PCB Soldering advice

[JHZR2]

Hello,

Building on my thread here:
https://bobistheoilguy.com/forums/posts/1764843/

I need advice on soldering PCB boards and/or how to disconnect the batteries that are already on it. Please note the batteries here:

With soldering on the back of the board looking like this:

How do I disconnect the batteries, and/or desolder the leads, and then get a good wire to the PCB to remote-mount my new batteries?

I kind of would like to just get the batteries off of their solder tabs, so that I can easily attach/solder wires to them. Otherwise, how do I best ensure a good, permanent connection?

I assume Ill need a solder wick of some sort, but how much heat do I want to apply? I assume I apply to the solder tab lead, on the backside, and then wick solder as it melts, right? When the battery releases, do I keep heating the remaining solder until I get all the old stuff?

What kind/spec do I get for new solder? I have some generic electrical solder that came with an old 12v iron I bought at a truckstop, but since then Ive gotten a much better soldering stand.

Also, Ill be connecting to these remote battery holders:

They will be mounted remotely so the batteries are easier to access. Any suggestions of how to solder the wires to these things? How about what to mount them into?

Thanks!

 

[brianl703]

I'd use a small screwdriver to break the solder tabs off the battery. It shouldn't take much. Then solder to the solder tabs sticking out of the board. You don't need much heat; a 25W iron is plenty.

If you must use solder wick because the tabs won't break off the battery, use a very small piece (like 3/8" long) and hold it with a pair of hemostats. Put the solder wick on the joint and then put the soldering iron on top of that. Make sure the iron is at full temperature before you do this.

For solder, 60/40 rosin core electronic solder is fine. Do not use plumbing solder. Any solder that Radio Shack sells will work fine.

 

[JHZR2]

So I guess Ill apply heat to the exact dots where there are solder points on the battery, and then pry? The screwdriver will act as a heatsync, but if I apply some heat for a bit, I assume it will get soft. Make sense?

How do I best attach the new wires to those tabs, if I can keep them on there?

If I do have to remove the batteries with tabs complete, what should I put in their place to make a good connection? Just feed the wire through the hole and then solder in?

Thanks!

 

[brianl703]

Those aren't solder points--the tab is welded to the battery. You will have to break it off. It should break without much force.

Just wrap the wire around the tab and then solder. You could bend the tab over the wire first--it looks like it's big enough for that.

If you do have to remove the battery, just feed the wire through and solder in. Hint: 24AWG solid wire (telephone/CAT5 wire) works best for this, because it's thin. You can then splice the solid wire to whatever other wire you intend to use to connect to the battery holder.

 

[JHZR2]

All the battery does is keep memory from being lost. It does not even to my knowledge light the service LEDs.

So I'd imagine that for a 2' run, some telephone wire would work well enough - im not moving much current... And it would be the easiest to run, as Id just have one wire for two batteries.

Thanks for the idea!

 

[Win]

The batteries are spot welded to the solder tabs - most of the ones I have used will not break free, but yours might break clean, it's worth a try.

If you have to desolder from the pads on the back of the PCB, I use and prefer a vacuum solder remover. Solder wick was OK for a lot of the older point to point stuff, but it is real easy to lift a pad on the newer pcb's with solder wick.

Radio Shack used to sell (maybe still does) a vacuum solder sucker about the size of a pen for about $10. It works very well.

 

[Win]

Originally Posted By: brianl703
just feed the wire through and solder in. Hint: 24AWG solid wire (telephone/CAT5 wire) works best for this, because it's thin.


The easy way to thread stranded wire through a PCB pad is to simply put a small dot of solder on the end of the wire to hold the strands together.

 

[brianl703]

Originally Posted By: Win

If you have to desolder from the pads on the back of the PCB, I use and prefer a vacuum solder remover. Solder wick was OK for a lot of the older point to point stuff, but it is real easy to lift a pad on the newer pcb's with solder wick.


Never had much luck with the vacuum solder bulb, solder wick always worked well for me, even on newer boards (that is actually all I have ever used it on). The key is to use a very small piece of it. It's copper,and conducts heat very well. What definitely does not work is to try to use the solder wick without cutting a piece from the roll. Then the entire roll of solder wick is sucking away the heat you need to melt the joint.

 

[GeaugaFletcher]

The Radio Shack solder sucker works well for me, solder wick not nearly so much... YMMV!

 

[JHZR2]

Originally Posted By: brianl703

If you do have to remove the battery, just feed the wire through and solder in. Hint: 24AWG solid wire (telephone/CAT5 wire) works best for this, because it's thin. You can then splice the solid wire to whatever other wire you intend to use to connect to the battery holder.


The application really just uses the battery to provide a voltage to maintain the memory on the service indicator board. That is really low current, Im sure. At most, it might be used to light an LED, again, low current.

That said, the telephone wire is a great idea to run the remote battery connection. However, any telephone wire I have is stranded, and most seem to be 26 AWG. I could tin the stranded, and what is really nice is that then I have four small wires in one exterior jacket - perfect for two parallel batteries.

Would stranded 26AWG telephone wire be OK? If not, where do I get the solid 24 AWG? Does HD sell it by the foot?

Thanks!