
Rechargeable vs. Alkaline Batteries - bookofjoe
https://www.nytimes.com/2019/06/06/smarter-living/wirecutter/are-rechargeable-batteries-better-than-alkaline.html
======
nrclark

      Electronics that constantly draw low amounts of power — such as
      some wall clocks, headlamps, or bike lights — work better with
      disposable alkaline batteries. Alkalines release power consistently
      right up until they die, whereas a rechargeable battery’s voltage
      gets gradually lower and lower over time, slowing down the device or
      cutting off power prematurely.
    

This is very wrong, and makes me doubt the article's correctness. Every NiMH
discharge curve I've ever seen is much flatter than a typical alkaline curve.

NiMH batteries drop down to around 1.25V pretty quick when discharging, but
they stay around 1.25-1.15V for almost the entire discharge cycle. Alkaline
batteries are almost dead by the time they get down to 1.2V.

So the reason why NiMHs drop out early on some devices isn't because they're
out of charge, or because alkaline batteries have a flatter discharge curve
(they don't). It's because some devices stop working at around a 1.2V cell
voltage, regardless of how much charge is left in the battery.

~~~
sixstringtheory
Slightly related, and maybe you could provide more knowledge here: common
knowledge for safety critical devices, such as avalanche beacons, is to only
use disposable alkaline batteries. The reasoning I've heard is that due to the
flat power curve of non-alkaline batteries, if you put a nearly-dead one in
the beacon and check the battery level, it will read as fuller than it really
is, and you run the risk of having it die on you during a normal usage period
(maybe 12 hours). With an alkaline battery, when it's close to done, it will
more accurately register as such on the device.

~~~
Gibbon1
Alkaline batteries start off at 1.5-1.6 volts and the voltage follows the
charge reasonably linearly down to about 1.0 volts. So that's correct,
alkaline batteries at 1.5V per cell are 'good' full stop. Where a rechargeable
at 1.2V might or might not be. Who really knows if it charged all the
way[1][2].

[1] Gallant is careful to put his nmh batteries in the the charger each night.
Goofus got high and forgot. In the morning Goofus swapped his dead ones for
the ones in Gallants charger.

[2] Power went out between 11pm and 6am while everyone was asleep.

------
KerrickStaley
I don't think this sentence from the article is correct: "Alkalines release
power consistently right up until they die, whereas a rechargeable battery’s
voltage gets gradually lower and lower over time, slowing down the device or
cutting off power prematurely."

If you look at the discharge curve for an alkaline battery (for example,
[http://madscientisthut.com/wordpress/wp-
content/uploads/2013...](http://madscientisthut.com/wordpress/wp-
content/uploads/2013/12/Kirkland-1024x458.jpg)), it seems more linear than for
a NiMH cell
([http://4.bp.blogspot.com/_7azY596Jbs8/TVHgoP3gUkI/AAAAAAAAG4...](http://4.bp.blogspot.com/_7azY596Jbs8/TVHgoP3gUkI/AAAAAAAAG4k/M2WIdx3gVKM/s1600/nimhChart1.png)).
In other words, it's the NiMH cell that gives consistent voltage until it
dies, whereas the alkaline battery will gradually lose voltage. (It's not
totally clear, some other graphs of alkaline discharge curves do show more of
a "knuckle", with a flat initial section and then a steep drop-off).

------
Johnny555
_Electronics that constantly draw low amounts of power — such as some wall
clocks, headlamps, or bike lights — work better with disposable alkaline
batteries_

I use low discharge NiMH rechargables in all of my battery bike lights and
they work great, they'll last for about 3 months of my usage (I run the
taillights night or day), but I charge them all at the end of the month (I
have 2 sets, so one set's on the bike and one set is charged and ready to swap
out). I'm on the same set of Eneloops I bought 6 years ago. Every year or so I
have my charger run a discharge test and they are still within about 90% of
rated capacity.

I'd have thrown away 24 sets of disposable batteries in that timeframe (since
I keep an extra set of batteries charged, so it's a ratio of 1:12). I paid
~2.50 each for the eneloops when I bought them, so cost wise it's been a good
investment, works out to around 20 cents each so far (ignoring the cost of
electricity)

It's getting harder to find non-rechargable bike lights, my main headlight
uses a non-replacable LiIon battery.

~~~
digikata
It's a shame that so many products default to built in, non-replaceable LiIons
now. For many products, it's nicer to have a replaceable rechargeable so you
can pop in charged battery and go instead of having to plan for state of
charge of yet another device.

