just got a new lipo battery pack with no ends im putting them in a mini pulse xt and they require the ec3 blue connector ends should i solder or crimp hopefully crimping will work but if need be i can get it soldered but i havnt done much soldering also do most lipo battery packs come charged?

Soldering will give you a far better electrical connection than crimping, as it assures that ALL wire strands are attached to the connector.
All Lipos have a minimum charge of 3.0 V per cell, but they usually arrive with 3.7 V per cell. They are not fully charged, but only "surface" charged when shipped.
Wrap the unused wire end until you are ready to solder it, and only deal with one wire lead at a time. Shorting out a Lipo can be quickly disastrous! (<3 seconds!)

I agree, solder is best.
Lipos don't loose charge when in storage and each manufactuer is different.
I had a couple of packs that where actually slightly overcharged (above 4.2 volts per cell) when I got them.
PS: never run a lipo pack empty, it can ruin the pack. Good rule of thumb is never let the pack go below 3.0 volts per cell and if your charger does not balance the cells invest in a cell balancer (an Astro Blinky is only about $25 and will help keep your lipos healthy)

Many tests by the military and space industry has proven that the crimp is more reliable and better than a soldered connection. However, that is a good crimp done with the proper tooling. A poor crimp like one done with a pliers may be quite unreliable so; unless you have the skill and tools, you are probably better off soldering the connection. And, yes, LiPos come with about a 50% charge, if they fall below 3.9 volts per cell, they may be damaged to the point where they are not salvagable. The fact that they have quite a bit of stored energy should warn you to be very careful on attaching the connectors. Be very careful to not let the cells short out as the fireworks can be upsetting to say the least.

Everyone that has replied has said the same thing, and I totally agree. One thing that I must reiterate is shorting out the leads. This can and will cause a fire to the likes you would never imagine. LiPo batteries are dangerous when maltreated and can cause serious problems.

There was (maybe still is) a video of a van that was totally gutted by a fire that was started by a faulty LiPo. Homes have burned down as a result of the uncontrolled fires caused by these batteries.

Just remember that if they are used properly, they are great and perfect for our applications and perfectly safe.

The other problem with soldered connections is the solder itself. The solder "wicks" up the wire a small amount and the point at which it stops is a transition point where the wire changes from stiff to flexible. It's at this point where breakage can occur. Applying heat shrink to the wire beyond this point will prevent failures as well as prevent short circuits.

What he said is right on especially in the high vibration environment of an RC plane. not to mention the corosiveness of glow fuel.
I happen to now a lot about fuel corosion as I got a $140.00 lesson when I accidently sprayed my transmitter with fuel... it is toast!
but now I have a spare TX battery and antenae!!

i would rather crimp what tools do you recomend

I always take mine to work (airline). The crimpers there cost over $250 depending on the size and type. Every type of connector needs its own special crimper legally too.

I do both. The crimping gives a good mechanical connection, and if done correctly, will also give some strain relief (crimp to the insulation. I then fill the crimp with solder, and then cover the connection with shrink wrap. That way I get the electrical benefits of solder with the mechanical benefits of crimping. Best of both worlds.

Brad

I was taught in both avionics electrical school (military) and college classes for electrician (civilian) to allow the solder to wick under the insulation (the insulation helps keep the unsoldered wires from breaking.)
Shrink tubing also helps.
Uninsulated wires in a crimped setup can break just as easily as soldered. It is the exposed wires flexing that cause breakage.