Back in abt 2006 we bought a few packs of Eneloops in the plastic case with a cable tie around it from Costco.

Took one unopened box tonight after abt 5 years and put 4 of the AA's in a Maha 9000 charger and set it to 'discharge' at 500 ma.

I'm curious to see what juice is left in them. Initial reading is 1.21 volts for each cell.

Then I'll charge them and do an eval of how much capacity they have.

Does anyone know how to date the batteries?

After 20 minutes at a discharge current of 500 ma, voltage is down to 1.15 and ~120 ma-hrs have been sucked out of them.

TAG for further review

At 75 minutes there have been ~520 ma-hrs harvested and the cell voltage for the 4 cells is 1.15 volts.

Printed on the cells is that they're rated for a min of 1900 ma-hrs, nominally 2000.

At 115 minutes, 1.14 volts and 870 ma-hrs harvested, typically.

Load is 500 ma so I don't understand only 870 in just under 2 hrs.

Should be closer to 1000 ma I would think...

At 2 hrs, 900 ma-hrs harvested

IIRC, they're aren't factory-charged to their full rated capacity. 80 percent seems to stick in my mind.

Apparently, pre-charging the stuffin' out of 'em reduces their shelf life somewhat.

I think that's correct.

So say 5% loss each year, times say 6 years, and they should have abt 50% capacity remaining charge right out of storage.

Or 1000 ma-hrs.

I'll watch them closely now...

Look where 1.14 volts is in the above chart. Remember they're warm.

At 136 minutes, 1038 ma and 1.13 volts.  Warm.

Strangely, I'm measuring an ave ~1.2 volts ACROSS the cell while the Maha charger reports 1.13 volts.

This makes more sense vs the chart info.

1100 ma @ 146 minutes. 1.10 volts as indicated by the charger.

Measured w/ DVM, fluxuating from 1.18 to 1.21  [eta, these numbers must be wrong] as the Maha must load and unload the cell.

.

160 minutes 1200 ma-hr @ 1.10 v Maha indicated.

1.16 volts ave as measured with DVM.

Starting to roll off more quickly.

180 minutes  1365 ma-hrs 1.05 volts per Maha.

DVM ave ~1.12 volts

I think Maha may be conservative in their reading of voltage so as not to be liable for damage to batteries or bad press.

So far we've drained the battery at a 1/2 amp rate for 3 hours with a voltage over 1 .1.

Not too shabby after sitting 5 or 6 years.

I have a couple more sealed sets I'll test in years forward if the world doesn't come to an end...

The 4 are done.

Maha typically ended at 1.14 volts, 1400 ma-hr  190 minutes.

The termination voltage is different from what the display was showing during discharge and more inline with my DVM reading. It appears Maha adds a fudge factor of about .05 volts so as not to discharge batteries too close to 1 volts. I can hear all the Weenies on CPF bitching if they did.

It appears Maha terminated at about 1.15 and so the actual capacity of the batteries was never reached.

Eneloop specs the battery to a termination voltage of 1.0 volts.

The capacity of these batteries after 5 or 6 years of storage and no previous 'conditioning' and considering Ski suggests they were only charged to 80% from the factory is nothing less than OUTSTANDING!

After discharging them I've put two into a Fenix LD20 flashlight and it dimmed very noticeably on turbo setting in one minute.

Putting the light onto the lowest setting now.

I'm getting bored running these tests but it appears there will be usable light on the lowest setting for some time.

Not bored again...

I've taken two Eneloops and two Olympus Camedia batteries of the same unused vintage, charged them in two separate chargers that came with the Eneloop kit from the day and put them into the Maha in discharge test at 500 ma discharge current.

It's 1:19

Flashlight is still burning the same on low ~ 13 minutes elapsed.

Update, the flashlight went out at ~22 minutes.

Wait'll I 'splain EMP to ya!



And send ya some crimpers...

One of the Olympus Camedia bats is shot, didn't hold a charge.

