Cheezeball DC Load: DL24P: Pump, or Dump ???

[interflexo]

Many items on AliExpress are free shipping...
Today I bought 6 DC contactors on AliEx and DHL shipping was 57,23 Eur (8 - 21 days).
If I try to ship those same 6 DC contactors from Europe to China via DHL probably 200 Eur won't be enough.
For this reason I don't complain much about these delays in AliEx.

[interflexo]

I finally received the 14 x DL24M eLoads.
Epic fail from my side. I assumed a USB connection would be provided just like on the previous models. I assumed wrong. The manufacturer ditched the USB interface relying only on Bluetooth.
I built a Windows application to handle all these eLoads from a 16 port USB Hub. The equipment as is is not useful to me.
There are no plastic clips to secure the LCD frame to a panel.
Can I tap into the bluetooth module rx/tx pins and install an USB interface from there?

[interflexo]

The manufacturer also replaced the Bluetooth blue PCB module used on previous versions (DL24 / DL24P). At first glance I can't spot the new Bluetooth module.
After testing, the unit responds to the same commands from a Windows App using a Bluetooth serial port.

[fubgumfaw]

My 2 DL24M load testers arrived over the weekend. This isn't what I was expecting. It's been a while now since i ordered, but I remember something else than what they show now. Maybe I'm remembering it wrong, but I don't remember this modular design.

https://www.aliexpress.com/item/1005002621436227.html?spm=a2g0s.9042311.0.0.5bf44c4dEGxk3v

I opened the box to find many smaller boxes inside. At first this was confusing as I distinctly remember the DL24M  differently from what I received.



This is the control module which is supposedly good for 150 watts. If that is the case, each added mosfet ought to add 150 watts. I'm somewhat skeptical...this is a Chinese product after all! No USB port and I'm guessing the BT module is inside the LCD shell. You use the 5 holes on each side for adding another mosfet for more wattage. A mosfet module on each side, plus the one on the control board ought to be 600 watts. It appears you can daisy chain them together a lot more than just 3 mosfet modules.








Far from enough screws and nuts, same janky PSU, same hardware set as the DL24P.



This is a mosfet module. There is no gate protection or a diode on board. All that is here is a mosfet and heat sink on a board. The 5 through holes on each side are identical and allow you to connect the mosfet modules in parallel with other modules or with the base unit. Since I have 6 mosfet modules, I have to wonder if I can connect them all to a single control module.





Too bad there is still a single TO-220 Schottky diode. This thing got hot on the DL24P. I bet at much more wattage it will be nuclear!



The rest of the main board logic looks similar to the older ones. I don't see any zeners here, but then I have no idea what all the smaller components are yet. Lots more shunts is good! I guess the board by itself is unjumpered. Adding mosfet modules and jumpering 200w, 450w or 600w is for 1, 2 or 3 mosfet modules. A set of instructions WITH the load tester would be nice and there is almost nothing. I wonder what those 2 8 pin chips are that have their tops scrubbed off?

[fubgumfaw]

I think these are the mosfet drivers. It appears that the left most one is direct connected and the other 3 are jumper selectable. 4 identical circuits and you have the main mosfet and 3 add-on mosfets...that's a bit coincidental IMHO. This is the same circuit as is found in the DL24P for driving the mosfet. They just copied it 3 more times.

[fubgumfaw]

The manufacturer also replaced the Bluetooth blue PCB module used on previous versions (DL24 / DL24P). At first glance I can't spot the new Bluetooth module.
After testing, the unit responds to the same commands from a Windows App using a Bluetooth serial port.

I was hopeful the android app had improved...it hasn't. It's still the same steaming turd it was 6 months ago. I can't say that it adds anything to the usability of the load tester. Making settings changes from my phone is more complicated and less intuitive than is using the buttons and the LCD. I guess the graphs are of marginal value, but that's about it. Like previously, I tried the app out for 5 minutes and uninstalled it!

[fubgumfaw]

The LCD...
If you take it apart, there are no clips, just plastic pins pressed into holes which can be snapped off easily. All those little slots around the edge of the shell, you should use them to lift off the back cover evenly.





Close-ups of the components. Can they make this thing any cheaper?! The BT chip says "BPD7587-58A2" on it. The main chip is impossible to read, but it sure looks like an STM32 to me. I think the 2 sets of open through holes are for programming the BT chip or the STM32.

[fubgumfaw]

A few more close-ups of the main board...

I think these are possibly ADC's and they each get an opto isolator for their digital data. I think each IC has 2 onboard ADCs. This would allow for each mosfet to have individual current sensing. Maybe that's not it all and one is for total voltage and the other is for voltage drop across all the shunts for current measurement.



No heat sinking, still the same wimpy part...this diode is going to cook!



What the heck is going on with these shunts? I thought they were all in parallel, but I see they are not. Maybe they get split off to the individual mosfet modules?

[HKJ]

I was hopeful the android app had improved...it hasn't. It's still the same steaming turd it was 6 months ago. I can't say that it adds anything to the usability of the load tester. Making settings changes from my phone is more complicated and less intuitive than is using the buttons and the LCD. I guess the graphs are of marginal value, but that's about it. Like previously, I tried the app out for 5 minutes and uninstalled it!

if you can get a serial port on the PC you can use TestController https://www.eevblog.com/forum/testgear/program-that-can-log-from-many-multimeters/ it works nicely with the DL24P load.

