J-battery

From Airsoft Community Wiki

A J-battery is a custom battery for the P90, it allows a higher rof than standard mini batteries and holds more charge, it is shaped like the letter J, hence the name. The gun requires a small amount of modification in order to accept a J-battery, and while fairly minor, cannot be reversed.

The modifications are all to free up more space inside the stock of the gun in order to squeeze the battery in.

Modification Procedure

1. The inside of the butt plate must be sanded or cut flat. As standard there are two vertical raised lines on the inside of it, these need to be removed, leaving the plate flat. Be careful however not to damage the mechanism for locking the plate to the back of the stock.

2. Two similar lines are present deeper inside the gun at the end of the shelf where the mini battery would rest, these must also be removed. This is time consuming, but can be done by slowly scraping them away with the end of a chisel as the housing is all made from ABS.

3. There is a piece of black plastic with a screw on each side holding the motor and gear box inside the gun, this needs to be cut down to leave the space underneath the motor accessible for the battery. Remove the plastic and cut it so that only the bar across the back of the motor (directly below the mini battery shelf) remains and then re-attach.

4. The fuse for the motor is in the way, it either needs to be removed, or re-located. One option is to simply remove the fuse and solder the two wires together, however this leaves the motor vunerable should there be a problem with the battery, and could lead to damage to the gun. Another option is to remove the casing from the fuse, wrap it in some thinner insulator (like electrical tape), and slide it down the side of the motor where it will not get in the way. Fuses are pretty rarely blown, so it's unlikely to need to be accessed much.

That's it, the J-battery will now fit inside the P90, you'll probably need to re-shuffle the wires a bit in order to get it in properly thought. It's also advisable to fit some sort of handle (such as a strip of gaffer tape wrapped round the battery and formed into a tab at the back) to the battery as removing a J-battery that's been jammed in firmly can be difficult with nothing to hold onto.

Cons

As with most airsoft modifications there are some drawbacks to offset the gain in rof and battery capacity.

The most obvious drawback is that as with any modification to improve the rof of a gun, it will decrease the lifetime of the gun. It is unlikely to be a very significant decrease, but it will have an effect.

J-batteries are an irregular shape, and so are more prone to physical damage than other batteries, it is quite possible to short parts of a damaged J-battery, resulting in anything from slightly burnt fingers to a broken battery or even a broken gun. Thus it is advisable to be more careful with J-batteries than with standard ones, and if the battery shows signs of physical damage, to get it fixed. Also their shape is not particularly conducive to carrying around spares during the game, however since standard mini-batteries will still fit in the gun these can be carried around instead, this still requires you to be able to carry the spent battery somehow.