Recommendations for 60V 20+A DC power supply to test RC brushless motors?

[LCA078]

Hello All-

New guy here looking for an 'okay' adjustable DC power supply to provide 20+A at a min of 60V (55V continuously).  More than likely I need to buy a new Brand X PSU unless someone here on the forum has a domestic one they need to get rid of quickly.  I'm located in the US so 110V is best as I don't have 220V at my bench...yet.

I'll be testing fairly large electric ducted fans (EDF) systems powered by brushless dc motors (BLDC's) common in the RC plane market like this one: https://hackermotors.us/product/stream-fan-120mm-kv700/ While these things are designed to handle monstrous power (5kW+!!!) for max thrust, I'll be testing them at the much lower power settings of 150-500w to test airflow efficiencies relative to battery pack power supplies.  None of the manufacturers test outputs in this low range because basically it's just a fan at these low power settings and not a propulsion system.  I'll use the DC power supply to mimic various arrays of lithium battery packs (12-50V) powering the motor's electronic speed controller (ESC) which produces the 3-phase power for the BLDC which means I'll primarily be in constant voltage mode only. Here's a typical ESC I'll be using https://hackermotors.us/product/mezon-evo-80-bec/.

My intent is to produce low-power airflow efficiency curves (0-30% max motor power) to find the sweet spot of combinations for fan/motors and then perform VERY basic durability testing (ie- the fan/motor combo doesn't burn up after a few hours).   More than likely I'll stay under 500W max for any motor because I can't handle that much continuous power draw from the final application.  My sweet spot power draw will be 200-300W continuous for 4-8hours for optimum weight/power....but I digress.

As you can tell, I don't need "precision" but would like a nice PSU if price is right. Duty cycle might be a problem but this is why I'm posting here for feedback.  Trying to stay in the sub $300 range if possible but open to higher $$ for the quality as needed.  And yes, I have a decent background in electronic/electrical engineering but just not in this range of power supplies. 

Thoughts?

[Martin72]

Hi,

On german websites I´ve found this here:

https://www.metro.de/marktplatz/product/0cc4f732-c30b-4a0d-9921-2267ea7e5468

1200W  output power, not bad...

Should be also avaible outside europe, for searching here the full name:
Stamos S-LS-41

[tautech]

Hello All-

New guy here looking for an 'okay' adjustable DC power supply to provide 20+A at a min of 60V (55V continuously).  More than likely I need to buy a new Brand X PSU unless someone here on the forum has a domestic one they need to get rid of quickly. 

Thoughts?

Welcome to the forum.

55V @ 20+A is a good ask especially with a $300 budget.
Looking at Siglents lineup the SPS5082X meets your requirement but the darn lead time is 8 weeks 
https://siglentna.com/product/sps5082x/

I have the 40V 60A SPS5042X and it's quite lightweight being SMPS and has a narrow but long footprint.
Here's the whole range:
https://siglentna.com/products/dc-power-supply/sps5000x-series-switch-mode-power-supplies/

[james_s]

A very cheap way of doing this is to modify 12V server PSUs by isolating the DC ground from earth ground and then connect them in series. You *may* have issues with insulation floating the output at such high voltage but I think there is a pretty good chance of it working. I routinely use a pair in series, I have run as many as 3 before for 36V and for 60V you only need 5 of them. They're so cheap on the surplus market that if it blows up it's not a huge loss, normally you can get them for little more than the cost of shipping.

[Martin72]

This is very risky in multiple ways....

[tautech]

This is very risky in multiple ways....

Lack of current limiting to contain the magic smoke the 1st.

[Martin72]

Lost of any insurance when something was burned down due to misused PSUs the 2nd..
Risk of electric shock the 3rd and so on...

[thm_w]

I don't really see too much difference in electric shock risk for a grounded 60V server PSU vs a floating output 60V PSU. Depends on the setup maybe.
A 30A shunt meter with relay disconnect can be had on Aliexpress for $20. Response would be very slow though.

Heres a wanptek 60V 20A for $200: https://www.aliexpress.us/item/3256801282757612.html
Quality unknown. This person never reviewed theirs: https://www.eevblog.com/forum/testgear/wanptek-kps-series-power-supplies/

There are a number of 30V 20A units that could be seriesed up for ~$300, also uknown brands.

[tautech]

There are a number of 30V 20A units that could be seriesed up for ~$300, also uknown brands.

