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Eneloop batteries question

pontifex

pontifex

Lifer
Ok, so maybe I misunderstood, but aren't the Sanyo Eneloop batteries supposed to keep a charge for a very long time when not in use?

I have 4 batteries that I charged about a month ago and I just checked them with a battery charge checking device and they are completely dead.

Or will one of these devices not be able to correctly read the batteries' charge?
 
You are correct. They have a very low self discharge rate so they work great in low draw devices like remote controls, etc. Plus, they can be sold as pre-charged since they retain a high percentage of capacity even on the shelf for a year. Check out Duracell pre-charged, the ones with the white tops are rebadged Eneloops. The gray tops are rebadged Rayovacs I think. I found the "duraloops" at Target.

After reading the OP, It sounds like you are having a problem with the Eneloops. I'm not sure about the charging issues. I guess the first paragraph is just restating what you already knew. I have always used the Eneloop charger because it came with the batteries figuring it was the least likely to wear out the batteries faster.
 
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Ksyder said:
You are correct. They have a very low self discharge rate so they work great in low draw devices like remote controls, etc. Plus, they can be sold as pre-charged since they retain a high percentage of capacity even on the shelf for a year. Check out Duracell pre-charged, the ones with the white tops are rebadged Eneloops. The gray tops are rebadged Rayovacs I think. I found the "duraloops" at Target.

After reading the OP, It sounds like you are having a problem with the Eneloops. I'm not sure about the charging issues. I guess the first paragraph is just restating what you already knew. I have always used the Eneloop charger because it came with the batteries figuring it was the least likely to wear out the batteries faster.
Click to expand...

I always use the charger that came with the batteries (I don't know if any of the other chargers I have will be ok to use with them?)

I forgot I had a spare pair of Eneloops in my laptop bag for my wireless mouse (don't use the laptop very much or often). I just tested them and they are fully charged and have been there for many months.

I bought the kit from Costco awhile back and I'm pretty sure the batteries in the laptop bag were from the kit. I also bought 1 or 2 packs from amazon a few months ago and I'm pretty sure these are the ones I tested as no charge. Maybe I got a bad batch?
 
Hmm... that sounds pretty strange. I guess I would try to charge them up and run them dead a few times and see if they hold a charge. If not, get rid of them. I've never really had a problem with them, but then again, they do have less capacity than your average Ni-mh battery out there, and it is a trade off in terms of capacity vs. self discharge rate, so maybe they just weren't charged up fully?

I'm not a battery nerd so I can't say for sure, I bought eneloops because of their reputation and performance characteristics. I can't really speak about the use of testing equipment, different chargers, charging rates, etc.
 
what device? any good charger costs more than 30 dollars alone.
dodgier chargers...can't measure jacksh*t.
 
huh I've been wondering what the deal is with these batteries. We've been selling a lot of them lately. Never bothered to research them, but I did wonder why so many people were picking up packs of them.
 
Locut0s said:
WTF. That's taking your batteries seriously!

Well I guess we can be thankful there are crazy people out there willing to put this kind of time into research like this so that some good solid numbers are out there. Beats me what they get out of it though.
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you should see how they measure flashlights🙂 some people benchmark videocards, some people benchmark flashlights hehe
super high end flashlights are kinda neat. its only now with ever increasing led tech that its become actually interesting.
 
Check them with a voltmeter, if you've got one. Admittedly, I don't know much about dedicated battery testers, but it's possible that if it's meant to measure alkalines (1.5V), it might think that a regular NiMH (1.2V) is dead.


And definitely use a good charger. Rapid charging will cause a lot of heat generation, and it's hard on the batteries. (But of course that means that you'll end up buying more cells to replace the dead ones = more money for the manufacturers. :hmm🙂
A good charger will be more expensive, but in any case, given the long life expectancy for (good quality) NiMH cells, it'll still end up paying for itself.
 
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It is best to use a charger that is designed for the batteries. Batteries have very specific charging requirements if you want to get the best performance from them.

to charge eneloop this is what a charger I would use would do:
Battery inserted and temperature measured .
Wait 4 seconds for cell to stabilize.
Battery is discharged through resistor until cell reaches .85V
Charge at 1.03V 220Khz .48A until cell measures 1.0V. If cell fails to reach 1.0V in 30 minutes charging is aborted.
Once at 1.0V charge at 1.18V 125Khz .85A until temperature exceeds .5C per minute.
Finish with 1.36V 150Khz 20ma until cell reaches 1.29V .
Charging aborts if cell reaches 50C or 1.65V.


Most of the cheap chargers are no more than a power supply set at 1.3Vdc with a diode .
 
Like I said, I only use the charger that came with the Eneloop kit from Costco.

The battery tester I was using could read the charge of other Eneloops, so I know it isn't the tester at fault.

The Eneloops just had no charge. I charged them overnight and just tested them again and now they show full charge. Let's see how long the charge lasts.
 
what battery "tester"?

any free enloop charger is going to be of dubious quality, i doubt even costco could sell a battery set with a decent charger without their customers facing a bit of price shock. bundled chargers are likely just 5 dollar cr@p.
 
Modelworks said:
It is best to use a charger that is designed for the batteries. Batteries have very specific charging requirements if you want to get the best performance from them.

to charge eneloop this is what a charger I would use would do:
Battery inserted and temperature measured .
Wait 4 seconds for cell to stabilize.
Battery is discharged through resistor until cell reaches .85V
Charge at 1.03V 220Khz .48A until cell measures 1.0V. If cell fails to reach 1.0V in 30 minutes charging is aborted.
Once at 1.0V charge at 1.18V 125Khz .85A until temperature exceeds .5C per minute.
Finish with 1.36V 150Khz 20ma until cell reaches 1.29V .
Charging aborts if cell reaches 50C or 1.65V.


Most of the cheap chargers are no more than a power supply set at 1.3Vdc with a diode .
Click to expand...

0.85V? 1.29V?

What are you smoking? If you discharge a NiMH cell to 0.85V, you have permanently damaged it.

If you only charge a cell to 1.29V, it is not fully charged. My Maha C9000 discharges to 1.0V and charges to 1.45V. Anything below 1.0V will damage a NiMH cell.
 
The charger that sells with those $20 for charger and 4 batteries are not good for getting full use out of batteries. Those chargers are often quick chargers designed to recharge batteries as fast as possible . Good battery charging takes time and there is no way to rush it without shortening the battery life.

You don't have to spend a lot for a charger but getting one that specifies conditioning or smart charging usually means that it is higher quality. Another way to tell a good charger is to leave the batteries in it and remove them the next day after it says they have finished charging. If the batteries are hot or warm that is a poorly designed charger because it should not be constantly applying voltage after the battery voltage is reached.
 
Eli said:
0.85V? 1.29V?

What are you smoking? If you discharge a NiMH cell to 0.85V, you have permanently damaged it.

If you only charge a cell to 1.29V, it is not fully charged. My Maha C9000 discharges to 1.0V and charges to 1.45V. Anything below 1.0V will damage a NiMH cell.
Click to expand...


That is per spec from the manufacturers, not internet rumors of 1.0v.
The 1.29V is pulsed at high frequency and the way the circuit works it measures the voltage at the battery for 1.25V. Again per manufacturers spec.

Putting 1.45V on a battery to bring it to 1.25V is a linear method of charging and is not recommended.
 
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