Batteries, Battery Box, and the start of wiring...

Decisions to be made (well, have already been made - but here is the logic)...

Batteries, and battery capacity:  I like lithium batteries - specifically EarthX.  Lots of views on this subject.  Regardless, that is my choice.  Next decision is size and capacity.

Size:  Need to be able to run everything for 1 hour minimum on battery power alone.  Panel will draw 10 amps, engine will draw 12 (including pumps).  Going with qty 2 EarthX ETX900's, which are 16.4Ah batteries.

Charging:  Already decided on batteries, now what keeps them charged.  The UL520T comes with a 50A alternator.  There is an option for a 2nd alternator, but when you do that you now need to control the charge direction - IE what alternator charges what battery.  2 alterators is more weight, then you add diodes that generate heat, add complexity, and slightly drop voltage.  All things considered, going with 1 alternator and 2 batteries seems to be the most prudent.  Best balance of benefits vs complexity.

2 batteries means 2 master solenoids.  No big deal... just need to find space.

Battery mounting:  My goal is to make this airplane serviceable... as easily serviceable as possible.  Changing batteries should be an easy process.  With that in mind, the battery tray is going to bolt to the aluminum angle framework.  No firewall penetration to remove the battery tray / batteries.

This battery frame is going to have an aluminum box around it with a blast tube.  The top and bottom will be open.  The shroud will have reflective stick on material.  At least, that is the plan...

Battery frame all drilled and clecoed.  Adding some .030 side pieces for a bit more rigidity.  Will drill some lightening / cooling holes in these as well.

Lot of drilling..... 

Everything primed and alodyned.

Initial test fit.  I am not going to commit to a location yet.  I need to see where the intercooler is going to be.  It is somewhere in this area.

Test fit with batteries.  Just need to make the hold down strap.

Unfortunately this design is not going to work.  After test fitting with the engine mount, it hits.  Didn't seem to matter where I moved it, it wasn't going to work - mainly due to its width.

Version 2 is stainless and narrower.

Will still be mounted on its sides in a cradle.  Hold down strap to keep the batteries in.  Changing the batteries will mean removing the whole battery box due to the engine mount, but its only 5 bolts to get it out.

Installed on the firewall - test fit...

Moved the ground bus bar up higher.... had no access to tighten the ground screws down.  I figure that the best way to figure out if this is a workable solution is to just wire it.

Needs tidying up, but I am not unhappy with the results.  Everything is accessible and safe.  I am not going to go much beyond this until the firewall is in for good.