NiMH Battery Buying Guide

Get the best NiMH batteries

Best AA NiMH batteries

Some readers want my personal recommendations, but the experience of thousands of customers on Amazon is more reliable data than just one person's experience.  (For the same reason, don't ask for recommendations for contractors on Nextdoor; one or two neighbors' opinions isn't nearly as authoritative as dozens to hundreds on Yelp, even after factoring in a small percentage of possibly fake reviews.)  Also, I used to recommend a brand I initially had a good experience with, but those batteries then died after a few years (after only dozens of charge cycles), making me regret my rec.  So now, please enjoy this survey of the highest-rated AA cells on Amazon that I did:

Best NiMH AA batteries

Brand	Capacity (mAh)	LSD?	1+2 star reviews	# reviews	Price per 8
Zonhood	2800	LSD	7%	385	$15.99
RayHom	2800	LSD	8%	469	$14.31
Powerowl	2800	LSD	10%	314	$16.98
Voniko	2600	LSD	4%	102	$14.66
EBL colors	2500	LSD	2%	107	$15.20
eneloop pro	2500	LSD	6%	3739	$41.98
Energizer	2300	LSD	5%	349	$22.35
Energizer	2000	LSD	6%	5333	$14.38
eneloop 4th gen.	2000	LSD	8%	661	$26.99
Energizer	2000	LSD	4%	1264	$32.82

"LSD" means low-self-discharge.
Data from July 2020.
Also see my recommended chargers.

Best AAA NiMH batteries

Here's my survey of the best-rated AAA batteries on Amazon in July 2020.

Best NiMH AAA batteries

Brand	Capacity (mAh)	LSD?	1+2 star reviews	# reviews	Price per 8
EBL colors	1100	LSD	2%	107	$11.19
Soluser	1100	LSD	5%	195	$11.99
Zonhood	1100	LSD	7%	166	$12.99
RayHom	1100	LSD	7%	198	$19.04
EBL	1000	LSD	6%	2230	$11.46
Voniko	950	LSD	1%	73	$15.99
eneloop pro	950	LSD	4%	83	$26.66
Eneloop 4th gen.	800	LSD	7%	95	$19.96
Energizer	800	LSD	3%	105	$20.39
Powxs	800	LSD	6%	232	$10.78

"LSD" means low-self-discharge.
Data from July 2020.
Also see my recommended chargers.

Project Farm testing

A YouTube channel called Project Farm (PF) tested various rechargeable brands in 2019.  The good part is that the batteries were in solar lights and got over 300 cycles over the one-year usage period.  The bad part is that it seems like PF tested only one cell for each brand for each kind of test.  So, for example, if there's a crappy brand where 25% of the cells die after a year, then PF's test will overestimate how good or bad that brand is based on whether the one cell they tested was bad or good in the testing.  However, for what it's worth, PF's main findings were:

1. Capacity (best to worst):  Duracell, Powerex, EBL, IKEA, Harbor Freight Thunderbolt, Energizer, Amazon Basics (black), Eneloop.  Rayovac was the worst but it's so poor I don't think it deserves to be in the list.
2. Self-discharge (best to worst): IKEA, Duracell, Amazon Basics (black), Energizer, Eneloop, Powerex, Harbor Freight Thunderbolt, EBL.

IKEA NiMH batteries

Readers asked me to comment on IKEA's “LADDA” brand of LSD NiMH batteries, so here you go:  At $6.99/4-pack (AA or AAA), they're cheaper than Amazon for AA but more expensive than Amazon for AAA.  And that's as long as you don't mind a trip to IKEA; if you want the batteries sent to you then I imagine the shipping/delivery charges will outweigh the savings versus Amazon batteries, but I can't say for sure because the IKEA website refused to tell me the cost of delivery because the batteries were out of stock.  As for quality, the stated capacities are 2450 and 900 mAh respectively, and if the customer reviews on IKEA's website are to be believed, the batteries themselves are fine.

Don't buy batteries on eBay

eBay has lots of off-brands you've never heard of that are pure garbage, giving only a tiny fraction of their rated capacity.  I've tested lots of these off-brand batteries, and I know before I stick them in the tester that they're junk because they're usually light as a feather.  I've tested batteries labeled as 1500mAh which are actually only 300!  So when buying NiMH batteries, you absolutely have to stick to the well-reviewed brands like those listed above.

Most NiMH are now "low self-discharge"

When NiMH first came out (around 2000), they had a high self-discharge rate, meaning they would lose their charge from just sitting around for a few months unused.  Gradually manufacturers came out with "low self-discharge" (LSD) varieties that don't suffer from that problem, and now (~2021) nearly all NiMH batteries that you're likely to run across are the LSD flavor.  The only advantage of non-LSD NiMH batteries is that they have a little extra capacity (~8%), so if your application means that you're running your batteries down quickly and charging every month or two, then you might prefer the non-LSD version.

