I use small 12V (8 to 10AH) lifepo4 batteries to power camping stuff not near the vehicle. Things like 12V pumps to get water out of a spring/well etc.
Anyhow, finding a charger in the 2 to 4A range for lifepo4 batteries with nice features etc is challenging.
Being an EE and having a little solidworks experience (very little), I knocked up a custom charger, wrote software for it, found a nice OLED display and of course needed a box. Has a powerpole for the input (vehicle 12V) and a powerpole for the output, the lifepo4 I want to charge. The charger chip is smart, has built in buck/boost and a bunch of nice features and can be configured for 4 cell lifepo4.
Anyhow, enough blabbering, here's some pics. Built 2, this one I finished today.
Finished product hooked to a 3S li-ion pack just to get the display up for a pic.
The guts, running, I have a red/yellow/green LED for status - but given it has a display that shows all that and more, the LEDs are essentially useless
I have 3D modeled powerpole 'building blocks' (with all the grooves etc) that I can reuse as needed. Roll pins to lock them in place. I have a nice 'clip/latch' design that I reuse that makes a nice lid to box closure.
The bright orange colour is to make the box easier to find in my camping electronics tote.
cheers,
george.