What did you do? I custom squeezed a 2400mAh (sub-C size) 8-cell (9.6v) battery into the stock of my PSG-1. In total it took me about two weeks (a few hours each day, maybe 20 25 hours in total) to finish this darn thing. If you ask me - no, I am NOT going to make another one. But here is the full detail for the project, for those who is interested.

In the beginning... To start with I took apart the PSG-1's stock and found that there is some space you can utilize. And after some careful measurement the stock is both thick and deep enough for a set of custom Sub-C cells, so I want ahead and tear it apart.

Concept: The concept started with using some of the spaces that the cheek-piece and adjustable butt-stock has wasted. The center-divider inside the stock has to be taken out (sable saw…) and some heavy sanding has to occur. I am not going into the detail here, but if you are interested just email me. The custom battery has 3 cells on top and 5 cells on the bottom, and a major part of the stock’s interior has to be taken out as well. Since the battery will be non-removable after I have completed the conversion, I created a 3-way wire that allows in-gun charging.

The following pictures should help you get a better idea of what I did. Again, if you need additional detail (I doubt anyone would be stupid enough to attempt this again…) feel free to email me.

1. Picture of the stock removed from the gun’s body	2. Interior of the stock before any modification. You can also see the shape of the custom battery.

3. Modification required to the interior	4. How the pieces looks like when they fit together. You basically slide this back into the gun’s filed down stock. Note the black shrink-wraps, as the battery cover can no longer be used, it is important to make sure the battery (originally yellow) doesn’t stand out from behind.

5. Custom 3-way wiring for the gun. Note the fuse box is retained, but only to the gun side -- so if I try to fast charge the battery (say, at 7-8 amps) it won't blow the fuse.

After I put the gun back together, you can’t really tell the difference from a stock PSG-1, except the new battery charging plug (that white piece under the stock in the next picture) and missing battery cover (Second picture, you can see the last cell of the battery). One of the draw back is that since the new battery took up so much space inside, the cheek and butt plate cannot be fully retracted. It works fine for me as I have a relatively long neck, but it won’t fit comfortably for shorter people (especially female players). In addition, if you try to turn the butt stock too much towards the inside of the gun, it will damage the battery.

You can click on the above two pictures for an enlarged view.

(Click here for a picture of the completed gun.)

With the new battery, I can probably go for a full-week organized airsoft event (if there is one that lasted that long) without needing to charge the battery. Even my older 10.8v 600mAh battery lasted more then a day (usually), and with the high capacity not only battery life, even ROF is not a concern at all. As a matter of fact, when I first pulled the trigger after the upgrade is done, the piston was withdrawing so fast that I almost couldn’t hear the gears noise as it sounded more like “zap” (which scares me). Also, for those who fitted a PSG-1 stock on their G3 for the look, now you can go full-auto with M150 spring upgrade without worring about battery life! Last but not least, if that extra bit of juice does matter to you, you can always use 3000mAh Ni-MH cells insted of 2400 mAh Ni-CD cells as I used here.