powerwall acting a little weird - only charging to 91% in advanced mode

[astrorob]

anyone seen this?

last night i tried to lower my reserve percentage (in advanced time-based mode) to let the PW run the AC for a while during peak. i don't know if this caused the problem but just now i found the PW idle but only charged to 91%, even though I'm 30 minutes from peak time starting. in other words, it's acting as though it's reached 100% charge. looking at PVOutput i can see that it reached this SOC at about 11:30AM and has been idle since then.

i switched the powerwall to self-powered mode and it started charging again.

i'm on 20.49.0 which i think is not new, right?

i tried stopping and starting the PW from the web UI in an attempt to reset it but i guess that doesn't do anything. would it be advisable to do a hard reset by cutting off all the power to the gateway and powerwalls?

thanks

 

[jjrandorin]

Those modes use algorithms to try to figure out what to do, so I am not surprised that it did that. Its sort of a black box (the algorithms) but I have read that it sometimes does that if it thinks you have enough power to get through peak from past usage patterns. I have also read here that it can do that based on a large off peak period coming up when it knows it can charge.

I dont use those modes ( i use self powered), but in order to help you deduce it, those who do and have experience with them will likely ask you "what do you have set for peak, off peak, and shoulder... share a screenshot of that screen".

So, I would suggest sharing a screenshot of your settings for those, and discussing what you have set, so that those who use those modes and have a lot of experience with them can help you.

EDIT: I doubt there is anything "broken" or "wrong" so I doubt you need to go through hard reset anything.

 

[miimura]

Mine used to do this in Cost Saving Mode when I was on the EV-A rate plan, especially late in the week like Thursday and Friday. I think it was an artifact of the rate schedule. There was generation during Part-Peak M-F but Off-Peak generation on Sa/Su. It figured that it was better to get the export credit during Part-Peak and recharge back up on the weekend. The problem was that if I had higher than normal Peak usage, it would run out of energy.
Now that I'm on EV2-A the schedule is the same 7 days a week and I use Balanced Mode. Now that I have enough generation, it charges to 100% right around the end of the Off-Peak period at 3pm.

 

[astrorob]

Those modes use algorithms to try to figure out what to do, so I am not surprised that it did that. Its sort of a black box (the algorithms) but I have read that it sometimes does that if it thinks you have enough power to get through peak from past usage patterns. I have also read here that it can do that based on a large off peak period coming up when it knows it can charge.

this thing has been operational since 4 november 2020 and has been in this mode (advanced, cost saving) since the first day it was enabled in the app. only recently has the PW been making it all the way thru the peak period in the evening, and that's only because i had lowered the reserve threshold from how i had it set in the winter. ironically i had lowered the threshold some more last night as described, which i suppose could be the cause of this issue. there's no off-peak period coming up so it could only be the new reserve threshold.

at any rate it has never failed to charge to 100% on any day between 4 november 2020 and today and has finished with > the reserve percentage a bunch of times.

if this is normal behavior then it strongly implies that charging the powerwall to 100% is bad for it. is that known to be the case? i would have thought they never truly charge to 100% and there is some headroom in the battery even when they report 100%. the fact that it kept charging after switching to self-powered mode would imply that there's nothing wrong with repeatedly going to 100%.

edit: @miimura replied after i wrote this - i guess rather than being self-preservation it is more likely to be cost optimization.

i guess i can increase the reserve percentage again after a couple of days and see if that's what's influencing this.

Mine used to do this in Cost Saving Mode when I was on the EV-A rate plan, especially late in the week like Thursday and Friday. I think it was an artifact of the rate schedule. There was generation during Part-Peak M-F but Off-Peak generation on Sa/Su. It figured that it was better to get the export credit during Part-Peak and recharge back up on the weekend. The problem was that if I had higher than normal Peak usage, it would run out of energy.
Now that I'm on EV2-A the schedule is the same 7 days a week and I use Balanced Mode. Now that I have enough generation, it charges to 100% right around the end of the Off-Peak period at 3pm.

yeah, i am on EV-A still. i guess then you are saying the same thing as @jjrandorin and the only thing that leaves me scratching my head is why it took so long for it to do this, unless it was lowering the reserve percentage that did it. still, there's no way it would make it to saturday morning - i only went down from 60% reserve to 45% reserve. to boot, it didn't take effect right away and the ACs ended up running for 1/2 hour at peak pricing, so all of this for nothing

 

[h2ofun]

Mine used to do this in Cost Saving Mode when I was on the EV-A rate plan, especially late in the week like Thursday and Friday. I think it was an artifact of the rate schedule. There was generation during Part-Peak M-F but Off-Peak generation on Sa/Su. It figured that it was better to get the export credit during Part-Peak and recharge back up on the weekend. The problem was that if I had higher than normal Peak usage, it would run out of energy.
Now that I'm on EV2-A the schedule is the same 7 days a week and I use Balanced Mode. Now that I have enough generation, it charges to 100% right around the end of the Off-Peak period at 3pm.

mine seems to work this way in your setings

 

[miimura]

yeah, i am on EV-A still. i guess then you are saying the same thing as @jjrandorin and the only thing that leaves me scratching my head is why it took so long for it to do this, unless it was lowering the reserve percentage that did it. still, there's no way it would make it to saturday morning - i only went down from 60% reserve to 45% reserve. to boot, it didn't take effect right away and the ACs ended up running for 1/2 hour at peak pricing, so all of this for nothing

Lowering the Reserve from 60% to 45% gave it the room it needed to attempt this cost optimization.
My early experience with EV-A and Cost Saving Mode when those modes were first introduced in 2018 was not good. A Tesla Energy support rep even told me that they did not expect Cost Saving mode to work properly if you didn't have generation during the Off-Peak period. EV-A does not have weekday generation during Off-Peak, so I changed to Balanced and never looked back.