Probably but you first need check the manufacturers ratings of how far their outputs can be elevated above mains ground which applies when using multiple units in series.

[Martin72]

I don't really see too much difference in electric shock risk for a grounded 60V server PSU vs a floating output 60V PSU.

It starts with the housing itself.
PC-PSUs aren´t made to use them outside the PC.
And they will be switched on/off by the PC.
Cutting off Ground is always a risk factor,  minimum you can get problems with EMI.
To get 60V/20A, you must buy five PC-PSUs, doing the "mod" to connect them together, make them switchable on/off.
Inrush current can be a problem for mains fuses.
Finally no current/voltage limitation....

[thm_w]

Ah I see yes if the chassis is no longer grounded. I would not want to do that, if possible, keep the chassis grounded and just disconnect the output.
In some cases this can be done. There is a plugpack that I use where they run a green earthing wire from the mains in to output, if you cut that the output is now floating safely.

[nctnico]

I'd look for a brand called 'Gophert'. They make a whole range of switching power supplies that are low cost, are of reasonable quality and should cover this application. Likely the (ab)use of old telecom / server power supplies is even more expensive.

[james_s]

I don't really see too much difference in electric shock risk for a grounded 60V server PSU vs a floating output 60V PSU.

It starts with the housing itself.
PC-PSUs aren´t made to use them outside the PC.
And they will be switched on/off by the PC.
Cutting off Ground is always a risk factor,  minimum you can get problems with EMI.
To get 60V/20A, you must buy five PC-PSUs, doing the "mod" to connect them together, make them switchable on/off.
Inrush current can be a problem for mains fuses.
Finally no current/voltage limitation....

Who cares? This is a bench testing rig, not a consumer appliance.

Surplus server PSUs have been the standard way of powering chargers for RC aircraft for quite a few years now, series pairs of modified PSUs to get 24V are extremely common, never heard of one blowing up. These PSUs are dirt cheap, I have at least 5 of them around here already though I've never tried running all 5 in series. Switching them on is as simple as bridging two terminals. They do in fact have current limiting, or rather overcurrent  protection, they shut off if overloaded. This can be a problem when powering something like a DC motor that has high inrush. Server PSUs are extremely robust, I've been abusing them for years, never had one fail yet.

[james_s]

Ah I see yes if the chassis is no longer grounded. I would not want to do that, if possible, keep the chassis grounded and just disconnect the output.
In some cases this can be done. There is a plugpack that I use where they run a green earthing wire from the mains in to output, if you cut that the output is now floating safely.

Huh? Says who? I lift the DC ground from the chassis, I don't lift the earth ground. The chassis stays safely grounded, only the output is now floating.

[james_s]

Probably but you first need check the manufacturers ratings of how far their outputs can be elevated above mains ground which applies when using multiple units in series.

The manufacture will tell you 0V, because from the factory the output ground is tied to earth. In many cases they are easily modified to change this though. When playing around with cheap surplus stuff the easiest way to find out is to just try it, if it fails, scrap it and start over with something else.

[zrq]

What about mobile base station "rectifier module"s .

In the part of world I was in few years ago, Emerson R48-2900U was very common in second-hand market and I clearly recall there was a tutorial about how to mod them to make them output 60V. The annoyance with this specific model is it have a soft start feature than ramps up the output to set point in a minute, not sure if it can be disabled or not. There should be some newer models can be modded without this problem and have even higher power density.

[james_s]

Actually there are a lot of those telecom rectifiers out there, they're very similar to scaled up server PSUs and with a default of 48V they're pretty close. There might be enough range to just dial one up to 55V without hitting the OVP.

[thm_w]

Ah I see yes if the chassis is no longer grounded. I would not want to do that, if possible, keep the chassis grounded and just disconnect the output.
In some cases this can be done. There is a plugpack that I use where they run a green earthing wire from the mains in to output, if you cut that the output is now floating safely.

Huh? Says who? I lift the DC ground from the chassis, I don't lift the earth ground. The chassis stays safely grounded, only the output is now floating.

Above, as I said, I would do as you recommend, keep the chassis earthed.

I'd look for a brand called 'Gophert'. They make a whole range of switching power supplies that are low cost, are of reasonable quality and should cover this application. Likely the (ab)use of old telecom / server power supplies is even more expensive.

Two of these: https://www.aliexpress.us/item/3256803507137876.html $450.
Don't know where the spec for o/p to ground max voltage is.

