capcitors for energy reserve

That's not accounting for the drop out voltage which on switchers, especially the cheap drop-in replacements, tend to be several volts. So if you limit your cap range to 9-7 vs 9-5 volts you probably need an even larger cap than the one you could get by with not using a regulator at all. lol

or rechargeable alkaline manganese (RAM)) is a type of alkaline battery tha t is capable of recharging for repeated use. The first-generation rechargea ble alkaline technology was developed by Battery Technologies Inc in Canada and licensed to Pure Energy, EnviroCell, Rayovac, and Grandcell. Subsequen t patent and advancements in technology have been introduced. The formats i nclude AAA, AA, C, D, and snap-on 9-volt batteries. Rechargeable alkaline b atteries are manufactured fully charged and have the ability to hold their charge for years, longer than NiCd and NiMH batteries, which self-discharge .[1] Rechargeable alkaline batteries can have a high recharging efficiency and have less environmental impact than disposable cells.

for sale.

Sounds like some people thought that they could make them once, but the cru cial ingredient stopped being available.

I had the same experience with orienetation-insensitive mercury-wetted reed relays. For a while there were a few manufacturers who claimed to be able to make them, but you could never buy them when you wanted them.

time. But you can recharge a regular alkaline if the cell voltage is about 1.3 volts or higher. We used to do that at work where flash lights were u sed a lot.

The manufacturers don't endorse the technique.

your hands on. I tend not to take them seriously until a broad-line distri butor keeps them in stock.

much at the sharp end of knowing more and more about less and less until yo u know almost everything about about practically nothing.

loser to practically nothing than anything.

Inter-galactic space seems to do better.

em for sale.

rucial ingredient stopped being available.

Why do you think that? I have no interest in buying any so did not look f or an industrial supplier. I may be mistaken , but do not think you are in terested in getting any, or you would have searched for them your self. So looking for an industrial supplier would just be wasted effort.

ed relays. For a while there were a few manufacturers who claimed to be abl e to make them, but you could never buy them when you wanted them.

t time. But you can recharge a regular alkaline if the cell voltage is abo ut 1.3 volts or higher. We used to do that at work where flash lights were used a lot.

If I were a manufacturer I would not recommend anything that would decrease sales.

et your hands on. I tend not to take them seriously until a broad-line dist ributor keeps them in stock.

closer to practically nothing than anything.

High vacuum in Inter-galactic space seemed to have little practical applica tion.

Dan

them for sale.

crucial ingredient stopped being available.

for an industrial supplier. I may be mistaken , but do not think you are interested in getting any, or you would have searched for them your self. So looking for an industrial supplier would just be wasted effort.

You implied that they were an off-the-shelf solution. They don't seem to be .

reed relays. For a while there were a few manufacturers who claimed to be a ble to make them, but you could never buy them when you wanted them.

hat time. But you can recharge a regular alkaline if the cell voltage is a bout 1.3 volts or higher. We used to do that at work where flash lights we re used a lot.

se sales.

Different markets. NiCd and NiMH rechargeable cells sell in respectable num bers, and I can buy them in my local supermarket. If alkaline cells could c ompete in that market - possibly with tarted up packaging, they would. they don't. so the assumption is that they can't.

get your hands on. I tend not to take them seriously until a broad-line di stributor keeps them in stock.

is closer to practically nothing than anything.

cation.

Interplanetary space is more accessible than it used to be, though I've not yet seen evidence that people are exploiting it as a manufacturing environ ment.

he crucial ingredient stopped being available.

ok for an industrial supplier. I may be mistaken , but do not think you ar e interested in getting any, or you would have searched for them your self. So looking for an industrial supplier would just be wasted effort.

be.

What makes you say that they do not seem to be an off the shelf solution. All I said is that I not looked to see the availability since I am not look ing for any.

ease sales.

umbers, and I can buy them in my local supermarket. If alkaline cells could compete in that market - possibly with tarted up packaging, they would. th ey don't. so the assumption is that they can't.

Alkaline batteries also sell in respectable numbers and in the same markets as Nicd and NIMH batteries. At least in the U.S. Maybe alkaline botterie s are not available in Australia

Dan

You have to specify the minimum voltage your load will accept at the end of the current peak.

In any capacitor based storage system, the voltage starts linearly drop as charge is removed, thus the load should accept as much voltage variations as possible. This might require using some switching regulator between the capacitor and actual load, say 24 V fully charged and 8 V at the end of the discharge cycle.

Depending on your life time and temperature requirement a secondary battery (such as NiCd) might be a better solution. Make sure that the charge current is only slightly above the _average_ load current. As long as your excess average charge current is well below C/10, the battery can dissipate that extra charge without overheating.

