Eneloops Left In Car For 1 Year - Results

[mattchase]

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]

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]

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]

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

 

[xcel730]

Impressive. Thanks for your test.

 

[RGB_LED]

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

 

[jezzyp]

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]

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]

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

 

[UnknownVT]

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]

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]

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

 

[FrontRanger]

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]

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]

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]

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]

: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]

PM's inbound with DC#

 

[Black Rose]

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]

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.