "intelligent" charger with a mixed algorythm of -dV, Max V, dTemp and chemistry knowledge could be a suitable jack of all trades and be the best possible charger for various cells. If I put my mind to it I could probably build one. I just suffer from a massive amount of apathy really!

All your replies have been very reassuring that the charger I have is suitable for new chemistry NiMH. Thanks for the tip off on DX too, I'll go with a UK supplier I've found with genuine HYBRIOs. Threads here seem to suggest that they are good cells, and the price for a box of 10 is quite cheap here.

scott2907 said:

It comes as a bit of a supprise to me that noone seems to have made the "perfect" charger. I know that each cell is different but a lot of threads seem to indicate that the specified or suggested termination methods just arn't working as indicated, or arn't suitable. It would seem that an "intelligent" charger with a mixed algorythm of -dV, Max V, dTemp and chemistry knowledge could be a suitable jack of all trades and be the best possible charger for various cells.

Click to expand...

Maybe because it would be really expensive and everyone has a different idea of the perfect charger.

My Sanyo NiMH charger charges AA eneloops at the rate stated in the Eneloop datasheet, terminates the charge at the ideal 1/minute dT limit and then turns off the charging entirely. Perfect enough for me.

Hello Scott2907,

I actually use a near "perfect" charger. The brand name is Schulze.

Tom