For the past year or so, Precision Circuits manufacturing looks tapped out for the BIM 160s. They only seem to supply that one only to the OEM builders. The Li BIM 225 is available but you probably don't want that as its charging algorithm is tailored to Li batteries.
Try for a used on on eBay since lots of people are upgrading theirs for the Li version.
Oh and when you find one and install it, wire the chassis battery to Bat A and the coach to Bat B. Thor installs them backwards and they don't work as well that way.
David
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