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I'm trying o use a LiSoCl2 battery in a low power GSM application. When the system is in standby only the microcontroller(MSP430) is powered(3.3v) and the GSM(5v) and sensor(5v) is turned off. The whole system consumes 50uA. The burst current when sending data over GSM is up to 2A, but my battery provides a maximum 400mA of discharge current. Some applications use auxiliary capacitor, but most capacitors have high leakage current. The converter used for provide 5v is LMR61428, when the system is in standby mode it is turned off.

What is the best way to avoid leakage current of an auxiliary capacitor? Is there a way to enable the capacitor only moments before using GSM to prevent leakage current?

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  • \$\begingroup\$ Are you equating high ESR with high leakage? And what does "high" mean in your case? \$\endgroup\$
    – Finbarr
    Commented Mar 6, 2019 at 14:18
  • \$\begingroup\$ Sorry, I corrected the question. I want to prevent capacitor leakage. \$\endgroup\$ Commented Mar 6, 2019 at 14:26
  • \$\begingroup\$ How much leakage are you expecting from your capacitor? \$\endgroup\$
    – Finbarr
    Commented Mar 6, 2019 at 14:28
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    \$\begingroup\$ If you know in advance when you (likely) need it you could start charging the capacitor then. But depending on network behavior it might take more energy than expected to get your message out. This will be a very challenging project to get right. \$\endgroup\$ Commented Mar 6, 2019 at 14:29
  • \$\begingroup\$ How much capacitance do you need? \$\endgroup\$ Commented Mar 6, 2019 at 16:15

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Manufacturers of lithium thionyl chloride battery packs use hybrid layer capacitors (HLCs) for this exact purpose. For example see Tadiran.

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