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Links for 2022-09-07

  • Serverless Messaging: Latency Compared

    Various AWS queueing/messaging services’ latencies compared in eu-west-1: ‘When latency matters, there are a few obvious winners. SQS Standard can deliver a message to a consumer in as fast as 14 ms and is seldomly slower than 100 ms, assuming low batch sizes. Kinesis with Enhanced Fan-Out is only slightly slower and allows for multiple consumers and a long history of events. SNS falls in the low latency category too, although the SNS FIFO option includes more moving parts and thus a larger latency spread, up to half a second. Step Functions and DynamoDB Streams take up the middle section, with P50 latencies up to about 200 ms. The highest latency is introduced by EventBridge and Kinesis Data Streams without Enhanced Fan-Out. These services add at least a few hundred milliseconds to your integrations, but can easily run up to a second or more.’

    (tags: aws latency messaging queues architecture ops sqs sns kinesis)

  • Energy Monitoring: 2022 Edition

    home energy monitoring using HomeAssistant, MQTT, and a set of power-monitoring smart plugs preflashed with the open Tasmota firmware. This is all very practical, and the power-socket-based approach means no rewiring is necessary. I think this is the best UI I’ve seen so far for a home energy optimization system

    (tags: home energy monitoring tasmota plugs electricity homeassistant)

  • Lithium-Ion Batteries: Charging Guide for Maximum Endurance

    tl;dr: “Lithium-ion and lithium-polymer batteries should be kept at charge levels between 30% and 70% at all times. Full charge/discharge cycles should be avoided if possible. Exceptions to this can be made occasionally to readjust the charge controller and battery capacity meter. Modern batteries do not have to be conditioned, and are at peak capacity out of the box. If you need to store batteries for long time periods you should charge them to roughly half their capacity and put them in the fridge. Very high and very low temperatures should be avoided, particularly while charging. When choosing a charger quality is key, and high quality chargers are by and large interchangeable.”

    (tags: batteries lifetime lithium-ion charging chargers)