DSSR50

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Dacian Todea

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Apr 26, 2021, 4:39:16 PMApr 26
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Just got the DSSR50 PCB's not sure when I will get the time to assemble and test them but hope to be soon.
This is just the first prototype and it will sure be another prototype when all the spacers and PCB's making the case will be made and just after that and multiple tests there will be a production run.

The PCB is a 4 layer as that was sort of needed in this case to keep the unit compact. The DSSR50 is same with as the DSSR20 just longer so it should not take much space when multiple will be installed next to each other.
There are two PV inputs the two on the top each with individual ideal diode so that no individual fuses for panels are needed same as it was with the DSSR20 and each input can handle two large panels even the newer panels that start to be available with 12A or so max power point current.
Then on the bottom there is one connector that connects to battery+
The connectors are similar to what I used on SBMS40 and this ones are rated 85A so plenty for the DSSR50 that is designed for 50A continues and peaks around 60A
The DSSR50 is 2.5x more capable than DSSR20 and while I did not fully calculate the price as I will need to have the final version before I do that the target is to not be more than 2x the price of DSSR20 without diversion so around or below 75CAD (60USD)
The connector in the middle of the board will not be used at this moment but it may be for possible future modular DMPPT if there will be enough interest. Also the same middle connector may be useful for those that want just to use the two ideal diodes part of the DSSR50. 

It will have a full case made of stacked PCB's similar to how SBMS0 is constructed or even more similar to SBMS40
The DSSR20 will still continue to be available (with diversion only) at least until the end of the year maybe a bit more based on the components I already have available and unchanged volume of sales but as the DSSR50 will start to become available some of the sales will probably move to DSSR50 and so DSSR20 may be still available for even a full year from now.
The diversion for DSSR50 will be available as a separate device as that will make it easier for people to add diversion later.

P1310544.JPG 
 

Dan Karau

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Apr 26, 2021, 9:02:39 PMApr 26
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Have you thought of making all your components DIN RAIL mountable?  This would make for a super clean install!

Dacian Todea

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Apr 26, 2021, 9:14:51 PMApr 26
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Yes the DSSR50 is designed to fit on this clamp mounting bracket https://www.aliexpress.com/item/32853965399.html
You can see the two 4mm holes are to install this on that bracket above then it can be installed on DIN RAIL
But you will need to get that yourself as it is to heavy for me to offer and not all people will want that.
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Dan Karau

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Apr 26, 2021, 11:09:14 PMApr 26
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So I'm I reading this correctly...you can connect 2 pairs of 2 parallel panels...so 4 panels per DSSR50?   When do you think these will be available?

Dacian Todea

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Apr 26, 2021, 11:21:50 PMApr 26
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Yes two pairs of two parallel panels per DSSR50 and not sure when they will be available it depends how the prototype's work and then how fast I can source the components but I do not expect to have them sooner than end of summer around August.
I will post progress in this thread as it is available.

DavidS

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Apr 27, 2021, 2:29:40 PMApr 27
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This is great Dacian. Excited for this new capability. 

michael clark

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Apr 28, 2021, 12:23:29 PMApr 28
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I am very interested in the DMPPT to utilize for diversion heating, and will gladly try out the DSSR50 when you have some ready. keep up the great work. As the weather improves here, I can get a little more assembled on the off-grid solar project.😎

Dacian Todea

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Apr 28, 2021, 1:06:47 PMApr 28
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Dan,

Here is a photo of how it will look like installed on a DIN Rail.

P1310549.JPG
P1310552.JPG



Dan Karau

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Apr 29, 2021, 9:39:21 AMApr 29
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Thanks for the photos!

