Have also installed a kings 12v 60ah battery into the car today. width is pretty much correct and the mount that you remove can somewhat fit if u reverse the bottom mount the other way and rescrew it back in with flatter screws. however I just basically ratchet strapped it down lol.
Only 2 things to make sure of
the + terminal on the byd has 2 lips that might prevent it from being seated flust with the bolt, dont overscrew it as it might crack the plastic. Will probably just add a washer underneath or a connection for a battery monitor underneath to make it a good flush fit.
the - terminal angle is fairly stiff at 90*, that needed a bit of work to screw on, but otherwise it works.
@jktiet, I also ratchet strapped the battery down. Hasnāt moved.
Just so you know, every 3 to 4 months, you will need to manually charge the battery using a common multi-stage battery charger to equalise the cells. The 13.8V from the vehicle is not high enough. I used an automatic 14.6V 8A charger and left it on until the charge cycle stopped and it went to float (it took about 3 hours).
I hadnāt done an external charge for at least 4 months, and I noticed the battery voltage suddenly dropped well below 13V for the first time. See the attached graph below from the Victron battery voltage monitor. Since the charge, it hasnāt dropped again.
Note, the timeframe shown on the graph below is over about 6 weeks.