How to control Samlex EVO with Electrodacus SBMS0

[twompark]

I'm building a system for my RV and decided to use the Samlex EVO-4024 and the SBMS0. Got the EVO and waiting on the BMS and the batteries, so I decided to set up a test rig to figure out the best way to have the BMS control the EVO. I connected some old batteries for testing, and in place of the BMS I set up 2 toggle switches to simulate the Enable Charge and Enable Drain signals from the BMS.



The exact behavior of the EVO is not documented well, despite the excellent manual. And like most inverter/chargers, support for BMS control is poor. The EVO has a single "disable input" that you can wire the BMS charge and invert signals to, but this just freezes it in whatever mode it is currently in.

However, I managed to come up with a way to wire things that I believe works perfectly. I tested all combinations of disabling charging or inverting, and plugging and unplugging AC power, and it always seemed to do the right thing. Took quite a while to figure out so I am posting it below. It takes advantage of the EVO's status relay, so that the disable charge signal only gets to the EVO if it is in charge mode. You will only need to add a Normally Closed signal relay, or an N.C. SSR (I'm looking at using an IXYS CPC1333G with a resistor).

One advantage of this scheme over others that control the AC input is that you don't need a large power relay, and you don't lose pass-thru AC power (and switch to inverting) if charging is disabled.

Posting here for others. I won't be able to build the actual system till the rest of the parts come in next month. Any comments, let me know.

 

[Bob B]

HMMM .... keep us informed how that works out. I was seriously considering the EVO but didn't think it was capable of stopping charge and inverter independently.
I even sent an email to Samlex support and they told me it was either one or the other also.

 

[Dzl]

Keep us posted, I've been wondering how the Evo would work with the SBMS0

 

[bri2k]

Hi. Just wondering if you've made any progress with this setup. I'm trying to figure out if there's good alternative to the Victron and this seems like a candidate, if your system works. Thanks

 

[Dzl]

Hi. Just wondering if you've made any progress with this setup. I'm trying to figure out if there's good alternative to the Victron and this seems like a candidate, if your system works. Thanks

Last activity on the site was the day they made this post, hopefully they will check back and update at some point.

 

[John Frum]

My understanding is charge and invert are mutually exclusive on the Evo.
Better described as charge/bypass and invert.
The big h bridge transformer is used for both functions but not at the same time.

 

[Craig]

My understanding is charge and invert are mutually exclusive on the Evo.
Better described as charge/bypass and invert.
The big h bridge transformer is used for both functions but not at the same time.

Yes mine either says charging or inverting just as Joey has said. This is why I chose to use DC-AC SSR's to either turn of AC power in or AC power out as necessary by BMS. Although the only time the batteries would ever get low is during a power outage as I have he Samlex set to charge the batteries to 15% of capacity should they ever drop down to 10% capacity.

 

[nebulight]

the optocouplers in the SBMS can only handle a max of 150ma. You should check the input side of the 12v on the bottom and measure the current to make sure you don't blow out the optocoupler.

 

[Refinished]

Has anyone heard from @twompark since this posting? After shelving the project for a few months, I am starting to look into integrating my SMBS0 and EVO again. If his solution works, that would be pretty great...

 

[bri2k]

I now have my own EVO 4024, batteries, and a SBMS, so I plan to start tinkering in the next few weeks. It's much easier to figure these things out when you have one you can test with. I'm sure we can figure out a way to get the two working together. I'm just hoping it doesn't get overly complicated.

 

[Refinished]

the optocouplers in the SBMS can only handle a max of 150ma. You should check the input side of the 12v on the bottom and measure the current to make sure you don't blow out the optocoupler.

The docs say these terminals on the EVO provide "+12.5 to 11.5 VDC source (up to 100mA)", so it should be ok. Better measure first! I think I read in one of Dacian's responses on a related topic that he would prefer that people kept the current to 50mA on the EXT IOs, but now I can't find it.

I now have my own EVO 4024, batteries, and a SBMS, so I plan to start tinkering in the next few weeks. It's much easier to figure these things out when you have one you can test with. I'm sure we can figure out a way to get the two working together. I'm just hoping it doesn't get overly complicated.

I *think* the OPs solution might just work and it seems pretty uncomplicated to me. Though, I think this will just turn the EVO off if the SBMS0 thinks the cells are too low. That would mean that if a charge source became available, human intervention is needed to turn the EVO on so charging can start. Testing is needed...

 

[bri2k]

I just wanted to share a quick update to this post since another member of the forum asked for an update. I'm in the middle of a move and didn't take any notes so I apologize for the lack of specifics. Anyway, I did get the SBMS and the EVO to play nice using a version of twompark's circuit. The main issue was that the 12v source that's provided on the EVO is only active when the EVO is already on or plugged in to AC power, so it can't be used to turn the EVO on when off-grid. Once you have the EVO setup to use the external on/off input (needed for low voltage cut off with the SBMS) you can still use the EVO control panel to wake the EVO up, but then you can't turn the EVO off with just the control panel. You have to interrupt the on/off circuit somehow. I didn't want to have to use both the control panel and a separate switch so I ended up wiring in a 12v voltage regulator to the house battery and feeding that through an on/off switch and the SBMS to the on/off input. So far, so good.

As far as actual operation, it's working as expected. When AC shore power is provided the EVO provides pass-through AC to the outlets and charges the house batteries. Once the batteries are full the SBMS stops the EVO from charging but the EVO continues to provide pass-through AC power. When off-grid, my external switch dictates the on/off state of the EVO's inverter unless the battery falls below the low voltage setting, at which point the EVO is shut off by the SBMS. The only thing I can't remember is if there's an issue when the battery voltage triggers the low voltage cut off and then AC power is provided. I'm tempted to say it doesn't matter but worst case, as Refinished mentioned, you can change a setting on the SBMS to temporarily re-enable to SBMS output to the on/off input.

 

[Refinished]

Thanks @bri2k. Would you mind posting details of your version of this circuit including the details of the relay used and the voltage regulator? I tinkered with this over the holiday and saw many of the issues you did, but I never got time to resolve them.