[interflexo]

"The BT chip says "BPD7587-58A2" on it."
It's strange, the markings don't shad any light and I don't know any Bluetooth transceivers with such a low pin count.
It does create a DL24M_SPP paired device (serial port profile). It worked a bit laggy with my custom DL24 software. The devices were 3 meters apart. The driver creates half a dozen serial ports but only one allows the connection to be established.

[fubgumfaw]

I was hopeful the android app had improved...it hasn't. It's still the same steaming turd it was 6 months ago. I can't say that it adds anything to the usability of the load tester. Making settings changes from my phone is more complicated and less intuitive than is using the buttons and the LCD. I guess the graphs are of marginal value, but that's about it. Like previously, I tried the app out for 5 minutes and uninstalled it!

if you can get a serial port on the PC you can use TestController https://www.eevblog.com/forum/testgear/program-that-can-log-from-many-multimeters/ it works nicely with the DL24P load.

That sounds interesting. On the DL24M, since it lacks a USB port, how do I connect to that?
There's 72 pages in that thread. In there somewhere does it tell you how to connect to a DL24P?
I have several USB serial adapters that may work.

[fubgumfaw]

"The BT chip says "BPD7587-58A2" on it."
It's strange, the markings don't shad any light and I don't know any Bluetooth transceivers with such a low pin count.
It does create a DL24M_SPP paired device (serial port profile). It worked a bit laggy with my custom DL24 software. The devices were 3 meters apart. The driver creates half a dozen serial ports but only one allows the connection to be established.

I agree...I can't find that part number either. I googled for BT chips hoping to find one with 8 pins...nada. Never the less, what else could this be? The antenna goes right to it.

[HKJ]

if you can get a serial port on the PC you can use TestController https://www.eevblog.com/forum/testgear/program-that-can-log-from-many-multimeters/ it works nicely with the DL24P load.

That sounds interesting. On the DL24M, since it lacks a USB port, how do I connect to that?
There's 72 pages in that thread. In there somewhere does it tell you how to connect to a DL24P?
I have several USB serial adapters that may work.
[/quote]

Try a Bluetooth adapter on you PC, it may create a serial port when it connects (See reply #127).

[interflexo]

About DL24M Bluetooth serial port:

"The BT chip says "BPD7587-58A2" on it."
It's strange, the markings don't shad any light and I don't know any Bluetooth transceivers with such a low pin count.
It does create a DL24M_SPP paired device (serial port profile). It worked a bit laggy with my custom DL24 software. The devices were 3 meters apart. The driver creates half a dozen serial ports but only one allows the connection to be established.

It is not as responsive as DL24 USB interface. DL24 does not need any extra Serial to USB  interface hardware it provides an internal CH340 that works pretty well IMHO.

[interflexo]

The DL24M AliEx adds clearly advertises the 32 bit ARM Cortex CPU in colorful pictures.
The 48 pin TQFP package probably must be some STM32WB (internal Bluetooth) Chinese clone, the right STM32WB footprint should be a UFQFPN48.
The 8 pin IC is probably just a standard antenna filter and matching network.
So I won't find the UART RX/TX exposed pads. As I said before these 14 x eLoads are useless to me. I signed up for an USB application.
If some hardware heavyweight would make a comment about this I would be much appreciated. I am out of my depth here.

[fubgumfaw]

The 48 pin TQFP package probably must be some STM32WB (internal Bluetooth) Chinese clone, the right STM32WB footprint should be a UFQFPN48.
The 8 pin IC is probably just a standard antenna filter and matching network.
So I won't find the UART RX/TX exposed pads. As I said before these 14 x eLoads are useless to me. I signed up for an USB application.

I think you are probably right. The pin count on that 8 pin IC seems awfully low for a BT chip. It makes sense it is some sort of filter and that the UART is inside the STM32.

[Brumby]

Bloody Murphy.

Have an SLA battery I've come across that I want to try to charge and check .... and do you think I can find my  ##$%$%#^***!  load?!!!


I know I've really only got myself to blame ... I "cleaned up" a month or so ago.   

[interflexo]

That's why most men don't like to "clean up". Undesired side effects may be observed.

[fubgumfaw]

Dude! "Cleaning up" is once or twice year you sweep the floor and wipe up grunge. Reorganizing stuff is always a bad idea!

Side effects include:
Inability to find stuff you know you have.
Stuff goes permanently missing and is never found again.
Stuff enters random worm holes and then reappears later.
Even though you KNOW you just put ABC in XYZ location it's NOT THERE!

As a result, I never reorganize anything! The negative side effects are too problematic. You just create new wormholes or accidentally find the ones you missed previously.

[Brumby]

Anyone else want to pile on?

Really - I don't mind.  I acknowledge my wayward action and take comfort in the fact that those of you who have highlighted my error have divulged one entertaining detail - you know about this, because you've done the exact same thing at some time in the past!   

[interflexo]

Right on the money Brumby.

If we didn't live on opposite sides of this beautiful planet I would send to you right now one of my 14 expensive DL24M paperweights.

[Brumby]

If you did, my lost unit would magically appear - because of Murphy's sense of humour.

[fubgumfaw]

I see you have done what I have done...
Can't find the one you have so you buy another one and then you find the one you already have.
Murphy is a jerk!

[mnementh]

mnem
I have two. No idea where in the world they fucking are.

[Brumby]

The standard response in this household is "It's in a box somewhere."