Cheap 18a 12v power supplies....

[Indubitably]

I was poking around for power supplies to use with an HTPC project when I ran across these... https://www.redplanettrading.com/Dell-DA-2-M8811-Y2515-D3860-MK394-D220P-01-Power-Supply-Adapter.html and it occurred to me that they might make for a pretty cheap charger if strung together in series. I don't know if they can do constant current limiting, but I figure you could just stick a meanwell s-350 or something in at the end of the stack. I was planning to keep an eye out for bulk sale on ebay and see if couldn't pick up 6 of them and a 24v s-350 to get the 92v I need for my 24s 40ah thundersky setup. What do you guys think, is this a viable option or am I missing something?

 

[Indubitably]

Ok, so, I just picked up a lot of 10 of these for $45 on ebay. Once I get a hold of them I'll crack one open and post a couple of pics (assuming they aren't embedded in potting goo or something). Since I've got so many of them I'd like to skip the meanwell charger if at all possible, so if anyone has suggestions they'd be appreciated.

 

[wineboyrider]

BUMP
8) 8) 8) 8) 8) 8)
I am kind of interested to see how this works or doesn't?

 

[SamTexas]

I was poking around for power supplies to use with an HTPC project when I ran across these... https://www.redplanettrading.com/Dell-DA-2-M8811-Y2515-D3860-MK394-D220P-01-Power-Supply-Adapter.html and it occurred to me that they might make for a pretty cheap charger if strung together in series.

18A! Good find. Please report back once you have tested one of them. Is it really 12.00V? Can it really sustain 18Amp for several hours without getting hot?

 

[Indubitably]

Well, if I'm not mistaken PC power supplies are generally rated for constant duty, but I'm guessing they aren't expecting to operate at max capacity for the entirety of that duty cycle. Even while operating within their intended range though they probably will get hot enough that I won't to want to strap them all together in a single bundle or the like. At any rate, I figure it would probably make sense to pull them back to 15a anyway if at all possible, since most 120v ac outlets will get toasty enough at a constant 1600w draw that the wall socket would wind up becoming the thermal weak link before the power supplies even had a chance to cause problems.

 

[heathyoung]

DA-2's don't last very long at 18A, trust me on this one. They don't have the heatsinking capability, and they are current limited by shutdown. Easy to change the voltage, and implement current limiting though. You also have to isolate them from ground ~ this is pretty easy to do (2 pin plug or remove the link internally). Ultrasonically welded cases, so its a screwdriver and hammer job to open.

Keep in mind that these laptop supplies are designed solely to charge 96Wh laptop batteries - and some of these models were recalled for overheating (and fires).

 

[Indubitably]

Are you saying that isolating the pack from ground will kick it into constant current limiting mode?
Edit:

Well, if I'm going to have to crack them open to do the mods anyway I guess I might as well stick them in a case with a fan. If I can bring the temp down to the point where they can sustain 15a for 6 or 7 hours I should be good.

 

[SamTexas]

No. I think he says that isolation would allow one to string them together or to use them in parallel on a large battery without breaking the battery.

Healthyoung: So how did you use this DA2 adapter? Just for charging those 96wh battery or for something else? Please share your experience with it.

 

[Indubitably]

No. I think he says that isolation would allow to string them together or to use them in parallel on battery without breaking the battery.

Healthyoung: So how did you use this DA2 adapter? Just for charging those 96wh battery or for something else? Please share your experience with it.

Yeah, I just noticed that myself and edited the comment (wasn't expecting such a fast response). I'll go ahead and add the original content back in so your comment makes sense.

 

[Hillhater]

Are these like the 3r160 Dell units (12v , 8 A ) and have a voltage monitor/regulator feedback to control the charge ??

 

[auraslip]

It would be cheaper and easier to use server power supplies. I'm working on some 585w 12v units I got for $5 each.

 

[Metallover]

It would be cheaper and easier to use server power supplies. I'm working on some 585w 12v units I got for $5 each.

Yes they can be found on ebay for very cheap. Here's an info thread - http://rc-monster.com/forum/showthread.php?t=27554&highlight=power+supply

I have 3, two of them are wired in series for a 24v 1150W power supply. Noisy but very cheap and they run like a champ!!

 

[Hillhater]

Server PSU's are great ( I use them ) but voltage adjustment is practically impossible.
some of these "power bricks" (like the 3r160) are actually designed a battery chargers with built in voltage regulation which enables simple voltage adjustment over a wide range using the sense contact.
IF these DA2's are similar , they would be very convenient bulk chargers for various pack sizes.
do you know ..Heathyoung .. ?

