1/3AA Lithium battery

This one?

This one?

Or a bunch here?

Prices may vary.

Peter Wieck Melrose Park, PA

I know they are not LiPo batteries, but if they are to be rechargeable, that should not matter. I am hunting another source for an actual LiPo device.

This one?

This one?

Or a bunch here?

Prices may vary.

Peter Wieck Melrose Park, PA

Hi Peter,

all those are rechargeable NiMH cells.

I need a battery that will keep it's charge over many years without recharging. This is a memory backup application, where charging of the backup battery is not possible.

Cheers,

Gareth.

I know they are not LiPo batteries, but if they are to be rechargeable, that should not matter. I am hunting another source for an actual LiPo device.

Sorry, I'm replying to your posts in the wrong order!

So, how long would you think a 1/3AA NiMH would remain able to backup a memory chip? I suspect current draw is negligible, it is more down to shelf life charged.

Cheers,

Gareth.

is

OK. Is this the standard 3.7V of the typical LiPo style battery or somethin g else? If it is that standard, how high can you go and how low can you go? I am thinking that you will need to cobble something with button cells to the correct voltage and use conventional watch cells. You could use LiPo wa tch cells and stack them - but in parallel, not series using little ladder devices (I could send you a sketch, having done it) and then shrink-wrap th e results to make it one piece. LiPos self-discharge at about 2%/year, or a t least the very good ones do, so several in parallel should do nicely for as much as 15 years before becoming 30% down (other than from actual use).

Peter Wieck Melrose Park, PA

Lithium Iron-suphide (Li-FeS2) has a 10-year service life in applications such as you describe.

Lithium Iron batteries (if you can even find them) go to 20 years, and are highly resistant to extreme ambient conditions.

I have not seen either of this in the configuration you need, nor have I really done any searching. But I have seen LiPo button cells - so that may be the most expedient approach.

Peter Wieck Melrose Park, PA

OK. Is this the standard 3.7V of the typical LiPo style battery or something else? If it is that standard, how high can you go and how low can you go? I am thinking that you will need to cobble something with button cells to the correct voltage and use conventional watch cells. You could use LiPo watch cells and stack them - but in parallel, not series using little ladder devices (I could send you a sketch, having done it) and then shrink-wrap the results to make it one piece. LiPos self-discharge at about 2%/year, or at least the very good ones do, so several in parallel should do nicely for as much as 15 years before becoming 30% down (other than from actual use).

Peter Wieck Melrose Park, PA

Datasheet says 2v minimum, it is a 5 volt device. Anywhere in between should be good.

I'm willing to try the watch cell thing, but am a little nervous about soldering directly to a Lithium battery.

I'm also thinking that in this particular application, you wouldn't necessarily expect another 15 years out of it. A good few years would probably cope with expectation here, we are talking Vintage Synths.

Cheers,

Gareth.

Y'all don't need to solder. you will get two small pieces of brass or coppe r flat-stock, and some thin PTFE (Teflon) sheeting. Stack the batteries to the correct height for the use. Between each goes a small piece of Teflon a s an insulator. Cut the flat-stock so little legs come out at battery-heig ht for each battery. One goes *UP* for the one pole, the other goes *DOWN* for the other. Shrink-wrap the entire shebang. That makes positive contact for as many cells as needed in parallel, not series. Lace your fingers, put a piece of paper between each, the left hand fingers are on the bottom of the piece, the right hand fingers on the top as illustration. If you are a fanatic, you will use a drop of electronics-grade (no acetic acid) silicon to seal the top and bottom but for where the copper strip comes out for con necting to the board.

Been there, done that. The application was a bias cell for a vintage 1930s Coronado radio.

That was 15 years ago, still going strong. I needed only 1.5V, but I wanted a bit more longevity than a single watch cell would provide.

Peter Wieck Melrose Park, PA

Y'all don't need to solder. you will get two small pieces of brass or copper flat-stock, and some thin PTFE (Teflon) sheeting. Stack the batteries to the correct height for the use. Between each goes a small piece of Teflon as an insulator. Cut the flat-stock so little legs come out at battery-height for each battery. One goes *UP* for the one pole, the other goes *DOWN* for the other. Shrink-wrap the entire shebang. That makes positive contact for as many cells as needed in parallel, not series. Lace your fingers, put a piece of paper between each, the left hand fingers are on the bottom of the piece, the right hand fingers on the top as illustration. If you are a fanatic, you will use a drop of electronics-grade (no acetic acid) silicon to seal the top and bottom but for where the copper strip comes out for connecting to the board.

Been there, done that. The application was a bias cell for a vintage 1930s Coronado radio.

That was 15 years ago, still going strong. I needed only 1.5V, but I wanted a bit more longevity than a single watch cell would provide.

Peter Wieck Melrose Park, PA

I haven't the room to do that.

I don't want to rely on physical contacts unless I have to, I would rather solder. That way I can guarantee a jolt would not erase the memory contents.

Cheers,

Gareth.

They are called CR1/3N or CR11108. Search for that, and you'll find. If you can find them with solder tabs, however, is another matter.

It looks to me like this battery is used only for keeping the SRAM data alive. If so, the current draw will be very low. If you can find a smaller 3V cell, that will still work for a long time.

You could also stack two LR44 cells. The size should be about right.

Rechargeables are not the right tool for this job.

That is a good idea. If you can find a combination of holder and battery that will fit, that would be a good solution. You could look for both dual 1.5V or single 3V solution.

Looking at the device, it does not look complicated at all. Are the high prices because of the collectible value, or would people be willing to pay similar money for a new, compatible device?

They are called CR1/3N or CR11108. Search for that, and you'll find. If you can find them with solder tabs, however, is another matter.

It looks to me like this battery is used only for keeping the SRAM data alive. If so, the current draw will be very low. If you can find a smaller 3V cell, that will still work for a long time.

You could also stack two LR44 cells. The size should be about right.

Rechargeables are not the right tool for this job.

That is a good idea. If you can find a combination of holder and battery that will fit, that would be a good solution. You could look for both dual 1.5V or single 3V solution.

Looking at the device, it does not look complicated at all. Are the high prices because of the collectible value, or would people be willing to pay similar money for a new, compatible device?