Strange problem with Eneloop AA batteries and BC-900

[Splashy]

Hi,
A couple of months ago I purchased a LaCrosse BC-900 charger and several sets of Eneloop AA batteries.
I was told it was best to charge the Eneloops at 200ma so that's the current I've been using.
I've noticed that on every charge, 3 batteries out of 4 finished charging while the last one kept charging for a much longer time until it finished charging.
It was always the battery in slot no. 2.
The last time it happened I tried removing the battery from the slot and placing it in in another slot, and another time I placed it in the same slot.
In both cases the display changed to "full after I had removed the battery and placed it in the charger again.
Can you tell whether it's a problem with the charger? I thought it might be a problem with the batteries but this happened with quite a few sets of batteries which makes me doubt it. Plus it always happened with slot no. 2.
Any ideas would be appreciated.
P.S. I just ordered a Maha C-9000 charger. What current is best for charging the AA Eneloops with it and also with the BC-900?
TIA,
Splashy.

 

[Mr Happy]

Hi,
A couple of months ago I purchased a LaCrosse BC-900 charger and several sets of Eneloop AA batteries.
I was told it was best to charge the Eneloops at 200ma so that's the current I've been using.
I've noticed that on every charge, 3 batteries out of 4 finished charging while the last one kept charging for a much longer time until it finished charging.
It was always the battery in slot no. 2.
The last time it happened I tried removing the battery from the slot and placing it in in another slot, and another time I placed it in the same slot.
In both cases the display changed to "full after I had removed the battery and placed it in the charger again.
Can you tell whether it's a problem with the charger? I thought it might be a problem with the batteries but this happened with quite a few sets of batteries which makes me doubt it. Plus it always happened with slot no. 2.
Any ideas would be appreciated.
P.S. I just ordered a Maha C-9000 charger. What current is best for charging the AA Eneloops with it and also with the BC-900?
TIA,
Splashy.

Hi, and welcome to CPF :welcome:

I'm afraid you have stumbled over a problem that is the subject of much debate here on CPF.

Who advised you that it was best to charge at 200 mA? That was really not good advice.

My advice is to charge your eneloops (AA cells) at 1000 mA. What is happening at 200 mA is that the current is too low to tell the charger when the batteries are fully charged and it can stop charging. At 1000 mA this detection is much more reliable.

For eneloops and for all NiMH cells, take the capacity, divide it by two, and use that charging current in mA.

 

[Splashy]

Hi Mr Happy and thank you for the welcome and the quick reply.
So I understand that the problem was caused by charging at too low a current and that the charger and the batteries are actually ok, right?
I was told on another forum that charging the batteries at 200 mA would be healthier for the batteries rather than charging them too fast.
Would charging the batteries at 1000 mA be healthy enough for the batteries? Meaning healthier than charging them at 2000 mA for example?
How long would it take to charge 4 Eneloops at 1000 mA?
Thanks again for your help, much appreciated.

 

[VidPro]

i would just point out this

I was told it was best to charge the Eneloops at 200ma so that's the current I've been using.

and say this opinion
charging eneloops at .1C or this 200ma would not damage the cells, but the Lacross 900 is NOT doing that.
the 900 is Pulsing 1000ma 1/5th of the time (averaged 200ma), and that is not the same thing.

the 200 part is well within a "slow" rate charge , the 1000ma is not. the rest i refuse to comment at this time
and i did not have sex with that woman, oh wait yes i did.

 

[DepotEco.com]

We only suggest you charge the eneloops with the eneloop charger for this very reason.. We have had sevral people tell us that using the Lacrosse charger seems to shorten the life of there loops. So after checking with our reps at Sanyo we are advising folks to stick with the eneloop, or other NiMH charger that simply senses the current needs and fills the cells.

While we to love our Lacrosse charger some times to many choices is not the best thing.. Keep it simply.. and you will be very happy with the performance of your eneloops..

Also on those lines we have folks trying to charge NiMH batteries with there PowerGenix NiZn charger.. This will not work because the NiZn from PowerGenix runs at 1.6 volts. And is a diffrent battery chemistry. So When you put a NiMH in a NiZn Charger the Charger shuts off as it thinks the NiMH cell is dead..

We have had great luck with the plane old NiMh chargers from Rayovac and energizer as an alternative to the eneloop charger..

Hi,
A couple of months ago I purchased a LaCrosse BC-900 charger and several sets of Eneloop AA batteries.
I was told it was best to charge the Eneloops at 200ma so that's the current I've been using.
I've noticed that on every charge, 3 batteries out of 4 finished charging while the last one kept charging for a much longer time until it finished charging.
It was always the battery in slot no. 2.
The last time it happened I tried removing the battery from the slot and placing it in in another slot, and another time I placed it in the same slot.
In both cases the display changed to "full after I had removed the battery and placed it in the charger again.
Can you tell whether it's a problem with the charger? I thought it might be a problem with the batteries but this happened with quite a few sets of batteries which makes me doubt it. Plus it always happened with slot no. 2.
Any ideas would be appreciated.
P.S. I just ordered a Maha C-9000 charger. What current is best for charging the AA Eneloops with it and also with the BC-900?
TIA,
Splashy.

 

[Marduke]

We only suggest you charge the eneloops with the eneloop charger for this very reason.. We have had sevral people tell us that using the Lacrosse charger seems to shorten the life of there loops. So after checking with our reps at Sanyo we are advising folks to stick with the eneloop, or other NiMH charger that simply senses the current needs and fills the cells.