~~~
Brakenshire
I suspect building them is in an environmental benefit in a lot of cases, a
lot of people just buy huge packs of alkaline disposables and can't be
bothered with rechargeables unless they're built in. I'd be interested to see
the statistics but I wouldn't be surprised if 80% of people use disposable
batteries given the opportunity.

~~~
opencl
I just don't get why replaceable standard-sized lithium ion batteries have
pretty much completely failed to take off other than those 18650 flashlights
and vape pens.

The proprietary replaceable batteries are an improvement over non-replaceable
but in anything other than cameras the replacements seem to get discontinued
by the manufacturer by the time you actually need one.

~~~
zokier
One concern about lithium cells is safety. Shorting alkaline cells won't do
much, and even nimhs are relatively benign, but lithiums can start fires or
explode when mishandled. Shipping lithum cells is for that reason bit of a
hurdle too.

~~~
digikata
I think that's why the raw cells aren't used as the level of swappable unit
very often. If the battery is at all removable, they're often integrated into
packs which have some level of built-in protection.

------
slacka
I was expecting an informative discussion on the impact of
producing/disposing/recycling Rechargeable vs Alkaline? Instead I just got,
rechargeable = better.

My gut tells me rechargeable is better, but only if they are properly
disposed/recycled 100% of the time. We don't need more heavy metals in our
air/water from rechargeables being incinerated.

Any recommendations for chargers that don't require paired batteries? Some of
my recent devices need batteries in 3's and 1's.

~~~
snowbrook
The Panasonic BQ-CC55 charger will charge from 1 to 4 cells, AA or AAA, in any
combination. I've got 2 and they've worked great.

~~~
wlesieutre
For about $10 more, also see La Crosse Technology's BC700. It can do some neat
things like measure the capacity that was charged or run a "refresh" cycle
that repeatedly drains and charges a battery (up to 20 times) until the
measured capacity stops increasing.

Like the BQ-CC55, it has four independent channels that can charge either AA
or AAA in any mix. You can even run different modes on each channel, like
charging 1 and 2 while refreshing 3 and 4.

~~~
Tomte
I've had the BC700 (or possibly one of the identical builds under a different
brand name) for years, but switched to the BQ-CC55.

The latter is "put in and forget". The former means fiddling with really bad
buttons (because you can! Not really because you have to. But if I can
manually set and micro-optimize the charging current, by God I will).

I worry much less about charging nowadays.

~~~
wlesieutre
I can't say I've used the custom charging current options, but the refresh
mode has rescued some batteries that (very unscientifically) did not seem to
be holding much charge.

IIRC the default behavior is to charge at 200 mA and discharge at 100 mA.

------
120photo
Photographers will tell you that using rechargeable batteries are the way to
go when it comes to using flash/speedlights. They charge up much quicker than
Alkaline and they either work or do not. Alkaline charges you flash at a
slower rate and will give you weaker inconsistent power when they are dying
(rechargeable give you all they can or just die out).

------
all_blue_chucks
Disappointing. No mention of rechargable lithium batteries than are extremely
popular for use in flashlights, among other things. No mention of the non-
draining NiMH (eneloop) in comparison to traditional NiMH batteries. Just a
reminder to use alkaline in smoke detectors, and even there it failed to
distinguish between alkaline types (some last far longer than others).

~~~
spear
I think the article makes the assumption that modern NiMHs are all of the
Eneloop type. I think that's fair -- it seems like almost all the NiMHs I see
for sale these days are the same type. The longer Wirecutter test article it
references does go into a bit more about the history of the Eneloops and all
the batteries it tested are the same type (which it calls "Low Self-Discharge
NiMH").

Also, despite the title, I think the article is really "rechargeable" vs.
"single-use". It doesn't explicitly say that the 10-year smoke alarm batteries
are alkaline. The ones I've seen are actually lithium.

------
Jedd
Probably not much of a coincidence, but I was researching smart chargers about
twelve hours ago and ended up going for Panasonic's flagship (bc55). (As
depressing as always, one bloke with a credit card can out-do any other
organisation's economies of scale when importing anything into Australia.)

I've re-embraced eneloops partly for cost (already covered by OP) but also
because they perform better (last longer, fail less frequently) in cold
weather. This bites me each winter with a bunch of residential grade
irrigation computers that use 2 x AAA. Confidence / reliability also factors
in - when those things die I might not notice for a couple of weeks, until
some plants start to look unwell, but aggressively replacing all the alkalines
every six months (they _usually_ last 9-12 months) worries me more from the
rampant waste perspective than cost.

~~~
fyfy18
Supposedly IKEA LADDA batteries are rebranded Eneloops. It's not official, but
the capacity and and discharge curves are the same:

[https://petapixel.com/2018/02/16/eneloop-pro-20-batteries-
ik...](https://petapixel.com/2018/02/16/eneloop-pro-20-batteries-ikea-
ladda-5-batteries/)

~~~
Jedd
That's interesting. My first thought was it's probably another of those things
that IKEA sells everywhere except Australia - but happily the LADDAs are
available here.

