A note of caution about Thunderbolt Magnum Heavy Duty batteries


Discount hardware store, Harbor Freight, sells packs of very affordable Heavy Duty batteries under the Thunderbolt Magnum brand name. Occasionally, Harbor Freight even gives large packs of these batteries away for free (with a coupon).

This is how I acquired a pack of 24 Thunderbolt Magnum AA cells earlier this year: for free during a store promotion.

In truth, I use quality rechargeable AA cells quite heavily (mainly Powerex and Panasonic Enloops). If I am reviewing a radio, I buy fresh Energizer or Duracell AA alkaline batteries to make sure the radio is receiving full voltage from the batteries during the evaluation.

But, on occasion, a cheap AA will suffice, right?

Not these.

I put three in a shortwave portable in June because all of my other batteries were in use. I had just planned to take the portable on a weekend trip.  Though it shouldn’t have been a problem, I forgot and left the batteries in the radio.

Tuesday afternoon, I checked the batteries because they were already dead. Turns out they were already leaking! I then remembered that other cells–from the same pack–had leaked in one of my kid’s flashlights.

It could be that I simply got a bad batch of batteries, but these cells really do feel of poor quality–I bet they weigh half that of most other Heavy Duty cells.

My advice? Free is too costly for these batteries. Stick with quality cells!

Now I need to go through my house and find where the remaining four batteries are hidden before they damage another device.

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42 thoughts on “A note of caution about Thunderbolt Magnum Heavy Duty batteries

  1. Jorg Breuning

    Thunderbolt Magnum Heavy Duty batteries certainly have leakage problems. Today 18th April 2020 i discovered that my heating thermostat was on error. I opened it and a lot of liquid was everywhere coming from one or more of the four batteries – after 3 months…
    In another device, they didn’t leak but were down also in a much short time than with other brands.

  2. K Mathewson

    I bought these recently at Harbor Freight and I have to change them in my remote control every two or three days. And it’s not like that remote even gets used non stop. So the life of these batteries is maybe 8 hours at best. Don’t buy they. Only take them if they are free and you don’t mind changing your batteries often!

  3. Jeff

    First of all they are carbon zinc, not alkaline. Alkalines in particular are leak prone. They all leak in occassion. One batch failure is no reason to sound the alarm. I had a big pack of Costco/Duracell alkalines and practically every one leaked, even the ones I had not used yet. I have not used the yellow carbon zinc Thunderbolts but I have used lots of the orange, alkaline Thunderbolts, without a single leak. While I have not run comparitive tests, they seem to do fine. At $4.99 with a sale coupon for 24, I like them a lot.

  4. patrick

    I use them all the time. In game controllers remotes and flashlights. Never had a problem. cant complain about free batteries!

  5. Joe

    You must have received a bad batch, we’ve been using HF’s Thunderbolt Magnums in flashlights, lanterns, remotes and other devices with no issues as long as we don’t leave them installed more than a year.

  6. David C.

    My 9 volt battery died today, date on battery says 12-2015… think they usually are the best used by date, which is usually 2 or so years. Anyhow, it must’ve been bad because it died 4 years later from that date, no leaks thankfully.

  7. Beverly Winstead

    We have used thunderbolt batteries (orange) that we purchased from Harbor Freight for a long time. However, this one time, my husband had a small flashlight that contained AAA Thundertbolt batteries in his shirt pocket. He was driving to work one morning when he heard a loud BANG whiche sounded like a gunshot. He felt a large pain in his left side of his chest. He immediately thought he got shot. He felt around on his door panel & then his chests left side feeling for bullet hole or blood. His left side of chest was hurting bad. He finally pulled out his mini flashlight from hist shirt pocket & it was very hot. He opened the flashlight compartment & that’s when he saw the flashlight had EXPLODED in the flashlight while in his shirt pocket. These batteries are dangerous if they can explode. Do not buy these batteries.

  8. Octavian

    Whatever. How can you complain about free batteries? I use them all the time after I use my “Free With Purchase” coupon. They work fine for what they are. They are cheap Chinese batteries, but they aren’t going to blow up on you. I put them in my remote controls, Xbox controllers, etc. I’ve probably used 200+ of these, I get them every time I buy something at HF because the coupon never expires. They’re pretty much just half of a regular battery. You definitely got a bad batch.

  9. Tori

    What’s the difference chemically between the yellow ones and the orsnge alkaline ones? Does the zinc chloride mean it’s more toxic if it leaks or must be cleaned differently?

