Rechargeable Batteries (Page 2): I do. Just like a car battery no load voltage is 12.6 volts. Now if the circuitry was designed to work down to, lets say, .8 V, then a NiMh would work...

Longshadow Loc: Audubon, PA, United States

chrissybabe wrote:

That's because a fully charged battery with no loa... (show quote)

I do. Just like a car battery no load voltage is 12.6 volts.
Now if the circuitry was designed to work down to, lets say, .8 V, then a NiMh would work just fine. As some do in some electronics.

Cool, are you an electronics engineer also?

BebuLamar

jerryc41 wrote:

Yeah, that's always struck me as odd. Everything is designed for 1.5v, but rechargeables don't quite reach that. Still, things work.

Most stuff are designed to work with a wide range of voltages so most of the time they work just fine. As Longshadow pointed out some cameras don't like rechargeable. I have one it's the Nikon F5. With 8 alkaline AA it's 12V and it's fine. With 8 NiMH it's about 1.4V per cell when fully charged and it gives 11.2 which is fine but they only stay in that condition for a very short time then they drop to their nominal voltage of 1.2 which gives 9.6V and the F5 threshold for low battery is 9.4V. So the camera would quit working when the batteries still have a lot of charge in them. Nikon rechargeable pack uses smaller cells and stuffs 10 cells in the pack so it works fine.

chrissybabe Loc: New Zealand

Longshadow wrote:

I do. Just like a car battery no load voltage is 12.6 volts.
Now if the circuitry was designed to work down to, lets say, .8 V, then a NiMh would work just fine. As some do in some electronics. Cool, are you an electronics engineer also?

I suspect that a lot of things could be designed to work down to say .8 v but for various reasons aren't. One reason I suspect is that an alkaline battery will run for twice as long as a charged NiMH. Or the light cells used don't work so good at lower voltages (remaining linear for example) so they have a higher cutoff.
Not sure what the 'also' means but the first 10 years of my working life was as an electronics technician in a university department and I have remained interested since. It helped when I joined DEC and computers have been my main job since until I retired. There was a spell in there as a wedding photographer but I soon got fedup having to act as a shepherd to people who couldn't take direction.

Longshadow Loc: Audubon, PA, United States

chrissybabe wrote:

I suspect that a lot of things could be designed t... (show quote)

Also - as in like I, an electronics engineer, including computers (for 50+ years).

JoeBiker Loc: homebase: Houston, TX

I occasionally have that problem with AA or AAA NiMh Batteries. Sometimes the device that I use them discharges them so far that my good battery charger won't recognize that a battery is installed. I have to put them in a cheap battery charger (that mindlessly starts applying a voltage to them) to get the voltage up to the point that my good battery charger will recognize them.

Discharging any battery that far isn't good for it, but they seem to survive.

Charging a dead battery directly from a good battery will also work, but isn't very good for either battery, unless you put a resistor inline to limit the current.

Longshadow Loc: Audubon, PA, United States

JoeBiker wrote:

I occasionally have that problem with AA or AAA Ni... (show quote)

And if the dead battery happens to be shorted, that would be like putting a paperclip across the terminals of the good battery. It could get very "warm".

Lucasdv123

If you have an 18v dewalt drill you can get the 20 v battery with the adapter to work on your 18v drill but if you leave the adapter on the the battery it will discharge the battery.

TriX Loc: Raleigh, NC

Everything using AA or AAAs in my house is powered with Eneloops (NiMH rechargeables). Except for remote sensors such as my weather station or pond and driveway proximity detectors, where the long life at low current of Alkalines is an advantage. The only occasional issue is Roku remotes, which seem to be very sensitive to low voltage and may not even pair when used with freshly charged NiMH cells. Even though the voltage is lower than Alkalines, the internal resistance is lower, so my flashes cycle faster with Eneloops than Alkalines.

chrissybabe Loc: New Zealand

Lucasdv123 wrote:

If you have an 18v dewalt drill you can get the 20 v battery with the adapter to work on your 18v drill but if you leave the adapter on the the battery it will discharge the battery.

Since the 18v and 20v Dewalt are essentially identical from a practical point of view (same batteries etc) it might pay to see if you can open up the adapter and remove/disable whatever is causing the drain. I would. Or see if a brand X adapter would be better. Or leave the adapter on the drill if that is possible.
This is shrinkflation in reverse making you think you are getting something better (20v v 18v) but it is purely a pointless marketing exercise with absolutely no value whatsoever.

Lucasdv123

The fact that 18v dewalt drills last forever they came out with the adapter but dewalt did not tell it's loyal customers that the adapter will drain the battery if left on the battery.i can not believe dewalt would do a thing like that.shame on them.

chrissybabe Loc: New Zealand

Lucasdv123 wrote:

The fact that 18v dewalt drills last forever they came out with the adapter but dewalt did not tell it's loyal customers that the adapter will drain the battery if left on the battery.i can not believe dewalt would do a thing like that.shame on them.

They are American. The dollar is king. You get what you vote for.

aphelps Loc: Central Ohio

chrissybabe wrote:

That's because a fully charged battery with no loa... (show quote)

You can also track internal impedance of the pack. When that value starts to climb the end is near for the pack that seems to be fine using an open terminal voltage.

Longshadow Loc: Audubon, PA, United States

aphelps wrote:

You can also track internal impedance of the pack. When that value starts to climb the end is near for the pack that seems to be fine using an open terminal voltage.

Yup, internal resistance increases with age.
The voltage drop for the internal resistance increases as the resistance increases thereby lowering the output voltage. The larger the drain (load), the larger the internal voltage drop, less available at the terminals.

BebuLamar

The DeWalt 18V battery was NiMH and it has 15 cells. The new DeWalt 20V Max is Lithium Ion and it has 5 cell. However the Milwaukee 18V is also Lithium Ion and has 5 cell so the voltage is the same as the DeWalt 20V max. The difference is that Milwaukee rated their battery with nominal voltage and DeWalt rated their battery with maximum voltage.

Dik

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