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Ode to the AA Battery

jeffgeerling.com

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Re: Ode to the AA Battery

#141

Post by [deleted] »

sowbug wrote: post #85
alnwlsn wrote: post #13

Designers have a choice in lithium-ion though. 18650 is is pretty large cell but there's 14500 which is AA sized or 10440 which is AAA sized. They make versions with the usual battery "nub" rather than the flat faces for spot welding, and built-in protection circuitry to prevent over-discharging. You probably would want to use ones of a different size than normal 1.5v cells though. A personal favorite of mine is RCR1…

I love the 14500 except for its footgun shape. 6 x 14500 is at least 21 volts, which won't play nice with a device that wanted 9 volts. I used to try to keep the 14500s far away from the AAs, but there's no stopping a kid in a hurry who wants to play with a toy or musical instrument.

[deleted]

Re: Ode to the AA Battery

#142

Post by pimeys »

aftbit wrote: post #32
everdrive wrote: post #26

Earlier quoted context omitted.

>Meanwhile, alkaline batteries can go to hell. You might as well plan on one leaking in the battery compartment. On the other hand, alkaline batteries never burn your house down. I also feel like they serve different purposes. Needed for long-term storage and only used in an emergency? (eg, a flashlight for power outages) You're probably better off going with old-fashioned alkaline batteries. Duracell claims they're…

No, there's basically no reason you'd ever want an alkaline battery except cost. For your use case of long-term storage or a rarely used flashlight (e.g. in a car emergency kit), you'd want a Li/FeS2 as the parent poster recommended, also called just a "Lithium" primary (i.e. non-rechargable) cell. They have a longer shelf life, don't leak, hold more energy, can provide a higher discharge current, work over a wider t…

There is one very good reason: the discharge curve. An alcaline battery loses voltage when it discharges, the lithium ones discharge with the max voltage until they suddenly stop working.

This is a reason insulin pumps require specifically high quality alkaline and lithium is considered a risk.

Re: Ode to the AA Battery

#143

Post by quickthrowman »

zabzonk wrote: post #22
jchw wrote: post #7

Earlier quoted context omitted.

I believe I have zero Alkaline batteries left in my house and I'm relatively surprised that pretty much everything works fine. If anything, I suspect the only problem is that some devices have an inaccurate account of how dead the batteries are. But I use Eneloops on everything, even things surely not designed at all to run on them. (And I reckon you could probably make more devices work if you really wanted to; addi…

I think I have only one device that uses AA - my central heating's radio thermostat. This thing has caused me untold hassle, which is only partially down to the batteries, but still... Totally OT, but does anyone have a good link on how the thermostat gets paired with the boiler? I'm thinking of getting replaced and would like to talk to the gas fitter from a vaguely informed point of view.

Thermostats (aka space temperature sensors) can have between two and eight wires. A boiler will usually have three: 24V power, call for heat, and common.

If your boiler has inputs on the terminal block for a thermostat, I would highly recommend buying a wired one, the 24V constant power removes the need for batteries.

If you can provide a link to your boiler’s installation and operations manual, I can tell you.

Re: Ode to the AA Battery

#144

Post by vel0city »

bigstrat2003 wrote: post #129
bxparks wrote: post #122

Earlier quoted context omitted.

Great in theory. In practice, the Duracell alkaline battery will leak caustic fluids inside the remote control and destroy it, and you will have to mortgage your house to buy a replacement on eBay, if it's even available. (I pick on Duracell because they are the worst. They leak if you look at them wrong, when they are brand new, inside the original packaging, before their "expiration date". But all alkalines are bad…

I have never, in my 40 years of life, had an alkaline battery leak and destroy something. I'm aware that it can happen, but in practice it doesn't happen very often.

I have many times in my less than 40 years of life. Often things that had batteries left in then and forgotten about for a few years, and often with the cheap batteries something came with. Often with kids toys, TV remotes and rarely used flashlights. If you're the kind of person that takes batteries out when you put things away or you change the batteries somewhat soon after they die you likely never had any leak.

I have a Canon AE-1 that takes a 4LR44 to operate the light meter. When I got it the battery had deteriorated significantly, causing a lot of damage to the battery area. I had to remake the battery contacts cutting and soldering in new springs and pads as the corrosion had practically completely eaten the old ones. That was probably the most notable leak I've encountered. But the previous owners didn't even know there was a battery in it, so it likely had that battery in there for a decade or more.

Re: Ode to the AA Battery

#146

Post by jdietrich »

BeetleB wrote: post #134
nickcw wrote: post #93

Eneloops are fantastic. I've been using them for 10 years. They have very low self discharge so you can keep them on the shelf for a year and they will still have 70% charge which is very different to most rechargeable batteries. They don't leak unlike alkaline batteries and you can run them to 0% charge without damaging them unlike Lion batteries. The terminal voltage is only 1.2v so there is the occasional thing th…

Eneloops were huge for use in DSLRs. And they are overhyped. Most of them are about 2000 mAh. Other NiMH batteries can have, say, 2700 mAh. So even though the latter have a higher discharge rate - after 6 months of storage the latter still has more juice. The benefit with the 2700 mAh, of course, is if you're using when full, you can use it for much longer. If they cost the same, I could see the hype. But most people…

Eneloop Pro cells have a rated capacity of 2500mAh.