Lead accumulators are available at 6, 12 and 24 V (nominal), so you can leave these on float charge for years on 6.9, 13.8 and 27.6 V.

Though compared to a cap they're expensive, heavy, short lived and prone to spray acid about.

NT

ry (such as NiCd) might be a better solution. Make sure that the charge cur rent is only slightly above the _average_ load current. As long as your exc ess average charge current is well below C/10, the battery can dissipate th at extra charge without overheating.

Normally, i would suggest battery as well. But in OP's case, he is running a 2 seconds cycle, which is probably not good for a battery.

Is an electrolyte capacitor or a "super capacitor" any better in this sense ? At least for applications requiring 10-50 years life time ?

ote:

aw at 120mA. This occurs every 2s. I am limited to 40mA current draw. I w ould like to provide reserve energy from a large capacitor. I have built a circuit that limits the input current to 40mA. This runs the circuit and charges the cap.

short a time. Is there any methodology for calculating required capacitan ce? Any ideas on implementation beside my current limiter plus cap?

nd of the current peak. In any capacitor based storage system, the voltage starts linearly drop as charge is removed, thus the load should accept as m uch voltage variations as possible. This might require using some switching regulator between the capacitor and actual load, say 24 V fully charged an d 8 V at the end of the discharge cycle. Depending on your life time and te mperature requirement a secondary battery (such as NiCd) might be a better solution. Make sure that the charge current is only slightly above the _ave rage_ load current. As long as your excess average charge current is well b elow C/10, the battery can dissipate that extra charge without overheating.

an leave these on float charge for years on 6.9, 13.8 and 27.6 V. Though co mpared to a cap they're expensive, heavy, short lived and prone to spray ac id about.

se ? At least for applications requiring 10-50 years life time ?

Neither. What application would require 50 years electronics life?

For most apps 50years would be nice.

NT

Why?

the crucial ingredient stopped being available.

look for an industrial supplier. I may be mistaken , but do not think you are interested in getting any, or you would have searched for them your sel f. So looking for an industrial supplier would just be wasted effort.

All I said is that I not looked to see the availability since I am not lo oking for any.

And nobody else has posted a link to a catalog entry.

crease sales.

numbers, and I can buy them in my local supermarket. If alkaline cells cou ld compete in that market - possibly with tarted up packaging, they would. they don't. so the assumption is that they can't.

ts as Nicd and NIMH batteries. At least in the U.S. Maybe alkaline botter ies are not available in Australia.

You mean rechargeable alkaline batteries?

I've not seen them around, despite Wikipedia. They would seem to be ideal f or the OP's job, since he isn't planning deep discharge, if he could buy th em anywhere respectable - not E-Bay, obviously.

On Sat, 4 Oct 2014 14:23:47 -0700 (PDT), snipped-for-privacy@care2.com Gave us:

In a society that morphs at the pace ours does. 50 Years is asking for a lot. This ain't the blacksmith pounding out a new horseshoe technology.

You have to remember that no one else is reading our posts.

No, I mean ordinary alkaline batteries. They recharge just fine if they are not deeply discharged.

Dan

I think Wiki is confusing. The old rechargeable batteries (lead-acid) used an acid electrolyte. When the first NiCd cells came out, they too were liquid-filled with little fill holes on top, only the liquid was alkaline (KOH, I believe).

So, there are lots of references in old literature to 'alkaline storage batteries' that are talking about nickel-iron and NiCd. Rechargeable, yes, and alkaline, but not the sealed-cell Zn/MnO2 things we call 'alkaline battery' today.

Don't do that! The solid electrolyte swells, which damages the seals, and caustic goo oozes out and destroys everything nearby.

Any warranty, on the battery, on not destroying nearby hardware is void if the battery is used in a recharging device, and there's 'explode or leak' warnings all over them. It isn't just talk, there really IS a problem.

The absence of responses is no proof of the absence of lurkers. This thread is now 65 posts long, which means that many people who aren't attracted by the subject heading will check it out just to see what's going on.

But there are caveats.

tery (such as NiCd) might be a better solution. Make sure that the charge c urrent is only slightly above the _average_ load current. As long as your e xcess average charge current is well below C/10, the battery can dissipate that extra charge without overheating.

ng a 2 seconds cycle, which is probably not good for a battery.

Why? It's a lot of shallow cycles, which might be bad for crystal growth in a NiCd. NiMH doesn't seem to have that problem, nor Li-ion. Super-capacito rs are pretty much batteries, and they are fine with that sort of use.