On Amazon, LSD batteries are advertised as such, and all flavors of eneloop are LSD.  In stores, most packaging doesn't specify explicitly, so look for "code words" that indicate that they're LSD, such as "Pre-charged" (since normal NiMH's always require charging before use), "Ready to Use", or "Hybrid".  And of course, the dead giveaway is anything on the package that says how much charge the batteries retain after one year or more.

No longer recommending Maha/Powerex

I used to recommend Maha/Powerex (highest capacity at the time, black with yellow lettering), but after a few years, most of them have severely reduced capacity (like 88%) and/or discharge within a few minutes of taking them out of the charger.

Most charge cycles

Sanyo claims 2100 charge cycle for their latest brand (4th generation eneloop), but even if you charge them every single day, then even batteries that get "only" 1000 cycles will last nearly three years, so for most users the extra recharge cycles vs. other brands (or older eneloops) aren't a big advantage.

C- and D-size LSD NiMH's

C- and D-size eneloops are available only in Japan, but other brands are available elsewhere:

• Powerex (C: 5000 mAh • D: 10,000 mAh)
• Acculoop Precharged  (C: 4500 mAh • D: 10,000 mAh)
• Tenergy Centura (C: 4000 mAh • D: 8000 mAh)

You could also get an upsizer (adapter) that lets you put an AA battery into a C- or D-shaped case.  (Adapters that take more than one battery are risky because if one battery fails, melting or a fire is possible.  Multiple batteries in an upsizing adapter is different from multiple batteries in most devices, because in most devices the batteries run in series, while in upsizing adapters, the batteries are parallel.)

eneloop varieties compared

There are lots of flavors of eneloops.  Here's how they compare:

1. Capacity.  eneloops used to have a stated rating for capacity, but now there's an "up to" figure, and a "minimum" figure, which is usually 100 mAh less than the "up to" figure for AA's, and 50 mAh less for AAA's.  My tables show the "up to" figures.
2. Discharge rate.  The 3rd generation eneloops are rated to have 70% of their original charge left after five years of idle time.  While I couldn't find five-year figures for the current generation of eneloops, I'm guessing that the five-year rating hasn't changed.
3. eneloop plus.  There an "eneloop plus" model with a special feature to prevent overheating (for safer kids' toys), but as I write this they're not available in the U.S. and I can't find good specs on them.
4. Panasonic/Sanyo.  Sanyo was the original manufacturer, then Sanyo was acquired by Panasonic.  eneloops have been a Panasonic brand since April 2014.
5. Temperature.  All all eneloops above are rated for use down to -4°F.  Only the very first generation eneloop was rated for "only" 14°F, which is still well below freezing and PFC (pretty freakin' cold).
6. Prices last checked Aug. 2020, and are for 4-packs without the charger.
7. History.  Eneloop debuted in 2005.  Here's its history.

And here's data on older eneloop models:

Sources for the eneloop tables:

eneloop Pro:  Charge cycles, capacity, 1-yr. self-discharge rate
eneloop lite: Panasonic
eneloop 4th gen.:  Capacity, recharge cycles, model number, 1yr. self-discharge 

eneloop XX: Charge cycles, capacity, self-discharge rate
2nd generation (1500x): Capacity, cycle life
1st generation (1000x):  Capacity, cycle life, temperature, model #'s (PDF), 2-year discharge rate, release date

Discharge rates: 1st/2nd gen, lite, and non-eneloop; 3rd gen. 3-yr., lite
Prices as per Amazon on 12/17/12
Other:  An eneloop fan has compiled lots of eneloop stats & info
I used to have more sources, but Panasonic/Sanyo removed the old pages from their sites, and most of them are not in the Wayback Machine either.

Various brands' actual capacities compared

Hobbyists have done capacity testing on various brands of NiMH batteries and here are the results:

• Non-LSD, 2013.  My tests of Sanyo and Powerex 2700 AA's are here for historical purposes, because Sanyo no longer makes theirs, and because both seemed to suffer from rapid self-discharge (like a few hours) after a few years and only dozens of cycles.  FWIW, my tests showed 2620 and 2690 mAh, for an average of 2655 mAh, and the Powerex 2700's were 2590, 2630, 2640, and 2660, for an average of 2630 mAh.  (Tested with a La Crosse BC-700 on the Refresh program, new out of the box.)
  
• LSD, 2011, by NLee the Engineer
• LSD, 2011, on Whirlpool forums (only 4 brands: eneloop, Imedion, Powerex, and Vapex) 
• LSD, 2009-11, at StefanV
  
• Non-LSD, 2008, on Candlepower Forums