The amount of deployment points you get is determined by the number and quality of your officers, the capture points you control during a battle and the game settings under "Settings" that set max battle size.
There's also a thread I started a week or so ago asking how to modify the game files so that both sides could have more deployment points. I'm sure it has a title saying something similar to yours.
If you set it to 400 max in the game, then your max deployment would be 60% of that or 240. I did take my settings up to 600 or so and I found the AI did a poor job of managing larger ships in what became a crowded space. One of the improvements expected in the next patch is that smaller ships do a better job of not staying in front of larger ships which prevents the larger ships from firing.
1. Check your max battle size. Make sure it's 400.
2. Hire some officers and max their skills.
I start with 224 deployment points quite regularly, prior to battle start, then I capture one capture point, which gives me my max of 240 quite easily. I do have my character plus 10 officers and each is at least level 5. Good luck!
Edit: I guess it wasn't me who asked. Here's how to change game files and battle size beyond 400.
https://fractalsoftworks.com/forum/index.php?topic=22499.0