# QUESTION ABOUT RECHARGABLE AA BATTERIES.



## surapon (Dec 6, 2014)

Dear Teachers and Friends.
Yes, I have so many NIMH AA Batteries by Sanyo Eneloop ( 40 of them) about 6-7 years for all my flashes, and never fail + super happy man, and rotate for use and recharge all the times.
The Big question that I want to ask = How long( Minutes) that I must leave the Batteries in the charger, after It complete Charge Light Come on ( Green Lights)= To get 100% charge ?

Past 6-7 years, I let it continue charging for 30 more minutes, after the green light on = Wrong method ??

Thanks you Sir/ Madam.
Have a great weekend.
Surapon


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## Mt Spokane Photography (Dec 6, 2014)

It depends on the charger, but batteries tend to be less than fully charged when the green light comes on.

I have about 20 -30 of the eneloop batteries, and over the past 5 years or more, none have failed. I've managed to forget them, and leave them in the charger for a month or more with no issues. I have my chargers on a battery backup just because they are on the same power strip as my computer.

I'd never have a concern about leaving the batteries on a smart charger for a few days.


Here are some FAQ's. Thomas Distributing is one of the premiere battery sellers and they seem to have reasonably accurate knowledge.

http://www.thomasdistributing.com/Battery-and-Charger-FAQ_ep_46-1.html


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## AprilForever (Dec 6, 2014)

6-7 years? I am going to have to get me some...


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## surapon (Dec 6, 2014)

Mt Spokane Photography said:


> It depends on the charger, but batteries tend to be less than fully charged when the green light comes on.
> 
> I have about 20 -30 of the eneloop batteries, and over the past 5 years or more, none have failed. I've managed to forget them, and leave them in the charger for a month or more with no issues. I have my chargers on a battery backup just because they are on the same power strip as my computer.
> 
> ...




Thousand Thanks, Sir, Dear teacher, Mr. Mt Spokane.
You have clear answer for my question, plus a great link too.
Have a Great Weekend, Sir.
Surapon


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## Mt Spokane Photography (Dec 6, 2014)

AprilForever said:


> 6-7 years? I am going to have to get me some...


 
I'd strongly recommend them. I've used lots of other high end NiMH batteries, and they fail much sooner.

The number of recharges is a big factor. By having a lot of batteries, there are relatively few recharges. I use them for more than photography, and since they store with a 70-80% charge for a year, Some of them have been only charged a dozen times.

The charger is also a big factor. A 15 minute charger will make toast of them. I use a slow charger that takes a few hours.


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## surapon (Dec 6, 2014)

AprilForever said:


> 6-7 years? I am going to have to get me some...



Yes, Dear Friend, Mr. AprilForever.

Please get these Sanyo Eneloop or Panasonic Eneloop ( I think Panasonic buy or get Pattant from Sanyo), For All your Flashes usage = You will love them, Yes It cost more than the Batteries from Walmart.
I give Sanyo Eneloop grade = A++

http://www.amazon.com/Sanyo-Eneloop-Charger-Rechargeable-Batteries/dp/B003VLAEPQ/ref=sr_1_15?s=electronics&ie=UTF8&qid=1417887197&sr=1-15&keywords=eneloop

Enjoy.
Surapon


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## dswtan (Dec 6, 2014)

Love Eneloops! Night and day difference to traditional NiMHs. In the US, Costco is a good source, especially when occasionally on offer. You tend to end up with a myriad chargers that way though, since they are always bundled (like Surapon's Amazon link shows.)


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## Mt Spokane Photography (Dec 6, 2014)

dswtan said:


> Love Eneloops! Night and day difference to traditional NiMHs. In the US, Costco is a good source, especially when occasionally on offer. You tend to end up with a myriad chargers that way though, since they are always bundled (like Surapon's Amazon link shows.)


 
I've haven't seen them bundled at Costco in a couple of years, but they combine AA and AAA, and I only use the AA, so I am reluctant to pay for the ones I won't use.

I did check them at my local Costco about a month ago, but did not like the mix of sizes. I have enough for now in any event.


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## ajfotofilmagem (Dec 6, 2014)

Dear friend Surapon.

"Smart" battery charger will cut off the power immediately after turning on the light indicating "battery full". Keep the batteries a few more minutes on the smart charger is innocuous.

If you want to squeeze up to fit the last bit of energy in each battery, charge one at a time. Charging 4 batteries at the same time will result in approximately 0.01 volts less on each battery due to voltage drop in the transformer when used at maximum amperage permitted.


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## surapon (Dec 6, 2014)

ajfotofilmagem said:


> Dear friend Surapon.
> 
> "Smart" battery charger will cut off the power immediately after turning on the light indicating "battery full". Keep the batteries a few more minutes on the smart charger is innocuous.
> 
> If you want to squeeze up to fit the last bit of energy in each battery, charge one at a time. Charging 4 batteries at the same time will result in approximately 0.01 volts less on each battery due to voltage drop in the transformer when used at maximum amperage permitted.




