Lithium AA and AAA batteries

Do you mean disposable lithium batteries?

I have 4 AA's in a digital SLR camera, no problems so far (about 6 months irregular use thanks to covid) They are 1.5v. They've certainly outlasted NiMH and alkaline. Quite impressed up to now.

That's the question. There are, apparently, rechargeable Li-ion ones that include the electronics to drop the cell voltage from 3.7 to 1.5. An earlier thread questioned whether they made sense.

Or there are the super high capacity disposables with much higher capacity than standard manganese alkaline, at a price. But they are worth it for things like exterior Blink security cameras, where two AAs will run the camera, IR lights, and WiFi comms to your router for 6 months. I've had a pair for several months and the battery is still showing as OK.

Unfortunately I was assuming that such batteries would be rechargeable but I have now found out that mostly that is not the case. Maybe I shall have to wait until more brands become available.

I think they understand enough about chemistry to make the voltages of batteries whatever they like. The issue is efficiency, The best efficiency is seldom giving the voltage you need for rechargeable. I don't know how the ones that have a voltage reducing circuit work, but however its done it has to use some power to do the voltage conversion, so I'd suspect that there are considerable trade offs. Brian

If they were rechargeable, they'd not be suitable replacements for things previously using 1.2v cells? Different charger needed?

Better to redesign the device to take a single 18650?

Do you mean the Energizer Lithium AA's ?. They are not rechargeable and cost about £7 for a pack of four. They are brilliant for those applications where you need to leave something unattended for a while and no main power is available, like wildlife infrared cameras.

The two sitting on the shelf in front of me have been used in an old Ricoh Caplio GX camera a few times (I use rechargeables but carry the AA lithiums for use when the rechageables die) and they still measure 1.76 volts.

Our garage door has a wireless sensor to detect when it is fully closed. It was only when the batteries in it went flat that I discovered there was another type of AA battery. The door takes two AA Lithium ER 14505 batteries at 3.6V each, non rechargeable and cost a packet with the cheapest I bought recently at £16+ for 4. The EEMB ones recommended by the door supplier are almost twice as dear again.

Richard

No it;'s against the laws of physics.

it's down to what traditionally was used in the past. It's down to multiple cells and how to make the 'correct' voltage up.

Some use buck converters tofor this. We run a lab where students make a buck convertor, they are more efficint that the traditional regulators and tehy work similar to switch mode PSUs

Isn't the main factor for the voltage of a cell the difference in the electronegativity between anode element and cathode element, probably the choice of electrolyte can have an influence too?