# Eneloops Left In Car For 1 Year - Results



## mattchase (Jun 17, 2008)

UPDATE @ 9:05pm: Fully charged battery runtime now posted.

Recap:
The original setup was 2 Eneloop AA's in my glove box and 2 Eneloop AA's left on my shelf for a period of 1 year. I used a Radio Shack Digital MultiMeter to check voltage, and a ZTS Mini-MBT battery tester. I always did at least 2 voltage and ZTS readings of each battery to confirm that I was getting the same reading twice in a row. I live in South-Central Texas where the temperatures range from the mid 30's in the winter (though don't stay there long) to the low 100's in the summer (and stay too long).

The good news is that the 2 batteries I put in my car did in fact remain in my car for a full year. The only times they weren't in my car was when I was taking readings off of them, which I usually did at night. The bad news is the 2 "control" batteries that I left on my shelf were needed about 4 months into the test, so I don't have any data from those to compare beyond that time. I also skipped taking data readings for 4 months in the middle of the test due to opening a new business and living there for the first few months. Finally I did runtime tests using a Fenix L1s.

The Data: (top - DMM voltage | bottom - ZTS %)






Runtimes:

Battery 1 from car @ 1 year





Battery 2 from car @ 1 year





Fully Charged Eneloop





There is a 22 minute increase in runtime to 50% power and a 16 minute increase in overall runtime for the fully charged battery compared to the 2nd battery from car runtime.

There is an increase of 27 minutes in runtime to 50% power and 37 minute increase in overall runtime for the fully charged battery compared to battery 1 from the car, but bare in mind I didn't let battery 1 from car discharge for as long as the 2nd battery or the fully charged battery, so the overall time difference should actually be less. It took about 10 minutes for battery 2 from car to go from 15 lux to 4 lux and about 7 minutes for the fully charged battery to do the same, so going in between and adding 8 minutes to battery 1 from car overall time would yield an increase of 29 minutes for the fully charged battery.

*Runtime Test Notes:

The flashlights were 1 foot from the lightmeter due to space limitations so the lux readings are not accurate representations of throw or flashlight power (based on the standard 1 meter test). I had several times when my light meter shut down during the first battery test as well as had some display settings different during the 2nd runtime test (5 sec graphing time span vs 15 sec graphing time span). I also stopped the 1st battery test with approx 15 lux still coming from the flashlight, while on the 2nd battery test I let it run all the way down to approx 4 lux. These factors contribute to the different appearance in the discharge curve from the 1st battery test to the 2nd battery test. On the 2nd battery test I also have a text file (click for file) with every reading in it from my meter taken during the test. For the fully charged battery test I let it run down to approx 4 lux to match the 2nd battery from car test (text file here).


----------



## Mr Happy (Jun 17, 2008)

You have not made any comment on those results, but they seem to show excellent performance from the Eneloops.

Your measured run times on the L1S after 1 year in the car are barely shorter than for the freshly charged Energizer 2300 at Flashlight Reviews!


----------



## UnknownVT (Jun 17, 2008)

mattchase said:


> The original setup was 2 Eneloop AA's in my glove box and 2 Eneloop AA's left on my shelf for a period of 1 year.


 
Thank you for your diligent work.

The runtimes for eneloops at 1 year stored in the car matches the FlashlightReview's runtime using 2300mAh Energizer NiMH.

According to SilverFox's NiMh Battery Shoot Out eneloop and Energizer 2300mAh NiMH are in a similar ballpark for capacity when recently charged - so the runtimes for eneloop with 1 year car storage would seem _outstanding_ to me.

It would probably be _very worthwhile_ to do a runtime with a recently charged eneloop in the same Fenix L1S as a control comparison, this would show the percentage remaining charge after 1 year car storage, in a more real world flashlight usage.

Thanks,


----------



## lowatts (Jun 17, 2008)

That's a pretty impressive showing for the Eneloops. That sort of heat exposure can probably be considered abusive to NiMH cells.


----------



## xcel730 (Jun 17, 2008)

Impressive. Thanks for your test.


