cpap battery

[John Frum]

This is my cpap battery.
2x dissimilar 30ah lithium batteries in parallel for ~532.8 usable watt hours.
Each battery has a separate port bms but I am charging through the discharge port because they are on the same bus.
I had a fancy setup with a double pole double throw relay but the coil didn't de-energise fast enough so I went with the simpler solution.
Last night my cpap machine drew ~125 watt hours with humidity set to 4.0 so plenty o'battery.
The button on the front bezel controls the atx power supply via the ps_on pin which in turn charges the batteries.
There is no charge termination logic so I charge the batteries to 12.2 ish to minimize the angry pixel stress.

 

[nogridhome]

That is really cool! What happens when you reach 88 mph?

 

[Fred S]

Nice! So many uses for old PC cases and power supplies!

This thing is a cheap low and high voltage disconnect, if you want to try it.
https://www.amazon.com/gp/product/B07YTVK1JK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I have one, I tested it, but as yet have not used it.