Back to power supplies

[murankar]

I have 2 power supplies that are the same as Gabas and Tony N.'s. Anyhow one has been floated and right now I am looking at the components needed to complete a charging solution. I will be able to put out just over 1000w at 24V but I want to be able to add a voltage regulator that will allow me to adjust the output. I hope that one day I can make a 36V PSU that I can adjust the voltage on. This is something that needs to be done if three PSUs are ran in series and your charger can only handle 30V max. By doing this I will be able to maximize my charger and hopefully improve efficiency. As for my build goes I would like to set this up with the regulator now so I can learn how to do this for the future. I have found digital voltage displays, I am thinking of getting two one for the 12v side and one for the 24v side.

Anyhow the concern is what is needed for the variable voltage regulator?

[danhampson]

I think Tony is probably the best one to answer that question.

[murankar]

I just want the potentiometer and circuitry to adjust the power output.

[danhampson]

I've seen a video on YouTube where the guy fits a pot and voltage display to this kind of setup but he was using 2 12v supplies. I don't really know that much about electronics to give you guidance

[murankar]

Or maybe a digital adjustment with push button.

I have heard of people doing this. I think Lees PSU is setup like this for his setup.

[pvolcko]

First, check to see if you can find a schematic or info to see if there is already a voltage calibration/adjustment pot inside the supply. Use it if available (extend it outside the case if you want to be able to adjust without tearing things apart each time).

Other options... This may be more difficult than it sounds. At the current and wattages you're pushing, you really can't do it with a simple variable voltage divider circuit with a potentiometer in it. Plus it would be hugely wasteful if you did (lots of inefficiency and heat in the resistors). And you can't put a rheostat on the input wall power since it is a switching supply and will pull whatever current it needs to make the target output voltage into whatever load is presented at the output.

You need a high voltage, high current variable voltage regulator. You can make such things, but my guess is you're talking a big pile of power transistors, a lower current (but still high voltage) voltage regulator, a pot, a couple resistors, and a few capacitors. Gvien the power handling, you can use one of those plastic bread boards to do this. Will need to do custom board layouts or maybe use that pre drilled grid board with liberal use of thicker gauge wire links to connect it all up. Heat sinking on all the current handlers (voltage regulator and the power transistors).

You may be able to buy something pre-made but my guess is that it will cost you, unless you find someone selling it and they don't know what they are selling.

[murankar]

I was not sure if it would even be possible. I was looking a attempting to drop from 24V to 18V. I figured if I could do that then going from 36 to 30 would be feasible. It sounds like it could get very complicated and thats not what I want. At this point its in planning and right now its a no go then. If I find something then I will post up but right now I think the voltage displays maybe all that I will be able to use, which is fine.

I am still looking at the FMA Powerlab PL6 which has a 30V max input but I think they have a buffer on it so it can handle small overages. With what I have already I can get 24V at just over a 1000W but the charger will be maxed below that 1000W due to it running on 24V vs 30V.

[KevG]

The voltage can be smoothed around the 12v internally but not dropped as it's supposed to be a constant output

[Tony]

Best thing to use would be a switched mode regulator, the output voltage would be through a MOSFET and high current inductor. Both these components would need to be on heatsink. I can knock a circuit up for you if you can't find an off the shelf one to suit your needs. I've probably got the components to make one..

[murankar]

Its not something need at the moment. I am still trying to plan out how I want it built. I am have yet to settle on a case and case design. I have the PSUs on hand but thats it, no wires, connectors or a case for all of it. Plus I still need the charger but would like to get most of the build done so all I have to do is drop in the charger. I have what I need for my power source but would like to have the third power source in series. all I need to charge at the moment is 4 3s lipo packs and 1 3s life pack so I dont need to go over kill. IF i can get a 550 heli then I may want to add to the system but for now its about reducing my charge times from 50 minutes a pack to about 45 minutes for all four packs. Its about getting the stick time once the Gaui is back in the air.

With winter here I can work on the charging solution as money is available.

[Lee]

Or maybe a digital adjustment with push button.

I have heard of people doing this. I think Lees PSU is setup like this for his setup.

My PSU isn't adjustable.
What it does have, is a circuit to cut the power if one PSU should die.
This is to stop a current spike from the one PSU still running, potentially damaging the charger.

[murankar]

I thought it was you that had one. Maybe it was Nick Lenn or Justin Pucci then that had it. I know someone had one.

