welding with Batteries

After returning from our last tip away to Klumbaru W.A where we had to get some welding done at a great cost and not done particularly well i thought i would make up a battery welder using two of my camp batteries . have been wanting to do this for a while as i have a welding background but didn't get around to it b4 leaving .
1st up i checked out a few vids on youtube aswel some on here by a member .

as you can see in picture outlined there was good penetration from two 100 ah batteries using 2.5 welding rods any amount of power for your average welding job
What was surprising was how little the welding took from the batteries after welding 5 rods the batteries went from around 12.6 to about 12.4 keep in mind these aren't in great condition .If you had something very thick to weld like suspension parts springs etc you could connect a 3rd battery and use 3.2 ~ 303 magna gold or similar welding rods .
Its NOT easy welding , as a welder you find it dosn't flow as normal and need to keep striking , pushing rod to keep it going but although not a good looking weld it is strong
2x 12volt in series = 24 volts 3 x 12 volt in series 36 volts
do your research to see how to hook up batteries up correctly & safely .
There are dangers in involved !!
I tried different connections in regards to negative & positive earth on the steel being welded and didn't find much difference unlike what some people said on youtube .