review this battery charger

tirsdag den 21. december 2021 kl. 04.16.48 UTC+1 skrev Cydrome Leader:

need a welder?

No Earth.

Joining wires by twisting alone is asking for a fire.

Sylvia.

They did solder the connection to the rectifier diode. I thought it was quite impressive. A lot of thought had gone into the design and it certainly made good use of recycled materials.

John

Besides the craft paper substitution, what made you think that the materials were recycled? Repurposed, maybe.

RL

That is what I was mainly thinking of. The core looked as if it might have been intended for some other purpose. I suppose the rust and grime on the laminations are good for reducing eddy currents. It did seem surprising that the guillotine operator appeared to have all his fingers. The diode heatsink casting might well have been recycled aluminium floor sweepings

John

I'm most struck by their work practices. Working on cracked concrete floor, no tables or chairs. I realize some cultural ethic may be a factor, but ergonomics & safety are "universal". Also, strange that they have some hand tools, like pliers, but no wire cutters (scissors is a painful way to cut wire!) or rubber mallet. And they have some power tools like the drill press and circular saw, but no electric or pneumatic screw/nut drivers, riveters, etc. And a sheet metal shear. I wonder if electricity there is a premium? Karachi is the capital city, but I would think, make electricity as available as possible for business-sector development. They might do well to host a manufacturing engineering consultant for a few days.

The third-world manufacturing videos are fascinating. It looks like people spending half their time throwing parts on the ground, and the rest of the time picking then back up again. It makes very little sense, but might explain why those places are such dumps to start with.

I'm sure they could teach a consultant more than the consultant could teach them. I would want to use a pushsstick though on that guillotine.

The wire isn't copper colour. I can't imagine them paying unnecessarily for plating. It's not iron wire is it? :)

I did not watch the whole thing,but if they did not solder but crimped or screwed the connections it may have been Aluminum wire.

Lots of wire comming from China seems to be aluminum with a plating of copper. Real crappy way for them to do things to cut the cost.

Fine for high frequencies like radio and tv, but not for DC or low frequency AC as house wiring or drop cords. YOU have to go up a couple of wire sizes to carry the same current.

It looked like cloth covered wire for the transformer. I can't imagine that's cheaper than varnish, but maybe there's another shop where they twist it on by hand.

Cloth-covered wire is very robust when the whole assembly is varnished, and can withstand a fair voltage. Probably cheaper than regular enameled magnet wire, as that is actually quite difficult to manufacture.

Joe Gwinn

Such transformers are commonly being used to steal power in India. a wild guess is that 20% of the power in India is stolen:

Here's a different power amateur power transformer as installed:

More:

In India: Cotton cloth costs Rs 65 ($0.85) per meter.

Varnish costs about Rs 145 ($1.92) per kg.

I don't know the relative wire coverage area for cloth vs varnish, but they seem about equal. However, applying cloth insulation is a one step process, while varnish requires thinning, dipping, drying, careful winding, testing for shorts, etc. Cloth seems easier.

It is the result of poverty.

Looks inefficient. Fiberglass wire so it can run hot? Half-wave rectifier.

These are people who find it worthwhile to rebuild truck batteries:

Hopefully they can achieve a minimal level of prosperity at some point in the not-too-distant future. OBOR should help a lot.

Typical of the third world shit countries that have no respect for their people. So those tools will work the better part of a day to to produce some garbage that's not even close to 15 minutes of western productivity. Those cesspools have resources, they don't have to work like that.

1m means something like 1x2m, though the width varies

If we guess wildly at 10mm circumference for the cloth insulation:

1x2m = 2sqm 10mm x 1m = So number of meters it covers = 2m/10mm = 200m

yes, one painfully slow process

I assumed it would set/dry almost instantly, probably applied hot. I can't see much upside in using a formula that doesn't.

I doubt they'd bother

If I were in the 3rd world looking to go ultracheap I'd possibly pick hot bitumenised paper.

Those transformers look big but either a) they're way ott for charging truck batteries b) or they're for something else, probably stealing power

In the real world (so not the slums of pakistan) cloth insulation is woven on with a machine and not cut up from bedsheets or whatever else you folks are looking at.

they look about right to charge a truck battery, considering they're probably about 50% efficient.

yeah, the core is made from scrap, not from a transformer alloy so it will need to run lower flux levels to avoid saturation.

I'm sure they are better than 50% energy efficient, but they are'nt space or mass efficient. If their customers are all nearby the extra shipping costs are not a big problem.