Though with one small caveat - the white LADDAs evidently come out of the same
Japan factory that makes almost all the other good eneloops, but the brown
LADDAs are known to come out of PRC, and don't exhibit the same quality.

------
m463
Alkaline batteries are NOT good at low temperature.

The most reliable power I have found are the single-use lithium batteries,
especially when the temperature drops.

I should also mention - use rechargeable batteries for devices you care about.

If they come with batteries, usually alkaline batteries, there's a good chance
they will discharge, then start leaking and either damage or destroy the
device they came in.

Meanwhile, rechargable batteries have much better sealing and rarely leak even
if fully discharged.

Small(ish) price to pay to preserve an expensive device.

------
post_break
I wish more products would adapt 18650 batteries. My flashlight can pump out
over 2000 lumens or still very bright for a really long time. 18650 has very
high density, can be charged and discharged rapidly depending on the cell, and
has safety fuses. I've thrown away a bunch of rechargable AA batteries and not
a single 18650.

~~~
extesy
With lumens like that you would want 28650 otherwise it wouldn't last for too
long.

------
notJim
Is there an easy way to get rid of rechargeables once they're dead? I have a
bunch of them sitting in a drawer, because it's a pain to go to the city
recycle facility. I highly doubt most people go to the effort. This is the big
drawback to alkaline batteries for me, since those can be thrown away in the
trash.

~~~
pmoriarty
Those "dead" rechargeable batteries may have more life in them. Don't throw
them away yet!

If your charger won't charge the battery anymore (showing the battery as
"null"), there's a way to make it charge again.[1]

The technique is basically to use a paperclip to connect the positive
terminals of a working and "dead" battery while they're both in the charger,
only (unlike in the video) I do this with the charger unplugged from the wall
socket. This only needs to be done for a few seconds for the "dead" battery to
come back to life.

I used to discard many rechargeable batteries that I thought were dead before
I discovered this trick. Since I started doing this, I've been able to keep
using my old rechargeable batteries continuously, except that after a while
they seem to hold less and less charge, so eventually I do get rid of them,
but I no longer do so simply because my charger tells me they're "null".

[1] -
[https://www.youtube.com/watch?v=rFapDUSOgnY](https://www.youtube.com/watch?v=rFapDUSOgnY)

~~~
sephamorr
Whatever you do, do NOT do this with lithium ion batteries. At low voltages,
chemical side-reactions start to occur which result in dendrite formation
which can pierce the membrane, shorting the battery: the result is fire. LiIon
batteries generally have protection that permanently blow a fuse if the
voltage goes below a minimum safe voltage, but raw 18650 cells often do not.
The video above refers to NiMH cells. Afaik, this is safe to do for NiMH.

------
Trias11
What about Lithium AA[A] batteries?

I'd use them for critical applications (flashlight during camping/desert
travel)

~~~
sixstringtheory
I asked about it in another thread higher up
[https://news.ycombinator.com/item?id=20502338](https://news.ycombinator.com/item?id=20502338)

In my trainings I've specifically been told not to use Lithium ion batteries
in critical applications, like headlamps and beacons.

------
Dylan16807
> Smoke alarms that are not hard-wired into your home’s electrical system get
> power in one of two ways: a built-in battery designed to last up to 10
> years, or a disposable 9-volt battery that you should replace once a year.

No, they definitely make smoke alarms that take two AA.

~~~
ceejayoz
New York state banned the sale of smoke alarms with removable batteries
earlier this year.

> Starting Monday, all new or replacement smoke detectors sold in the state
> must either be powered by a non-removable battery good for at least 10 years
> or be made to be hard-wired to buildings.

[https://www.nbcnewyork.com/news/local/Law-Bans-Smoke-
Detecto...](https://www.nbcnewyork.com/news/local/Law-Bans-Smoke-Detectors-
With-Removable-Batteries-for-Sale-in-NY-507915901.html)

------
tomohawk
> built-in battery designed to last up to 10 years

Good luck with that. I have yet to see any of those make it past 10 weeks, let
alone 10 months. And when they false alarm, you have to destroy the device to
turn it off.

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RickJWagner
Great article, encourages me to go buy another battery recharger.

We have an XBox in the house, and 3 enthusiastic users. Lots of batteries....