[pvolcko]

An option may be to simply have both a 12V and a 24V power tap. And a 36V one when you series up another PSU. Current will be limited to what that Tap point's PSU set is capable of and would have to be accounted for if you were wanting to do two chargers in parallel, one on 12V and one on 24V input.

In my case I have 24V and both the iCharger and PowerLab eat it up.

[murankar]

That's something I was considering. If I keep a 12v and a 24v plug in it will give me more flexibility. When (at this point) I get the pl6 I can still use the ac6 charger at the same time. My thought would be to use the ac6 as my dedicated life pack charger. I got all winter to get it figured out since my ac6 still works.

[Graham Lawrie]

Coolice makes a circuit to attach to the PSU to protect what Lee said, your charger. What you are wanting to achieve is possible but it is wahat value and benefit it will be to charging?:)

[murankar]

Here is the info on the PSU: HP DPS-600PB B, Part Number: 321632, 575 Watts, 47A amps (on the +12.15).

Just looked at the PL6 manual. It claims that it can go up to 32V on the input side, so really I need to see if this power supply can be turned down internally. If so then that will solve the whole voltage thing. GOing 4 volts is easier than 6 volts.


Okay I think I found what I was looking for:

http://www.rcgroups.com/forums/showthre ... 09&page=40

Whitedg, the DPS-600pb also has these pins.
Use a 1k ohm pot between pins 3 and 9(+12 return sense) to increase voltage above 12v.
Use a 1k ohm pot between pins 5 and 9 to decrease voltage below 12v.
Or use a single 2k-10k pot with the outer legs tied to pins 3 and 5 and the center wiper to pin 9 for voltage adjustment above and below 12v.
I've modified a pic by mrforsyth to show how to do this.
Voltage is adjustable up to 13.8v on this supply. OVP starts at 13.82v.
If the PS shuts down at 13.8v with a load then just back down to a voltage that works for your particular situation.
Short pin 4 to ground to slow fan speed to a minimum or use pot for variable speed.
Once pin 4 is grounded, fan speed will be automatically adjusted based on load and ambient temperature.
Pin 4 is already internally connected to ground on the PS-3601-1C version of the ESP135 series.
Therefore, connect it to +12v to set fan speed to maximum.
Pin 11 is the +12v current share pin.
Short pins 6,8 and 10 together to power up.

A link to a 2k-10k ohm pot would be helpful since I am not to confident in what I am looking for. I think the 2k-10k ohm pot would add better flexibility even though I am not planning on increasing the output.


Now could I do all these connect
ion from the ribbon cable inside or am I stuck soldering to the pins? Soldering the pins is a real PITA.

[Graham Lawrie]

I just used normal servo plugs to short the pins and then heat shrunk them in place to stop them coming out:)

[murankar]

I have all my wires extended and the breakout boards removed. right now I just need some funds so I can order a few more things for the project. I will be doing some extra overtime over the next few months in hopes of getting ready for the 2015 flying season.

What I need at this point is:
10g wire (red and black)
wire end rings
velcro
2 or 3 switches
acrylic
mounting hardware for acrylic
heavy duty PSU power cables ( I think I have some I just need to find them. I have not seen them since before the move)

[murankar]

Today I made some small progress on the PSUs.

I made a trip to Radio Shack because 2 of our 3 stores are closing and they had some great sale prices. To my dismay the two stores closing had almost nothing left. So I went to the store that was staying open and was able to pick up some small stuff. I had to get some solder because my current roll is MIA,I ended up getting a thicker wire than intended but my iron handled it just fine. I also got some more shrink tube but this time I got a mix pack so I could get some smaller diameter stuff. I finally ended up getting a few more things, misc washers a binding post set and some crimp on connector, a large variety pack. Finally the gem of it all a $25 USD butane soldering iron and torch. So far I love it but I have not really used it to solder yet. I used it to shrink some tubing and loved how quick it worked.

As for the PSUs, I sized the PRC 10 AWG wire down by half making 2 1.5 feet lengths of both red and black. These will be my main leads from the PSUs and I crimped on somering ends to one of each color. Now I have 1 complete set main leads, just need more ends to finish the other set. I also undid all the insulating tape and replace it shrink tubing. I have removed the break out board a few months back and exteneded the ribbon cable. The joint locations are fragile due to the ribbon cable so I used heat shrink to support and insulate those joints.

As for the first test all I did was power on my cheap 50w charger and it worked so PSU #1 is done now to finish PSU #2 and complete the build.