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Battery management or CT clamp issue?

Troglodytes

Member
Jun 28, 2020
30
25
Florida
Hello Tesla Energy forum...

I have the system listed in the signature installed for a bit less than a year. Tonight I noticed the lights flickering a bit and checked the Tesla app to see power draw and if we had switched to backup.

At first the app showed standby, then flickered to charging, and then to discharging. Less than a second on each status. It proceeded to do the same changes for an hour or so that I was checking on it. The state change seems random in nature.

I switched the setting for the system to self-powered from backup-only and don't see any oddities to the system while on that setting.

I don't believe the flickering lights had anything to do with the charging/discharging/standby indication in the app. The flickering just brought my attention to the app. That belief is based on monitoring for an hour where the lights did not flicker while the app's rapid state stage was happening.

After switching back to backup only. There has been no repeats of the rapid state change for the last hour.

20.49.0 SW version on the Powerwalls. Powerwalls were sitting at 98% SoC when the flickering was happening. The system was on self-powered until the SoC reached 96% when I changed it back to backup.

Thoughts on if this was a battery management behavior that I caught or maybe a CT clamp issue?

I assume it to be a CT clamp issue. How best to check the correct operation or insure that the position of the CT clamp is correct?

Anyone have a good document/reference for the Powerwalls battery management system that includes behaviors?
 

Vines

Active Member
Jul 20, 2018
1,876
2,202
Silicon Valley, CA
Was the sun up or down during this event? Have you experienced the effects of "Frequency shifting" before? What happens to your PV production when the flickering happens on self powered mode?

The battery management is all internal to the Powerwall 2 AC, so that's unlikely unless one of the units is outright failing.

What happens when you go to backup power by opening the main breaker? It would be strange for a CT to suddenly just fail unless someone was messing around in the panel, or the settings.

How long between changes of state in your app? You said each state lasts less than a second?

I know a good bit on the design side but as I still don't have my system installed I am not the best at troubleshooting.
 

getakey

Active Member
Jan 28, 2020
1,247
413
95762
are the CTs Nurios?
I had one fail. Installer said he has never seen one fail before. The behavior was the app started reporting strange flows
 

Troglodytes

Member
Jun 28, 2020
30
25
Florida
Sun was down.

No frequency shifting issues that I am aware of.

Nighttime experience with the issue only so far. (Will be monitoring more closely now to see what happens during PV production times.)

Have not tried switching main breaker related to this issue. Last time I did so was months ago and behaved as expected; that being rapid switch from grid to batteries.

State changes seemed to correspond with data pulls in app. iPhone shows a little spinning icon next to wifi signal strength indicator. That spinning icon I believe represents data being exchanged between app and gateway. State change coincides with the spinning icon showing and disappearing. Frequency of the appearence of the spinning icon is 4 seconds.

Issue has returned as of this post. 9 polls of data stayed standby, then 3 polls showing charging, then 2 of standby, have also seen discharging too.

No changes within panel or settings of recent.

Nurio, yes. Assume the CT clamps are from Nurio. Looking at pictures from install day I can only tell that the CT clamps have a black and white wire each. I can't see any labeling to confirm manufacturer.

Thanks for your responses and thoughts on this!
 

Vines

Active Member
Jul 20, 2018
1,876
2,202
Silicon Valley, CA
Yea, its the Neurio CT's that are the only ones we have seen fail. Gather more data and reach out to Tesla support, they should be able to remotely see your issues and help confirm. Not likely to be charging when sun is down unless that's somehow enabled.

The only CT otherwise that enable charging is the PV ones, so I would suspect them at first.
 

h2ofun

Active Member
Aug 11, 2020
2,464
423
auburn, ca
Was the sun up or down during this event? Have you experienced the effects of "Frequency shifting" before? What happens to your PV production when the flickering happens on self powered mode?

The battery management is all internal to the Powerwall 2 AC, so that's unlikely unless one of the units is outright failing.

What happens when you go to backup power by opening the main breaker? It would be strange for a CT to suddenly just fail unless someone was messing around in the panel, or the settings.

How long between changes of state in your app? You said each state lasts less than a second?

I know a good bit on the design side but as I still don't have my system installed I am not the best at troubleshooting.
Is there documentation as to where to put the CT's in a setup?
 

h2ofun

Active Member
Aug 11, 2020
2,464
423
auburn, ca
Last edited:

Troglodytes

Member
Jun 28, 2020
30
25
Florida
Thanks for the link. My install happened just before the Gateway 2's started to be used in the US. So, I actually have the original Gateway, but its good to see what the install guide says for a compare/contrast purpose. Based on the link and my pictures from install I would expect if it is a CT issue its going to be the solar production leg. Unfortunately I'll have to open the panel to confirm as I can't quite tell from the pictures which leg of the solar its on. That will be done at a later date due to other projects at the house.

Whole house here too BTW.

Some additional information on what I've seen since last night.

I ran the house on self-powered last night and had a reduction of a bit more than 10% SoC. Pretty normal for this house when AC/heat isn't needed. I left it on self-powered as PV production started up and saw flow from solar eventually get split between house and Powerwalls.

Fairly thick clouds all day today so production was low, but enough to charge the batteries fully and excess production shifted out to the grid.

Electric hot water heater has kicked on a couple of times in the afternoon and I saw grid draw for a little bit. But, otherwise it appears to be behaving normally at the moment (no flickering of status between charging/discharding/standby).

Something I will note here about this system is that normally I never see this system at 100% SoC. Normal for it in standby is to report 98% SoC and bleed down to 97% SoC over the course of the day and then 'sip' solar at first and last light/production of the day when the production is in the tenths of a kW to get back up to 98% SoC. Well after yesterday and changing from backup > self-powered > backup the SoC sits at 100% SoC.

I will check behavior and update this post again after production ends and a few hours have passed later tonight.
 

Troglodytes

Member
Jun 28, 2020
30
25
Florida
Last night (no solar production) I left the system in backup mode at 100% SoC. I observed the app showing grid-to-house usage only.

Later in the night (no solar production) I switched to self-powered. App showed batteries-to-house usage only.

Still at night (no solar production) I switched back to backup with 98% SoC. App showed grid-to-house only.

So far today everything seems like its operating properly.

The original problem of the fast state changing indicator in the app hasn't happened again and hopefully never does. But, I don't have an explanation I can provide for why it happened in the first place at the moment.

Thanks again for the comments and reads of this post.
 

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