The Electrodacus SBMS thread (SBMS0, DSSR50, etc)

[mitiempo]

The link in post #458 shows how to connect the Electrodacus to Auxiliary 1 and 2 on the Multiplus. Alternatively the Cerbo GX has 2 relays that can be either normally open or normally closed.

Here's a link to a short video explaining the Cerbo GX

 

[APhoton]

I've posted the latest version of the Beginner's Guide to ElectroDacus in this forum's Resources section:

Beginner's Guide to ElectroDacus

The ElectroDacus system takes care of solar charging, lithium battery monitoring, and optionally, diverting excess solar power for other uses. Its modular components can function as a BMS, a charge controller, and a thermal controller. It was...

diysolarforum.com

@Will Prowse you might like to look it over if you're working on a new ElectroDacus review video.

Any additions, suggestions, and corrections are very welcome!

Thanks so much for your guide! I purchased the SBMS0 and two DSSR20s. My plans are to use in a van build. I thinking of a 24v system and believe that I can get 3 60 cell panels on the roof. I believe that you are designing a system for a van. Would you care to share your design?

 

[Oberon]

I can get 3 60 cell panels on the roof. I believe that you are designing a system for a van. Would you care to share your design?

That would be a nice amount of power, I was only able to fit 2x 300W panels on my van roof but that has been plenty so far. I'm working on an update to the guide and I'll include details of my design in that, most of it is already covered in the current version anyway.

 

[APhoton]

I've read all 24 pages on this thread! I was very much sold on SBMS0 and 24v system after watching @Will Prowse video. I must admit that I was like a dog when someone yelled squirrel. I purchased it along with DSSR20 to use in my van build. My general takeaway from reading this thread is that it is ideal in colder climates with large PV arrays. Where you can purchase 60 cell PV cheaply. Not exactly what you would have on a van! But I'm going to move forward with two or three 300w panels and 24v system using 280ah cells. Generally, did I miss something?

 

[Dzl]

I've read all 24 pages on this thread! I was very much sold on SBMS0 and 24v system after watching @Will Prowse video. I must admit that I was like a dog when someone yelled squirrel. I purchased it along with DSSR20 to use in my van build. My general takeaway from reading this thread is that it is ideal in colder climates with large PV arrays. Where you can purchase 60 cell PV cheaply. Not exactly what you would have on a van! But I'm going to move forward with two or three 300w panels and 24v system using 280ah cells. Generally, did I miss something?

The only thing I would add is that the SBMS0 is not at all dependent on the DSSR20. What you say above is accurate in the context of using the DSSR20. You can choose to use SBMS0 + DSSR20 or you can choose to use SBMS0 with a traditional MPPT charge controller like the Victron Smartsolar. In the former case, you have a more unique and integrated solution with its own unique pros/cons, in the latter case you have a pretty traditional arrangement, the SBMS0 fills the role of BMS (plus some extra capabilities), the MPPT is the solar charge controller, and you don't have to worry about the DSSR specific considerations.

 

[Oberon]

it is ideal in colder climates with large PV arrays. Where you can purchase 60 cell PV cheaply. Not exactly what you would have on a van

This is exactly what I have on a van, with two 315W 60-cell panels and a 6kW battery. It works beautifully. I also added backups with alternator charging and shore power hookup, but rarely need them. If you only go with one panel, I think you may regret your power limitations, I would highly recommend having two.

 

[1 watt]

Two 280w panels with a 12v system, never used shore power. We do have alternator charging in case of “snow on the panels” but had to use that only twice.

The SBMSO is working great!

 

[grizzzman]

Has anyone here installed a smaller active balancer that is controlled by the SBMS0?

 

[mitiempo]

If your cells are properly top balanced you shouldn't need an active balancer.

 

[APhoton]

This is exactly what I have on a van, with two 315W 60-cell panels and a 6kW battery. It works beautifully. I also added backups with alternator charging and shore power hookup, but rarely need them. If you only go with one panel, I think you may regret your power limitations, I would highly recommend having two.

Thanks for your feedback. what do you think of my plan attached?

 

[Oberon]

what do you think of my plan attached?

Looks good with a quick review. Will you have a Class-T fuse between your load shunt and main disconnect? You may want to give yourself more space in your positive busbar, you're likely to add more draws over time. Also I'd suggest upping your Battery Protect to the 100A one, it's not much more money and it's nice to have some extra headroom.

You'll need to check if your inverter has an internal bond to chassis ground: https://diysolarforum.com/resources/grounding-details-for-specific-make-model-of-inverters.156/ and wire appropriately. I'd also say that 1/0 wire for your chassis ground is overkill, 6ga should be plenty.

Overall, nice job. You've done your homework!

 

[APhoton]

Looks good with a quick review. Will you have a Class-T fuse between your load shunt and main disconnect? You may want to give yourself more space in your positive busbar, you're likely to add more draws over time. Also I'd suggest upping your Battery Protect to the 100A one, it's not much more money and it's nice to have some extra headroom.

