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'[EE] Rechargeable Lithium AAA cells'
\\@b by peter green

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On 05/02/19 18:35, David Van Horn wrote:
> Just FYI, I was unaware till yesterday that these things exist.
> www.amazon.com/AAA-Batteries-Rechargeable-Charging-Pre-Charged/dp/B07D1LMMDD
> The capacity of the cells in the link is 400mAh, which is WORSE than carbon zinc.
An interesting question would be whether that is 400mAh at the cell or 400mAh at the output, given that as you say these things have a built-in buck converter.
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'[EE] Rechargeable Lithium AAA cells'
2019\02\05@133540 by David Van Horn
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Just FYI, I was unaware till yesterday that these things exist.
www.amazon.com/AAA-Batteries-Rechargeable-Charging-Pre-Charged/dp/B07D1LMMDD
The capacity of the cells in the link is 400mAh, which is WORSE than carbon zinc.
The output voltage I saw was over 1.7V which could be a problem for some designs. Many LDOs have a max Vin of 5.5V which is perfectly safe with 1.5V alkaline cells.

They have a small SMPS (buck?) that is ALWAYS operating, with a voltage ripple of about 150mV on the cells I tested.
These cells create a large amount of RF noise, even when not loaded and sitting in their plastic cases.
When loaded, the noise spectrum changes as you'd expect, making the interference worse or better depending on your specific system.

Basically, a disaster for any noise sensitive electronics that might be relying on batteries to be a QUIET power source.




--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: spam_OUTdavid.vanhornTakeThisOuTspambackcountryaccess.com<.....david.vanhornKILLspamspam@spam@backcountryaccess.com>

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2019\02\05@165448 by David Van Horn

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I wouldn't trust the ratings nearly as far as I could throw it.


--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: david.vanhornspamKILLspambackcountryaccess.com 

{Original Message removed}

2019\02\05@170420 by Jim

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All,

I would think that would be at the output of the converter.
Further, the terminal voltage of 1.5V I would think would be correct if
you were drawing 400mA from the battery/SMPS converter.  Try putting a
load of 400 mA on it and measure the terminal voltage.  I would wager it
will be very close to 1.5V.  It would be not unlike a transformer, say
6.3V @ 100mA.  This is saying that the terminal voltage would be 6.3
volts when you draw 100 mA of current from the transformer.  If you draw
less than that, the terminal voltage will go up, and vice versa.

Regards,

Jim

> ---{Original Message removed}

2019\02\05@173619 by David Van Horn

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All,

I would think that would be at the output of the converter.
Further, the terminal voltage of 1.5V I would think would be correct if you were drawing 400mA from the battery/SMPS converter.  Try putting a load of 400 mA on it and measure the terminal voltage.  I would wager it will be very close to 1.5V.  It would be not unlike a transformer, say 6.3V @ 100mA.  This is saying that the terminal voltage would be 6.3 volts when you draw 100 mA of current from the transformer.  If you draw less than that, the terminal voltage will go up, and vice versa.

Regards,

Jim



My measurements were open circuit.   Lots of loads draw only microamps when "off" and an excessive voltage there could be a big problem. The cells I have are lower voltage than lithium primary cells, but not much lower, and I don't trust the regulator circuit.
Given the "pedigree" and the noise, I probably wouldn't use these at all, and certainly not in any sort of radio receiver.


--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: .....david.vanhornKILLspamspam.....backcountryaccess.com 


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2019\02\05@183503 by Jim

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Understood.  I was just giving the meaning of the specifications
presented.
With any SMPS, there will be noise.  I agree, I wouldn't use it in a
radio receiver.
I am a ham operator and understand about noise and receivers.  I also
understand that many devices,
especially today, draw very little power.


Regards,

Jim

> ---{Original Message removed}

2019\02\05@201033 by mike brown

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You should really think twice before buying any batteries from Amazon.
Here are some real gems:
https://www.amazon.com/9900mAh-Battery-Rechargeable-Batteries-Charger/dp/B072XHMN3P/ref=mp_s_a_1_17?ie=UTF8&qid=1549415246&sr=8-17&pi=AC_SX236_SY340_FMwebp_QL65&keywords=18650+battery&dpPl=1&dpID=41zMrFlJfML&ref=plSrch

On Tue, Feb 5, 2019, 17:40 Jim <EraseMEjimspam_OUTspamTakeThisOuTjpes.com wrote:

{Quote hidden}

> > ---{Original Message removed}

2019\02\06@081244 by David Van Horn

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Yeah, that seems a bit..... Optimistic.  ðŸ˜Š

--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: david.vanhornspamspam_OUTbackcountryaccess.com 



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