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31st Jul 2018, 3:04 pm | #21 |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,130
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Re: Battery tag spot welder.
I presume that that the reference was to single core flexible cable with a cross sectional area of ten square millimetres.
The "tri rated" bit means that it conforms to the national standards for 3 different countries, Canada, the USA and the UK. (and is indirectly accepted for use in many other nations that accept one of those three standards) Primarily intended to simplify the production of equipment for export, but has become the de facto choice for many applications that need a good quality single core flexible. Pretty the same thing as panel wire, apart from the international approvals, and available in larger sizes, up to at least 50mm. |
1st Aug 2018, 2:16 pm | #22 | |
Octode
Join Date: Nov 2010
Location: Cullompton, Devon, UK.
Posts: 1,435
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Re: Battery tag spot welder.
Quote:
John |
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1st Aug 2018, 3:22 pm | #23 |
Pentode
Join Date: Jul 2008
Location: Nottingham, UK.
Posts: 151
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Re: Battery tag spot welder.
Nice project. I've been planning on building one myself for the same application (welding battery terminals) for a while now and got as far as sourcing and modifying the transformer. Like you I removed the secondary with a hacksaw and hammer. I also removed the shunts, and re-wound with two turns of 10mm2 copper. Your project is encouraging me to get on with finishing my own version.
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1st Aug 2018, 4:47 pm | #24 |
Octode
Join Date: Nov 2010
Location: Cullompton, Devon, UK.
Posts: 1,435
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Re: Battery tag spot welder.
I would double up the 10mm2 and then run the windings in parallel this will give more current, if you trigger it with sold state relay and use a timer it will give a good account of it self.
John |
1st Aug 2018, 4:58 pm | #25 |
Pentode
Join Date: Jul 2008
Location: Nottingham, UK.
Posts: 151
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Re: Battery tag spot welder.
Cheers - that's useful to know. Admittedly I was just guessing when I rigged it up.
Is a solid-state relay essential? I have a couple of large 10A mechanical relays in my parts box... |
1st Aug 2018, 7:18 pm | #26 |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,130
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Re: Battery tag spot welder.
A heavy duty mechanical relay should be fine if generously sized, but may not give such accurate time control, as neither the pull in nor the release times are accurately known/repeatable.
To guard against the relay contacts welding or sticking I would prefer to use two relays with the power circuit contacts in series. Preferably with some form of monitoring to warn of stuck or welded contacts on either relay. |
1st Aug 2018, 11:36 pm | #27 | |
Octode
Join Date: Nov 2010
Location: Cullompton, Devon, UK.
Posts: 1,435
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Re: Battery tag spot welder.
Quote:
john Last edited by jonnybear; 1st Aug 2018 at 11:56 pm. |
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2nd Aug 2018, 10:09 pm | #28 |
Heptode
Join Date: Feb 2011
Location: Washington DC, USA
Posts: 619
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Re: Battery tag spot welder.
I am still waiting for my timer from China, but in the meantime here are some pix of my transformer.
I cut off the HV windings with a hacksaw and pushed out the remaining copper with a cold chisel, and also removed the two magnetic shunts. This gave me lots of room to wind on a couple of turns of welding cable, which is very flexible. As you can see I did not have to touch the lams.
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David |
3rd Aug 2018, 10:46 pm | #29 |
Octode
Join Date: Nov 2010
Location: Cullompton, Devon, UK.
Posts: 1,435
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Re: Battery tag spot welder.
I think you should be on a winner there once you have the timer, I would also use a solid state relay, see thread #27 for reasons.
John |
5th Aug 2018, 6:56 am | #30 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,670
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Re: Battery tag spot welder.
One of these in kit form came up on the EEVblog tother day see - https://www.youtube.com/watch?v=e4lIkonz7Rw @ 45:10 The kit used a whizz bang battery.
In the past I've soldered battery tags with a very hot iron, ok if you keep the dwell time to a minimum. Andy.
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Curiosity hasn't killed this cat...so far. |
6th Aug 2018, 3:14 pm | #31 | |
Pentode
Join Date: Jul 2008
Location: Nottingham, UK.
Posts: 151
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Re: Battery tag spot welder.
Quote:
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7th Aug 2018, 6:47 am | #32 |
Heptode
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 664
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Re: Battery tag spot welder.
This is a great DIY project. A great job!
I repaired MWO's for about 20 years. The transformers are great for projects like this. Of note: Some put the primary on the outside and the secondary on the inside of the windings. Makes it a pain , and best to find another tx. If you manage to find an original, old commercial Raytheon MWO transformer- its worth its weight in gold. they are huge and put out mass current. (Also make a great PS transformer for a hi power CW rig.). If you get one that has welded laminations, a grinder is the way to go. Sometimes I'd luck out and get ones with just bolted laminations. The cats pajamas to disassemble! The newest ones use an SMPS and are good for little but a few parts. Just heft the oven to tell if its got real iron in it or not. I might consider using a car starter solenoid or relay, since I have a box of them, but a solid state one is likely the best way to go, as you did. |