I can't think of any good applications for conventional NiMH cells any more - they're dominated by LSD NiMH cells in low-discharge applications, by lithium primary cells in ultra-low-discharge applications and by the various lithium secondary chemistries in high-discharge applications.

Re: Ode to the AA Battery

#147

Post by dfe »

bxparks wrote: post #122
jandrese wrote: post #89

Earlier quoted context omitted.

There are a handful of applications where alkalines are better. IR TV remotes run effectively forever on a couple of batteries and the slow self discharge on the alkalines makes them ideal for the task.

Great in theory. In practice, the Duracell alkaline battery will leak caustic fluids inside the remote control and destroy it, and you will have to mortgage your house to buy a replacement on eBay, if it's even available. (I pick on Duracell because they are the worst. They leak if you look at them wrong, when they are brand new, inside the original packaging, before their "expiration date". But all alkalines are bad…

I've only had batteries leak in remotes left unused for over a year. I just pick up Duracell or whatever is at Costco.

I've also bought two replacement remotes off of Amazon in the past year, one Samsung and one Insignia. I think they were $15-20 each, which seemed very reasonable to me.

Generally they won't have the manufacturer's logo, but everything else on the outside looks 100% identical, and all the buttons worked.

Re: Ode to the AA Battery

#148

Post by dragontamer »

BeetleB wrote: post #138
dragontamer wrote: post #12

Earlier quoted context omitted.

NiMH chemistry allows for safe overcharging though. If the chemistry allows for it, why not take advantage of it and have cheaper chargers? The downside is that "save overcharging" only works at very low charging rates. That's why the double-charger designs all have 10+ hour charge times (mine actually has a 20-hour charge time). But in practice? Its cheaper to buy 4 extra AA NiMH batteries to keep charged rather tha…

I think what he is referring to is this: If one battery is 50%, and the other at 70%, and you put both in, one will end up at 80% and the other at 100%. When one is full, those cheap chargers stop charging the pair.

That's not how it works at all.

When one is 80% and the other is 100%, the full one enters a state of over charge, reaching 105% or even 110% charge. This is safe.

The H2 reaction then rapidly speeds up, leaking energy in the form of heat. The full battery heats up from overcharge but is otherwise safe.

You end up with both batteries at 100% and maybe 110%, and a day or two later the 110% overcharge settles down to 100% by leaking out.

-------

So you waste a bit of power but as long as the trickle charge is safe and as long as the overcharge is only for a few dozen hours or so, it's fine. In the very long term (if you keep doing this) the NiMH could get damaged. But if we are talking about a once-per-yeqr top off charge, then it's fine.

The problem is like I said before: the safe rate of overcharge is low. This means that these chargers must charge slowly, maybe 10 hours or longer.

Any faster risks blowing through the NiMH innate ability to take an overcharge and convert it into heat. (This results in a forceful vent, a 'pop' sound that permanently damages the NiMH as the H2 gas escapes the safety hatch).

------

Note that these super cheap chargers are simply a glorified 10+ hour timer. They don't even check the state of the AA cells.

So if you stick a 50% full battery in, it will charge the battery to 150%, most likely. (But safely, as the NiMH just leaks out the excess energy as heat, as I said earlier).

Re: Ode to the AA Battery

#149

Post by jdietrich »

pimeys wrote: post #142
aftbit wrote: post #32

Earlier quoted context omitted.

No, there's basically no reason you'd ever want an alkaline battery except cost. For your use case of long-term storage or a rarely used flashlight (e.g. in a car emergency kit), you'd want a Li/FeS2 as the parent poster recommended, also called just a "Lithium" primary (i.e. non-rechargable) cell. They have a longer shelf life, don't leak, hold more energy, can provide a higher discharge current, work over a wider t…

There is one very good reason: the discharge curve. An alcaline battery loses voltage when it discharges, the lithium ones discharge with the max voltage until they suddenly stop working. This is a reason insulin pumps require specifically high quality alkaline and lithium is considered a risk.

Lithium primary cells have a shallower discharge curve than alkaline, but not completely flat; measuring state-of-charge is essentially trivial for any competent design engineer. Medtronic specifically recommend FR6 lithium cells in their insulin pumps.

https://data.energizer.com/pdfs/l91.pdf

https://www.medtronicdiabetes.com/sites/default/files/librar...

Re: Ode to the AA Battery

#150

Post by Rebelgecko »

alnwlsn wrote: post #13

Designers have a choice in lithium-ion though. 18650 is is pretty large cell but there's 14500 which is AA sized or 10440 which is AAA sized. They make versions with the usual battery "nub" rather than the flat faces for spot welding, and built-in protection circuitry to prevent over-discharging. You probably would want to use ones of a different size than normal 1.5v cells though. A personal favorite of mine is RCR1…

There's some flashlights which take either 14500s or AAs. Seems like it'd be pretty handy as a backup (iirc the AAs can't put out quite as much instantaneous juice)
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