My new battery fried.

[Devildog]

Once again I bring before you my new CA M4 CQB Seal. I just bought a new battery for it (9.6v Crane stock with three sets of cells). The installation of the battery described in the manual is that the two side cells go inside the side tubes of the crane stock and the third cell goes inside the buffer tube. I then have to pull the mechbox wire through the buffer tube, past the center cell which is closely touching it, and into the back of the stock where the plugs are connected. Having put a full charge on the battery I fired about 40 shots before the battery died and the gearbox would not cycle. Upon smelling melting plastic and wiring I quickly removed the smoking battery from the stock and buffer tube. The third cell inside the buffer tube had fried all its contacts as well as melting through the mechbox wire that was touching it. I assumed it shorted out because the wire and cell were too close together. But what I don't understand is why it would do that even though that's how the manual states the battery be installed. The battery also just happens to be cheapy that I got from Ebay. I most certainly will buy a better quality battery now, but I don't know if this one will also short out. Is this a result of the gun or a cheap battery? Will things work better if I get a battery that does not require a cell inside the buffer tube?

[Knief]

That should not be the result of a wire being close to a battery. As long as the wire has proper insulation, you shouldn't have anything to worry about. It's more than likely a result of the crappy battery you bought on Ebay. The other possibility is that you pinched a wire somewhere while running the wires to the rear of the gun and created a short. In the first case, you just need a better battery*. In the second, you'll want to run through all of the wiring in the gun and make sure it's not split, pinched or fraying anywhere. But that's ok because you'll pretty much have to rewire the gun anyway since you melted through the harness in the buffer tube. If you've got a short, you'll do the same thing to any battery you put in the gun.

*The price difference between a good battery and a bad battery is rarely significant if you know where to shop. Pick up a quality battery from www.cheapbatterypacks.com and enjoy it for years.

[Devildog]

The wire that melted was the inside the buffer tube. Could it have affected the wiring in the rest of the gun? Could this wire be fixed by simply splicing the wires and taping/reinsulating them?

[Knief]

If the wire that melted is the only wire that has a problem, then no, it shouldn't have affected anything in the rest of the gun. However, if you have a short somewhere else in the gun, the battery burning and melting the wire is just symptomatic of the larger problem. You'll want to inspect the wire throughout the entire gun before you play with it again. A short anywhere can cause battery problems.

As for fixing the damaged wires (if the rest of the wiring is fine, pending your inspection), I'd replace everything between what was damaged and the last set of connectors. I don't know how CA wires their guns, but on many guns, the wires that go to the battery don't run straight to the gearbox or motor. Instead, there is a connector somewhere in between. If you replace that whole section of wiring, you won't have to worry about your own job being too bulky to run along your battery in the buffer tube, or maybe having a bare spot and shorting out again, or anything like that. Replace the whole section and you'll be much better off in the long run. Shoddy electrical work can make any gun a pain in the ass in short order.

[Andrew]

Yes Knief is correct, CA style wires do have a connection between the gearbox and the battery, but to be honest anyone with a soldering iron and 16-18 g wire can make a repair. Just cut out the piece that was bend or damaged; then solder and heat shrink in new wire.

[Fugazi]

I would play it safe and buy a new wiring kit. Like a SystemA low resistance or something. Make sure your motor tabs are nicely connected to your wires, because that could cause a lot of resistance. Heat means resistance, so obviously there was resistance somewhere. Rather than take a risk and possibly destroying a new battery, just rewire the whole thing.

[Alucard]

I would add a recommendation of buying a resettable poly-fuse. Or something of the sort.

[Raptor]

Yep I fried one of my batteries once. The short I had resulted from the pinion gear on my motor sawing through my wires because I didn't put them back into my gearbox correctly.