Then you are going to need a big big battery charger. When you run your generator, do you have to leave it on for 8 hours to get the batteries topped off?
Make or modify a transformer, and charge the batteries at a couple of hundred amps.
Here I was welding and running the vacuum cleaner, all off the same homemade transformer.
Need to do some welding?
You could be in the same situation that I was in 15 years ago. I had purchased a small hobbyist grade wire feed welder for $89, from Home Depot. I welded up sheet metal with it for years. It worked great. It’s low power was an asset, because you never had to worry about burning holes in the metal. It couldn’t.
But then, every once in a while I would have to weld something bigger, and it’s low power was obvious.
One day after inventing a way of making and modifying transformers, I decided I needed to fix that welder.
I took one of my transformers that was running the Invincible vacuum cleaner, and added some turns. Picked up a couple of diodes, made a simple choke made out of an old motor, and I was in business.
I could weld 3 inch pipe together all day. I was using the wire feed part of my Home Depot welder with the transformer, and welding at 160 amps. 100 % duty cycle!
Do you have a need for a big battery charger?
I can show you how to build a battery charger that will be as big as you want, plus you can build it for way less money then you could buy one for.
Why would someone want a big battery charger?
1. Let’s say you have a motor home or bus conversion, in order to have as much time in the outback as possible, you get as big a battery or batteries as you can carry. The problem is how to recharge them. A small battery charges fast but doesn’t last long, so you get a big battery bank, and it will keep you going for days. But then it takes days to recharge it, from a measly 35 amp charger. That might be okay if you are parked and hooked to shore power, but not so good if you are planning to do it from your 12 kW generator. You are not even loading the generator down.
2. Let’s say you have a solar home and live off the grid, you need a charger that is big and powerful. Here you have much more in the way of batteries. So maybe you want to have a 300 amp capability. Now I will say this: These battery chargers we are building, are not regulated in the sense that they are going to provide four stages of charge. They are brute force chargers that supply the big amps. If a person was really good at electronics, they could make the necessary setup to regulate the charger, but that is not necessary. All you have to do is use the big amp charger when you are low and in a hurry. Then a timer turns it off, and the smaller regulated charger takes over.
3. Thought about building an Electric vehicle to commute to work? It will have a bunch of batteries in there. Again, you come home and put the big charger on to get things started. They can restore the batteries fast, and then have the more delicate charger take over.
What is so unique about my design? You see when I was selling plans for my three phase motor converter, I found that lot’s of people in the UK, Ireland, Australia, and Canada were emailing me saying “Where do we get a transformer?” They had no surplus places, loaded with scrap stuff that people were tossing out. So I came up with an ingenious way of making a transformer out of a scrap motor. What happened next was an advantage to us: When I first started, copper was pretty cheap. I had to get a scrap motor, take it apart, remove the old copper, and wind new wire on. Then when copper went up in price, the motor rewind shops started figuring that it was not bright of them to just send all these junk motors out to the scrap yard, for pennies on the pound. They started to take the motors apart and remove the copper themselves. This meant that the cores were sent to the scrap yard for pennies on the pound. We use the cores for our transformers, and now we can get them all cleaned up and ready to use. This saves us a bunch time and work.
To build a welder or battery charger you need to get a used transformer, or make your own. Then we modify it, add some diodes, and you can charge at what ever rate you like. You make it for your situation. If you want to be able to put 100 amps into the battery, then we can do that. You need to figure out how many amps the batteries can safely take, and then shoot for that maximum. Or near it. Make sure the batteries have the proper ventilation, if they are wet cells.
How much is this going to cost? A lot depends on how good you are at scrounging up used surplus equipment. The big thing is finding a transformer. The more familiar you become with them, the more you will realize they are available. You just didn’t pay any attention to them before. Diodes are the things that change the AC to DC, and we need two of them. For the welder, I was using ones that were rated 300 amps and they cost about $30 each. Hooked together, they can handle 600 amps of power. So figure, if they are $30 each, then ones that could handle 150 amps have to be somewhat below that. My opinion is when they say rated 300 amps they mean on a big heat sink, with a cooling fan. If you spend less on the diodes you need a bigger heat sink and fan. I prefer to over buy, and then run with less of a heat sink and fan. In the welder example above, I used the 300 amp ones and didn’t even need a fan. The diodes got slightly warm when I was welding at around 150 to 175 amps. They were mounted on some aluminum sheet stock, to dissipate the heat.
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