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I have a security/alarm system running, it uses multiple door/window sensors (433Mhz), which use A23 12V batteries. These A23 battery are non-rechargeable and quite low on capacity (used in 433Mhz remote controls as well), they are drained after about 3 month when installed in the mentioned door/window sensors and I'm sick of buying new and replacing every so often.

I'd like to use a single 18650 battery to power a sensor (salvaged from old tech with higher capacity, should be enough for 1-2 years). So I tried a small step-up converter but discovered that it draws ~1mA without even the sensor being attached. This would drain the battery after ~2000 hours (80 days), so I end up with even shorter time on the 18650 battery.

Wrong approach? I searched the net, but end up with charge-modules and things, which do not help. My experience with micro electronics is rather basic.

Thank you in advance! o)

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    \$\begingroup\$ Please add a schematic for one of these sensors. \$\endgroup\$ May 28 '21 at 19:20
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    \$\begingroup\$ That current, the 1mA consumed by the regulator with no load is called quiescent current. The abbreviation used in datasheets is Iq. So you are looking for a regulator with an Iq of 10 uA or something. Or at least less than 100 uA. The other option is to use 3S 18650 pack with no regulator. Although that makes for a large battery pack. You could also use 4S LiFePO4 cells. \$\endgroup\$
    – mkeith
    May 28 '21 at 19:24
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    \$\begingroup\$ How much current do the window sensors draw (at 12V) when idle, and what type of sensing do they use? \$\endgroup\$ May 28 '21 at 22:33
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    \$\begingroup\$ also do they use power continuously or only when doors are opened or closed \$\endgroup\$
    – Jasen
    May 28 '21 at 23:41
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The easiest to way use 18650 cells would be to put three in series.

This avoids the problem of quiescent power for a boost converter

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