Martin's corner on the web

Selective type RCDs exist

Selective type RCDs exist

TIL that selective type RCDs exist. I learned this lesson after an RCD in my DIY emergency power switchover box started tripping more often than expected. The schematic indicated a type S RCD was needed, but I didn't understand what that meant until today. https://www.electrical-installation.org/enwiki/Coordination_of_residual_current_protective_devices

Green metallic beetle’s larvae

Green metallic beetle’s larvae

Our composer is infested with that otherwise beautifully looking green metallic beetle’s larvae. I need to use the compost now. Are the larvae pest (kill) or harmless (move elsewhere)? Never mind, our daughter came to see what the fuss is about, and “kill” is no longer an option. She is supervising the moving now, but…

Wireless outdoor temperature sensor

Wireless outdoor temperature sensor

Had to move a wireless outdoor temperature sensor I designed ages ago, noticed a memo inside I left for the future self with last battery change date. Still sending readings every minute since May 2018, thats 4 years and 9 months on couple AAs and still going strong. #IoT #rfm69

LiFePo4 (LFP) chemistry

LiFePo4 (LFP) chemistry

Interesting paper on "Degradation of Commercial Lithium-Ion Cells as a Function of Chemistry and Cycling Conditions" here: https://iopscience.iop.org/article/10.1149/1945-7111/abae37/pdf; Three degradation factors are explored: 1) Temperature, 2) DoD and 3) Discharge rate. (1/2) I specifically care about LiFePo4 (LFP) chemistry, because our solar system's BYD battery is such. Strange to see that a 100% DoD doesn't…