What's inside the box? (70A Adjustable power supply)

[Andy6ft4Tall]

After noticing this adjustable power supply on Aliepress, that is clearly made from a PC power supply and an adjustable DC regulator.
I was wondering if anyone any idea which regulators would i need to buy?
I already have a PC power supply with an output of 65 amps at 12v.
So i just need to regulate the output of the volts and amps and a digital display.

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I would be using this as a bench top power supply to bulk charge 12v (4 cells) Lifepo4 packs

 

[RCinFLA]

If it is an add on DC-DC it would be a buck switcher. It is possible to put both adj voltage and adj current limit on a flyback power supply which is same as most computer supplies.

You can put these DC-DC buck converters on an old 12v computer supply output. It will draw about 5 amps from 12v input for 3.65v @ 15A output. They are about $8 and you can put several on 12v supply, just break up batteries across the multiple 3.65v buck converters. I have eight of them on a 12v 500 watt switching supply.

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There are also flyback power supplies that have adjustable CV & CC.

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[tim0shel]

After noticing this adjustable power supply on Aliepress, that is clearly made from a PC power supply and an adjustable DC regulator.
I was wondering if anyone any idea which regulators would i need to buy?
I already have a PC power supply with an output of 65 amps at 12v.
So i just need to regulate the output of the volts and amps and a digital display.

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I would be using this as a bench top power supply to bulk charge 12v (4 cells) Lifepo4 packs

I have one of these that I use time to time. I mostly charge with solar but when I need a good fast charge then I will use that. Issue is the wire is too small for the current mine puts out. I have 75 amp one and looks like 12 or 10ga wire. I have put a SB50 Anderson connector on the end.

 

[Supervstech]

What wattage is your pc power supply?

 

[Supervstech]

It better be a GOOD 1000W supply to output 70A at 14V...
And you will need an adjustable boost converter to get the steady 12V output of the supply to produce 14V

 

[100 Proof]

Mine is only 300 Watts, but I made it out of a cheap buck-boost, an old PC power supply I had, and other stuff I had laying around. I used it to both top balance my cells and tin plate my copper lugs.

 

[Andy6ft4Tall]

I have one of these that I use time to time. I mostly charge with solar but when I need a good fast charge then I will use that. Issue is the wire is too small for the current mine puts out. I have 75 amp one and looks like 12 or 10ga wire. I have put a SB50 Anderson connector on the end.

Is there any chance you can open up the regulator, so we can see what components they have used?
I would order one rom China but its going to take 2-3 months for delivery to the UK and I already have the 65A PC power supply.
Small components like the voltage regulator and the display i can buy in the UK or get the small delivered directly from China only take 10-14 days.

 

[Andy6ft4Tall]

What wattage is your pc power supply?

The PC (server power supply) i have is 12v at 62.4 amps. Rated at 750W.
So i should comfortably pull close to 45A-50A at 14v.
It's a reliable and clean power supply that i used to power my Ham radio until i got a dedicated power supply.
Now it's sitting in the cupboard collecting dust.
So it would be nice to make use of it again.

 

[tim0shel]

Is there any chance you can open up the regulator, so we can see what components they have used?
I would order one rom China but its going to take 2-3 months for delivery to the UK and I already have the 65A PC power supply.
Small components like the voltage regulator and the display i can buy in the UK or get the small delivered directly from China only take 10-14 days.

Actually not a bad Idea! Give me some time but I will try to see if I can open it up and investigate or at least post some photos.

 

[Andy6ft4Tall]

Not a project for a novice
I don't want anyone getting an electrical shock

After digging around online i found these server power supplies are designed to supply just over 15v if you bridge two of the connectors.
Then you have a second pair of terminals you can add a 10K Potentiometer to lower the voltage to 14v.
The Potentiometer is just an adjustable resistor that tells the power supply what voltage to supply.

For my needs i just want this to bulk charge so i dont need to reduce the amps.
When you consider you can buy a 700W server power supply for less than £10 ($10 USD) and buy a pack of five 10K Potentiometers for £1 ($1) then add a cheap volts/amps display and this could become a very cheap battery charger.
The whole charger can be completed for £10-£15
If you want to reduce the amps it becomes more expensive.

If you need more or less than a 50 amp bulk charge its just a matter of buying a larger or smaller server power supply.
These server power supplies are designed to work 24/7 for years.
The 400-450W units are even cheaper.
Bang for Buck the 700W is the one to buy.
The 1000W units cost £20-£30.
If you wanted to use two units you have to insolate between the two power supplies.
The adjustable resistor (Potentiometer) has a third leg which needs to be earthed to dump the tiny amount of energy, otherwise the Potentiometer will burn out after 3-6 months. I see so many people use a Potentiometer without connecting the third leg to earth.

I'm going to dig around in my parts boxes tomorrow because i'm sure i'v got some 10K Potentiometers left over from a project.

 

[DJSmiley]

You do need to adjust/bypass the ovp.
I do have some powersupplies from old servers but never managed to get then above approx 13.5-13.8v before the ovp kicks in.
Feedback circuits are pretty hard to figure out, let alone adjusting ovp.
Also, there are many variations of powersupplies. Mine came from some fujitsu servers and were slightly different than the HP serversupplies.

I now use an Meanwell RSP1000 powersupply. I was able to adjust the voltage to 14.2V (adding a resistor to the circuit). Didnt allow me to go higher (ovp kicks in) but it does work fine as a charger for initial charging at 60 amps

Depending on the design you might want to add a diode, to prevent voltage feedback. They aren’t designed to act as a charger. If you connect the battery first, without powering on the supply, youre basicly providing power to the outputs which might fry the supply. A diode will prevent that, but you have to compensate for the voltage drop.

 

[ericgrand]

I have purchased the same type of power supply than the OP, but in 24V. It is basically 2 server PS connected in serie, one without current limitation, adjusted to 15V, and the other one being adjustable both in voltage and current.
Components in the regulator box are blanked/scratched, so no reference available. The current is adjusted through a 5K pot, measuring less than 1V between full resistance.
I would like to be able to adjust the current externally to charge batteries only with solar power in excess, before it fed the grid. I have a first PV router which divert power in excess to my water heater, but once the water heater is hot, the power is diverted to the grid.
My goal is to drive this power supply via a signal (could be digital, analogic...) sent by a Wemos D1 driven by my domotic system to adapt roughly the charging power to the solar power in excess. No need to be very precise, but the goal is not to charge the batteries through the grid...
I have a bank of 6 Valence batteries salvaged from an electric car I plan to use as storage to feed 2 enphase M215 inverter during the night.

So I'm looking for any solution to regulate this power supply externally.
Any other option is welcome, I was also thinking of DC-DC buck converter but was not able to find any that is capable of outputting 50A...