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Drilling and tapping LiFePO4 battery terminal practicality? (programming.dev)
submitted 1 week ago by sobchak@programming.dev to c/askelectronics@discuss.tchncs.de
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I'm wondering how practical it would be to drill and tap terminals to add posts to batteries like this: https://batteryhookup.com/products/2x-sunwoda-lf314-314ah-lfp-prismatic-cells-grade-a-qualified-rohs-certified-ultra-long-life-10-000-cycles

The description says that you can only drill 5mm at most. Anybody do something like this before? I do have a shitty Harbor Freight drill press and couple hand tap wrenches.

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[-] NaibofTabr@infosec.pub 5 points 1 week ago

You can get handheld spot welders intended specifically for battery terminals for US$30-50. Spot welding is a lot less likely to damage the cell or risk puncturing it. Here's an example:

https://ebay.us/m/adsJwa

[-] sobchak@programming.dev 3 points 1 week ago

I don't think those would work for these large batteries. I have one that I use for small cells though (i.e. 18650/21700).

[-] NaibofTabr@infosec.pub 1 points 1 week ago

OK, I'm no expert but it says this at the end of that product listing:

Secure this matched 2-pack of premium Sunwoda 314Ah cells—fresh stock from a respected brand, with flat studs for easy welding/integration.

Are you saying they need a heavier gauge bus bar for the current, something too thick for a small spot welder? Would you MIG/TIG weld a battery contact?

[-] sobchak@programming.dev 4 points 1 week ago* (last edited 1 week ago)

Yeah, these are 0.5C cells, meaning they can safely discharge 157A (I would be using them for offgrid solar), so those little nickle strips would melt. I think TiG welding these would be extremely dangerous and produce too much heat (and I've never TiG welded before; just badly MiG welded a couple times). By "welding" in the description they mean commercial laser welders.

this post was submitted on 02 May 2026
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