Dacian Todea

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Apr 30, 2021, 6:51:05 PMApr 30
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I assembled two DSSR50 prototypes today and just did a fast bench test and all seems to work. Will need to setup again the GBS battery and add some panels tho that battery is a bit weak and will likely not handle 50A charging but I will find a solution to test. I need to do quite a bit more testing before working on second prototype version but things look very good for the first prototype.
The connectors will have M3 hex screws that will look better this where just what I had available for the prototype. The did soldered surprisingly well even if the manufacturer decided to modify my stencil design (hate when that happens but I understand why they did that so I will make so changes there for the next prototype and mention not to touch my design).

dssr50-1.jpg
dssr50-2.jpg

Jhon

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May 1, 2021, 7:25:45 AMMay 1
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Not an electronics person, but as always I am amazed how small these units look small compared to the wires that will be connected. I don't understand how the PCB boards cope with the mechanical stresses, especially at the point where the terminal connects to the PCB, although this one seems to be bolted on.  I like that they can be mounted on a din rail.  A cover of some sort, although not strictly needed,  would complete the looks and prevents some clumsy mistakes by people like me.

Even without a cover I see no reason why this, could not be the goto unit be for small systems like boats, vans, cabins and even energy efficient homes, providing wire runs are not too long.   I really like the "no waste heat" philosophy.  (LED light bulbs that are hot to the touch just boggles the mind.   A laptop that runs so hot that it burns your lap is utter nonsense!!) I also like that you keep it open source.

I don't often get exited about new technology, there is just too much hype, water cooling a processor and/or graphics card is NOT a desirable feature, but I am exited about these products as an end user.

And a question, on the DSSR20 (with or without diversion), what should is the gauge of the negative wire, and can they be strung together and have a single wire run back to the battery or negative buss-bar?   (judging from my clamp meter I am guessing it is just to provide some power to the electronics, however I used 10 gauge because the size of the connector)

Dacian Todea

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May 1, 2021, 1:35:29 PMMay 1
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Hi John,

Wires should be secured especially in a high vibration environment like RV's. But the connectors both on DSSR20 and DSSR50 are fairly well connected mechanically and there was no reported problem related to connectors for any of them.
Yes a lot of devices are engineered to the limit to be more optimised for cost than for longevity as people will select products mostly based on price when there is more to choose from.
The minimum size for the negative on DSSR20 is 18AWG as that is just for self power and transient protection and yes you can connect all of them together (not sure how many you have) and then continue with one a bit thicker wire to battery. The DSSR20 is usually very close to battery anyway.
On DSSR50 the negative wire can be just 20 AWG.
The DSSR50 will have similar thermal characteristics as DSSR20 just 2.5x more capable and is almost as narrow 45mm vs 43mm on the DSSR20 but a bit longer 90mm vs 58mm. DSSR50 will also be less tall just around 25mm including the case due to lower profile connectors.

Dacian Todea

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May 1, 2021, 3:55:27 PMMay 1
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I was able to install the DSSR50 today and just added the PV cables that where installed on the DMPPT450 each of the yellow cables 8AWG contains 4x 260W panels but is suny and super windy today not super warm around +23C ambient and I can only connect 4 panels as they put out 40A already 39 to 42A (just seen 42A as I was writing this likely some stronger wind gust cooling the panels and there are some small clouds so also some edge of clouds effect). 
I also tested both PV inputs 70A total for a few seconds only as there will be to much heat for longer period.
At 39A on a single input for a few minutes I measured +60C for the PV mosfets and 53C for Battery mosfets (but not sure how accurate the thermal camera temp measurement is as I could touch the mosfets with no problem but likely I was cooling them).
When current is shared between the two PV  inputs it should not be more than 25A on each input from two panels 50A total with 60A max allowed peaks for below 1 minute.
I was expecting less power from the panels today as it is fairly warm but I think the high wind speed and clouds help getting the spec 260 even 270W form the 260W panels.
Keep in mind 40A is not allowed on a single PV input this is just me doing tests the manual when it will be available will be clear to the limits and the DSSR50 is designed for two parallel panels on each PV input panels ideally will be 60 cells and have a max power point current below 12A that should include all the currently available 60 cell panels.
Forgot to mention that I installed the DSSR50 on my main house battery as that can take easy the 40 to 70A test current and there was no change for the old 100Ah GBS to handle that.

