Boost Start Mystery

[Hea!]

I'm new to rigs with generators, but have a couple of related questions.

1) My engine battery was dead yesterday so I thought I'd use the Boost Start switch, but to no avail. Click in the engine compartment seems legit, but no bueno.
Also, the generator would not start. Is this normal?

Grabbed a dumb charger and charged the engine battery for a few hours and it started.
Testing today, it looks like it is at ~600~ CCA's
My battery (https://www.interstatebatteries.com/products/mtp-65) appears to have 750 CCA's when new.
Definitely suspect.

2) Generator starts and runs smoothly.
While running, disconnect the engine battery and the generator quits. Is this normal??

3) Because the Boost may use a smaller wire gauge, should I press-and-hold before attempting to start?

Thanks in advance!

[Hea!]

Engine battery definitely NG. Replaced.

[chin_k]

1, For my 2000 Concourse, the chassis battery is the one that starts the genset. So it sounds normal that the genset won't start if you have a bad chassis battery.

2, the genset need the 12V to keep the control circuit going, so it also sounds normal that it quit when you disconnect the battery. There is no direct connection from the 110V AC thru the inverter/charger thru the Surepower solenoid to the chassis battery, so the fact that the genset is running is not going to keep the circuitry working in a perpetual cycle, if you know what I mean.

3, some people hold it a bit so to get the chassis battery more time to get up on capacity. It is not big enough, as you noticed, to use it as a jumper cable, so it surely is not good to hold it for too many time.