[PLUG-TALK] Rechargeable NiMH Batteries Question

Larry Brigman larry.brigman at gmail.com
Tue Jun 14 22:19:14 PDT 2016


How the circuit is designed for the battery usage that will determine if it
can use NIMH instead of alkalines.

http://eznec.com/Amateur/1.5_vs_1.2_Volt_Batteries.pdf

On Tue, Jun 14, 2016 at 9:37 PM, joe at joseph-baker.com <joe at joseph-baker.com>
wrote:

> A voltmeter alone won't give you a totally accurate picture of the
> batteries capabilities.  As batteries age, they appear to have larger and
> larger output resistances.  The volt meter alone doesn't test the battery
> when it is supplying current.
> This will not be as noticeable as the effects that Russell has
> illustrated, but this is another reason to not use the lower voltage NiMH
>
> Sent from my mobile
>
> 503-720-9871
> Idea to Product to Market
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> http://www.joseph-baker.com
>
> On Jun 14, 2016, at 8:31 PM, Russell Senior <russell at personaltelco.net>
> wrote:
>
> >>>>> "Rich" == Rich Shepard <rshepard at appl-ecosys.com> writes:
>
> Rich>    This is a question for all the electrical gurus here.  My clock
> Rich> radio takes a pair of AAA batteries for backup when the house
> Rich> electrical system goes off-line. A couple of weeks ago the unit
> Rich> indicated the batteries needed to be replaced. I charged a pair of
> Rich> NiMH rechargeable AAA batteries and put them in the clock
> Rich> radio. The discharged battery icon continued to blink. So, I
> Rich> recharged the batteries and found the same result.
>
> Rich>    Replacing the NiMH batteries with alkaline, non-rechargeable
> Rich> ones, turns off the icon, indicating that they're fully
> Rich> charged. The NiMH batteries each read 1.39 or 1.40 volts so they
> Rich> are fully charged.
>
> Rich>    What might make the clock radio not recognize charged batteries
> Rich> if they're NiMH and accept alkaline ones?
>
> The normal voltage of a fresh alkaline cell is about 1.6V, which is higher
> than a fully charged NiMH.  Also, NiMH are more likely to discharge over
> time.  If the purpose is backup power, you are probably better off with
> alkaline anyway.
>
>
> --
> Russell Senior, President
> russell at personaltelco.net
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