Battery desoldering itself

[Hot Rodney]

I am running an Arrianne with a 1527 Neu and a Swordfish 300a pro esc. with a 6s batt. The boat runs well except that the positive terminal on the battery will desolder itself.
It is not due to a colder solder! The wire and the cup are very close in diameter (not enough room for filler wire - see photo).

Any ideas on how to prevent this from happening?

[Mike snell]

I was having the same problem are you using silver Sauter because once I switched to that it solve the problem

[jingalls007]

Use a torch to heat the bullet, melt solder (silver, non-leaded, 400+ degree melt temp), then insert your tinned terminal in the cup. Heat the bullet with your torch while inserting your tinned lead so they ‘marry’ and properly
Bond.

[Hot Rodney]

I will have to try using silver solder and try using the torch method. I'll let ya'll know how that works!

[donhuff]

Hot Rod,

You can use the "lead free" type if your afraid of lead, but the higher temp solders are actually mostly lead. Lead free solder is mostly Tin, and it has a lower melting point than pure lead does. Lead- 621.5F vs Tin 450F

This is what I use now and I have not had a de-soldering problem, since I switched to using it. It has 1.5% silver for strength, and 1% tin to help it flow, but it really does not flow well at all. You wont get good joints unless you "tin" first, and "lead free" solder works good for this. I get good results by "tinning" both parts with regular solder first, and while still molten, throw, shake, that solder off. That will leave a thin film of the soft stuff, and the hard solder will stick, and flow out a lot better.

https://www.mcmaster.com/solder/high-melting-point-solder-for-electronics-and-electrical-applications-10/

You will have too use a small torch to melt it, harbor freight or home depot both have cheap butane torches for sale that work perfectly for this. Works good for shrinking heat shrink to!

[Fluid]

I have used ~60/40 rosin core solders and an 80 watt iron on my boats for several decades, and I cannot remember the last time I had a solder joint come apart under normal conditions - including setting many SAW records with high-amp boats (burned-up controllers don?t count). The boaters in my clubs have used normal solder without issues - as long as the solder job was good and the boat setup was reasonable. If the OP is having his solder melt then his problem is likely not the solder type or the lack of a torch. The fuzzy photo doesn?t help much, other than showing that the temperature of the wire was hot.

Poor soldering jobs are common with newer boaters especially, and I?m not convinced that it was not a cold solder joint. But if we assume it was a good solder job then the issue is too much heat in the wire. Either too high of an amp draw (most likely) or too much resistance in the wire/connector. The OP is running a Neu 1527, but what Kv? What prop? How long does he run? Has he logged his amp draw? He should examine these potential heating causes before he just throws money at fancy solder and a torch - the vast majority of FE boaters don?t use them. Consider the solder a fuse, warning you that your setup is too extreme.






.

[Hot Rodney]

There are a lot of good suggestions here. I will try the silver solder and the torch (which I already have).

Fluid also has some good points. I have not logged my amp draw because Hiei software does not work on a Mac. I know I am running the boat on the edge, but if I can get one more lap, I would be thrilled, so the silver solder may get me there. Is my setup too extreme - probably, but it is very competitive in a race where everyone is running setups that are "too extreme".

Was it a cold solder, I doubt it. I also use an 80 watt iron and solder from the wire to the connector, not the other way around.

I appreciate everyone's input.

[RaceMechaniX]

Rodney,

I agree with Don and Jay on the type of solder to use. Silver solder is mostly for mechanical joints like soldering flex cable. I also use 60/40 electronics solder on all my boats. I do use a liquid rosin and pre-in the wire ends in a solder pot before soldering to a plug. When soldering to a plug, I heat the brass plug with the soldering iron, not the wire. When solder melts and flows nicely into the socket I then move the wire into position letting it warm up against the cup. When the solder in the wire starts to melt I fully seat the wire into the cup adding a little more solder. I will let the iron sit on the plug for enough time till the connection reflows and is fully wetted. On large 8mm plugs I believe an 80W iron is marginal. I use a 200W chisel tip iron which quickly transfers the heat. The issue with an under sized iron is the heat will flow quickly out the wire and/or the connector depending on what is supporting it.

Second point: It may not be the solder joint that is causing the problem. It can be the connector to connector resistance. If you have a weak mechanical connection between the male and female plugs, it will self heat when high current passes through. So the connector heats up and reflows the solder leading to the wire slipping out. If this is happening you need to improve the connection by increasing the spring force on the fingers, lighting sanding any oxidations off the contact surfaces or replacing the plugs all together with better ones. Bigger does not always mean more current. I have seen plenty of 8mm connectors with poor fits or thin walls.

-Tyler