Using Automotive Batteries
Another Sunday morning with little else to do but tinker in
"the shed" ;-)
Most DC welders work at around 40 volts, and a general purpose
electrode of 3.25mm will need about 120 amps for good penetration
of weld. 36 volts is available from three automotive batteries
connected in series. The batteries we use in 4WDs are more than
capable of supplying the amperage for an ample amount of time for
a repair weld; after all, they supply winches at up to 400 amps,
and starters on diesels at 300 plus!
There is no danger of electrical shock using automotive
batteries in this manner; however, the batteries should be
disconnected from the vehicle, and protected from welding sparks.
1) In the late seventies, three other Land Cruisers and mine
traversed the Canning Stock Route in Western Australia. In those
days the route was ill defined and there was no support in the way
of fuel dumps, and water supplies were unreliable. We carried
heavy loads of fuel and water (650 litres fuel and 60 litres water
each) and supplies for 20 days.
The weight and rough conditions caused one vehicle to break a
front wheel bearing spindle. We painstakingly filed the fracture
to a vee for welding, welded it, filed it to refit the bearings,
and it lasted 100 metres before breaking again. We then hack sawed
off a piece from the inner axle and welded it through the spindle
to make a solid unit. The vehicle no longer had 4WD, and required
towing over some dunes, but it made it home.
2) In the early eighties I built six land yachts, and with some
friends, circumnavigated Lake Frome (large dry salt lake in South
Australia). One of our group was nicknamed "Disaster
Dave". In thousands of square kilometres of lake, Dave was
quite capable of having a head on with one of the other yachts;
and he did, breaking his yacht's chassis in half. We were able to
use battery welding to get him mobile again.
3) On two separate occasions while doing some cross country
exploration in the Simpson Desert, we successfully welded broken
main leaves in a Hilux and MQ Nissan. This was done with general
purpose rods by filing the breaks to a vee, warming the spring in
a fire to weld, and burying welded area in warm sand to slowly
cool and stress relieve the weld.
4) The photo of Bal and Richard (bottom picture) shows them
constructing a makeshift drive shaft from a piece of water pipe.
This became necessary when the shaft banged on a rock and was
twisted completely in two pieces.
This is all you need for battery welding. The light jumper
leads joining the batteries are carried in my tool kit
specifically for this purpose. The various size general purpose
electrodes and glass from a welding mask are carried in the
plastic electrode box, and held against movement by a rag stuffed
in the box with them. The electrode is more easily held by a pair
of vice grips than it is by the jumper lead clamps.
You will notice that the earth to the work is positive. This is
the norm in DC welding.
One would normally keep the work as far as possible from the
batteries, and cover the batteries with a ground sheet or blanket.
This reduces the possibility of sparks from the weld igniting the
hydrogen gas produced by the batteries.
Batteries do not need to be all the same size. If three
batteries are not available, 24 volts can be used, but it will be
difficult to hold an arc unless you are an very experienced
welder. With 12 volts only, an acceptable weld is virtually
This shows one method of introducing resistance to the circuit
to reduce amperage for small diameter electrodes. It is simply a
piece of "good ole" No 8 fencing wire. It can be
increased/decreased in length to change resistance, and held to
battery post by vice grips or tight twisting. Be aware that this
piece of wire will get very hot; perhaps to the point where it
will droop and melt the plastic battery case(s). KEEP AN EYE ON
Heavier wire, or smaller wire doubled up, can be used to join
batteries if no jumper leads are available.
In this case Bal was able to scrounge a welding mask. If no
mask is available, tape your welding glass into a cut-out in a
piece of cardboard. A mask and skin covering is necessary to
prevent radiation burn (like sunburn) only if you are doing any
appreciable amount of welding.
If the weld is going to be short (a few seconds only) simply
hold the glass close to your eyes.
In high ambient light (bright sunlight) you will get away with
using a couple of pairs of sun glasses on top of each other. DO
NOT attempt to weld without proper welding glass in low ambient
light conditions. In these conditions, heavily dilated eye pupils
will allow intense welding light to damage eye retina.
