[tthrsn]

This is the original battery:
https://www.amazon.com/gp/product/B010TXTNP0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

The replacement has different branding, but (I am told) was built to the same specs,

This one doesn't seem to be one of their deep discharge models. I think that you need deep discharge.