Disclaimer

LiPos are dangerous. I'm an amateur. Use this design at your own risk.

Build Description

1. The boost buck converter input is connected to the battery, and tuned to provide 24V to the fans.
2. The resistors are connected in series. Connecting them in parallel will get them very hot and melt the enclosure. Trust me, I'm sure.
3. Be careful to cover anything that might be connected to a battery, and fuse the positive terminal of the battery.

I plan on using a low voltage disconnect to allow me to use this for storage charging. I have an XH-M609 laying around I might be able to use for that purpose. Or I'll melt in. Here's to messing around and finding out.

Testing

I put 26V(6sHV) for a few minutes, then I put 20V in it for about an hour. The resistors were hot, but had not sagged.

Parts

Mine was pretty much built from spare parts, but the amazon links should get you what you need. I used 18awg wire for the main power and 22awg for the fan wires. 22awg should work for the whole thing. I fused the battery input at 5A.

1. 2x 10 Ohm resistor:
   1. https://a.co/d/hZf4tU5 
2. 2x 24V Creality 10mm x 40mm Fans
   1. https://a.co/d/8rAHfqm 
3. 4x M3 Threaded Inserts 
   1. https://a.co/d/33arD3z
4. 1x XL6009 DC-DC Buck Boost Voltage Converter
   1. https://a.co/d/7mhgePv 
5. 18awg Stranded Silicone Wire (main power route)
   1. https://a.co/d/6zF8n5R
6. Heat Shrink Tubing
   1. https://a.co/d/frd2Vf6 
7. M3 Screws
   1. https://a.co/d/2XNL90v
8. Male XT60 adapter
   1. https://a.co/d/8Wf3SMn
9. Fuses
   1. https://a.co/d/cbO7tcm