From South Africa:
I read of welding with car batteries on the 80's LCOOL site
about six months ago and forgot about it until this past Dec. I am
writing this in case anyone find themselves in a situation where
this can be used.... Hope it will not happen but then sometime it
On our way from Vioolsdrif to the Richtersveld in South Africa
we used the road through Helsekloof pass and Eksteenfontein. Yes,
the road was badly corrugated but at about 80km/h it feels OK in
the Cruiser. I towed a Venter Bush Baby trailer with standard leaf
springs and without aftermarket shocks.
We were 3 cars in the convoy: Cruiser, Range Rover and Hilux
2.8 TD. The road started taking its toll. The RR's back doors
opened every now and again and the familiar call over the radio
that the RR is stopping to close the doors came trough every so
often. The Hilux had an after market extra petrol tank and about
40km from Kuboes the pick-up pipe inside the petrol tank broke
off. Result was that we had to change the petrol pipes running to
the engine around so that it uses the "return-to-tank"
as its pick-up. Don't know if it work the same on the Cruisers but
it is something to keep in mind.
About 20 km south of Kuboes I saw my trailer jumping violently.
Stopped to asses what was going on. The axle moved and the wheel
was touching the back of the mud guards causing it to jump each
time the tyre touches the mud guards. The leaf spring bracket
broke where it attaches to the trailer body. We pulled the axle in
line and secured everything with some wire. Whilst we were doing
it a Local came past and we were taken to his Uncle in Kuboes for
a welding job. Welded, fixed and paid....at least we thought.
We entered the Richtersveld at Sendelingsdrif at about 20:00
and was routed to Potjiespram for camping. The next morning we
returned to reception at Sendelingsdrif, completed the paperwork
and proceeded to Richtersberg camp site. The trailer was checked
every so often and everything was OK. At Richtersberg we did a
recon of the campsites and whilst reversing with the trailer the
leaf spring bracket broke again. For those who have not been there
- Richtersberg is about 3 hours drive from the closest
infrastructure through quite hospitable terrain. Towing a trailer
fixed with some wire was a last option. We did the beer thing and
thought..... I mentioned that I have read about welding with car
batteries but was met with a healthy dose of scepticism. One of
the guys with us welds for a living and he offered his
talents if we could get the welder going...BUT... We did not have
any welding rods.
That is where Koos comes into the picture. Koos is a local
herdsman and stays at Richtersberg. He had a battery problem which
we sorted buy jumpering his Hilux and borrowing a spare battery to
him for a day. We explained the situation and he offered to get
some welding rods on his scheduled visit to Kuboes the next day.
So said, so done.. Koos arrived the next evening with some welding
rods... but the only ones he could find is 3mm. This normally
required around 140A if you use an ordinary welder. The welder-man
The next morning we took out my 2 105AH Deltec's and a 55AH
Raylight. Now we have the batteries but it was clear that the
jumper cables would not suffice as welding leads because they are
way to thin. As luck would have it I installed some welding cable
for my additional battery in the luggage compartment.
I took out the earth strap and used it for the welding earth
lead. I had an off-cut of the welding cable in my toolbox which we
used as the positive. We connected the 3 batteries in series
giving us about 36 Volts - amps unknown. To limit the welding
current we used a piece of "Bloudraad" (thick bluish
wire) between the terminals as resistors.
We took a battery terminal clamp to secure the end of the
positive lead to the welding rod and used a vice grip for the
TEST - It works fine but it was burning holes in the metal so
we removed one of the batteries and only used the 2 Deltecs in
series to provide less amps. One could have probably lengthen the
resistor wire to limit the Amps as well but in any case ......
Our pro-welder did not have a welding helmet but closed his
eyes whilst welding. It worked fine.
30 mins later the job was done.
We left the park after the trailer was fixed. The weld held
through the rest of the trip (down to Hermanus (on the SA
west coast dirt roads), Jeffrey's Bay and back to Pretoria).
- I have now made up a set of jumpers with welding cable
- I will always carry welding rods (2mm, 2.5mm, 3mm) and a
loose smoked welding glass insert.
- Make sure that the connecting wire between the batteries
makes good contact with the battery's poles. My one did not
and took away half of one of the poles. I used a vice grip
after this to secure it properly to the poles.
- Always remember what you read......
Hope this will help somebody in future.
Pretoria, South Africa
LC 80 VX TD