----------



## RGB_LED (Jun 17, 2008)

Thanks mattchase, that is fantastic work on your part. :thumbsup: I'm amazed, is there anything that eneloops can't do?


----------



## jezzyp (Jun 17, 2008)

Great work, thanks for taking the time.
I've got eneloops in one light in my cars and my ZTS shows 100% at 6 months although I don't keep records or anything. I just test all my stored lights every now and agim.

I continue to be impressed by eneloops. I now have 24 AAs and keep thinking about buying more but I would want to mark the new ones in case they lose capacity after a few years use. Only time will tell as to how many years we can get out of these babies.


----------



## mattchase (Jun 17, 2008)

I'm glad you guys find this useful...you were probably wondering where I had gone (if you even remembered me from that one post a year ago!).

I had thought about giving my opinion in the first post but wanted to let others judge the data for themselves. Now that some have done that I will say I am very impressed and a bit surprised. I had high hopes the batteries would live up to their reputations and advertising, but didn't think they would hold their charge this well with the constant hot days - cool nights - hot days of being in my car. I was pretty well sold on Eneloops (and low self discharge in general) when they first came out, but now I see little reason to have anything else for my normal AA and AAA use. As an aside, I keep a MagLed 2AA in my glovebox and a Mag 8AA hotwire in my car door compartment, both of which have Eneloops in them. I have recharged the batteries in the hotwire a couple of times because of use (poor Eneloops...it's an 1164 bulb) but I have not replaced the batteries in the MagLed as of yet and I know they have been in there since the first of this year, if not longer, and the flashlight has gotten some use. Both lights have sat for months between uses and have always lit up without a problem, and while this is subjective the times I've used them they haven't lacked any punch in terms of brightness. My testing was done with the batteries not in a flashlight, but the latter proves that even when they are in a flashlight they still hold their charge. Of course this could vary depending on what device you have the batteries in as some are better at not draining batteries in standby than others.

So to conclude this test I am currently doing a runtime on a fresh Eneloop. I charged it using my Maha MH-C800S in "soft mode" last night, and it sat overnight on my desk (it wasn't inside the flashlight). I will update my first post in a couple of hours when the test completes.


----------



## mattchase (Jun 17, 2008)

I've updated the first post to include a fully charged Eneloop runtime.


----------



## UnknownVT (Jun 18, 2008)

mattchase said:


> I've updated the first post to include a fully charged Eneloop runtime.


 
Thanks for that update - some quick calcs -

charged eneloop runtimes -
total = 3h04m = 184mins
to 50% = 2h12m = 132mins

1 year car stored -
total = 2h37.5m (Av) = 157.5mins
to 50% = 1h47.5m (Av) = 107.5mins

Total runtime remaining usable capacity =
157.5/184 = *85.6%*

to 50% - remaining capacity =
107.5/132 = *81.4%*

So these remaining capacity % figures of 85.6% and 81.4% seem to corrolate well to Sanyo's claims of approx 85% remaining capacity after a year - especially considering the extreme conditions that the eneloops were stored.

Good stuff, thanks for your efforts and diligence.


----------



## Beamhead (Jun 18, 2008)

Great contribution.:thumbsup: I love your pics on your site.
What Fenix lights do you have? I have an extra P1CE I would like to send you for your effort, just shoot me a pm if interested.


----------



## LukeA (Jun 18, 2008)

It took dedication to perform this test. Nice to know that Sanyo is telling the truth.


----------



## FrontRanger (Jun 18, 2008)

LukeA said:


> It took dedication to perform this test. Nice to know that Sanyo is telling the truth.


 
+1, as they say. Thanks, Matt! Best of luck with your new business.


----------



## Burgess (Jun 18, 2008)

Thank you, MattChase !

:twothumbs



I am VERY impressed by your results !


Not simply by the performance after 1 year,

but after 1 year* in the Texas Heat* ! ! !


:wow:

_


----------



## mattchase (Jun 18, 2008)

Vincent,

Thanks for doing the math for me. 

Beamhead,

Wow! That is a very generous offer and I really appreciate it. I'd be happy to send you a print of one of my photographs in exchange if you would like.

