I may be able to use only a coin cell non-rechargeable, like this one:
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But it has no temperature max data, I need minimum 60 degrees c
Anyone know the max temperature from the technology used?
I need minimum cost, 10 years operation (so reduced leakage) and as always minimum cost (very high yearly quantities)
A rechargeable can also be possible, but cost is normally higher than for non-rechargeable - and charging above 40 degrees is normally not allowed for some reason
can operate up to 130C, which might be a bit of an over-kill. Their regular lthium thionyl chloride goes up to 85C (and I used that technology back in 2000 when I worked at Haffmans BV in Venlo, Netherlands.
At the time I posted a query here looking for a rechargeable system that worked when that warm, but nobody knew of one.
The Tyva web-site seems to clain a 20-year life for the general thionly chloride based parts.
They are just agents for the Korean XenoEnergy company.
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who could probably tell you about the charge retention over time at high ambient temperatures. It's clearly going to be less than 20 years - they recommend storing at less than 20C.
Silver oxide batteries are almost there at your temperature spec. On page 3 Energizer states 55C max but you could write to them and ask about the trade-offs at 60C:
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I believe self-discharge will be your enemy because of the 10-year requirement so you may have to seriously oversize.
I assume you have looked into harvesting from some available energy and strage into a cap, maybe too expensive or not enough energy available.
Also, check Seiko for availability and pricing on these rechargeables:
or non-rechargeable - and charging above 40 degrees is normally not allowed for some reason
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looks interesting. The website claims a 10uA self-discharge rate at 72C, wh ich is 6.2 years for the 550 mA.hour part. If your device doesn't get hotte r than 60C you might get your ten years, but asking the manufacturer could tell you more. Self discharge at 20C was only 2uA, so assuming that self-di schrage rises as an exponential function of tempeature, that would about 7u A at 60C or roughly nine years to complete discharge.
If your environment only got to 60C some of time, you would probably be fin e.
Yeah, that's why I aimed for a 6mAh part even though I only need 2mAh
I have looked into that. For that to work I would need a good high capacity capacitor, with very low leakage, and I have not been able to find that. Also, the harvesting idea might not work, and cost more than just a coin cell
for non-rechargeable - and charging above 40 degrees is normally not allow ed for some reason
which is 6.2 years for the 550 mA.hour part. If your device doesn't get hot ter than 60C you might get your ten years, but asking the manufacturer coul d tell you more. Self discharge at 20C was only 2uA, so assuming that self- dischrage rises as an exponential function of tempeature, that would about
7uA at 60C or roughly nine years to complete discharge.
ine.
Correct, we have a load profile, so it is not 60 degrees all the time, abou t 50%. The rest of the time is at 40 degrees
Interestingly, Lithium batteries cannot be shipped by air, so that set limi ts on the supply chain. Also, for batteries inside products, 2 faults must not be able to short the battery, so FETs needs to be added for protection
an for non-rechargeable - and charging above 40 degrees is normally not all owed for some reason
, which is 6.2 years for the 550 mA.hour part. If your device doesn't get h otter than 60C you might get your ten years, but asking the manufacturer co uld tell you more. Self discharge at 20C was only 2uA, so assuming that sel f-dischrage rises as an exponential function of tempeature, that would abou t 7uA at 60C or roughly nine years to complete discharge.
fine.
out 50%. The rest of the time is at 40 degrees
mits on the supply chain. Also, for batteries inside products, 2 faults mus t not be able to short the battery, so FETs needs to be added for protectio n
The web-site is tadiranbatteries.de so delivery by truck should be practica l.
"The battery is not pressurized. Its ingredients are not hazardous accordin g to the European RoHS and battery directives."
The website tells you what happens when you short the battery, which doesn' t warm up all that much or burst.
Supercaps spec badly because they don't have the time to test them. There's a 1/f tail (ionic diffusion) that takes over a week to settle down, and an exponential dependence on voltage, since after all it's an electrochemical cell. A very slow diode if you like.
I've got a 25F NESCAP laying around here, that I topped up to 2.5V a few weeks ago. It's been sitting at ~2.1V for most of that time.
Of course the leakage will be that much worse at elevated temperature, so YMMV there. :-/
Tim
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