You'll need to check if your inverter has an internal bond to chassis ground: https://diysolarforum.com/resources/grounding-details-for-specific-make-model-of-inverters.156/ and wire appropriately. I'd also say that 1/0 wire for your chassis ground is overkill, 6ga should be plenty.

Overall, nice job. You've done your homework!

No, I don't have Class-T fuse. I do have the MRBF Terminal fuse block on busbar going to Inverter. I should add Class-T. I think larger busbar and battery protect would be nice and add little to overall cost.

In reference to ground, I found this on Amazon

Question:
Can the battery negative and ac neutral both be safely terminated to ground?
Answer:
Yes,it is.
By XIJIA SELLER on March 4, 2021

 

[Oberon]

I should add Class-T.

Definitely. They're expensive but this is one place where you don't want to save money.

Also highly recommended to read FilterGuy's excellent 4-part series on grounding, especially the mobile systems part: https://diysolarforum.com/resources/grounding-made-simpler-part-4-mobile-systems.159/

 

[BiduleOhm]

A MRBF fuse is plenty fine for a 4 or 8S pack. It start to get a bit borderline for 16S packs but that's not the case here so it's fine

 

[APhoton]

Definitely. They're expensive but this is one place where you don't want to save money.

Also highly recommended to read FilterGuy's excellent 4-part series on grounding, especially the mobile systems part: https://diysolarforum.com/resources/grounding-made-simpler-part-4-mobile-systems.159/

I decided to add Class T fuse even though some say it's not necessary. I think for the added protection; it's worth it.

Why do you think some are so adamantly against Electrodacus?

 

[Airtime]

Why do you think some are so adamantly against Electrodacus?

That's pretty vague... who are the "some" and what are their objections?

 

[LB3]

Why do you think some are so adamantly against Electrodacus?

Dacian believes that solar panels are so cheap that MPPT no longer makes economic sense for off grid applications. He’s drawn lots of fire for that which is odd to me because every BMS he has ever made has been compatible with MPPT charge controllers.

This does come with some design constraints that require building a system that matches the mpp of your panels to your battery which basically restricts you to 60/120 cell panels. It also means you can’t put your panels in series which increases wire costs (but reduces fusing costs).

He also doesn’t like the use of electrolytic capacitors b/c they have a limited useful service life somewhere between 10 and 20 years. This also seems to be offensive to some people.

Basically DIYers like to do things their own way by choosing products best suited to their use case and budget and Dacian’s systems are much more constrained.

 

[Airtime]

Dacian believes that solar panels are so cheap that MPPT no longer makes economic sense for off grid applications. He’s drawn lots of fire for that which is odd to me because every BMS he has ever made has been compatible with MPPT charge controllers.

This does come with some design constraints that require building a system that matches the mpp of your panels to your battery which basically restricts you to 60/120 cell panels. It also means you can’t put your panels in series which increases wire costs (but reduces fusing costs).

He also doesn’t like the use of electrolytic capacitors b/c they have a limited useful service life somewhere between 10 and 20 years. This also seems to be offensive to some people.

Basically DIYers like to do things their own way by choosing products best suited to their use case and budget and Dacian’s systems are much more constrained.

Actually you misquoted me, that question you quoted me as saying was from @APhoton. I’d still like to hear from him on it.

Dacian’s DSSR solar charging is completely optional, his BMS works fine with MPPT. So that is not a constraint. I use a Victron MPPT in my system.

I find his BMS to have less constraints than most. For example, most FET-based BMSs are much more constraining. Especially common port.

 

[LB3]

Actually you misquoted me, that question you quoted me as saying was from

Sorry about the misquote. I corrected it. I should have started with the original post.

 

[orangezero]

I'd like to know what these people are comparing the electrodacus sytem to.

Some do not like that the electrodacus system (sbmsX) is limited to 24v and 8s. This is due to the chip he designed the entire system around.

It may be frustrating to have someone say "ignore MPPT" after decades of it being the sane answer. His design works well as a smart on/off switch between the solar panels and the battery and charges them well. It keeps the voltages close in my 8s pack, and the solar generation is good.

The amount of "stuff" my sbms120 can do, and the size, just blows my mind. This thin, tiny device replaces something like a midnite solar device or other large, solar charge controller. Seems to be at least twice as much, but also needs an expensive combiner box, and doesn't have a bms...

Each of my two panels run in parallel with 10 awg cable connected to a DC breaker. 10awg doesn't break the bank and unless someone is running hundreds of feet of cable I don't really get that argument about cables being extra costly. If anything, it seems like a win to avoid additional electronics that will fail at some point with slightly more expensive cable that lasts a lifetime.

There are a lot of people who will miss out on electrodacus devices because:
-firstly, they already own incompatible solar equipment so sunk costs
-it is off-grid only
-they've been educated to want MPPT (it isn't bad, but not essential in 2022)
-they've been educated to want high voltages by putting panels in series
-they've been educated to geek out on the solar panel tech

I did all this stuff, but before I purchased things I looked at what else I'd need if I didn't get a sbms120, and it didn't make sense to do anything else.