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Sep 24, 2018, 10:01 AM
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Converted DPS-750 PSU info_dump

Originally Posted by vimy g eaou
And like you, I was shocked at the price of these SMPS's compared to what they used to be.
I also had a pair of DPS-1200s die after using them off a generator. They were in series, and the generator is an inverter type

Lol at the prices on these now. Blame the cryptocurrency nerds!

I replaced them with some DPS-750s, also in series. These are cheap for now at around $19 off of eBay.
(turns out that I didn't really need 900+ watts to run half my charging station)

Also - I've bought 6 of these and converted them to run in series. The conversion procedure is identical to the DPS-1200s


turns out that there are different types of DPS-750s which are not compatible with each other. pairing incompatible ones in series invariably - and quickly (literally within minutes - kills one of the two supplies.

went through three PSUs before I discovered that little nugget of information I thought I was doing something wrong when floating the ground or maybe they were just dodgy from the start but Nope not quite - it just so happened that I managed to pair up incompatible ones. Twice.

the last set I converted and paired up for 24V a little over a week ago. They passed my initial testing and worked as expected for this past weekend's charging activities. So far so good.

if they continue working I'll tear the vinyl off of them and post pics as to exactly which part numbers seem to be the compatible ones... and most importantly which ones are not


BTW the compatibility bit I mentioned above is not an issue if you're running DPS-750s separately.

(note the PSUs in the background. ~3-year old single DPS-1200 on the left, 1 week old DPS-750 pair on the right)

4 6S 3000 packs hooked up in parallel to a single 250W charger, powered by a single converted HP DPS-750 power supply


Originally Posted by vimy g eaou
Yes, visioneer, I know who's responsible for the demand and hence the price hike. LOL

So the DPS750 SMPS you have is the same but different to the other DPS750's.

Therefore, even if the pin connections are the same, connecting different brand names in series will fail.

Or, is it worse than that, is there incompatibility within the same brand, with different version numbers?
Results time !

My 750W 12V and 24V PSUs have survived a proper torture test. I ran both for 12 hours, each supplying a constant load to recharge a bank of marine deep-cycle batteries. I loaded the 12V PSU to 340W and the 24V PSU to just under 500W. Noisy AF but they never hiccuped and no magic smoke so That's nice.

It appears that there are at least two different HP 750W power supplies. There is the part # HSTNS-PD18 and the HSTNS-PL18. Both are converted for our purposes in the same way that you convert a DPS-1200 - by soldering a 330-1000 ohm resistor across terminals 33 and 36.

the procedure to disassemble and isolate the ground on both types is similar. I did note one difference internally - the PD-18 units have a ground wire which links the daughterboard to the case. The PL-18 units do not have this. extra wire

In stock form that ground wire does not link the negative rail to the case, so I elected to leave it in place on the two I floated

Note : both types work just fine standalone

So far, it appears that the PL-18 units can be safely run in series

The PD-18 units are definitely incompatible the the PL-18 units. I am not 100% certain but I also believe that they are not pairable period, as I initially floated two of my three now-dead ones ... I know at least one of those was paired PD to PL, but I cannot remember whether I paired a PD to PD

I am not inclined to order up another pair of PDs to test that theory

above : $45 bucks of e-waste

I have however got another pair of PLs on the way


Originally Posted by vimy g eaou
So, at this stage do not use PL series DPS750 power supplies, even when trying two of them in series.

My two PL units seem to be fine when used in series. See above. My one remaining PD handled 12 hours run singly and loaded heavily. It made a heap of fan-noise in the process, (as expected) but it came through like a champ.

Its when you try running PD units in series that things get expensive

Originally Posted by vimy g eaou
Interesting thing about that earth strap on the PD unit and missing on the PL units.
I have to wonder if me not removing that strap is the reason for those supplies dying as they did. I did keep the cases isolated from touching each other though, so ???

When the next two PL units arrive I'll document the innards as well as exactly how I isolate the board. Pretty simple really - rather than drilling out the two front standoffs I substitute 2.5mm nylon bolts and washers for the original steel ones. They thread directly into the original standoffs. The rear mounting bolt and ground strap are already isolated from the main board's neutral bus so I reuse them as-is.


Originally Posted by vimy g eaou
I misread your post, so the PD units are the troublesome ones.

If that daughter board is on the 12V side of the PSU and it's earthed to the case, the 12V float may not have worked as it may have still been connected. Did you actually check to see if the 12V was isolated, or just took it as a given, that the float procedure did work?
12V was isolated, as there was no path between the main board and the secondary ground strap, which is pictured here.

My second set of PL units are here! Commence picture-dump

Load resistor added. I solder 4mm bullets flat to the (+) and (-) rails, hence the puddle of solder on the (+) rail.

Powered up for initial test. 12.29V on one and 12.28V on the other. No adjustments needed.

As I mentioned before, I leave the existing standoffs completely as-is. I remove the two steel bolts at the front and replace them with nylon ones, with a nylon washer placed in between the standoff and the bottom of the board. The two rear bolts are not electrically connected to the 12V rails so I reuse those bolts.

PSUs buttoned up, connected in series and ready for testing!
Last edited by visioneer_one; Oct 25, 2018 at 11:05 AM.
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Sep 24, 2018, 02:34 PM
Lori, hey, you're home early
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Great info. Thanks.

I need a PS so I was thinking of ordering one. This looks like the same one you have:

Can I install an on/off switch?
Oct 24, 2018, 09:46 AM
Registered User


I have these power supply's and I would like know how to increase the voltage from 12v to 13,8v
Anybody can help me ?
Paul [email protected]
Nov 09, 2018, 08:24 AM
Registered User
Hello Visioneer,

I have just been given 4 off HP DPS-1200SB PSUs can you tell me how to convert them of point me at a post.

Cheers Zmeu
Oct 25, 2019, 03:46 AM
Registered User
Originally Posted by on6dp
I have these power supply's and I would like know how to increase the voltage from 12v to 13,8v
Anybody can help me ?
Paul [email protected]
I also want to do this, did you find a solution?
Apr 17, 2020, 08:00 PM
Registered User
I am building a 24v PSU using two HP ProLiant 750W PSU Power Supplies. One is a PL18 variant and the other is a PD18. I was under the impression that I could put these in series to provide 24v so I was concerned to come across your article about the incompatibility between these variants. I have dismantled the PL18 prior to removing the grounding of the earthing as discussed in other posts. The PD18 will be the master and remain earthed. As the additional earthing wire in the PD18 will remain do you think that this configuration will work?
Can you please confirm that it is only necessary to replace/insulate the two setscrews adjacent to the power terminals. Also, can you please confirm that the earth wire to the 240v AC is disconnected. I hope that you can help as my project is currently stalled until I find out how to proceed.

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