I have a 5FGC20 Toyota fork lift that has a cranking/ starting issue.

I replaced the starting battery with a new AC Delco 685CCA Battery.
When I turn the key to the ON position the 2 red rectangular lights light up on the dash panel.

The lights stay on and when I turn the key to the CRANK position to crank the engine nothing happens.

When I connect a booster / starter charger to the battery and turn the key to the ON position the lights come on then turn off and when I cycle the key to the CRANK position the engine starts and stays running with or without the battery charger connected until I cycle the key to the OFF position.

To restart I have to follow the same process as above.

Any idea as to what the problem maybe ?

Thanks Pete S