 

[SamTexas]

...
some of these "power bricks" (like the 3r160) are actually designed a battery chargers with built in voltage regulation which enables simple voltage adjustment over a wide range using the sense contact...

Can you elaborate on the above? It sounds like the output voltage can be easily adjusted. How? For example how do I change from the default 12V to say 11.5V or 12.5V?

 

[Hillhater]

With credits to Torqueon....

Re edited due to info left out and spelling

I have 9 Dell 3r160 power supplies for the old dell optiplex . red and brown are parralell + black and white are parralell - Green yellow parralell, a sense wire. i installed a 10k pot, center to the sense wire, I can vary voltage from 3.7 to 12 volts and the volts hold well while aplying different loads. With a large shunt I charge all 24 headways in paralell for initial balancing, success!!
Wire harness is set up to charge in groups of 12 volts time's 3, so I seriesed 2 dells, set one to 7 volts and varied the other with a 10k pots. This time without shunt, some fiddling it worked out great 1.5 hrs per bank. success!!
Now for bulk charging 36 volts, 4 dellls in series, set 3 at 10.5 volts and vari the 4th one, no shunt Here is when things get weird, as the volts on batts increased i keeped turning up the volt via the 100k pots installed, while watching the volts of each dell after adjustment. increase one and one or the other would drop, all the while total of the 4 units produces the same volts. Much like circus ballon being choke off at varing points and swelling elsewhere.

Notes : Forgot to mention the A C ground must be removed from all.
10k pots used on single PSU and on 2 seriesed PSU
100k pots used on 4 seriesed setup . I bet thats why things got weird, will try again with 10k

Update on 4 series dell optiplex PSU's . I replaced the 100 k pot with 10 k pots, now the voltage and load is stable within the 4 units in series. The batteries are getting a happy meal, I am feeding them 5 amps + or - These PSU units are rate at 12 volt by 12.5 amps, I don't think i can pull that much but 5 amps works for me.

A side note is that i understand there is a bigger similar PSU made by dell rated at 12 volt 18 amps

 

[SamTexas]

It's Greek to me. But thanks for the reply.

 

[NeilP]

Firstly, Hands up, I may be repeating things in this post, that have already been said...I have not read al the thread...just scanned through...Lazy I know but hey ...I was looking for other info and came across the thread

Admittedly those units are easier and neater to deal with, but you could as previously suggested use either server or PC supplies. Server supplies are probably better, but PC supplies can usually be had for free from your locla dump/recycle centre.

If you use the 5 volt line rather the 12v line then you can usually get more amps from them. I have a string of them on the 12v line to give me 84 volts...As i find some more I am going to use a string of them with the 5v line rather than the 12 volt line to give me more current

Here is my string

BTW this is not my main charger. My main bulk charger is a pair of Meanwells, and balance charge with an iCharger...but for day time quick bulk charging when I am in the workshop, I use this string of PC supplies

With PC supplies you find that some of them are stable and stay 'on' and other trip out when connected to the battery pack. Some are adjustable...others not. I have trashed maybe 7 or 8 at least playing with them...but they are free from the local dump. Reasons for letting the smoke out vary from just doing something stupid ( connecting the output to 240volt mains rather than the battery pack ) to turning the wrong adjustment pot (when there is more than one) and spontaneous death.

See this thread...and others...
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=28632


Word of advice...If you try stringing them together make sure the negative line ( black ) is isolated from the chassis/earth/case...usually done by cutting the traces on the PCB where the mounting posts hold the pcb off the case. When you do this, sometime you need to re make the connection with a jumper wire

 

[heathyoung]

Voltage regulation on these IIRC is a TL431 driving an optocoupler - Crude but effective. I used the ones I had for running those little 50W Lipo chargers.

 

[Indubitably]

Ok,so the power bricks came today and these things are monsters. I expected them to be bigger than your average power brick but this is closer to what you'd expect from a 1u psu than a power brick. They're not terribly light for that matter either, but they are all at least uniform pancake shape, so I should be able to stack them in a form factor that will fit on the bike pretty easily once I get them open. Speaking of which, the case is held together with security torx screws, so it may take me a bit to track down the right driver, but I should have pics up relatively soon.

 

[Indubitably]

Sorry this took so long people, real life kind of snuck up and bit me on the ass, so I just haven't had much time for projects, but anyway...

It was very easy to get the case open with a security torx driver, but the board was wrapped in multiple layers of shielding and insulation. The shot you see here is after I removed an aluminum top plate that seems to double as a means of making the whole package more rigid while adding a little extra heat syncing capacity to the board. As you can see some sort of solidified white potting goo has been dabbed through out the package for what I'm guessing is stability and electrical insulation reasons, it made removing the top plate a bit of a pain and I would probably try to avoid cracking more open unless absolutely necessary out of fear that I might damage components.