[nctnico]

I'd look for a brand called 'Gophert'. They make a whole range of switching power supplies that are low cost, are of reasonable quality and should cover this application. Likely the (ab)use of old telecom / server power supplies is even more expensive.

Two of these: https://www.aliexpress.us/item/3256803507137876.html $450.
Don't know where the spec for o/p to ground max voltage is.

60V DC shouldn't be a problem. At least these PSUs are designed with floating outputs, current limiting and adjustable output voltage.

This one looks closer to what the OP is looking for in a single box: https://aliexpress.com/item/4000352693776.html

[LCA078]

You guys are great- I love the responses and bickering.  Reminds me of my younger days when I repaired military avionics and listened to the Chiefs going back and forth with each other on how to  troubleshoot aircraft.  I miss having a well equipped bench like I did back then.  Now it's just a folding table in my garage with DMM's.  Not even a cheap scope.    

For this project I was hoping to find something like an older, but good name, power supply on ebay but no dice.  And yes, I don't mind hacking something together but just prefer to buy off the shelf if easier.  And also much safer than using 3 automotive batteries in series without fuses...   

This one looks closer to what the OP is looking for in a single box: https://aliexpress.com/item/4000352693776.html

Yes!  That's what I was hoping for- a simple PSU.  Hopefully it's fairly clean on the output.  Looks pretty solid.

Heres a wanptek 60V 20A for $200: https://www.aliexpress.us/item/3256801282757612.html
Quality unknown. This person never reviewed theirs: https://www.eevblog.com/forum/testgear/wanptek-kps-series-power-supplies/

I saw this one in a video  before I posted my first post.  It looks like it's doing a decent job so I wondered if there are other PSU's out there for a bit more $ but much better on quality.  The Gophert looks pretty nice with the extruded aluminum case.

Hmmm... might be worth it to buy one of each and see how they do. 

 

[nctnico]

It looks like the Wanptek is 220/230VAC only from the Aliexpress link. Perhaps there is a 110V version as well though.

[LCA078]

Dang- I missed the Wanptek is only 220/230VAC.  Looks like the Gophert is way to go. 

[ci11]

Since you're in the US, you can get a Sorensen DCS 60V 18A 1U rackmount supply usually for around $400 or less on eBay. These are industrial-grade supplies made to work in factories, not an Amazon offering made to meet a price. Sorensen has other models with more features at higher prices and they all work well and deliver what that datasheet states. Reach out if you have questions, I own a few so can probably answer most questions.

[tautech]

Probably but you first need check the manufacturers ratings of how far their outputs can be elevated above mains ground which applies when using multiple units in series.

The manufacture will tell you 0V, because from the factory the output ground is tied to earth.

Only crap PSU's have a grounded output, those that are constructed to provide a decent featureset, their outputs can be elevated considerably above mains ground, limited by PCB clearances and component limitations.

In many cases they are easily modified to change this though. When playing around with cheap surplus stuff the easiest way to find out is to just try it, if it fails, scrap it and start over with something else.

Or in the first instance use an instrument made for the job, or relevant to our discussion a multichannel PSU designed to have channels placed in series (or Parallel) and allow for several units configured this way placed in series, all with none of their outputs tied to mains ground !

Some time ago I contacted Tech support for clarification of the SPD3303X-E datasheet Insulation specification on P4:
https://siglentna.com/wp-content/uploads/2020/10/SPD3303X_DataSheet.pdf

Insulation: Case to Terminal ≥20MΩ (DC 500V), Case to AC line ≥30MΩ (DC 500V)

I was informed multiple units could be used in Series not exceeding the insulation rating.
Tech support also sent me pictures of two 30V 3A units configured to provide 120V !

[LaurentR]

I'd look for a brand called 'Gophert'. They make a whole range of switching power supplies that are low cost, are of reasonable quality and should cover this application. Likely the (ab)use of old telecom / server power supplies is even more expensive.

Two of these: https://www.aliexpress.us/item/3256803507137876.html $450.
Don't know where the spec for o/p to ground max voltage is.

60V DC shouldn't be a problem. At least these PSUs are designed with floating outputs, current limiting and adjustable output voltage.

This one looks closer to what the OP is looking for in a single box: https://aliexpress.com/item/4000352693776.html

I have the CPS 6017, which I use for that exact purpose and it works very well for the price. At 1000W, they are pretty close to what you can pull from a regular US wall plug.