How to desolder the battery holder from the circuit board?

I’m working on a new back case for my uConsole that adds additional 18650 cells. To do this I want to desolder the battery shield from the circuit board and connect my own battery case. I haven’t been able to get the current solder to melt at all, it stays fully domed, with none getting picked up by my copper desoldering wick. I even added some no-cleanup flux thinking that was my problem, but it made no difference. I’ve tried my soldering iron from 200-357C, or 392-675F. I confess I’m a total amateur, so it might be something easy I’m missing.

When desoldering such large joints I found higher temp is the way to go. For large joints, especially if they’re connected to a large ground plane (which acts as a heatsink) I use 450C.
The type of soldering iron and tip size matters a lot as well. You want a big thick tip which has a lot of thermal mass to keep driving the heat into the joint; don’t use thin tips as they cannot conduct the heat fast enough. A proper soldering station is also beneficial, as some solder pens like the TS100 or TS80 might not be able to keep up with the heat dissipation in the joint.

Hope this helps

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you might try melting some lower temp solder onto those and use the heat transfer from that to help you melt the existing solder. I have seen that done when people are repairing electronic devices.

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Thanks, I’ve been dragging my feet figuring out workholding, guess I need to get it done. I’ll try that temperature and make sure I’m maximizing contact surface with my iron tip.

Braided desoldering wick is going to help get the bulk of the solder off. Once you get those blobs off it should start to get a little easier to heat up with your iron. Use a higher temp than you would with soldering.

I’ve used a heat gun before (like a hair dryer on steroids). The higher setting can scorch circuit boards and ruin plastic, so it’s a bit risk, but very fast. Wrapping the plastic with some foil is enough to keep the heat off it. I ruined a board covered in 16P IDC connectors (for eurorack power) trying to go a little too fast with the high heat trying to remove a LOT of high pin count stuff at once.

A bigger soldering iron, like for plumbing and jewelry-making, can also work with large terminals. Again you run the risk of burning the boards. But great if you want to go fast on big parts like battery terminals, banana plugs, and other heavy-duty connections.

If you mess something up, you get to learn a new skill. How to fix it. Which is perhaps more important than learning how to do it right the first time, but super stressful.

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Put some flux on it and really tin the tip / “drop” of lead.

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Flux is good for getting solder to stick to things and to keep it clean. I don’t think it helps that much with removing solder, except maybe if you have a dirty tip and the solder is not wetting onto the tip properly.

You can buy tip tinner which is just flux and tin in a paste to keep your soldering tip clean. Or you can scrub the tip while cold with a polishing bar then flood it with solder as soon as you heat it up.