Here we have the bottom of the board. In the top upper right hand end of the picture you will see a spot where a chunk of trace got pulled off when I was trying to remove shielding that was soldered direct to the pcb. I'm not sure if heat syncing or just some sort of special solder, but even at the maximum setting my butane soldering iron could not melt this solder, so I would strongly suggest clipping the shielding where it contacts the board instead of attempting to unsolder the connection.

PS: If the images are too large to view in your browser just download them, they haven't been auto cropped by the bbs, so you should still get the whole picture.

 

[Indubitably]

Ok, so I'm planning to power a few of these up soon, and string them together to see what voltage I get. Does anyone know what I should do with the sense wires? Do I just short them, or do I need to supply a voltage or something?

 

[Indubitably]

Ok, so getting them started up is simply a question of jumpering the "remote" wire (output pin 5) to ground. I'm going to try to run a couple in series next, my plan is simply to cut the AC ground wire and disconnect the shielding in order to isolate the supply from ground, then string them together.

 

[NeilP]

I read your post about sense wires earlier, but did nto understand...but now maybe.

On a normal PC PSU there is usuallly a sense wire on the orange line...sensing voltage at the board...so i would suggest either jumpering it to the output or run it to where the load is taken so it can work as intended as a sensing wire monitoring voltage at the load and therefore controlling the PSU output.

Are these single output supplies? or do they have multiple voltages out? +12 -12, 3.3 5 volt etc..etc ...if they have multiple outputs like a normal PC psu, then you may have to find out which voltage it is supposed to be sensing

 

[Indubitably]

I read your post about sense wires earlier, but did nto understand...but now maybe.

On a normal PC PSU there is usuallly a sense wire on the orange line...sensing voltage at the board...so i would suggest either jumpering it to the output or run it to where the load is taken so it can work as intended as a sensing wire monitoring voltage at the load and therefore controlling the PSU output.

Are these single output supplies? or do they have multiple voltages out? +12 -12, 3.3 5 volt etc..etc ...if they have multiple outputs like a normal PC psu, then you may have to find out which voltage it is supposed to be sensing

Unlike a regular pc power supply it seems that these only produce 12v, and I'm looking at where the the wire I thought was a sense wire (labeled "reserved") attaches to the pcb, but it doesn't seem to lead anywhere on the board. Apparently with other dell optiplex power supplies the sense wire could be used to conveniently alter voltage, but that doesn't seem to be the case here. I thought maybe fooling with the one pot I found on the pcb would tweak the voltage, but no luck there either. What I'm looking at now is ending my stack with a current limited meanwell, which will probably double the price, but I don't see any other convenient way of doing this.

 

[torqueon]

I read your post about sense wires earlier, but did nto understand...but now maybe.

On a normal PC PSU there is usuallly a sense wire on the orange line...sensing voltage at the board...so i would suggest either jumpering it to the output or run it to where the load is taken so it can work as intended as a sensing wire monitoring voltage at the load and therefore controlling the PSU output.

Are these single output supplies? or do they have multiple voltages out? +12 -12, 3.3 5 volt etc..etc ...if they have multiple outputs like a normal PC psu, then you may have to find out which voltage it is supposed to be sensing

Unlike a regular pc power supply it seems that these only produce 12v, and I'm looking at where the the wire I thought was a sense wire (labeled "reserved") attaches to the pcb, but it doesn't seem to lead anywhere on the board. Apparently with other dell optiplex power supplies the sense wire could be used to conveniently alter voltage, but that doesn't seem to be the case here. I thought maybe fooling with the one pot I found on the pcb would tweak the voltage, but no luck there either. What I'm looking at now is ending my stack with a current limited meanwell, which will probably double the price, but I don't see any other convenient way of doing this.

I suspect that these work the same as 3r160 units that i have been using all season with out failure Great way to charge.

Mine have a 6 pin plug 2 pins are common, 2 are + hot, the other 2 are the sense wires, one is labeled as remote the other is labeled reserve, both these wires are common to each other. If you connect the sense to common you will get 12 volts. If you connect to hot you will get 3.6 to 3.8 volts. sense connected to nothing give's nothing 0 volts. Wire in a 10k or 5k poteniometer you can vari the volts 3.6 to 12. If I am correct yours have an 8 pin plug, chance's are you have 3 commons and 3 hots. Once you sort that out you should be good to go. Chop of the ground pin on the A.C.side on all in series, except one of them, there more stable having one unit grounded.
Forget about opening these up, just a waste of time.
Please post your results Curious