Any Tips for Soldering Big Terminals?

Electronics
#1

Hey guys,

I’m putting together a lithium battery pack for our little teardrop camper and my first attempt at soldering some 12GA wire to the terminals didn’t go well. Solder flowed fine over the wire but didn’t really adhere to the terminals. I think I’m just not getting them hot enough. I was just using the regular blue iron on the bench, should I be using something else? Any other tips on how you’d get this done?

I don’t really have much experience, I’ve only done much smaller projects: @Dale_Wheat’s LED kit (great class by the way) and some speaker crossovers.

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#2

Did you swap out for the largest tip we have? The Hakko 951 is a fairly high power iron but it’ll still need a large tip to do the job.

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#3

I did not, but that’s a good… TIP. Eh? eh?

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#4

Solder flow is about getting both metals heated evenly. If the terminal takes longer to heat then start with the tip entirely on the terminal. Dab a little solder at the junction of the terminal and iron. Then move the iron so it touches both the terminal and the wire; dabbing a little more solder to keep some flux and help the heat transfer. Keep dabbing the solder at the junction of the iron, terminal, and wire until the solder starts to flow. You will know you got the terminal hot enough if the solder spreads out on both the wire and terminal.

Didn’t get the solder to flow even? Wick the solder off and try again heating the terminal longer. With luck you will not overheat something and melt it.

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#5

The Weller D650 is amazing for soldering bigger stuff. I use one for 10 AWG and 12 AWG for RC stuff. If there’s not one around the space already then it’s worth getting one. It’s roughly five times the wattage of the Hakko units we have. The Hakko units are great for a lot of stuff but they have their limits.

https://www.amazon.com/Weller-D650-Industrial-Soldering-Gun/dp/B000JEGEC0

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#6

You could always take them to a Batteries Plus and get them to spot weld everything together…

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#7

I could help i have the equipment. if you need me to help you please message me privately.

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#8

Thanks for the help guys. It sounds like the path forward is to put a bigger tip on the Hakko irons and give it another go, unless we’ve got one of the big daddy pistol grip ones Luke is suggesting.

Can you spot weld wire? I’ve seen it with those Nickel strips they use for DIY battery packs, but what I’m looking to do is get the wires connected for the BMS and charge/discharge ports. The cells are already connected in the correct configuration.

#9

If it were me, I’d use one of the Metcal irons with a huge tip. Because of the way they are inductively heated you’ll probably have a faster thermal reactivity without the overshoot you’d have on the ceramic heated Hakkos.

Yes, you can, but it would be better to solder it to a strip of nickle and then spot weld that. In any case, if you can directly solder that would be better.

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#10

Apply flux to wire and terminal. On big stuff the flux core in the solder usually isn’t enough. On large gauge stranded wire, apply flux, heat up and solder wicks down into the strands.

Flux is in the small plastic bottles with metal “needle”.

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#11

Wash joints thoroughly when done. Because acid. If the needles have holes in them that’s why. :face_with_monocle:

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#12

ELab has 91% Iso Alky to do clean up. Needles on plastic bottles are stainless - not aware of any problems other than members leaving them on their side creating yet another mess.

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#13

This is sort of lame, but sometimes I use 2 irons…

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#14

How big is the terminal? I would tin the wire. Then heat & fill the socket, With the socket still molten, put the wire in it. Ive also used a torch in the past as well for like 2/0 wire.

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#15

The liquid flux we have up there is magical. Be sure to wet everything with it before soldering. Night and day difference in solder flow.

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#16

Key words i would use to look for in soldering larger components is “thermal mass”. The book Schaums “heat transference” could give you an equation. I tend to look at heat transference like two cups. In my analogy i have my transference cup (solder pen) and the destination cup(soldering component)( and i am using power from the wall which is my source bucket). So i have bucket of water and need to fill my destination cup by using my transference cup. So i have big transference up it is one shot really quick and less like to spill water. (a cup too small will take multiple trips to fill the destination cup). (filling the destination cup means turning the solid state soldering weld into a liquid state metal.) In a similar way a soldering pen with large thermal mass because of a bigger tip will cause less heat to spill and thus usually causes less damage things around like plastic. (This is my understand let the verbal critique begin so that i am not confusing people.)

lukeiamyourfather suggestion of the https://www.amazon.com/Weller-D650-Industrial-Soldering-Gun/dp/B000JEGEC0 . it has a great conversion rate so it does the same as larger thermal mass. kind of like hose rather than a cup. and the tip also has alot more mass. then smaller weller pens. if you looking to solder plumbing or refrigerator pipes then lukeiamyourfather may also work as well. I have only found it hard to find replacement tips for the lukeiamyourfather suggested Weller. i never had to replace the tip on 40 watt pen but it take a long while to heat up. Mine is the cheap a… route. expect to pay for with the time it takes to warm up.

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