What's the equivalent eneloop pro AA/AAA for 9V batteries?

Zachary on 01/05/2018 - 14:39

I suppose I could just simply buy 8 AA Eneloop Pros and have them in series so that they're equivalent to a single 9V NiMh battery but I don't want to recharge 8 cells individually when the power goes flat and would rather just do it in one go with only one battery.

I've googled a bit but apparently eneloop pros don't come in 9V sizes….there are other NiMh 9V batteries but haven't heard of their brands before so for all I know they won't have the same quality factors that eneloop pros carry; mainly long lasting, but not as long as lithium ones but I don't have a lithium charger, only NiMh and that it's got Low-Self-Disharge (LSD) perfect for when you need it to idle for a long period of time….

So far I've seen 9V batteries in 300mAh, 250mAh and 150mAh, which isn't gonna last very long……compared to eneloop pros with their 2500mAh rating…

Thanks!

Electrical & Electronics

Comments

    • Zachary on 02/05/2018 - 14:30

      Oh so 9V batteries are no better than traditional AA cells? huh…

      • D C on 02/05/2018 - 19:58

        You can get Li-Ion ones now, https://www.ebay.com.au/itm/302697082997. The things you find.

        Not sure if I believe the numbers on that listing, but there is a standard 650mAh LiPo battery that's about 1/2 the thickness of a 9v (and you'd need two of them), so it is possible.

        That would be easily double the capacity of the NiMh ones.

  • Nugs on 01/05/2018 - 15:14

    LSD but only 200mAh

    http://www.varta-consumer.com/en/products/rechargeables/over…

    we've had a bunch of their AA's & AAA's for at least ten years. none have failed with only moderate use despite using the 15 minute chargers.

    our second 15 minute charger died recently. have ordered a zanflare C4 as a replacement.

  • techno2000 on 01/05/2018 - 15:25
    +2

    If you are planning to use these in smoke alarms be aware that rechargeable 9v batteries are not recommended as they will suddenly die without giving sufficient beeping warning.

  • dcuksuop on 01/05/2018 - 15:53
    +3

    Can't compare mAh of different voltages like that.
    Better way is to compare watt hours.
    1.2V * 2500mAh = 3Wh
    9V * 300mAh = 2.7Wh

    • D C on 01/05/2018 - 16:32
      +1

      Yep.

      Similar capacity, just re-arranged differently.

      9V rechargeables are just 6 or 7 1.2v cells in series. They're not even 9v, usually only 7.2v or 8.4v.

      9V * 300mAh = 2.7Wh

      More like 7 x 1.2V * 300mAh = 2.5Wh. 300mAh is a bit generous too.

      I hate 9v batteries.

      • Zachary on 02/05/2018 - 14:26

        I found one that's rated for 9.6V: https://www.protog.com.au/powerex-precharged-9v-9.6v-230mah-…

        I think this is their official store page: http://www.mahaenergy.com/powerex-precharged-9-6v-230mah-1-p…

        • D C on 02/05/2018 - 16:16

          Not quite sure what the point of that is, most 9v stuff is happy to run off the 7.2v ones and alkalines don't stay at 9v for long. Somebody must have a need, I guess.

          At least they're honest about capacity, that works out to be 8 x 1.2v x 230Mah = 2200mAh. Still pretty ordinary though.

          I wouldn't be surprised that there isn't a lithium ion 9v battery around these days, like those AA ones you can get. Probably get double the capacity of NiMh.

          I've got a couple of 9v things I run off a single 18650, uses a little boost circuit to get 9v and charges off USB. Only a few dollars in parts. Used to be a common project back in the day, to boost a C cell or whatever to 9v.

        • D C on 02/05/2018 - 19:46

          So I had a look, and there are Li-Ion 9v batteries out there. Two types, in fact.

          First type is as I describes, USB charged with a boost circuit.

          Second type uses 2 lithium cells in series, giving 8.4v when fully charged (4.2v x 2), would cut out around 6v. Similar to other 9v batteries. You could charge these in a normal charger, the cells would have a over-voltage protection circuit that would stop the charge once full.

        • techno2000 on 03/05/2018 - 08:10

          @D C:

          Very interesting indeed. I had no idea that there were li-Ion 9v rechargeable batteries around.

          https://www.amazon.com/EBL-Battery-Lithium-ion-Rechargeable-…

        • D C on 03/05/2018 - 16:53

          @techno2000: Me neither, I was surprised there were two versions.

          The one you've linked probably has two of these: https://www.aliexpress.com/item/Polymer-752438-medical-devic… inside. That's the battery a lot of quadcopters use.

          Their capacity is about the same as an alkaline, not bad.

          Cute version of the USB charged type: https://www.banggood.com/OKcell-9V-800mAh-USB-Rechargeable-L….

          That 800mAh is the lithium capacity, a comment in the reviews says at 9v it's about 275mAh, on par or better than NiHm but still only half of the other type. On the other hand you can't beat the convenience of USB charging.

        • Zachary on 03/05/2018 - 20:13

          @D C: Oh it was in reply to your comment that no 9V NiMh exist(Which is true as they apparently go in steps of 1.2V for each cell….) which I read wrong, I thought it read no 9.6V ones exist….my bad! hee hee … 😅

        • D C on 03/05/2018 - 22:56

          @Zachary: Thanks for the post, today I learned Li-Ion 9v batteries are a thing.

          I'm going to get a few of the USB rechargeable ones for tools like meters and temp guns, not fussed about the capacity, and maybe a couple of the other type to see how they go in smoke alarms. Possibly may not trigger the 'battery low warning'.

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