P90 Enhanced Battery How-To

 

Welcome to the P90 battery DIY How-To, hope you have some tools ready.
For this you'll need the following:

  • Dremel
  • Soldering iron
  • Shrinking tube
  • Hot air blower (a cigarette lighter will suffice, but be careful not to burn anything)
  • Insulating tape
  • AA-sized cells with soldering lugs

Please note, that the cells used in this How-To are Panasonic HHR-210 AA, their spec sheet can be found here. The spec sheet doesn't mention any high-flowing applications of these cells, but they keep the rate of fire of the P90 / EG1000 with a gearbox upgraded way beyond forum limits very high even without highspeed gears, trust me on that one...

You will also need to make a little space by either using insulating tape instead of the plastic housing of the fuse or get rid of the fuse as a whole. I tried both solutions and they seem to work fine. If you have the choice, I recommend keeping the fuse for security purpuses. It's much cheaper to replace a fuse than to replace a motor.

We will start by modifying the gun's stock cover, by sanding down the grid on the inner side with the dremel. Please use safety goggles while using a dremel on soft plastic parts, they have a habit of flying off while they're still hot and last thing you want is a hot sharp piece of plastic flying into your eye. Here the mesh goggle nightmares could come true, so use transparent glasses ;)


 

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Before modification

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After modification

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Both versions compared

Next, you will have to make sure, that an AA-sized cell based battery will fit into the gun's body. Normally it would be slightly too long, even with the rear sanded down, so you'll have to make more space inside by getting rid of the horizontal piece of the guns body on the inside. The change happens at the end of the tunnel ;) I used a dremel with a flexible shaft and a very slim grip. Other possibilities include splitting the gun's body in half (which you'd need to do anyway if you want to put a Laserex realsteel laser inside). You'll also need to cut down the plastic piece that holds the gearbox in place. Make it so that there is enough space for the battery between the motor and the gearbox's upper section (the part with spring, piston etc in it). Do it according to the pictures and you're on the right track.
 

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Before modification
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After modification

Now it's time to get the battery done. Grab some solder, your trusty soldering iron and a hot air blower (as already mentioned, a cigarette lighter will suffice, but if you want to be serious about stuff, get a blower).

Please keep one rule in mind: never apply heat to the soldering lugs for longer periods of time than necessary, it would heat up the cells and probably damage them permanently. If you don't get one point right, take the cells apart, let them cool down and try again to fit them together. The cooldown periods are always crucial.
 

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Now it's time to solder the first cells together. Always look at minus and plus, as you don't want do put two positive ends together. The left picture shows, how the first cells should be put together. It really helps to put solder on each of the lugs before putting them together.As seen in the picture, it's also nice to have some 3M tape to hold the cells in place while soldering. I used transparent tape for illustration purposes, but you get the idea. When you're done fitting the first pair, tape the next two cells together and solder them to the other end of the first pair. Note the orientation of the second pair's cells, the lugs should be bent away from the cells, so that you can get a fine fit when it comes to soldering the first bend of the battery.
After soldering, grab the shrinking tube and cut a piece from it. Size should be the same as the first four cells. Put it over the cells (be careful not to bend or even tear a lug off a cell, it will be impossible to get them back on the cell as they are welded on in the facory. Welding it back on would mean to take the cell apart, which is no option, so try to get it right the first time). After putting the tube over, it's time to heat it up so it shrinks to fit the cells' size and it will add much stability, so that you won't have to worry about the soldering points being stressed too much during a skirmish. Take a break half way through if the tube doesn't shrink fast enough so you don't heat up the cells more than necessary. By the time you can see the cells' outlines through the tube, you're done. Be sure to cut off excess tubing on the right hand side (assuming your battery lies in front of you as to be seen in the pictures), 'cause the battery will be a very tight fit, so you can't afford to waste space for something that doesn't serve a purpose...
 

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On the side where the lugs come out of the tubing, the next two cells are soldered onto the battery. Rotate them so, that the soldering lugs align over each other completely. Like done before, put solder on each of the lugs, then press them together and heat them up so the liquid solder comes together. If you don't get it right the first time, remember to take the cells apart again for another try. Avoid heating for long periods of time at all costs. After you have put the cells at the rectangular joint together, flip up their soldering lugs and put another piece of tube with the correct length over them. Shrinking and then forward to the finish lane :)
Use insulating tape to cover the open contacts. I kind of framed the battery with the tape for added stability. Any mechanical stress should be absorbed by the battery assembly and not the soldering joints as they tend to break over time if they are stressed too much.
 

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So, you need to attach the last pair of cells to the battery, this doesn't need further explanation, as it's almost the same as done before. Take a look at the layout below to figure out what's the main difference between the joint to be soldered now and the one already done. The last remaining pair of cells sits on top of the assembly, not on front of it. Be sure to do it the right way, or the battery won't fit in the gun. Now it's time so solder a connector onto the cells. If you use an already assembled connector (as I did), be sure to check the connectors polarity by connecting it to the gearbox for comparison. Note that the red wire on the connector comes together with the black one on the gearbox and vice versa. This has to be kept in mind for the final attachment of the connector to the battery. I ended up having to attach the connector's red wire to the minus side of the cell. But I'd rather have confusing wire colors than a broken gun... Of course this only applies if you get a complete connector at the shop, if you do your own, you can also do the wiring with the colors done right.

When you're done with the wires, put some tube over the last two sells, shrink it and once again cover open connections with insulating tape.

 

Important note: The pictures show how some red wires are connected to black ones. Please be sure to check polarity before soldering the connector to the battery and check again when connecting the battery to the gun. It was done "wrong" on purpose in the pictures, the connector which was used had the wires attached the wrong way!! When attaching my factory prewired connector to the one on my gun, the plug didn't fit the other way round, so i decided to solder the red wire of the battery connector to the negative end of the battery, so all ended up fine during my attempt. Be sure not to connect a battery the wrong way to a gearbox as the motor will turn into the other direction, which can lead to a completely destroyed gearbox!!!
 

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Congratulations, you are done! Now plug that battery to your charger, load it up fully and enjoy. Please note, that the cells don't show their full potential at their first loading cycle. With proper care and maintenance, they will last ages and their performance will slightly increase. When loading them first, I could get 2067mAh into the battery, three cycles later I was up to 2178mAh. I'm pretty confident that the 2200mAh barrier will fall soon. :)

Big kudos and thanks go out to R22Master for proofreading and helping me with creative input during the writing of this. Cheers mate :)