The 2 old timey [~5 or 6 YO] Eneloops took a nice charge and registered ~1950 ma-hrs on the Maha charger analyzer. Exactly what they are rated for.

One of the 1200ma-hr Olypus bats did come close to it's rating but the other was weak.

Now remember, the Eneloops are 5 or 6 yrs old and the Olympus probably way older, I have no idea when I bought them but it was long ago.

This thread appeals to my inner geek.






Thanks for the detailed analysis.  This type of technical data is much more interesting (important) than "What kind of AR should I buy".

Thanks for the effort EXPY, I have a Maha charger and my first eneploops on the way.

I don't know what kind of meter you have. Depending on how the Maha is doing the discharging, it may not read correctly if the meter is not a true RMS meter. Most lower cost meters are not true RMS so irregular waveforms don't read as one might expect. It is also possible your meter is off. A few hundredths of a volt is pretty tough to read accurately with most meters. It is well within the tolerance of the meter. With such a small difference in the readings, it is even possible that the way you hooked them up might make a difference, although I would expect the external volt meter readings to be somewhat lower.

The other thing is that if you are reading them out of circuit, you should expect a slightly higher voltage then when they are in circuit.

I don't have a Maha charger and I have no idea how they do their discharge test, so it is hard to comment on whether it is as meaningful as some seem to think.

I have been thinking about rigging up a test at work with a couple of the Ray-O-Vac batteries I bought and some precision resistors, so I know the actual test conditions. I do not have a precision volt meter available at work either.

I've noticed mine are also very consistent at meeting their advertised specs - even the ones that are several years old. They don't ever seem to need many "rejuvenation" cycles to bring them up to full specs, either.

Was using my handy high accuracy Harbor Freight $3 DVM.  

I can check cal with an HP meter, however I've found the H-F's to be surprisingly accurate..

My company designs and builds Ni-MH / Ni-Cd battery chargers for esoteric applications. I'm a Mechanical bozo but some of the stuff sinks in after a while...

1.0V discharge limit - a cell (single battery) can be discharged down to zero but there is little useable energy left below 1V. If the cells are configured in a series battery pack, the generally accepted low voltage cutoff is 1.0 v / per cell. This is to prevent reverse charging the 'weakest link' cell (lowest capacity cell). When this cell depletes its energy, the current from the other cells still flows thru it, reverse charging it. Mucho malo for that cell….

It may not be the meter. Does the Maha take its reading under load or read OCV (open circuit voltage)?
Our chargers use an algorithm that stops the charge and lets the battery rest for 1 sec before reading the OCV. This way we always get the same relative measure, regardless of load. IIRC, most battery specs are done with a constant current load, which would read lower than the OCV.

Anyway… the cells you have sound like they have held up very very well regardless of how you read the voltage!

I recieved 12 and 8 AAA eneloops with two four slot Sanyo chargers yesterday. Are the Sanyo chargers that came with sets any good?  I looked at the eight slot Maha. Thanks.

Bump for charging advise. Looked at the Maha chargers which 8 port on a tight budget?  It took the Sanyo chargers 4-8 hours to charge the four AS that I ran unit dead in scanner. Also thinking of buying more AA batteris, are the 2500 mAH MAHA any good?

Why do you need an 8 slot, the 4 slot is probably less $$$ and works good.

The 4 slot chargers that came with the Eneloops I bought years ago seem to work fine.

I was thinking that in SHTF event I could charge more batteries during the generator run cycle of 2-4 hours. I am looking at owning 24 AA and 24 AAA eneloops. I read that the MAHA chargers can charge faster. I may even seek out a 12 Vdc option for the eneloops charging.

That's a REALLY handy item to have.

Running a generator for several hours just to charge a few AA or AAA cells is a huge waste of fuel. Otherwise, you have to wait until the next time you're using your generator.

Powering the charger with a car battery allows you to charge AA/AAA cells any time you wish - in complete silence, and without wasting any fuel.

Very few meters, even good ones can accurately read 0.07 VDC difference.