To answer your question I currently have an L0D and L1S (with L2S extension). I also have a couple of Mag D hotwires (one with FiveMega 2.5" throw master head) , a Mag C with Terralux dropin, Mag AA LED, one of those battery free shake it till your arm falls of and you might get a little bit of light flashlights, a couple of cheap headlamps, an old Coast LED, an even older 2 AAA bucklight and a few heavy 1-2mcp floods. Not a big or fancy collection, but I only recently accepted that flashaholicism is not a bad thing (and am on a tight budget right now). Oh, almost forgot...my HTC Titan (Mogul) PPC phone. Seriously, it's got a great short range floody LED on it for the camera that a very smart person wrote a program for so I can turn it on and off as a flashlight.

FrontRanger,

Thanks for the positive thoughts! In addition to my "real" job I am working on better promoting my photography too, I have a small office I am going to turn into a part time gallery and am working on getting more of my photos posted online (I've spent the last few days going through the first few folders...only about 12,000 more photos to go...and I've already deleted all the bad ones!). Did I mention I also manage an office building? Man do I need a life (ie. girlfriend)!


----------



## Beamhead (Jun 18, 2008)

mattchase, Your offer is even more generous, your pics are incredible, I would feel like I got the best of you if I accepted. So even though I would love a print of "Barn and Windmill" or "The Bank II" I would feel better if you just accept my offer.


----------



## mattchase (Jun 18, 2008)

:thanks: and a humble:thanks: again.

I will be sure to put it to good use next time I am out in the dark taking pictures.


----------



## Beamhead (Jun 18, 2008)

PM's inbound with DC#


----------



## Black Rose (Jun 18, 2008)

Excellent information Matt (and really nice photos too).

I was debating whether to buy some lithium cells for the LED Minmag destined for the car or whether my Eneloops could be used.

If the Eneloops can handle the Texas heat, they'll certainly be OK here heatwise. 

Now the cold is a different thing altogether....it can easily get to 0F/-17C or lower here in the winter..Eneloops are said to be able to still be OK at 23F/-5C.


----------



## mattchase (Jun 18, 2008)

Unfortunately I can't speak for their performance in really cold weather. The coldest it got during my testing was 26F back in January, but most the time the lows were in the upper 30's to low 40's, and daytime temps often still hit 50 during the winter months. And on top of that I wasn't actually using the battery.

It should also be noted that I park out in the open, I don't have a garage nor even a carport, so my car is exposed to the sun most of the day. I never did take a thermometer out into my car but I wouldn't doubt that it was 150F+ in there many days.


----------



## kramer5150 (Jun 18, 2008)

Wow... I don't know whats more impressive, your dedication to this project or the performance of the cells.

How about that?... honest product marketing:thumbsup:

THANKS!!


----------



## UnknownVT (Jun 18, 2008)

mattchase said:


> Unfortunately I can't speak for their performance in really cold weather.


 
My understanding is the self-discharge rate is higher - higher the temperature.

So cold/low temperatures will actually slow the self-discharge.

However I think we may be thinking of cross-purposes - 
where the battery itself at low/cold temperatures may not deliver - 
whereas Lithium batteries are capable of working at lower temperatures.

Energizer e2 lithium AA L91 -
Recommended Lithium Operating/Storage Temperature: -40°C to 60°C

eneloop AA -
Discharge condition - 0 - 50 degC

Compare to Alkaline - Energizer E91 AA -
Operating Temp: -18°C to 55°C (0°F to 130°F)

eneloop's discharge operating temperature range seems to be the same as any other typical (non LSD) NiMH - eg: 
Energizer 2500mAh NiMH -
Discharge: 0ºC to 50ºC (32ºF to 122ºF)


----------



## etc (Jun 18, 2008)

Thanks for the review! These are very encouraging results.


----------



## REDLINEVUE (Jun 18, 2008)

I'm a little confused here..:shrug: and I'm 99% sure most everyone here will immediately want to "bash" me after this but OH-Well...

