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Old 12th Jul 2018, 9:04 am   #14
jonnybear
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Join Date: Nov 2010
Location: Cullompton, Devon, UK.
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Default Re: Battery tag spot welder.

Quote:
Originally Posted by MrElectronicman View Post
I built a spot welder to use on battery tags using an old microwave transformer.
I removed the high voltage winding and using 5 mm welding cable wound 2 turns on the transformer, the O/C voltage was 2.6 VAC. The current running though a 3 mm bolt for a short circuit, measured more than 1000 amps on my clamp-on-Ammeter, perhaps not surprising as the Microwave was rated at 1200 Watts. Needless to say the bolt only lasted a few seconds as it became white hot and melted.

Since the experiment appeared to be much too aggressive for a simple spot welder, I abandoned it for the time being, but I have some 2.5 mm welding cable I might try one day
Hi David
I think your transformer with the 5mm welding cable will be fine for spot welding the secret is the short duration of the weld, using a momentary switch and a timer would sort it out, split seconds required not seconds.
John
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