[ddmckee54]

Using two different flavors of batteries you'll have different discharge curves. I think you'll need to tie the commons (-) of both battery packs together so all of the electronics will have the same zero reference. Also be absolutely sure that only the signal leads are shared between the house and the chassis electronics. Otherwise, as the packs discharge the higher voltage pack will try to charge the lower voltage pack through the electronics. This usually results in letting the magic smoke out of something.