(rechargeable) Battery chemistry best suited for storage abuse

I'm getting totally outside of your box, here, but it may work best to use cranked generators and no batteries.

Batteries, unless you can store the electrolyte separately, just degrade over time. They essentially work by controlled corrosion, and corrosion is such a sloppy reaction that it'll happen in a quite uncontrolled manner, too.

With the exception of silver-air hearing aid cells (which may not even be available any more, and are teeny at any rate), I don't think there are any suitable batteries that you can trust for years, much less rechargeable ones.

Note: I will be neither disappointed nor offended if I'm proven wrong!

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

What do you then do when the alkalines *die* FROM USE? The advantage of rechargeables is not that I can revive them when I *initially* need them but, rather, after they have been depleted in the first day or two of use. That's the big appeal of the crank flashlight, radio, etc. I think the crank radio plays for 15 minutes at a time; if I risk replacing the NiCd/NiMH cells inside, I could obviously extend that... using the cells to store energy instead of the mechanism (though I'd have to rely on the internal solar charger to do that or add an external generator/crank unit)

And, to a lesser extent, having a genset and car alternator (easier to store energy in gasoline than in batteries)

I've crank powered "nominal" flashlight (i.e., it sure won't shine as far as something with a few D cells!) and AM/FM radio (on the assumption that there will be *something* of interest on the "public airwaves").

But, crank powered devices have pretty small power capabilities. The radio will play for 15 minutes on a "full wind"; 14 hours if left in the sun to charge the internal batteries (which need to be replaced but I debate the risk of the whole thing going "sproing" when I try to disassemble it).

[Flashlight has shorter lifespan (due to size of the BATTERY within) but it's relatively easy to keep winding it.]

Neither would be acceptable to power the 2m rig -- or even a "CB". You'd need far more "mechanical storage" to address loads of that size. (I've looked into trying to buy/build a small/portable, ~20W unit even if using it would be intermittent -- due to the "physical load" it would represent). The same problem applies to the GMRS/FRS handhelds. Chemistry seems to be the easy way to solve the "peak" demands!

I agree, in general. What I'm looking for is how far I can stretch things before being "disappointed" when I need them most!

I've considered cannabilizing the crank radio and converting it into just a genset, of sorts. And, replacing the motor/generator with something that operates at a higher voltage -- more directly useful for loads other than the dinky AM/FM radio.

[On the assumption that I could at least power some of the *receivers* even if Tx was impractical!]

Without resorting to a detailed mechanical analysis (of which I am incapable!), I make the following shirtcuff assessments:

- a "full wind" powers the radio for about 15 minutes

- a full *charge* (of the internal batteries) powers it for 14 hours

- therefore (roughly) the batteries store ~60 times more energy than the mechanism

- batteries are (when new) 2/3AA x 2 NiCd/NiMH -- about 600mAHr

- "ideally", the batteries represent 1.44WHr

- therefore, the mechanism scales to ~24mAHr No idea how scaling the generator output will impact the mechanism's capabilities (is it currently oversized?)

[It's too early in the morning... have I munged my math? I should learn to use a calculator. I think there's even a magic button here for that...]

I'm also playing with some designs for larger "crank units". The problem is usually (for me) a mechanical one. Especially if you want something that will be *portable* (and not another BEAST to lug around with you!)

In one sense, this is just an entertaining puzzle -- you expect never to need this sort of stuff. OTOH, going through the motions (instead of blissfully ignoring the possibility) would be REALLY disappointing if the need arose and the plans were inadequate! :-/

Of course! OTOH, if BEING prepared represents a significant maintenance effort, one has to wonder if there's much advantage over your other neighbors who are doing *nothing*. :<

[We are reluctant to advertise the genset as we KNOW that the neighbors will feel "entitled" to use it in the event of a genuine need. Yet, not feel required to prepare for themselves! To date, our uses have been primarily convenience -- power outages, etc. One suspects that things would quickly "get ugly" in a REAL emergency.]

