Q: How are these primary batteries differed from the vanilla personal batteries?
A: Unlike vanilla personal batteries, the primary batteries CANNOT be recharged, no matter portable solar panels or portable fusion generators are present or not.
However, these primary batteries are available much earlier! Also they are cheaper to craft, considering you have to accumulate enough circuits to craft the first solar panel, which is still quite slow in power generation.

Q: Do the primary batteries have any use from mid-game?
A: Since the portable fusion generators give energy for FREE, the use of primary batteries will diminish. But even then, a stack of primary batteries in inventory can be a lifesaver. When your energy shields and personal laser defense drain all the power away, the primary batteries can serve as your emergency power.

Q: What are the changes to the early armours?
A: The two vanilla early armours (light armor and heavy armor) do not have any equipment grid. This mod add a small grid to them, so you can put in the primary batteries.

Q: Why I cannot put in energy shield (or other equipment) to heavy armor?
A: The newly-added small grid are supposed for the primary batteries only, not a substitute of advanced armours. Think of this as merely pockets of an armour vest, rather than an integral system of an advanced powered armour.
You still need to upgrade to at least a modular armour, to utilize the benefits of the whole equipment system.

Technical Details

Dry battery

• Requisite technology: None. (Available from the start.)
• Capacity: 10 MJ

Alkaline battery

• Requisite technology: Battery.
• Capacity: 30 MJ

Full List of New (or Changed) Items

Equipment

• 2 battery:
  • Used battery [Dummy item]
  • Dry battery
  • Alkaline battery

Armor

• (2 changed) laser:
  • Light armor [added equipment grid]
  • Heavy armor [added equipment grid]

Technologies

• (1 changed) battery-related:
  • Battery