I am charging the bater outside ( with batter charger I did not charge the battery on the portable and then place it in the portable. is this OK or need to be on the portable and charge while power on ?
In theory, you can charge the battery anywhere. My strategy with the new battery I have is to keep it outside of the Portable, on a battery maintainer, like I do with my car and lawnmower. This way I can pack the machine away and not have to leave it all out and set up just to charge the battery.
The other thing to remember is that, as others said, not all batteries are the same, and not all will power it. For instance, I used one 6V lead-acid battery that would not power the thing. Once I found one that was close to spec with the original, it worked fine. The issue was that the first would not supply enough continuous amps to power the machine.
Here is the battery that I found that worked fine. I found it at a local battery store, it is made by the same manufacturer as the original.
View attachment 25357