Thread: Batteries for emergency welding

welding requires large amps, starting batteries are designed to supply them (for short amounts of time though). Depending on the type of AGM they might pull it off, deep cycle is not meant for that. Gel batteries are certainly not designed for it and lithium is outright dangerous but most if not all of them have a BMS that will simply shut down on short circuit.

-P

Hi Keith and as -P replied, Starting Batteries are the way to go and as long as you are not welding for hours at a time, they will be perfect.

Remember, they are used for winching and that requires much higher currents than welding is likely to draw.

Thanks for the replies.
Thought that might be the case but have not kept up on battery advances.
I have an Autoarc that I installed in my 2b camper and only had to use it once when my late wife and I travelled the French Line 30 years ago. Cracked a spring hanger and it welded up OK. Transferred it to the 6x6 camper when I built it and never used it. Transferred back to the 2B now I am using it again and thought I had better see if it still works. It doesnt so I pulled it out again and will carry its leads and rods etc and just rely on using the start batteries if the need arises.
My start batteries were dated 2019, still worked well but I decided to replace them anyway. I travel solo so want to be prepared for this years desert trip if it ever dries out. I have the old batteries on charge now so will use them for a practise run to see what sort of a bead they will run.
I guess the Autoarc is binned unless I can find a sparky that can fix it.
Keith

Mind you if emergency welding is required than you will use whatever is available but normal starting batteries are preferable.
We've used AGM's only and a mixture of AGM and starting batteries to achieve the end result. As long as you aren't trying to weld up a battleship then most welding jobs take bugger all out of the batteries.
Don't forget to reverse the polarity positive to the ground and negative to the electrode, 36v (three batteries) is smoother and easier to start the arc than 24v (two batteries) but you need some means of controlling the current, typically a short (300mm) length of multi strand automotive wire with insulation removed will do the trick, just make sure it's nowhere near any flammable items as it will glow red over it's length during welding. You remove strands of the short length to adjust the current.
If the batteries are nearby place an old hessian sack or canvas over them to prevent explosions from escaping gas, best to weld outside in the fresh air and take the phone out of your pocket when welding as the hot red bits will burn into it as well.

Thanks for that.
I had a go this morning using some rods I had here. It does not weld as nicely as the Autoarc did , but I finally got a reasonable weld. I did not know about the reverse polarity trick or the resistance wire gadget. Might try again later.
The yellow container is Gemini 316L for stainless. 2mm rod for 30 to 50 amp. No good at all. Just got red hot and smoked . Maybe the resistance thing would help.
The other container has Weldall for hard to weld steel.2.5mm for 70 amps. After a bit of coaxing is laid down a reasonable bead. I can live with that.
The first goes I used the Autoarc leads which are quite long, but was having difficulty so swapped them out for leads from another portable engine driven welder. Quite short. Earth about 1 meter and electrode 2 metres. They worked the best.

IMG_2836 by Keith Cree, on Flickr

IMG_2835 by Keith Cree, on Flickr

Keith

Originally Posted by oka374

Mind you if emergency welding is required than you will use whatever is available but normal starting batteries are preferable.
We've used AGM's only and a mixture of AGM and starting batteries to achieve the end result. As long as you aren't trying to weld up a battleship then most welding jobs take bugger all out of the batteries.
Don't forget to reverse the polarity positive to the ground and negative to the electrode, 36v (three batteries) is smoother and easier to start the arc than 24v (two batteries) but you need some means of controlling the current, typically a short (300mm) length of multi strand automotive wire with insulation removed will do the trick, just make sure it's nowhere near any flammable items as it will glow red over it's length during welding. You remove strands of the short length to adjust the current.
If the batteries are nearby place an old hessian sack or canvas over them to prevent explosions from escaping gas, best to weld outside in the fresh air and take the phone out of your pocket when welding as the hot red bits will burn into it as well.

This current controller, do you only need it with 36 volts or with 24 as well?
Keith