[kizza42]

I used that exact battery in my DX7 for 8months before I got the new radio. I think I charged it twice maybe three times in that period (And you know how I leave my radio on at the field all the time!)

You will need to shorten the cables as its a bit of a tight fit.
There is a way to get into the service menu on the DX7 and change the low voltage alarm up to 10v as well but you will need to adjust your mindset to charge the radio when it hits 11.2v anyhow