D, C, AA, and AAA rechargable cell recharging?

[ericmark]

Not talking about batteries made for cameras, drills etc where the charger clearly matches the battery, but the likes of the AA cell which has over time changed from 600 mAh with NiCad to 3500 mAh with Ni-Nh and other modern rechargeable cells.

The old battery/cell charger had a number of methods to recharge, from Delta V where it looked for the characteristic dip in voltage when it became fully charged, to a really low charge rate unlikely to damage the cell, to a temperature sensor and lid to retain the heat to sense when fully charged.

However designed to charge the old 600 mAh cell it would often also have a time out, so if the sensing did go wrong, it would stop anyway, but when there were no Ni-Nh cells made, the charger will not have a warning on it to only use with NiCad or with cells under a set mAh rating. Neither did most have a date of manufacture, so it is likely some chargers will time out before the cell is fully charged.

It seems some batteries have the charge regulation built in

picture from Wikipedia and one must question how this works with a Delta V charger, or any charger which stops the charging with time or temperature sensors. We can buy a 3500 mAh cell, but can we use the battery to its full.

I have bought over the years so many chargers, some using USB some go into the mains, some only charge pairs, as a battery others charge single cells. I have also bought many rechargeable cells, and today no idea of age. I got 8 C cells for my FT290R radio which were rather expensive at the time, after the power plug part disconnected and as a result fried the originals when the 12 volt lead acid battery connected to the NiCad as the switch on the power plug connected both together, modified after that with diodes instead of switch to stop a repeat. However the replacements must now be some 20 odd years old, still going strong. The charger is simply very slow, there is no regulation. But can transmit at 2.5W so it must be quite a drain on the battery. The charger will just about hold its own on receive.

So what should we be looking for on chargers and batteries to get the full out of them?

 

[flameport]

A summary:

C and D sizes are gone - for the few items that require those, adaptors are used which take AA.
NiCd are gone, other than a few specialised applications where they are usually installed in specific sized packs for certain pieces of equipment.
NiMh are the usual choice for AA and AAA.

For lithium variants that are not built into a product, 18650 are the most common. Those with protection circuits and those without, which one depends on what it is installed into.
Products such as powerbanks typically have the protection circuit built in, so cells without protection are used there.
Items such as torches would require those with protection circuitry in the cells, to prevent over discharging.

As for chargers - everything from those with 'intelligent' contents to those which simply shove a certain current through whatever is connected to it.

Personally I don't bother with any rechargeable efforts - known brands from normal retailers are far too expensive, others are cheap but you have no way of knowing exactly what you are buying, the whole concept of having some in a product while others are charging is inconvenient, and it just cheaper, easier and quicker to buy bulk packs of alkaline AA or AAA.

 

[JohnW2]

C and D sizes are gone ....

What exactly do you mean by that? They are certainly still manufactured and sold - e.g. here .

Kind Regards, John

 

[ericmark]

My hobby is photography, I have a flash gun which takes 2 AA cells, best quality non rechargeable looking at around 15 flashes, the cheap non rechargeable simply don't work, with 2500 mAh rechargeable looking at around 35 flashes often more, I do think the 1980's flash is heavy on batteries, but just forget non rechargeable as when you go out don't know if you have 5 flashes left or 15 flashes, with straight off the charger I know I have at least 30 flashes per set, so really no way would I want to fit non rechargeable cells.

For my central heating because the shelf life is short with rechargeable cells, I always fit best quality non rechargeable, one because the voltage is not high enough with most rechargeable although I did pick up some rated at 1.5 volt once, but then found most of my chargers would not recharge them, but my electronic TRV heads want 3 volt not 2.6 volt so forget rechargeable even if they would hold their charge.

The problem/beauty of the rechargeable is the high current they can deliver, with my flash gun that's why so good, needs to recharge the capacitor, but some of the early flash guns the thyristor shorted out the battery for a few seconds, not a problem with zinc carbon very little output, but the rechargeable battery can fry the thyristor. The other problem with most is lower voltage, I had a CB handy using 10 zinc carbon with two spacers, but took 12 rechargeable batteries.

Problem with non rechargeable all they say is 6 times longer than zinc carbon when they are also zinc carbon, OK there are others, but no quantity of power, how they get away with it I don't know, can you see 12 ounce jars of jam and 16 ounce jars of jam sold without having how much they contain written on the jar, well that's how we buy non rechargeable, with best by 2027 written on some batteries they do have a long shelf life and I see the problem saying how much they contain. But if you need to know how much energy a battery has, then has to be a rechargeable.

However this leaves the first question, how do you know it is fully charged and the charger has not stopped before that point has been reached.

 

[aptsys]

Personally I don't bother with any rechargeable efforts - known brands from normal retailers are far too expensive, others are cheap but you have no way of knowing exactly what you are buying, the whole concept of having some in a product while others are charging is inconvenient, and it just cheaper, easier and quicker to buy bulk packs of alkaline AA or AAA.

Generally I agree, but some high current demand products such as flash guns perform poorly on non-rechargeable cells and also blast through them very quickly. Agreed they are a PITA and some NiMH cell and charger combos cause charging to prematurely terminate.

However this leaves the first question, how do you know it is fully charged and the charger has not stopped before that point has been reached.

You don't, you also don't know what percentage of the energy you've put in is usable on the discharge either. Even on primary cells you won't usually get the full capacity out of them depending on the load.