Here is a bit of a blurry photo. The LED will be amber(orange) and it looks much more bright than in real life due to photo long exposure.
As mentioned yesterday all seems to work great so that is good news as there should be almost no changes to second prototype mostly panelizing them and arranging some components around plus tons of PCB's that will make up the case as there will be quite a few different PCB's both for back and especially top to cover the connectors.
P1310617.JPG

Jhon

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May 7, 2021, 5:03:00 PM (11 days ago) May 7
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Looks like another awesome product Dacian, again so small compared to the wire sizes...  I already got 6 DSSR20's here, if I hadn't I would have been happy to use 3 of these instead, as I like the smaller footprint.  I also like the screw (Allen key) connectors, the other connectors covered the wiring better.   Seeing it wired up, without a cover, I would make up a plexiglass one, on standoffs, open on the sides to prevent me doing dumb things or any one else poking their fingers in.  It might make the design and assembly easier on your part and it would be rather simple to make on my part.

Is there any way to measure the current from each of the strings?

Dacian Todea

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May 7, 2021, 7:55:35 PM (11 days ago) May 7
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Jhon,

Plexiglass has lower temperature resistance and it is not fire proof thus I prefer to use FR4 (PCB material) for this reason plus there will be many layers so that connectors are isolated from the rest of the circuit so wires can not be inserted so much that can touch components since the FR4 layers will prevent that.
As with multiple DSSR20 you will have the total measurement current by the PV shunt on the SBMS0 so there is no individual current measurement. But if you have the same model of panels then current will just be equal and if you suspect that one of the PV array is not performing for some reason you can just disconnect the others and see what current that respective array produces.
It will be quite a bit of cost added to have a small microcontroller and current shunt amplifier for each PV input to report current for each separate input. Most will not benefit from this amount of info and there will just be extra cost added to each DSSR50.


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Dan Karau

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May 7, 2021, 9:31:19 PM (11 days ago) May 7
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For safety, mount them inside of a DIN Rail box...they come in multiple different sizes to accommodate the size you need.

michael clark

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May 8, 2021, 9:11:59 AM (10 days ago) May 8
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the yellow is the incoming positive from the solar panels and the red is the outgoing positive to the positive bus bar or directly to the battery correct? the small blue and green will be the sense wires to the SBMS0 and the larger blue wire also?? I would like to try these out and am hoping you will make a DMPPT to utilize for more efficient control for heating. I have extra 60 cell 250-watt solar PV panels and some LiFePo4 batteries in a 24-volt configuration. this is great news. let me know. thanks, Michael

Dacian Todea

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May 8, 2021, 1:53:29 PM (10 days ago) May 8
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Michael,

Yes the yellow wires are from solar panels positive so two separate arrays each with two solar panels in parallel.
The Red wires (I used two 12AWG silicone cables in parallel as that is what I had close to me when I installed this for testing) Should be an 8AWG same as those wires on the solar PV inputs. This red wire goes to battery+ not directly as there are also the current shunts to measure the current and maybe a fuse or breaker between shunt and DSSR50
The small green and white/green (I know that for some reason that looks a bit blue but is a green pair from CAT6 cable) go to EXT IO4 set as type 1
The thicker blue wire is going to battery negative so that DSSR50 can power itself.
First I need to have the DSSR50 available and it will take a few months then I can think about a diversion module and after that a DMPPT0 that will control one or max two DSSR50 plus a diversion module to create something like a DMPPT100 but that will take time and I will need to be sure there is demand for something like that.


Dan Karau

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May 10, 2021, 8:49:54 PM (8 days ago) May 10
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Dacian...with the DSSR20 you recommend 60 cell panels for a 24V system...with the new DSSR50 will it be able to fully use 72 cell panels or are 60 cell panels still recommended?

Dacian Todea

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May 10, 2021, 10:11:32 PM (8 days ago) May 10
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There is no difference in this aspect both DSSR20 and DSSR50 support 60, 66 and 72 cell panels but the 60 cell panels are the closest to the max power point to a 8s LiFePO4 battery.
There is no DC-DC conversion so panels should match as close as possible the battery in therms of max power point.
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