Different use by device of NiMH and alkaline cell

When I put an AA cell in my voice recorder, the menu asks if it's NiMH or alkaline.

Could the recorder be working differently depending on what type of cell I am using?

Perhaps the type of cell affects the battery gauge, low voltage switch off, etc. Maybe there is even something in the functional electronics which can be made to work differently?

Reply to
pamela
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What did you tell it?

What's your guess?

Perhaps. Did you read the manual?

Reply to
John S

The voltages are different. So on something simple and/or old fashioned, NiMH may look a bit like a low battery (except that it obviously knows of the existence of NiMH).

"Voice recorder" is really not giving us much to go on.

Reply to
newshound

It would certainly impact any battery level detection.

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Tim Wescott 
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Reply to
Tim Wescott

That's quite likely. Alkalines, NiMH, and lithium primary cells differ a lot in their initial voltages and in their discharge curves.

Alkalines start out at somewhat above 1.5 volts, and decrease in voltage gradually until fully discharged. Lithium primary AA cells start out at above 1.8 volts, and also drop gradually while discharging.

NiMH and NiCd start out at around 1.35 when fully charged, drop fairly quickly to around 1.2 or so, and stay there with little change until almost fully discharged... at which point they fall off the edge of a cliff.

So, a low-battery detector or charge-level indicator does need to adapt to the characteristics of the battery in question if it's going to give useful results.

Reply to
Dave Platt

I tell it alkaline when I use alkaline and NIMH when I use NIMH. Are you expecting something different?

In the past I would say not and I never saw the option presented but I'm not familiar with the latest developments in electonic components and wonder if this may have changed.

Based on your up to date knowledge of electronics, do you know anything about this?

There's honestly no need to provide an ambiguous answer to every question I ask if you have nothing to say.

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Reply to
pamela

I would guess this is now a feature of many voice recorders. Mine is a Sony and I imagine several models in the range will work the same way. This is the one I have:

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Reply to
pamela

Can anything fancy be done nowadays in the electronics (such as a changes in audio bias voltage) for the circuits to continue to work at lower voltages? I rather doubt it but who knows if there's some impressive new changes nowadays.

Reply to
pamela

There are certainly tricks you can play with the electronics, depending on what you're willing to give up and how much you're willing to pay. There are some pretty hard stopping-points, though... if you want to use silicon bipolar transistors and diodes, for example, you're going to need more than .6 volts of headroom if you hope to get them to "turn on" with any useful amount of current.

Another approach is to incorporate a voltage booster circuit... for example, the popular "Joule thief" which lets you use a white LED (needing 5 volts or so) with a single alkaline battery as the power source.

Diminishing returns will still getcha, though. By the time an alkaline drops to 1.2 volts, or a NiCd/NiMH to 1 volt, it's got only a few percent of its original energy content left, and you won't get useful work out of it for very much longer even if your device has a splendid tolerance for low-voltage input. A Joule Thief might be able to eke out the last few percent from the battery... but then device goes dead rather abruptly when the battery is sucked dry.

Reply to
Dave Platt

Yes, the discharge profile and terminal voltage are different. It's interesting that they would ask, though.

Gas gauge. If you discharge an alkaline too far down it'll often leak. If you cut off at the alkaline's terminal voltage, the NiMH will still have a lot of juice left in it.

Reply to
krw

You don't want to discharge a battery below it's terminal voltage. There isn't a lot of energy down there and it can damage the battery (and the appliance).

Reply to
krw

An alkaline cell still has roughly 40% of its energy at 1.2V, compared to terminating discharge at 0.8V.

Cheers, James Arthur

Reply to
dagmargoodboat

Remember folks, that is the voltage between its terminals, irrespective of the state of charge!

ROFLMAO!

The point of teaching English and having dictionaries is to express things unambiguously.

Shame that government decided that clear communication was not something they wanted to have avaialble for mere citizens.

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Reply to
The Natural Philosopher

** The usual term is "end point" voltage", avoids a nasty ambiguity.

The "end point" is the terminal voltage when a battery or cell has delivered over 90% of the stored energy. For an Alkaline this happens at 0.8V and for a NiMH it is at 1V.

.... Phil

Reply to
Phil Allison

No. Then what is your question on this particular point?

I would have more to say if you had more to offer. Are you a troll?

I'm not going to read and interpret the manual for you.

Reply to
John S

I too find it surprising the device would ask. It's an annoyance to set each time you charge the cell outside the voice recorder.

I get the impression the purpose is mainly to help with the gauge although I'm not really sure why they bothered.

Reply to
pamela

It's nice many electronic devices such as my recorder now run on

1.5 volts. I had a few 1.5 volt recorders years ago but they were never as nice sounding as my modern Sony and I wonder if that was down to the voltage provided for the mic.

Back then I had to use a battery box to drive an external electret with a higher voltage than provided by on-board Plug In Power.

Reply to
pamela

Maybe a step up DC converter isn't as inefficient as I thought. I figured it would be too inefficient to use with a small capacity cell but maybe it's more feasible than I realised.

Reply to
pamela

I'd always been taught "terminal voltage" as the final discharge voltage. IIRC that's what the Gates Secondary Battery manual used, as well. Of course, you have all sorts of funny animals and words, down under.

Reply to
krw

It'll allow the device to get the maximum life out of the battery without damaging the battery or the device. It's a good thing, IMO.

Reply to
krw

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