Gear Mods: move your PolarStar FCU into your grip.

Moving the FCU and battery to inside your grip is a worth while mod for anyone running a PolarStar pr-15 fusion engine.  It does involve a bit on soldering knowledge, and as with most mods, you run the risk of breaking your gun.

Before you start here is a list of tools / materials you will need.

• Soldering station / solder 
• #1 and #2 philips screw driver
• small jewelry slot head screwdriver
• 7.4v 250mha lipo
• heat shrink tubing 
• lighter or heatgun 
• wire cutter 

Save yourself some time and do a test fit to make sure the FCU and battery will actually fit in your pistol grip.  You dont want to tear everything apart just to find out your battery is too big, or the chamber in your grip is too small.

Once you know everything will fit break down your gun and removing the fusion engine.  With the fusion engine on a clean surface open the side cover.

Thread the FCU wire through the bottom of the fusion engine.  It is a tight fit, but there is enough room.

Close everything back up and run the FCU control wires down through the grip with the air hose.  I trimmed my FCU control wires a bit.. but this is optional.

I also trimmed the wires on my FCU a bit so I would have more room in the grip, once again this is optional.  I strongly recommend using heat shrink rather than black tape.  If you are using heat shrink make sure you put it on BEFORE you solder everything together ..   

Here is a view with the heat shrinking almost done.

Test to make sure everything works, before you hook up the FCU control wires.

Now that you know your battery connections are solid connect up your FCU control wires and test the unit.  Make sure the solenoids fire on both semi and full auto.

Finish up by stuffing everything back in the grip.  One thing to watch out for, make sure you dont press the FCU dpad or the unit will go on safe and you will not be able to fire.  I actually had enough room to screw in the bottom grip cover.

I love the fact that now I dont need to have a battery pouch on my stock, or anything in my buffer tube.

Hello new hotness :)

Shot of the new battery for reference.  Amped boasts this battery with a full charge will run your FCU for 20,000 shots.  I am inclined to believe them.  I ran mine for 15 mins of solid full auto fire and it was still GTG.  Some quick math 60sec * 15min * 28bb/s = 25,200 shots.