Thank you, Sir Dear Teacher , Mr.ajfotofilmagem.
Wow, That are the great Idea to get more power from the Batteries by Charge one at the time.
And Thanks for the Infor of the Smart Charger, Which 6-7 years ago, All the Chargers that I have = Still Not Smart yet.
Have a great weekend, Sir.
Surapon


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## wopbv4 (Dec 6, 2014)

Hi Surapon,

I use eneloops all the time. I buy them in 50 packs (AA) at 4$ each.
What I do after the block of 12 batteries has been fully charged, I switch off the power to the adapter, but I leave the batteries in the adaptor. After 15 min when the batteries have cooled enough, I switch on the power again and I get another 30 min charge on top.
Having said that, I use 12 battery for each of my 600EX-RT, 4 in flash, 8 in battery pack and that combo gives me enough to work a full afternoon without fully draining the batteries, but they do need several hours of recharge thereafter. The above combo, compared to batteries in flash only, recharges about 3 times as fast, 4 seconds for full flash goes down to about one second. Is it worth the additional weight of the battery pack? For me yes, but each has to decide.

Hope this helps

Ben


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## Old Sarge (Dec 6, 2014)

Friend Surapon (and other Enloop users), what charger do you recommend with these batteries? I use some inexpensive rechargeable Interstate brand and matching charger but I only use them for household chores (earphones I use for TV since my hearing is going and I don't want to disturb my wife's enjoyment of shows, flashlights, etc.). Since I have read so many glowing recommendations on the Enloops, it may be time to try some of them. Probably a dozen or so AA and a few AAA would meet my needs.


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## ajfotofilmagem (Dec 6, 2014)

wopbv4 said:


> What I do after the block of 12 batteries has been fully charged, I switch off the power to the adapter, but I leave the batteries in the adaptor. After 15 min when the batteries have cooled enough, I switch on the power again and I get another 30 min charge on top.


If I understand correctly, you expect the batteries to cool after being charged, and then make a new charging? 
In this case, you will have no gain in battery duration, but will only shorten its lifetime, burning cycles uselessly. :-\

I recommend NOT recharge a battery that is already full. :-X


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## wopbv4 (Dec 6, 2014)

ajfotofilmagem said:


> wopbv4 said:
> 
> 
> > What I do after the block of 12 batteries has been fully charged, I switch off the power to the adapter, but I leave the batteries in the adaptor. After 15 min when the batteries have cooled enough, I switch on the power again and I get another 30 min charge on top.
> ...



Hi ajfotofilmagem,

please help me with this!

After I charge the batteries and let them cool down, I have measured the voltage and it is on average 1.1V. When I put them back in the (eneloop) charger, the light goes red and it charges for another half hour before light goes green. I take the batteries out, let them cool again and re measure, I get a voltage of 1.15 - 1.18 V.

Furthermore, with nearly empty batteries, it takes a long time for batteries to recharge in a 12 battery block, several hours. During the charge, the batteries do get warm, guess about 40 DegC , 105 deg F. I have been worried about this as I have heard stories of exploding batteries. From first hand experience, I had a battery in my Macbook Pro that became very hot and burned out.

I happy to take any advice

Ben


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## ajfotofilmagem (Dec 6, 2014)

wopbv4 said:


> ajfotofilmagem said:
> 
> 
> > wopbv4 said:
> ...


Whereas your volt meter is working properly, your batteries with only 1.1 volt are damaged, and will never be charged with the nominal capacity.

NI-MH batteries good quality should have actually 1.39 to 1.45 volt immediately after end the charging. I recommend making sure your charger is the intelligent type (and fully functional), avoiding overheating and premature deterioration of batteries.


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## wopbv4 (Dec 7, 2014)

ajfotofilmagem said:


> wopbv4 said:
> 
> 
> > ajfotofilmagem said:
> ...



Hi ajfotofilmagem,

thanks for the advice, you are 100% correct.
I used another voltmeter and indeed the batteries read 1.45 volt when fully charged. Another charge on a full battery does not change that reading, stays at 1.45 V.
So, the green red light can only be trusted in the case of (partially) drained batteries, not on full batteries. This is an important lesson for me.

As such, I retract my previous comments

Again thanks for your help

Ben


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## lion rock (Dec 7, 2014)

I charge them, 2 or 4 at a time in the Sanyo charger that comes with a battery set from BandH starting at about 7PM., until the next morning.
I tried charging them until the green light turns solid, and it seemed not to provide as much power as slow charge over night.
-r


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## Hjalmarg1 (Dec 7, 2014)

surapon said:


> Dear Teachers and Friends.
> Yes, I have so many NIMH AA Batteries by Sanyo Eneloop ( 40 of them) about 6-7 years for all my flashes, and never fail + super happy man, and rotate for use and recharge all the times.
> The Big question that I want to ask = How long( Minutes) that I must leave the Batteries in the charger, after It complete Charge Light Come on ( Green Lights)= To get 100% charge ?
> 
> ...



Dear Surapon,

SMART chargers tend to cut current flow/changing when the battery is reportedly full. My experience is that they rarely reached 100%. I have left my Sanyo Eneloop, Canon and Energizer batteries on the charger way longer than required, normally overnight with no problem. Other non-smart chargers may continue charging but not sure how they work.


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## surapon (Dec 7, 2014)

Hjalmarg1 said:


> surapon said:
> 
> 
> > Dear Teachers and Friends.
> ...




Thanks you, Sir, Dear Mr. Hjalmarg1
Have a great Sunday.
Surapon.


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