...Missing data... Compromised controls and a faulty "glitching" light meter... call me crazy:tinfoil:, but I would never suspect this group of enthusiasts, hobbyists and professionals to refer to this type of experiment as "Great", "Excellent", "Diligent", "Fantastic", "Impressive" or anything short of "fun".... Please understand this post is not meant as a personal attack on anyone but only my observation and OPINION which stats this experiment is flawed.... With no baseline, results from a control or runtime progression, how can this still even be considered a valid experiment(or am I just missing the point)? 

so great, now we know that an eneloop left in a car can hold 80% of its charge, but;
-what about the ones on the shelf?? 
-would a control eneloop have held 85% just as the package suggests... ?? 
-did the heat cause a 5% loss?? 
-what was the avg temp/day for the months tested?? 
-Is this anything special or would any battery hold up the same??
-would they hold a charge longer in your fridge??

I can only see casting great accolades, if the results were measured over a years time (faithfully) from TWELVE eneloops', TWELVE energizers, TWELVE Duracell's and TWELVE e2's left in a vehicle as well as the same group in a controlled environment (where they wont get used).... then at the end of each month, test ALL the batteries with a meter and then do a runtime test with one of each brand (car and control) using a FUNCTIONING light meter. 

I'm not volunteering.. just putting it out there!


----------



## Mr Happy (Jun 18, 2008)

REDLINEVUE said:


> ...Missing data... Compromised controls and a faulty "glitching" light meter... call me crazy:tinfoil:, but I would never suspect this group of enthusiasts, hobbyists and professionals to refer to this type of experiment as "Great", "Excellent", "Diligent", "Fantastic", "Impressive" or anything short of "fun".... Please understand this post is not meant as a personal attack on anyone but only my observation and OPINION which stats this experiment is flawed.... With no baseline, results from a control or runtime progression, how can this still even be considered a valid experiment(or am I just missing the point)?


The missing factor is that this is not the only test that has been performed, nor is it the only data point.

There is an abundance of tests storing Eneloops on the shelf under ordinary conditions. It's been well established that Eneloops will indeed hold 85% of charge after a year at room temperature, and typically more than 75% charge after two years.

Likewise there is an abundance of experience that ordinary (pre-LSD) NiMH cells will not last a year without becoming totally empty. The worst of them will not last a week.

So the only expectation to be tested here is would the Eneloop be flat after a year in a car exposed to summer temperatures, or not? The fact that two Eneloop samples not only remained charged, but in fact fared hardly worse than the known room temperature performance, is certainly evidence of exceptional performance.

Would twelve Eneloops all perform as well as two? You have a reasonable question, but the 100's of previous room temperature storage tests and the remarkable consistency found between Eneloop samples when measured suggest a great deal of confidence that they would.


----------



## Burgess (Jun 18, 2008)

Yep !


The real "wow" factor was discovering that Sanyo Eneloops

can handle a *Summer of Texas Heat*, and still perform well. 


We already knew about "room temperature".


Wanted a *tough, harsh-environment test*, and it fared very nicely.

:twothumbs

_


----------



## mattchase (Jun 19, 2008)

Redlinvue,

You bring up a very relevent point and I would ask that no one bashes you for it. In fact if you go back to the post from a year ago when I started this test you will see others brought up this same point, and I agree this test was not done in a "correct" manner scientifically speaking. Originally I was only going to have 1 battery in my car and that was it, but through others suggestions I added the 2nd battery to my car and the 2 batteries to my shelf to try to make it slightly more viable of a test. I actually own about 18 Eneloops, acquired through 2 seperate purchases (from 3 seperate packages), and randomly selected the 4 that I did for the tests. While 2 of them didn't make it to the finish, 2 of them did, and these 2 were not sent to me from the manufacturer as "perfect" samples for testing. They were exactly what any of us would get when purchasing new batteries at the store. That said, I do agree that as in any scientific test having more samples would give a better overall view of their capabilities, I don't know if that should be 12 or 5 or 27, but 2 is a rather small test pool. At the time it was what I could spare.

There were many times I considered stopping this test, partially due to not following through with data every month, partially because I could have used those 2 batteries on a number of occassions, and a few other personal reasons. But I decided I started it, I posted about it, so I would finish it. As for the 2 I put on my shelf as "controls", I wish I could have kept them as such but as others have pointed out there have been many other tests conducted on Eneloops under climate controlled (in house) conditions. Also, I never set out to test these against Energizer or Duracell or any other brand, I was only testing them to see how much of a charge they would have after a year of being in my car. If I was comparing them to other batteries, I most definitely would have had at least 2  of each of those other batteries to compare with.

