eneloops

[rockz4532]

i got some eneloops from amazon today, but have a oldie charger that doesnt have auto switch off. what is the charged voltage off-the-charger that i can measure to assume it is fully charged? the charger is CHM 24 and charges at 70mah per cell (140mah for 2 batteries, 2.8v)

 

[Mr Happy]

An Eneloop can be considered fully discharged when the voltage after resting is 1.2 V. It is fully charged when the voltage fresh off the charger is about 1.45 V or higher (but note this voltage will drop below 1.4 V after a few hours resting).

Now your charger charges at 140 mA (it is not correct to divide by two) and it fortunately happens that the timed 15 hour charge on that charger is almost perfect to fully charge Eneloop AA cells from empty. So when they are discharged, put them in the charger, wait 15 hours until the green LED comes on, and they will be done.

However, you should consider that in the long term there are better quality (so called "smart, fast") chargers that will do a better job of maintaining top performance of your Eneloops. You might think about upgrading your charger at some point if you will use your Eneloops a lot.

(Note: the CHM24 does not have the capability to charge AAA size cells.)

 

[rockz4532]

is that right? 15 hours times 140ma=2100ma, more than twice the capacity of the battery

 

[Black Rose]

Mr. Happy's info was for AA cells.

I guess you have 800 mAh AAA cells.

 

[Mr Happy]

is that right? 15 hours times 140ma=2100ma, more than twice the capacity of the battery

Yes, as Black Rose said, I was assuming AA size Eneloop cells. The Energizer CHM24 charger can only charge AA size NiMH or NiCd cells, either two or four at a time. It cannot charge AAA size cells.

 

[rockz4532]

Yes, as Black Rose said, I was assuming AA size Eneloop cells. The Energizer CHM24 charger can only charge AA size NiMH or NiCd cells, either two or four at a time. It cannot charge AAA size cells.

oh i didnt put that in the description, they are aaa cells, and im using magnet spacers in it

 

[Mr Happy]

oh i didnt put that in the description, they are aaa cells, and im using magnet spacers in it

In that case you will need to charge them for 7-8 hours, or until they get warm, whichever comes first. Stop the charging manually when the time is up. Don't charge them for too long because such small cells will be damaged by overcharging at that current.

 

[rockz4532]

In that case you will need to charge them for 7-8 hours, or until they get warm, whichever comes first. Stop the charging manually when the time is up. Don't charge them for too long because such small cells will be damaged by overcharging at that current.

ok thanks, but how do they get damaged by 140ma when most chargers are 300 or more? what if they are low power, but not completely flat (i.e. in a two way radio, when the batt meter goes :thumbsdow) then would it damage the aaa if it is charged for 8 hours?

 

[Mr Happy]

ok thanks, but how do they get damaged by 140ma when most chargers are 300 or more? what if they are low power, but not completely flat (i.e. in a two way radio, when the batt meter goes :thumbsdow) then would it damage the aaa if it is charged for 8 hours?

Well, two things. Firstly the chargers that use 300 mA or more are smart chargers that stop charging automatically when the battery is charged. Your charger is a simple timed charger that does not have the ability to sense when the batteries are full. Secondly, most chargers that can accept AAA cells have separate terminals for the AAA cells to connect to and use lower charging currents for those cells. Remember your charger is not designed for AAA cells and you are using it in a way not intended by the use of magnets.

 

[rockz4532]

hmm ok, when its at the 6.5 hour mark ill stop charging them. the old man wont let me buy a new aaa charger.

 

[yellow]

dont use chargers that need the cells put into in series; single cell (smart charger) is the way to go

else You loose most of the benefits You think You get from these cells.

 

[rockz4532]

heres a picture of my setup