Hi all.

I currently have a sunsynk 5kw inverter (MCU 3381-1515) and a 5.32kwh battery installed. The install was done a couple of months ago and initially all was fine.

Early this month we had load shedding in the morning and I was curious to see what the battery SOC was. I saw that the battery got drained down to about 34%, which supprised me.

After doing some digging I found that the battery SOC was reducing below the timer settings while the grid was availible. Initally the inverter did hold the SOC at the timer setting.

All settings seemed fine so I contacted Sunsynk support for advice. After much back and forth they advise that the battery firmware needs an update. Strangely Sunsynk does not handle this and I need to arrange with Herholdts to do the update.

For me it does not make sense that the battery firmware is at fault as things innitially worked fine. 

Anyone else experiencing this? 

 

 

23 minutes ago, Killerwatt said:

Hi all.

I currently have a sunsynk 5kw inverter (MCU 3381-1515) and a 5.32kwh battery installed. The install was done a couple of months ago and initially all was fine.

Early this month we had load shedding in the morning and I was curious to see what the battery SOC was. I saw that the battery got drained down to about 34%, which supprised me.

After doing some digging I found that the battery SOC was reducing below the timer settings while the grid was availible. Initally the inverter did hold the SOC at the timer setting.

All settings seemed fine so I contacted Sunsynk support for advice. After much back and forth they advise that the battery firmware needs an update. Strangely Sunsynk does not handle this and I need to arrange with Herholdts to do the update.

For me it does not make sense that the battery firmware is at fault as things innitially worked fine. 

Anyone else experiencing this? 

 

 

Do you have a graph where it went as low as 34% SOC as this one shows 65%.

I will dig it up. I did not want to post that as my timer settings were different at the time (think I let the battery come down to 50% in the mornings).

 

1 hour ago, Killerwatt said:

After doing some digging I found that the battery SOC was reducing below the timer settings while the grid was availible.

Interesting - you mention it happened earlier this month, was this a once-off observation or do you find that the battery drains below the pre-set SOC with grid present repeatedly? I'm sure you've done your analysis, but obviously the time category SOC doesn't apply during LS (only the battery shut down etc.). Can it definitely be excluded that on that particular day there wasn't perhaps a bout of load shedding during which the battery drained more than expected, or that during grid present a geyser drained the battery to it's min pre-set SOC just ahead of load shedding (taking it lower than expected for that time of the night or early morning), say because the setting was on "limit to home", and then LS starts which took you lower than usual? 

I can think of scenarios whereby a high actual SOC can get whacked quickly by a so-called non-essential, when grid is present and the inverter is set to allow non-essentials to draw from battery, and then LS starts when you're already on the back-foot. 

On the settings you posted, you only have one time slot ticked for grid backup, not sure if this is relevant here (not sure what you had ticked when you experienced the issue).

Having to take the battery back to Herholdts (where my SS also come from) sounds like a massive PITA, hope that can somehow be avoided.

As an aside - what refresh rate have you set for your readings? The time intervals seem very long (hence the big steps). You can change that to a 1-minute interval, which results in much more accurate and smooth charts. 

1 hour ago, Kalahari Cruiser said:

You can change that to a 1-minute interval, which results in much more accurate and smooth charts.

I didn’t know this. How?

Via sunsynk.net /. ->  Gateway. Click on More / Settings  and chose time interval for refresh

 

Thank you. 

12 minutes ago, Kalahari Cruiser said:

Via sunsynk.net /. ->  Gateway. Click on More / Settings  and chose time interval for refresh

 

 

@Killerwatt did you have bad production days prior to this happening? This problem happens with other batteries as well, if you don’t charge the battery to 100% for few days. The cells become unbalanced. Try to charge the battery to 100% from the grid and hold it at 100% for couple of hours for the balancing to complete. Then see if the issue is still there. 
If the above doesn’t resolve the issue, the do a firmware upgrade. 

@Kalahari Cruiser Thanks for the tip on the refresh rate. It would be nice to get a bit more resolution. Fair point on the LS and SOC. That particular day could have been a 4hour afternoon seesion as well as morning LS. I need to find the graph of that day to be sure.

@PowerUser You make an interesting point. There have been a few days where the battery hasnt held 100% for much time. I just assumed that cell balancing would occur above 90% for some reason. I've enabled a grid charge tonight to hold 100% for a good few hours. I will monitor and report back.

18 minutes ago, Killerwatt said:

I just assumed that cell balancing would occur above 90% for some reason

No, the balancing is happening at 100% and when it drops to 99% should be finished.

@Killerwatt is it possible that the grid was up but at low voltage? My inverter disconnects from the grid if voltage gets too low, and I'd bet it's not the only one that does this.

Where I live we've been having problems with low voltage. Last week it dipped under 170. And voltage is ALWAYS low on restoration, so my inverter usually ignores the grid for a while and keeps on using battery if there's no PV. 

I think your problem is with the time slots, it needs to run sequentially from 00:00 in the first block. Start your first block (top left) with 00:00 (12 at night) and end your last block (bottom right) at 00:00 again, so you cover 24hr from top to bottom. There are some threads on here that discuss how the inverter does weird things when not programmed this way.

2 minutes ago, JL10 said:

Start your first block (top left) with 00:00

I'm not sure - someone reported experiencing problems doing it that way (start/finish at midnight / change of day). I have my timer starting and finishing at 00:30, and no issues. Maybe what was reported had a different cause altogether. I'm wondering why only timer block is ticked for grid backup. 

4 hours ago, JL10 said:

I think your problem is with the time slots, it needs to run sequentially from 00:00 in the first block. Start your first block (top left) with 00:00 (12 at night) and end your last block (bottom right) at 00:00 again, so you cover 24hr from top to bottom. There are some threads on here that discuss how the inverter does weird things when not programmed this way.

My timeslots have never started at 00:00 and I don't have any issues.

You may just a have a faulty unit. My Sunsynk would not charge from the grid no matter what I specified in the system settings (timer on or timer off, grid charge ticked etc). Sunsynk do not downgrade firmware and there was no update at the time so they had to RMA the unit. You can try do a firmware update and see if it helps. If not send in for repairs but be prepared to wait 12 weeks.

I seem to have the same issue but mine is intermittent. Sometimes it works and sometimes just ignores the Time settings.

I can have it respect times today and tomorrow ignores them as if they don't exist. Very frustrating.