I try to be prepared without being INCONVENIENCED. For example:

- the foodstuffs in the freezer extend our capabilities for fresh or refrigerated foods -- yet aren't bought *solely* "for an emergency"; we'll eat them in the normal course of events

- Canned foods extend the capabilities of the frozen (and are similarly usable day-to-day)

- A small, portable, inexpensive, single burner propane "camp stove" can allow us to cook by salvaging the propane I keep on hand for the torch; the small propane cylinders being portable enough that we could carry them out with us (not true of the propane tank on a grill!)

- Charcoal can supplement the propane when it is exhausted -- yet be of use to us when we want to BBQ

- UPS's provide protection for my computers against power outages and "glitches" -- and also give us a quick means of lighting the house in the early stages of an "event" (plug a CFL into a light fixture, run an extension cord down the hallway and plug it into a UPS)

We *don't* for example, keep 20 pounds of beans/legumes on hand JUST for an emergency (dense source of protein, long storage life) -- for the simple reason that we wouldn't consume them as part of our day-to-day routine (I hate beans!). As such, they would be an "inconvenience"

Its not much of a sample size, but I had 12 or 16 AA NiCds from the early 80s that went back into service in 09, and nearly all worked fine after over 20 years sitting around flat.

If you want better reliabilty I suspect keeping a rechargeable battery dry is the logical step. I gather NiFe are simple to make. If you just want convenient, buy new NiMH now and then.

NT

The appeal of (a large) SLA is that it could address a wider range of loads.

E.g., my GMRS/FRS handhelds use AAA cells; the "walkie talkies" use AA cells; the mobile 2m/CB rigs need a power source with "oomf"; etc.

Outfitting a modest size SLA with a small, efficient regulator wouldn't significantly change the size, weight, formfactor of that "power source" yet potentially allow it to address all my needs.

The trick would be *remembering* to "grab the battery" before leaving the house :-/ (assuming you could then keep it charged and ready to go -- possibly as part of some other piece of kit that you normally use)

I may put a set (of 4) in one of the handhelds and see how they hold up alongside the NiCd's that I've been using. Currently, I replace the NiCd's every year or so as they tend not to like the environment. It would get pricey doing that with better batteries!

[And, my ideal goal is to stop having to remember to do this "maintenance"]

I've found these dry charged PbAc batteries useful as backup power supplies. Good for 18 AH and fully charged.You just add the acid that is supplied in a sealed package and it's ready to go. A12 volt battery gives you a lot of options for charging, including solar.

$65 including shipping is not a bad price. They are around $90 at the local auto parts place.

I believe NiMH is intended/designed to be stored flat; the high-self-discharge ones certainly end up that way, whether they were charged from the factory or not!

Tim

--
Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Contract Design 
Website: http://seventransistorlabs.com

Toss them. But in at least one of your use scenarios, you won't have time to charge batteries before needing them. Having a few powered-up cells handy fixes that.

I've been beyond disappointed with the crank units. They're a pain to crank even when they work, then they break. I'd vote solar instead. I like a little charger I got from Harbor Freight--paid $9. It's BoB-sized. HF #41427. I don't see it on their site now.

This solar AA-charger might work for you:

400mA into one cell--not bad.

Overall, from what you've spec'd, NiMH. The LiIon backup cell-phone chargers are handy too, but you'd have to charge them every 1/2, 1, or two years, depending on self-discharge.

Cheers, James Arthur

I believe that the long history of experience with lead-acid batteries shows that chemistry to be superior WRT crummy and changeable environments (including poor charge maintenance).

I have "ignored" both lead-acid and NiCd cells for a few years (initial state was charged) and seen both types hold a charge (room temp environment); the NiCd not so good on storage capability afterwards. Lead-acid cells/batteries seem to not like storage for long term if not charged (sulphate).

Question is, "how long do you want to survive?"

I picked up a generator a garage sale. Deal too good to pass up, but I wish I had. Later found a good deal on a DIY changeover switch. Deal too good to pass up, but I wish I had. Now that I had the pieces, I set out to install it. Permits, codes, cost more than the generator. And the breaker box needed to be replaced... Anybody wanna buy a gas generator?

All this led to a lot of thinking about disaster.

