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shawn

Senior Member

Joined: 30/03/2010
Location: New Zealand
Posts: 210

Posted: 11:04am 03 May 2010

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HI all I have just picked up my new bank old telecom 2 volt 1000 amp hour 12 of them would like to bring these up to charge and have herd about converting welders can any body give a little more detail on how this is done 12000 amp hours is a bit more than my 4 ah car charger can handle.

Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 02:57pm 03 May 2010

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Forgive me question your maths but if you take one 2V/1000Ah battery and connect 12 of them in series you get a 24V/1000Ah battery bank.
I'm curious what you are going to do with a 2V/12000Ah battery bank as you would get if they are connected in parallel.

I think the 24V/1000Ah bank would be less of a charging problem

I made a linear 12V/40A battery charger and its a mighty beast. Welding transformers are not ideal IMO for such an application - has to do with higher arc striking voltage compared to arc maintaining voltage.

Klaus

VK4AYQ
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Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 03:09pm 03 May 2010

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Hi Shawn

I got one of those little inverter welder on ebay for $50 and it works a treat as a fast charger, it will do 140 amps into 24 volts but gets hot at that, it will do 70 amps continuous without cooking it is rated at 50% duty cycle so that is about right, an extra diode in line for safety, the output is a bit spiky on the cro but I like that as it tends to desulphate better.

So far the magic smoke has stayed in.

If you don't have power on or access to same, you could try a truck alternator driven with a old lawn mower engine most of the US ones have a dead rectifier or regulator so just bring out the leads and hook up a three phase rectifier and regulate with engine revs.

You could start your solar panel collection and hook up a couple of them, slow but it works and I don't think you will boil the batteries with that capacity, but not good for desulphating as the power is to gentle use a desulphator on old batteries like these to get the best out of them.

All the best

Bob

Foolin Around

Downwind

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Joined: 09/09/2009
Location: Australia
Posts: 2333

Posted: 03:37pm 03 May 2010

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I would be a bit carefull with running a alternator without a regulator to charge batteries, as i have made welders out of them in the past and 70 to 100 volts is what they will punt out unregulated with the field windings at full power.
By adding a series light globe or 5 watt resistor in the field windings excite line will reduce the max output, but the amps will drop back too.

The other thing is when the voltage gets upwards it tends to blow the diodes out of the rectifier.

If you are going to build a portable alternator spend the $15.00 and buy the regulator, its cheap insurance.

Pete.

Sometimes it just works

shawn

Senior Member

Joined: 30/03/2010
Location: New Zealand
Posts: 210

Posted: 07:06am 04 May 2010

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thanks tinker midnight and braindead when I posted this
As most guest 24 is my voltage and sounds like truck alternator could be the go do have an old 8 hp brigs & straton in my shed this will run it I guess these should have far better amps than car alternators.

VK4AYQ
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Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 08:52am 04 May 2010

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Hi Shawn

It is good to have a shed with good junk and don't worry about the brain dead bit as the only question that's stupid is the one that isn't asked, as we all benefit from the interchange of ideas.

All the best

Bob

Foolin Around

Downwind

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Joined: 09/09/2009
Location: Australia
Posts: 2333

Posted: 10:30am 04 May 2010

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Hi Shawn,

If you can get your paws on an small portable mig welder (the cheap gasless ones) they work very well as a 40-50 amp 24 volt battery charger.

I had one here i gave to a friend whos off grid and he uses it on his battery bank for when the generator is running for welding etc. to top the batteries off, as well in winter when there has been a spell of low light and little wind.

Pete.

Sometimes it just works

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