You did not answer my question about whether you were reading the battery volt in or out of the charger. if it is not in the charger beign discharged the voltage will be a little higher then when it is being discharged.

What do you do for a living?

Sleep...

Sorry, missed it.

I was checking the voltage in circuit in the Maha chgr with the regular negative probe contacting the negative area of the battery and a Motorola straight dental probe contacting the positive terminal because it's very tight there.

The voltage was fluxuating and I sort of averaged it.

It's easy for me to measure .05 volts steady state, but not when it's bouncing all over the palce like in the charger so I took an average.

I've got an HP 3478A bench DMM, and I can cal for what we're talking abt because it's really nothing re difficulty. I was going to check the meter tonight but I forgot it and I'm fixing some !@#$%^ very high end network PTZ cams I bought cheap on ebay last summer/fall. And I fixed one that's had issues already.

The Eneloops after about 5 chg/dischg cycles are just above 2000 ma each and match well.

I've been testing some Energizer AA rechargables from the same vintage as the Eneloops.

They are rated at 2500ma and are in a green colored box with a copyright label of 2005, made in Japan for Energizer.

They are showing about ~2350 mah and are well matched after 3 cycles.

The Camedia rechargables, one failed out of the 4 so they are going in the trash.

I now understand why folks might want an 8 position charger.



What's the difference between the

Maha 8 Cell Battery 1 Hour Charger PowerEx MH-C801D

and the...

Maha MH-C800S Eight Cell Smart Charger?

Ones cheaper on ebay but the look the same.

Tag so I can find a good cheap 8 slot.

The statement in red is inaccurate. 6 of the Flukes I personally own have much greater accuracy and resolution than needed to measure .07 VDC; in fact, 2 of them accurately measure micro-volts. All are calibrated yearly, and several of these meters are affordable enough for the home user or hobbyist to own at least one model.

A DMM than won't accurately and repeatably measure ± .001 V is archaic unless you simply need to check your line voltage for ± 10%, and in that case you'd be much better served by a Wiggy. For many years now, the type of accuracy you allude to has been the norm, not the exception.

Tested some more Eneloops and have cycled them a few times.

Their capacity has stabilized at just over 2000 ma-h. Their spec'd rating.

Very pleased with how these old timers have held up.

Any comments on 8 positions chargers?

Tonight I checked the cal on 5 H-F el cheapo meters, 2 yellow ones I've had for maybe 8 or 9 years that cost abt $2.99 ea, and 3 red meters maybe 5 yrs old and cost abt the same.

Used a HP bench top DMM that will read way way finer than we're talking abt. Used a single AA lithium battery as the 'reference'.

The older yellow meters were within abt 10 mv and the red ones within abt 5 mv after all these years. Of the HP reading.

One yellow meter was 18 mv higher. It was an easy fix as there's a pot inside that can easily be adjusted to set the meter right on. I suppose that cal related to all the other readings but I didn't check.

I really like the H-F cheapie meters and have used them for many years all the time and they rarely fail. Out of the 35 or so I have at different places since the early 90's or so when they were first carried, I've had two fail that I can remember. Most are still in service here and there and the batteries seem to last for many years.

The link and picture below show only the red meter and there's 3 models now from $4.99+ and less on sale. I remember when they were $1.99 IIRC for the yellow ones and I always got hollered at for buying so many.

They are good enough for a SHTF considering you can have many for redundancy and they are my go to meter since they don't have the PITA autoranging, you just select what setting for what you want to look at and they are small and don't take any room on the WB.

They are a most incredible bargain.

The ones now have a socket to test transistors and read their h-FE. Many of mine don't have that feature, as it only been out initially for a dollar or so more and available for maybe 12 years. I don't think I've ever used it, maybe once or twice mainly to see if it worked.

There's also a diode test position and a 1 1/2 volt and 9 volt battery test postion. Use the diode test once in a while because it reads directly the forward voltage drop. I think I played with the battery test function a few times.