The great majority of power outages last for a few seconds or less. If it's out longer than that, depending on where you live, it's gonna be a while. Probably longer than you have energy capacity to run a generator.

There are local inconveniences. Take a nap and it will blow over. There are local disasters. You can go elsewhere 'till it's over. There are widespread disasters. You can kiss your sweet ass goodbye. You're already dead...just matters whether you wanna suffer for a week or a month. Not much you can do about the big one.

I have enough free harbor freight flashlights to keep me from stumbling in the dark for weeks. And enough gas in the car to run the generator to keep the furnace on so the pipes don't freeze. For a while.

Beyond that, there's not much to be done. I contend that, in a prolonged disaster, having a stock of ammunition is far more important than an extra battery.

I quit worrying about it.

So, now I've got devices with *no* power source!

"Buy more"? Well, if I can *buy* batteries to replace the dead ones, then there's no issue with storing *any* batteries! If the stores are open, it's hardly an "emergency"!

Having "live" cells isn't my primary goal. Having cells that I can *make* live, is! Having single use cells with long shelf lives is only good if your goal is to have them "available" when the emergency strikes. Once they *die*, then you might as well discard the battery powered devices as they are of no further use to you (until you can purchase new cells).

Having *flat* cells that can be recharged allows you to reuse them multiple times even if you can't REPLACE them.

For shelter-in-place, I can recharge damn near any cell I have on hand. UPS's, genset, automobile driven inverter, etc. all can push charge into flat cells.

For drive-out, I can charge from the car battery/alternator (how many ounces of gasoline are packed in an AA cell?)

For walk-out, I can charge from the small solar panel I have, one of the crank flashlights (has an "output" connector) or, if I make the modifications, the crank radio.

[If I can get a lightweight case for a larger "crank generator", that's the fastest option]

The crank flashlights tend to be disposable. The crank radio is much better built -- it includes some clockworks and a "mainspring" to store potential energy (instead of relying on the rechargeable cell that is hidden in most crank flashlights).

Mine is 1.38W into a 6V "load" -- charging one cell at a time is sort of self defeating. I.e., install 4 cells in the charger and I can power one of the GMRS handhelds (once the charger has topped them off)

Once upon a time, I was in the 2way radio business and had plenty of experience with everything from lead-acid flooded cells on vibrator power supplies, to NiCd and NiMH cells in later battery packs. I have no idea how many battery packs we went through, but they were in the thousands. Most were killed by overcharging, but we also had our share of those allowed to discharge and sit around for a while. In general, new NiCd and NiMH packs would discharge to about 10% and sit there forever. They could be slowly recharged successfully, but not fast charged. The problem was cell reversal. No two cells were identical and when charged in series, sometimes that polarity across a cell would get reversed. That's fatal to the cell. I would often find 12V packs with 9 perfectly good cells, and 1 dead cell. Unless you're prepared to build a "balance charger", that monitors each cell individually, or charge slowly at about 0.1 to 0.4C, or matching cells in a battery pack, letting a battery pack totally discharge is going to a crap shoot at best.

Thanks. I have a fairly good supply of Eneloop AA cells and find little need to experiment as they work quite well. I accidentally buried 4 cells in the back of my battery storage cabinet about a year ago. I haven't tried them to see how they do yet, but will do so when time permits. Oh swell... I can't find my last test data on these cells.

What's a BoB? Yep, and they're not rechargeable. Well, there is rechargeable alkaline, they can only be recharged about 10 times, and then only if not discharged below about 50% of full charger.

A non-rechargeable lithium battery, such as a 123A cell, is quite different from a rechargeable LiIon battery. Note the 10 year shelf life and that they're not rechargeable. I'm not sure if I would buy anything with the word "fire" in the name.

No, you cannot leave LiIon fully charged for very long: Modern laptops now include a feature where the user can set the upper battery charge limit to about 50% to avoid premature battery failure. I've had the displeasure of watching laptop batteries left 24x7 on charge die after about 10 months. This is also the reason you don't see UPS (uninterruptible power supply) products stock from the manufactory with LiIon batteries. UPS batteries spend most of their life at 100% charge. Manufacturers would have a difficult time explaining why buyers should only charge to 50% of capacity and tolerate a short runtime. There's also the not so trivial problem of transporting hazardous materials:

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

I'm only "planning" for the nominal 3 days before things "settle down".