  10. VegasDude

    Never had a problem with Harbor Freight Heavy Duty’s, or the packs at the 99cent stores..

    I had some Energizer D cells leak in a Zenith Transoceanic battery pack a couple years ago……
    Who cares?? baking soda and water… toothbrush……… sizzle…. foaming action…. wipe… DONE…

    IF I buy a name brand now it’s RAYOVAC FUSION batteries…..
    They kick the the overhyped, and overpriced Bunny and Copper Top to the proverbial Curb….

    They are now BOYCOTTED… :0)

  11. Andrew R

    I bought 400 batteries total; 200 AAA’s & 200 AA’s from TigerDirect when they were having a huge sale. $75 for 400 batteries, I was definitely taking the chance. 4 years later, these batteries are still working fine, no leakage.

  12. kketchum

    when it comes to rechargeable batteries, the only way to go is brand name, it’s just the way it seems to be, but there are professional battery makers who also have quality items, but the price usually will spell the story, you get what you pay for especially when it comes to rechargeable batteries, (experience, 20+ years dealing with rechargeable batteries of all shapes and sizes, etc,

  13. John

    I put Harbor Freight batteries in a new weather radio and forgot to remove them. In about a week the batteries leaked so bad that it ruined my NEW radio. The leakage voided the warranty, LIVE AND LEARN!

  14. Kim

    Thank you for the information, I’ve been questioning whether these batteries are safe or of decent quality. I know of at least one time, a good year ago, that the Thunderbolt AAA batteries had leaked in a flashlight, but I doubt I’ve really used them much since. I have switched almost exclusively to Duracell batteries because if a Duracell leaks & ruins your device, you can send that device in to Duracell WITH THE BAD BATTTERIES STILL IN THE DEVICE, & they will replace the device! To me, that is worth the price of high quality batteries! I do look for discounts & coupons to help with that cost, & I have peace of mind about the things I use the batteries in. Like you said, the cost of free can be too high, & in this case, it absolutely is. Thank you for taking time to do the research we needed

  15. Jeannie

    Who do I contact about these Thunderbolt batteries? I bought them from Harbor Freight and messaged them but they are closed now. I put them in candles and placed them on my window sills and 7/15 leaked battery acid onto my window sills!! We just built this house and moved in on 12/31/16 and now have dark stains, some bigger than a 1/2 dollar on 7 sills. I am using white vinegar to try to lighten the stains but it isn’t working. It is a natural wood and the stains are dark brown-black. I took pictures of everything!

    Any help is appreciated!

  16. Steve

    Same experience with these same batteries. Powered a LED flashlight 10 mins before dying out. Voltage was sub .10, there is literally something wrong with the chemistry of these Batts.

  17. Jeff

    First if all, the yellow Thunderbolts are are carbon zinc, not alkaline. Comparing them to Duracell alkalines is comparing apples and oranges. Carbon zinc batteries do not do well under heavy loads The orange Thunderbolts are alkaline and I have gotten good life from them and no leaks. I had some Costco (Kirkland) AA’s made by Duracell and almost every one leaked. Nobody is immune. It takes more data than one bad experience to come to a conclusion and warn people off a product. Pick any brand, read the reviews, and you will see leak complaints, especially Duracell. That may be because they probably sell rhe most batteries and discontented people write the most reviews.

  18. Bryan Cookson

    the yellow HF thunderbolt batteries are absolute junk, i mean they (set of 3) cant even run a basic LED strip for my toolbox for more than a couple days and thats a VERY LOW draw, wont last in an XBOX controller for more than an hour, and my bluetooth keyboard on this computer only lasts a few days on a set of them, whereas my old crappy walmart or energizer NIMH’s (by old i mean well over 3-4 years old and sitting for months at a time before i find my smart charger due to being homeless) and they will last weeks in the same devices. and i have a 1000 true lumen LED flashlight for work it takes 9AA’s and has a 15W or 16W diode in it, and it will wipe these batteries out in about 20-30 minutes of continuous use, and i know the draw is approx 1A per bank of 3AA’s x3 rows (=9 total) so that would lead me to believe they only hold 400-500ma at thier prime

  19. Chris M

    Thanks for the heads up. I was looking at my new Harbor Freight mail-out this morning and was ready to bite. PASS!

