Troubleshooting SMA and REC - Mostly (all?) Solved

[SilverbackMP]

Fairly certain my woes are cured. I think it was mostly the generator sensitivity but I also think the battery size was wrong and it’s right now.

 

[1201]

Fairly certain my woes are cured. I think it was mostly the generator sensitivity but I also think the battery size was wrong and it’s right now.

Yes!!

That's bloody exciting. Please keep us updated. I want to know how many minutes or hours you are able to run without it shutting off and what max amp rate it'll take. Thanks

 

[SilverbackMP]

Yes!!

That's bloody exciting. Please keep us updated. I want to know how many minutes or hours you are able to run without it shutting off and what max amp rate it'll take. Thanks

It’s set at 240 amps (battery charge) right now charging around 9.5 kw. I didn’t realize it, but my electrician had installed a 50 A main breaker in the generator sub panel as temp measure as he didn’t have another 125 A and #1 wire on hand. As soon as I got right in the Sunny Islands, it started firing off that breaker. It’s been running an hour straight like this. I would give odds it will work at higher amps when we get the main generator breaker and wire replaced. Final breakers will be 125 A from the generator (@240) and 70s for each of the SIs (@120v).

 

[1201]

It’s set at 240 amps (battery charge) right now charging around 9.5 kw. I didn’t realize it, but my electrician had installed a 50 A main breaker in the generator sub panel as temp measure as he didn’t have another 125 A and #1 wire on hand. As soon as I got right in the Sunny Islands, it started firing off that breaker. It’s been running an hour straight like this. I would give odds it will work at higher amps when we get the main generator breaker and wire replaced. Final breakers will be 125 A from the generator (@240) and 70s for each of the SIs (@120v).

Cool. Glad it's working because I know a couple of people had mentioned trouble with the sunny island synching to the generator.

What type of generator do you have if you don't mind my asking?

 

[SilverbackMP]

Cool. Glad it's working because I know a couple of people had mentioned trouble with the sunny island synching to the generator.

What type of generator do you have if you don't mind my asking?

Ingersoll Rand 30KW powered by a Cummins 4BT. Bought used six or seven years ago.

 

[SilverbackMP]

So this morning I set the battery charging current max to 200 A (@ 48v) so that it corresponds to 80% of the temp 50A breaker @ 240v).

No more breaker shut offs.

I have been (this morning included) noticing that it would charge at 8-9 KW and drop down to 4-5 KW after some time.

I thought it had something to do with SI charging algo but started digging around in the REC manual.

My “Max charging current per inverter device” was set like at 30 A.

I changed that to 56A and the charging from generator returned to 8-9k.

It is also set (I didn’t do this) for “Max discharging current per inverter device” at 62 A.

My question is…should this be raised to 112A per current device to allow for max start up surge per SI stated capability?

I don’t want to make magic smoke.

 

[SilverbackMP]

 

[Hedges]

BMS tend to have a spec for continuous and surge.
SI current settings don't.
One approach would be to size batteries big enough that they can supply SI's continuous demand. Then if SI does provide surge, it is limited to seconds anyway.
Another would be if BMS managed this by communicating max current.

I was going to say current draw is limited by SI, should be OK to tell REC to allow more. But with parallel batteries, some could be disconnected and then SI could draw too much from one.

Does REC BMS have separate limits for continuous and surge, with time limit for surge?

 

[SilverbackMP]

Does REC BMS have separate limits for continuous and surge, with time limit for surge?

I don’t see anything that looks applicable.

On the batteries… I have the pieces and components for three more including the boxes that I built last time I was home.

Thinking about adding four to six more (for a total of 12 or 14) if I can get this proved out and if I can still get the BMS units (since they switched models mid stream of my build).

 

[kommando]

My question is…should this be raised to 112A per current device to allow for max start up surge per SI stated capability?

This is from the REC manual from the start of the thread

Maximum charging/discharging current per inverter device 90/100 A

So I would not enter 112A to cover the inrush as that then leaves it open for 112A to occur by accident at another point and damage the REC.

If only the inrush is the issue then I would keep the 60A and use resistors or loads with a 3 way switch to cover the inrush by limiting the amps to below 60A.

As the 60A is only an issue during the inrush then fix the inrush instead of leaving a setting above what the REC wants.

 

[SilverbackMP]

This is from the REC manual from the start of the thread

Maximum charging/discharging current per inverter device 90/100 A

So I would not enter 112A to cover the inrush as that then leaves it open for 112A to occur by accident at another point and damage the REC.

If only the inrush is the issue then I would keep the 60A and use resistors or loads with a 3 way switch to cover the inrush by limiting the amps to below 60A.

As the 60A is only an issue during the inrush then fix the inrush instead of leaving a setting above what the REC wants.

I can work around most surge issues…my HVAC (part of it anyway) are inverter mini splits. Most of my wood working stuff (3 HP sawstop, Harvey 2 HP G700 Dust processor, etc has soft start or on board VFD).

The one that concerns me are a 2-3 HP compressor coupled with a to be acquired 50 A plasma cutter (probably Hypertherm). The compressor can be outfitted with a new 3-phase motor and VFD. The plasma cutter on the other hand…not sure. Not sure if it even has surge or if it’s just a continuous 40 or so amps.

Might be best to consider a second generator just for it if I get serious…or “waterfall” a Victron setup with the Sunny Islands suppling some level of “grid.”

 

[Hedges]

Does plasma cutter have transformer front end or rectifier/capacitor feeding inverter?