The problem is the wrong choice of charge current. The charger itself works fine when used with the correct settings.

 

[DepotEco.com]

The problem is the wrong choice of charge current. The charger itself works fine when used with the correct settings.

Right.. That's My Point. If you know the right current then your good to go.
But most folks don't and thus the damage to there loops .

 

[Mr Happy]

Hi Mr Happy and thank you for the welcome and the quick reply.
So I understand that the problem was caused by charging at too low a current and that the charger and the batteries are actually ok, right?
I was told on another forum that charging the batteries at 200 mA would be healthier for the batteries rather than charging them too fast.
Would charging the batteries at 1000 mA be healthy enough for the batteries? Meaning healthier than charging them at 2000 mA for example?
How long would it take to charge 4 Eneloops at 1000 mA?
Thanks again for your help, much appreciated.

The problem is with the charger and not with the batteries. Eneloops and other NiMH batteries can accept a wide range of charge currents from 200 mA up to 2000 mA, but the charger is not always able to control the charging properly when the current is too low.

Charging the batteries at 200 mA repeatedly when the charger does not stop the charging properly can actually damage the batteries due to overcharging.

Yes, charging at 1000 mA is perfectly healthy for the batteries. It will take about two hours to charge eneloops at this rate. A charge rate of 2000 mA is the highest recommended, but I personally tend go with 1000 mA unless I am in a hurry.

 

[Splashy]

Thanks for all your replies.
About charging the Eneloops at the wrong current, I was following the advice of people from another forum.
I am willing to read and learn about taking good care of my batteries.
I'd rather use an advanced charger rather than Sanyo's charger simply because I'm a quick learner and I like computers and I'm good at it too and I also like gadgets and appliances (and I got plenty of them ).
You only have to tell me once. I will charge my Eneloops at 1000 mA from now on
Thanks again to everyone for your advice.

 

[Marduke]

Right.. That's My Point. If you know the right current then your good to go.
But most folks don't and thus the damage to there loops .

That's user error though, not charger error.

 

[VidPro]

now i can finish my comment

Charging at 1000 will allow the 900 to SEE the signal it needs to see to terminate the charging. The cells V-drop (voltage going down at overcharge).

charging at the digitally averaged 200ma setting, a pulsed 1000ma 1/5th the time , the charger may Not see the signal it needs to see to terminate the charge.
and
Because it is hitting the cell at 1000ma anyways, it still hits it harder than a slow rate charge would. **


** in pulses.

 

[Splashy]

Hi,
Now I'm worried I might have damaged my batteries by charging them at 200ma.
My question is, how do I determine whether they're damaged?
Is running a test cycle on my BC-900 good enough indication?
Meaning if the batteries capacity is ~2000ma, does it mean that the battery is ok and that I haven't damaged it?
TIA for any ideas.
Splashy.

 

[VidPro]

thier eneloops dont worry about it
yes 2000ma close enough.

 

[Splashy]

Great, that's good to know. Thanks for reassuring me, VidPro. :thumbsup:

 

[MarioJP]

I just got the BC-9009 charger. Very nice charger that actually tells you whats going on. Whats cool about it is that you can adjust the charging rates.

So I decided to charge the batteries at its closest rated capacity but never exceed it.

Charging at 200ma is not only slow but can miss the termination signal as well.

I suppose i can use the 200mah as a top off charge??.

Also how sensitive is a nimh battery from being overcharged. I figured out a sweet spot for me which is between 1C-1.8C depending of the capacity of the battery.

AA 2000mah and up 1C-1.8C (1.5C-1.8C can only charge 2AA-AAA at a time in 1 and 4 slots only.)
AAA 800-1000mah 0.7C

I do notice that fast charging causes a strong signal termination. Sometimes it terminates too soon. When I test the battery in a battery tester not all the lights are lit.

 

[Mr Happy]

Also how sensitive is a nimh battery from being overcharged. I figured out a sweet spot for me which is between 1C-1.8C depending of the capacity of the battery.

1.8C on a 2000 mAh cell would be a charging current of 3.6 A. I don't think you mean that.

 

[MarioJP]

3.6A? The cells hardly get hot, warm yes hot no. The application that I use these cells draws about 2C.

I keep the charging rate close to the battery's rated capacity.

 

[Marduke]

Well, since the 15 minute charger is faster than that, and the BC-9009 can't go that high, just what do you use to charge so fast?

And to reiterate, 1C would be much healthier...

 

[TakeTheActive]

I just got the BC-9009 charger. Very nice charger that actually tells you whats going on. Whats cool about it is that you can adjust the charging rates...

IMHO, you'll LOVE the La Crosse BC-900/BC-9009 *UNTIL* you use the Maha MH-C9000. (I did. )

...I suppose i can use the 200mah as a top off charge??.

IMO, *ONLY* if you MANUALLY time it. The BC-900/BC-9009 can miss -DeltaV at <0.5C Charge Currents and push up to 3300mAh into a cell @ 200mA.

...AA 2000mah and up 1C-1.8C...

• 1.0C: 2000mA (C9000 Maximum)
• 1.8C: 3600mA (not possible!)

 

[MarioJP]

Cordless soldering iron that takes 4AA. And also use these batteries for my mobile usb charger.


Since the 2000mah battery takes about an hour to charge at 1.8C. The current cuts off when the ma readings is nearing 2000.

Did thought about maha charger but that's a big charger. Plus it checks for impedance, and is a bit expensive compared to the bc-9009. The prices can change though.