Your mistake was trying to "do it right"! :> I just run a power cord (I have a 100' Hannay reel for that purpose) from the genset to the freezer (the thing that is the most important to keep running in the short term) -- but only if I suspect it will be a prolonged outage (like when the Xformer for the neighborhood caught fire).

Likewise, as soon as the power fails, I run an extension cord from one of the UPS's into the living room and drag out a table lamp that I can put a CFL in to read, and not stumble around in the dark.

Yes. We never see those as the UPS's deal with the few things that "get upset" with minor glitches (I surely don't care if the lights go out for a second; or if the electric oven experiences a dropout... nor will the *food* care!)

[Computers, OTOH, tend to be unforgiving if they were in the middle of some operation when the power glitches -- especially if I can't recall what I was doing in each session on each machine, etc.]

Our lengthiest outage was about a day (that Xformer). The issue then becomes how long can you keep the inve$tment in the freezer (meats, etc.) from going bad?

We don't even bother napping. Last "inconvenience" was the city losing natural gas supply. OK, so we'll be a bit cooler than we'd like... but, no need to drive off to some other place (outside of town!) in the hope that *they* have heat!

Not always. There are parts of town where the roads periodically get washed out. Those folks are essentially stuck until someone (gummit) can sort out a solution.

Don't worry about "The Big One". Worry about the ones that you *can* do something about.

Neighbors grumble (after the fact) when they see *we* had "lights" while they were in the dark. Granted, it's not a matter of life or death (we're not afraid of The Dark). But, it's sure a lot less inconvenient to be able to watch TV, surf the web, answer mail, do a bit of work, etc. despite the fact that your neighbors are in the black.

We keep crank lights and the little HF "9 LED" lamps in almost every room. They're small and relatively easy to locate in the dark. Cheap insurance against an unfortunate *fall*!

We don't have to worry about freezing. And, the genset is not large enough to run the ACbrrr. But, we can "be warm" for a while if that's the issue. Or, run a fan.

I'd actually say that having a *vest* is more important! Everyone has guns. How many have defenses against them?? :>

We don't worry. We prepare. We don't "lay in provisions", buy "survival kits", practice "drills", etc. We just make sure the things we would *want* to rely on are organized in a way that makes them easier to access and employ when we might otherwise be "distracted" by events around us -- would you have *cash* available? A record of your various bank/brokerage/credit accounts? etc.

Yikes! *Big*! I'm not sure I'd want to lug 10 pounds of battery around...

I was thinking more like one of the ~7AHr units in the smaller UPS's

snipped-for-privacy@yahoo.com wrote in

I have an ebay crank USB charger now, and so far it works, but not used a lot (at all :-) ).

You must be kindding right? Live in Sahara desert at noon on a cloudless day and no sunspots, plus a backup car battery.

I have 80 W solar panel the size of a small window and on a cloudy day here 400 mA at 12 V would be cool.

No way no way, with that thing.

My laptop is supposed to run for 3 hours when power fails. But my cable modem needs many Watts, I am sure their amplifiers are not backuped either...

I have a sealed lead acid many amp-hours for a transceiver in the attic. Candles for light Cookies for food. A week....

After that, back to the stone age, cut trees I'd think, would have to build a stone thing... think I am out of cement, but who needs that right? Eat the cat, the dog, invaders, you will find when the nukes rain. Fish, now that is a possibility. But all will be radiating so much you don't need no lights, So there really is no problem.

Yeah, she's already grumbling about some of the "non edible" items that I've got hidden in the back corners!

Looks like I could "rely on" no more than 4-8 months in the garage (i.e. 30C is probably a reasonable nominal temperature; 40C might be more common for much of the year!)

The most "telling" detail is: "Charge may fail to restore full capacity. Do not let batteries reach this state." (60% capacity)