  20. 6PTsocket

    In a study of various battery types, one study said alkalines in general are prone to leakage. My last batch of Kirkland batteries leaked badly, after years of success using them. I believe they are from Duracell. One leaky bunch is not much of an evaluation. I have yet to find a really thorough head to head test that has a big enough sample to mean something and is based on more than “These batteries lasted twice as long in my whizbang”.

  21. Darshan

    Never use single use batteries in a radio or camera that you do not intend to use every day. Use only rechargeable Ni-MH (read eneloop).

    The reason is if you put the radio away, the batteries will eventually discharge and LEAK, even Duracell and other quality ones.

    Use single use batteries only in case of emergencies and remove once the emergency is over.

    Instead, buy a bunch of eneloops or amazon basics precharged (same as eneloops) and a quality smart charger like powerex or La Crosse and have peace of mind.


  22. Mario Filippi

    As an old-timer I can remember dry cell batteries leaking back in the 50’s and 60’s. Then for the longest time they seemed to be better. Over the past several years the leaking has started again. Just like old times.

  23. paul

    They will all leak, the good ones and the bad ones. I had a Davis Vantage Pro that I had Energizers in the console. They leaked and ruined the console AND the table it was sitting on. It cost Energizer big bucks. Because of their “no leakage” guarantee, they had to buy me a new Vantage Pro. The problem was by that time you could not purchase the same weather station so they had to buy me a new wireless Vantage Pro 2 at a cost of over $600.00

  24. Dan Robinson

    I too went into panic mode a few weeks ago, going through every single box and radio and removing any batts. It’s the only way to guarantee not ruining your radio via leakage…

    1. rtc

      While we’re fussing,has anyone else noticed today’s alkalines
      don’t seem to last as long?
      Could it have something to do with the mercury being removed?
      My Sony M37 Walkman appears to go longer on a AAA rechargeable
      than it did on an alkaline,for the same use.
      Brings back memories of the old carbon-zinc cells… .

      1. rtc

        BTW,(from the Antique Radio Forum) try some vineger
        or Real Lemon on alkaline leakage with a Q tip,it will
        clean it right up-if it’s not too severe.

  25. rtc

    Same here…this was discussed (and cussed) at length on an Antique Radio
    Forum thread back in the summer.
    Bottom line: none of them are any good,even the name brands leak like
    a sieve.
    Found that out the hard way, even some new ones still well
    in date in the pack had leaked.
    The forum guys recommended checking all alkalines every six months
    regardless of use.
    The suggested use of rechargeables is excellent
    since name brand alkalines now cost about
    as much,even at Wal-Mart.

    1. Bob daTank

      Alkaline batteries leak and lithium batteries catch fire. I remember the old Rayovac batteries lead-acid batteries all said they guaranteed that is the product was damaged to mail it in and they would replace it. Not anymore, I don’t think….

  26. William Pietschman (W8LV)

    Same thing with the Dollar General 9 volt Alkalines. ..they are no damn good. I’ve had several go bad on their original sealed package!

    No problem though, with the Dollar General AA or AAA Alkaline Batteries, at least so far…and they certainly do save money!

    Your Mileage may vary,

    73 DE Bill W8LV

  27. Robert AK3Q

    Good advice – I had a similar problem with Walmart-branded batteries some years ago, as well as Radio Shack. I tend to stick with Duracell or Energizer. For some years I got away from rechargeables all together, preferring the full power of AA cells, avoiding drain during unused periods, and just being able to keep a bunch around.
    Now I have gone back to rechargeables where possible, using only Enloops, because of their ability to maintain a lengthy charge for those things which get used only occasionally. The reason? I have had both Energizer and Duracell leak in products where they had only been in the radio or similar item for 6 months. That is unacceptable to me with today’s technology.
    Obviously there is a lowering of the quality of these batteries, pushing people toward, I believe, the high-end lithium batteries made by these companies. I think it is comparable to dishwasher detergents-have you noticed?- you keep having to buy the latest greatest versions of them to get things truly clean. There are three or four levels of cleaners and only the top one gets things really clean, until that level is replaced with a “new and improved” top level, and suddenly only that formula really get things clean. Just one man’s rant!

    1. Richard Mason

      These comments are contrary to my experience. I’ve tried both their yellow jacketed heavy duty and their orange jacketed alkaline batteries with no problems.
      They consistently yield voltage greater than 1.5. Usually around 1.8v. No leakages.

      1. Roman

        You were maybe just
        Lucky..the fellow who started this topic is right on…junk! They may show 1.5 or greater but very weak amperage. Trust me as well junk!


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