Finally, the results.

For the sake of being completely truthful in my testing I included the information about my light meter shutting off during the first runtime test. I considered not including this runtime test because of this, but in fact it did not affect the test because I wasn't measuring power, I was measuring runtime. The flashlight never shut off and the data logging program continued to record data (not to mention I wrote down the starting and ending times by looking at my watch). I feel that my stopping the first test at 15 lux instead of letting it go to 4 lux (as in the 2nd and 3rd tests) actually affects the results more than the light meter shutting off during the test. During the 2nd and 3rd tests I had no problems with the light meter and paid more attention to the entire runtime to make sure it was as accurate as I could make it.

The missing voltage and ZTS data is unfortunate, and the techy side of me wishes I had it as I'm sure some of the more techy of you guys do too. However, my main purpose of this test was to see if I could leave these batteries in my car for an extended period of time and still have useable batteries for my flashlight when I needed them. In this respect, even if we throw away my incomplete voltage data, ZTS data, and the slightly glitchy light meter runtimes, I can say with confidence that (barring any major battery malfunctions) I can leave Eneloops in my flashlight in my car for extended periods of time and still have a working flashlight when I need it. My evidence of this is that I sat at my desk for more than 5 hours one evening and 3 hours the next evening, watching my flashlight shine brightly, very slowly start to dim, then quickly drop off in output. All recorded data aside, that is all I was really looking for and makes the test valid for me.

As with anything in life, your mileage may vary.


----------



## Beamhead (Jun 19, 2008)

While Redlinvue made some valid points I still consider mattchase's data useful in a Field test real world sense.


----------



## LuxLuthor (Jun 19, 2008)

kramer5150 said:


> Wow... I don't know whats more impressive, your dedication to this project or the performance of the cells.
> 
> How about that?... honest product marketing:thumbsup:
> 
> THANKS!!



+1 Your contributing this information is really appreciated and useful. :thumbsup:


----------



## REDLINEVUE (Jun 19, 2008)

mattchase - please accept my apologies for having called your experiment "invalid". ... I guess I just didn't get the point of the test as I never saw your original post. I just stumbled onto to this tread and saw the runtime charts and battery "testing" that you were doing and just figured that you were looking for more specific data on HOW heat affected the batteries not just whether the battery would even function after being in the heat... I guess then(had controls never even been mentioned), it would have made sense to me right off the bat.. but I see controls being used and just deduced that a comparison of some sort was taking place.

With that having been said, if your point was to simply find out if the battery would still function (and to what degree) I have a few more questions; 

1) Wouldn't it have behooved you to use a few other low discharge battery's for comparison? 
2) What was the purpose of using the "controls" at all, if as others have stated, much is already known of the eneloops performance indoors. 
3) Wouldn't it make sense to add periodic temp readings (of the inside of your car) along with the voltage tests?

I have now re-read this message no less than 5 times to try and ensure that it is worded so that you(and everyone else) understand I'M NOT TRYING TO BE DIFFICULT, but honesty just trying to understand the results.

Thanks for the kindness of your reply to my original post. :twothumbs

William


----------



## bob_ninja (Jun 19, 2008)

REDLINEVUE said:


> 3) Wouldn't it make sense to add periodic temp readings (of the inside of your car) along with the voltage tests?



I can answer that one. Manual temp readings are time consuming. We all have a life and priorities. He didn't have the time for manual temp readings. Simple.

Now I supposed one could setup some equipment to take periodic temp readings - costs money. So bottom line is, he is doing an experiment using limited time and resources. Again, take it for what it is.

Back to temperature:
"from the mid 30's in the winter (though don't stay there long) to the low 100's in the summer (and stay too long)."

I understand you cannot possibly take temperature readings on any sort of consistent basis without some equipment. However, if cells are kept in the glove box, which is made of plastic being a decent insulation, I wonder what would be the actual temperatures INSIDE of the box????