Everyone should have a few of these and LEARN TO USE THEM in accordance with what you do or need to do. I've diagnosed and fixed more stuff with these than I can count.

I remember getting my first VOM and it was one from Lafayette Radio and it was way bigger than these with a rounded top part of the case. I can't remember where I last saw it, sadly. I thought I was on top of the world when I first got it.  



http://www.harborfreight.com/catalogsearch/result?keyword=volt+meter

EXPY: Sorry, I really don't have the experience to be able to add anything useful in the way of 8 bay chargers; my background is with rather large (up to, and occasionally exceeding 360 Amp DC output) Ferroresonant and SCR chargers for FLA, AGM, and Gel cell batteries in 12-84 volt configurations.

I thank you for the comprehensive write-up on the eneloop batteries; it is very thorough, and adds considerably to the knowledge base here. Also, your response regarding Digital Multimeters is not only informative, but should lay to rest any misconception about basic DC accuracy (or lack thereof) even in less expensive meters. Your advice that everyone should own, and know how to use at least one DMM before it is needed bears repeating. Electricity really is not magic, but unless you can define and measure it's characteristics, it may as well be.

Always enjoy your posts; keep up the good work!

Regards,
Greg

+1

I have a Lacrosse 4 port charger that I just took apart. It uses a single die-on-board chip to control all 4 ports. If the chip fails, you lose all 4 stations. Assuming the 8 ports units use the same single controller scheme, I think you would be better off with 2) 4 port chargers for redundancy....

––––––––––––––––––––––––––––––––––––
If don't remember if it was in this thread or another one but I think you ask about a way to run the charger off a 12v battery. I have long thought a LM317 w/ a pot would do the trick but I see you can now buy both a universal buck and universal boost multi voltage output adapters that use a cigarette lighter for the input. They come with all the major output jacks that should cover most of this low voltage junk we now have. Each cost approx. $10 landed.

$20 buck gets you all the major voltages from 1.5 to 24 VDC. The damn Chinese are taking all the fun out of tinkering any more…

Depending which model you have, the Lacrosse charger can draw up to 4 amps at 3.0 VDC. That's a lot of voltage to drop across a linear voltage regulator...

(12.8 volts  - 3.0 volts) X 4 amps = 39.2 watts of heat wasted inside the linear regulator!

Ideally, you'd use an adapter that uses a switching-type voltage regulator instead.

I haven't found a pre-assembled switching-type adapter that'll supply that kind of current at 3.0 volts - None of the laptop "travel adapters" can be set to produce an output voltage that low. However, you could build one, using a DC-DC converter module like this one.

I did a Mouser DC/DC Converter search this morning too and found this one:
Mouser Part #:  580-OKL-T/6-W12N-C

$10 is cheap enough. It has a pretty flat 90% efficiency curve in the 2-6A range for 3V. Looks like it might work.

Then.... I started looking around at all the possible stuff I would want to run off a car battery and the volt range was wider than these switchers will handle. One is 9v.
Any suggestion for an adjustable wide output switcher?

ThanksSpectre!

Re the voltage converters, there are many on ebay and I have a couple saved searches there that show up everyday in my email.

Do a search for "buck converter" and "boost converter".

There are also buck/boost converters. They are so inexpensive that I often buy one or two of interesting and useful ratings to add to my "collection".

There is a lot of knowledge to be gleaned on the latest tech out of China from reading the specs, parts used, and looking at the ckt bd layouts, etc!

[Kind of like Batman collects flashlights]  

That's a good find!

Note that the 12 volt battery voltage when the engine is running can easily exceed 14.0 volts - which would also exceed that converter's maximum input voltage. As long as you only use it with the engine turned off (or stick a beefy silicon rectifier in series with the DC input to drop the supply voltage by around half a volt), it should work great.



Do any of the other devices require high current at a very low voltage? If not, using a separate, linear-type adapter for those devices might be the best approach.

Example: If you only needed 100 mA at 9 volts, a linear regulator would waste about 0.4 watts  - which would be entirely acceptable.