Crimps properly made are as good if not better than soldered joints - hence their use in critical applications. To get a good crimped joint though, you need to make sure you have the right crimp tool for the job.
For spades and things, stick to the Red, BLue and Yellow tpye crimps with a suitable tool - ratchet is best, but I get good results with a plier type crimper - the trick is to crimp until the handles are in the fully closed position. Other sorts of crimps - forget it without the right tool, which can cost a significant wedge (Last one I bought was £150.00)
However, if the wires are pulling out ofthe crimps - couple of reasons:
1/. The crimp was not made properly - use the right tool and the right pressure
2/. You were trying to remove the connector by pulling on the cable - don't do it, whether the joint is crimped or soldered. It is actually better that you use a crimp if you are going to pull on the cable, because the failure mode is when you pull it. With a soldered joint you can get a degradation of the joint through stres that will bite you on the bum at the worst possible time.
A spade is designed as an anti-vibration connection - the hole in the spade itself mates with a pip onthe crimp part - this is designed to stop the male and female parts walking apart. You have to overcome the significant holding force to separate the connection. If you need to do it use pliers on the shoulder of the spade.
Remember though that spades are not designed to be separated repeatedly. I would be surprised if the rated life was much more than 5 or 10 disconnections. If you need a charging connection, it is best to provide a suitable connector so the spades can remain undisturbed. I use a 1/4" mono jack for charging the SLAs, which are mounted in the boat permanantly.. IAt the moment, they are set up so the jack socket is wired striaght across the battery (tip positive) so you have to turn off the power to the rest of the boat before charging. Considering using a DPDT switch for the next one so it is pit into charge mode when the power is off
Wom