For instance, if a day high reaches 100F in shade, whereas glove box is below dash board shielded from sun by many layers, how long would it take for box interior to reach 100F, if ever? Wouldn't box interior on average be 10%-20% cooler?

What do you think?


----------



## Mr Happy (Jun 19, 2008)

Just as one anecdotal data point, I left my car parked outside in the California sun one day, and on the way home when I went to get some coins from the coin holder for a toll booth the coins were so hot I couldn't hold them. That similarly is a shaded plastic box, but after a day in the sun it apparently had reached a very high temperature.

I don't know what temperature "too hot to hold" is, but I'm guessing it is 160 F or more.


----------



## mattchase (Jun 19, 2008)

Redlinevue,

Questioning things is how we prove or disprove what we know, so I have no problem with that. You didn't have all the information in regards to my (admittedly simply) point for the test, so there is no way you could have known that I wasn't too worried about the absolute scientific accuracy of it.

Having used other LSD batteries in this test would have given it a larger scope and I'm sure anyone using those other brands would have appreciated the info, but when I purchased my Eneloops I had decided that I wanted to try to stick with one battery type for all of my AA batteries. This was a personal decision, but it is part of why I had no other rechargables included in this test.

I had originally not intended to have any controls, which is why halfway through I wasn't too worried about it when I decided I needed to use those battieries. In the posting a year ago that started all this it was suggested to have some controls in the test, so I added them. Since then (and even a bit before then) there have been many other people who have posted positive reports of their Eneloops under climate controled conditions, and to be honest if I were to do this test again I would probably skip the controls from the start (that would give me more batteries to leave in my car!).

I had considered taking temperature readings inside my car but decided I didn't want to go to that effort. Yes, I got lazy on this one. I have a Davis weather station hooked up to my computer so I can provide monthly high and low temps if you guys want. Of course these don't give the full story of what the temperature was in my glovebox. Ok you talked me into it...I've been thinking about getting a new digital thermometer to put in one area of my loft to help monitor my A/C, so next time I am at the store I will get one and stick it in my glove box for a few days so we can get a better idea of just what the temperture can get up to.

Bob_ninja
The thing about cars and heat is that it's like an oven. The heat just builds and builds in there during the day. I lived in Las Vegas for 10 years and even in the winter months upon getting in my car I would often turn on the A/C for a few minutes to cool the inside. Heck, a couple of weeks ago the side window on my mom's truck blew out because of the heat built up inside the car (it had been sitting out in the open for about 5 days with all the windows closed)! As I mentioned above I am going to get a thermometer to leave in there for a bit, though I can also say that I did check the batteries a few times during the day and they felt very hot, not so hot that I couldn't hold them but hot enough that I didn't really want to hold them. Just yesterday I pulled my flashlight out of my glovebox (MiniMag) and it was almost too hot to hold, the outdoor temperature was about 102F. As far as "how exposed was my car", here is where I parked for all but the last couple of months of this test (the sectioned off space just left of the pickup)...







For the last couple of months I parked at the end of the street in the foreground (going to the left). In the morning there was shade, but by about mid-morning my car was in full sun until late afternoon.


----------



## bob_ninja (Jun 19, 2008)

Oh man I am a dummy :thinking:

I forgot the windows and heat being trapped inside, plus dark (black) interior absorbing heat, etc. Of course, car interior is actually well above temps outside.

I was just wondering how well is box insulated, but come to think of it not really much at all. There is likely enough openings around the box for a free air circulation.

Anyway, I was just wondering about temps inside of a car compared to outside, like typical +10% or +20% or ????

thanks


----------



## horizonseeker (Jun 19, 2008)

very nice work, the results are very encouraging for So Cal weather as well. I feel better and better about my eneloops.


----------



## 5S8Zh5 (Jan 29, 2020)

Glad I found this thread. I'm just south of Vegas and next thing you know, high temperatures will be here. I'm now thinking that my two AA Quark QK2A will be my car light. I'll also try a G2 with M61LLL 219B V3 and see how Surefire CR123As hold up. Getting a recording thermometer to see how hot it really gets.


----------