Transformers have inrush (highly variable, has to do with magnetization of core by AC phases), and capacitors have inrush.

So long as they can be powered on without load (unlike compressor motor), could power up through something resistive, such as an Antherm thermistor. The thermistor is automatic, and runs HOT to maintain low resistance.

A series resistor with bypass switch could precharge. That could even be a length of wire, if the resistance is sufficient. For instance a roll of Romex, current goes out through the black, connect to white, back through that. No inductance that way, just wire resistance.

Want to avoid "brownout" with excessive resistance/time, in case SMPS in the device can't handle that.

 

[kommando]

Five 48v batteries so 5 REC's at 60A each is 14kw or 18HP

At 90A is 21kw or 27HP

Even if you reduce those figures to cover what you have on in the rest of the house I don't see a problem unless you have a few other Silverbacks to operate the machines all at the same time.

 

[SilverbackMP]

Five 48v batteries so 5 REC's at 60A each is 14kw or 18HP

At 90A is 21kw or 27HP

Even if you reduce those figures to cover what you have on in the rest of the house I don't see a problem unless you have a few other Silverbacks to operate the machines all at the same time.

Could have quite a few minisplits going on at the same time.

One l8K BTU for my moms house (possibly 2x 6K BTU for two upstairs rooms),

3x 12k for the main area for my shop, 1x 9k for a shed extension, 2x 6K for the mezzanine.

9k for the power shed.

9k for another out building.

Possibly in a 12-18K for climatized storage in a foamed shipping container.

I doubt I will ever have all of these going full bore at once…but worse case.

I can also shut down any of them too when I go to use more power. (They will be shut down in the immediate vicinity of dusty/smokey activity even though I’m going to build filter boxes for those in the shop).

End goal is not to have to worry too much about it and keep adding until I get where I want to be.

If I build a house here, I will definitely need more power.

Workable with this system? Sure. But I don’t really want to juggle power usage too much. I’ll watch all of that on Homestead Rescue.

 

[SilverbackMP]

Does plasma cutter have transformer front end or rectifier/capacitor feeding inverter?

Transformers have inrush (highly variable, has to do with magnetization of core by AC phases), and capacitors have inrush.

So long as they can be powered on without load (unlike compressor motor), could power up through something resistive, such as an Antherm thermistor. The thermistor is automatic, and runs HOT to maintain low resistance.

A series resistor with bypass switch could precharge. That could even be a length of wire, if the resistance is sufficient. For instance a roll of Romex, current goes out through the black, connect to white, back through that. No inductance that way, just wire resistance.

Want to avoid "brownout" with excessive resistance/time, in case SMPS in the device can't handle that.

I doubt they have transformers…judging from the physical size….which are about the size of new school stick welders.

 

[Hedges]

Capacitor inrush, will depend on AC phase at time switch turns on. If it is a problem you can soft-start it somehow. Get that done fast, a few AC cycles, so not brownout. The amount of resistance needed to shave surge current should be minimal voltage drop at no-load operation.

Some SMPS have a soft-start resistor and relay bypass, but most I've seen don't.

We have some 1kW SMPS fed 208 or 240V. Breaker is 6A. Spec sheet shows up to 35A inrush, but I only measured half that after a number of tries. With multiple SMPS it could exceed fast-trip spec of breaker, but some of those document higher current handling for a brief time. Most trip curves extend to zero milliseconds.

A transformer, forget if it was 1200VA or so 120V, but occasionally got massive inrush, might have been 70A?

 

[SilverbackMP]

So here’s a new one. We turned on one load too many and popped that 50 A breaker.

The Sunny Boys remained at green status with no errors and showing 7 Watts (their idle).

Left them that way for an hour or so to see if they would start producing.

Sunny Island was showing mostly ExtVoltLo errors with a few ExtFreqLo errors.

I think Sunny Island was confused as to where to set the frequency after the breaker popped.

What is perplexing is that it hasn’t exhibited this behavior when I manually switch off the breaker before shutting down the generator.

Maybe the breaker starting heat messed to the voltage and frequency just before popping? That’s my theory.

Anyhow, I restarted the system and the Sunny Boys are back to normal behavior and pulling in 700-900 watts each from under the snow.



I doubt this will be a long term worry. I’ll leave enough current for normal living when I reset parameters after I get that 125 A breaker. Maybe set the batteries to be able to charge with 65-70% of that breaker and leave 10-15% or so for daily activities.

And with 72 panels…that shouldn’t be that often unless I’m using a lot of power equipment or if Missouri decides it resides north of the Yukon (once or twice every few years).

 

[G00SE]

Ingersoll Rand 30KW powered by a Cummins 4BT. Bought used six or seven years ago.

That’s a beauty

 

[G00SE]

I’m really pumped for you that you got it ironed out. I had waffled on sunny islands in the past. Even picked @Hedges brain for weeks and got cold feet
Been following this thread with extreme interest.
Went from thinking I dodged a bullet to “ehh these are still worthwhile” all in a couple days ?
As you know, they contain all sorts of usefulness but the quirks were what scared me

 

[Hedges]

I suspect the quirks are mostly about BMS and lithium. Which is everything, these days.
Apparently just settings were OP's issue, hopefully solid hardware and firmware makes it reliable now.

I just added 3x Sunny Boy Storage 5.0 kW to my stable. Those may turn out to be white elephants.
If I can find an economical BMS that talks with them there could be hope.

And I'm getting SI + AGM ready for another backup system. Connected just to keep them at float.