 

[astrorob]

interesting, though i mistyped - i think i went from 55% to 45%. still this must have been what did it. i might have been able to figure this out except that for whatever reason reserve percentage changes made in the app don't seem to take effect immediately, though mode switches do.

as far as i can tell it's operating fine in cost-saving mode, though i was really only ever expecting it to just shave off the peak time and not try to optimize the cost further. it's only been in the last month or so that i've actually reached 100% before peak kicked in. to be honest i'm one of those people that wish the powerwall could be at 100% all the time but also want to stick it to PGE, so i've actually been happy with charging to 100% in the morning and then just covering the peak even if i end up with some larger reserve. i know that if the power fails in the middle of the night i might not make it to morning given the always-on loads in the house so i do prefer higher reserves.

i do see the advantage of trying to defer charging to the off-peak time on saturday though.

i will probably just crank the reserve back up until september/oct or whenever we get an extended stretch of hot weather. this hot snap is kind of unusual for march/april and i expect i won't need to run the AC in the evening past tonight for some time. or maybe climate change will surprise me and this is the new normal

 

[jjrandorin]

As I said, I dont use the advanced modes... but reserve percentage changes I make in self powered mode take place in seconds (like 5 seconds or less). I have my gateway hard wired to my network via ethernet though. Maybe the reserve changes in the advanced modes dont apply right away for some reason?

 

[astrorob]

As I said, I dont use the advanced modes... but reserve percentage changes I make in self powered mode take place in seconds (like 5 seconds or less). I have my gateway hard wired to my network via ethernet though. Maybe the reserve changes in the advanced modes dont apply right away for some reason?

not sure but i have observed this multiple times, and i think i read about this lag here. it definitely happened last night - i had almost hit the reserve when the AC kicked in so i went into the app and lowered the reserve but the PW kept acting like it was going to hit the reserve (lowered its output power) and then finally stopped supplying the house...

 

[h2ofun]

As I said, I dont use the advanced modes... but reserve percentage changes I make in self powered mode take place in seconds (like 5 seconds or less). I have my gateway hard wired to my network via ethernet though. Maybe the reserve changes in the advanced modes dont apply right away for some reason?

So what do you gain not using advanced? I using advanced balanced. Set my reserve to 10%. Peak 3pm to 1am. The batteries, charge the house 100% starting at 3pm, and most times do most all during the day when my heater is off. Solar charges batteries and house until 100%, then extras goes back to gird.

 

[jjrandorin]

So what do you gain not using advanced? I using advanced balanced. Set my reserve to 10%. Peak 3pm to 1am. The batteries, charge the house 100% starting at 3pm, and most times do most all during the day when my heater is off. Solar charges batteries and house until 100%, then extras goes back to gird.

I have mentioned this before, but because of when I got my solar (2015) I am not on a time of use plan, so WHEN i use my power doesnt matter in the slightest, just how much. I dont "need" to shift usage to nighttime or anything. I just need to use as little as possible from the grid, in general, to make sure I never go above "tier 1" usage rates.

Self powered mode attempts to use as much of your own power as possible, with no algorithms etc. I have no benefit using advanced modes for myself, because I benefit by pulling as little total power (at all times) from the grid. Self powered does that. Starting about the first week of march or so, through about the last week of october, I generally use no grid power and send power back to the grid for credit (with the exception of a few rainy days etc).

Just like the rest of stuff around energy products, there really is no "one size fits all"... either for installs, or usage.

 

[h2ofun]

I have mentioned this before, but because of when I got my solar (2015) I am not on a time of use plan, so WHEN i use my power doesnt matter in the slightest, just how much. I dont "need" to shift usage to nighttime or anything. I just need to use as little as possible from the grid, in general, to make sure I never go above "tier 1" usage rates.

Self powered mode attempts to use as much of your own power as possible, with no algorithms etc. I have no benefit using advanced modes for myself, because I benefit by pulling as little total power (at all times) from the grid. Self powered does that. Starting about the first week of march or so, through about the last week of october, I generally use no grid power and send power back to the grid for credit (with the exception of a few rainy days etc).

Just like the rest of stuff around energy products, there really is no "one size fits all"... either for installs, or usage.

Interesting idea. I also could probably use less grid by just using battery. Now, they do lose at least 10% compared to grid. So if one has enough, does it really matter. I guess since I am TOU, I want to send ideally 100% of the little solar I do produce back to grid starting at 3. I guess self powered would not do this.

 

[astrorob]

I have mentioned this before, but because of when I got my solar (2015) I am not on a time of use plan, so WHEN i use my power doesnt matter in the slightest, just how much. I dont "need" to shift usage to nighttime or anything. I just need to use as little as possible from the grid, in general, to make sure I never go above "tier 1" usage rates.

i wonder if this was even an option for me - got solar in nov 2015. i already had an EV though so i wanted to get on EV-A. anyway i was under the impression that PGE was forcing TOU plans on solar people even before that date. of course it looks like you are in SCE territory so i'm sure things are/were different.

 

[jjrandorin]

i wonder if this was even an option for me - got solar in nov 2015. i already had an EV though so i wanted to get on EV-A. anyway i was under the impression that PGE was forcing TOU plans on solar people even before that date. of course it looks like you are in SCE territory so i'm sure things are/were different.

I am in SCE territory, yeah. I didnt have an EV then, but oversized the solar at the time with the expectation I was going to get one in 2016. I didnt end up getting it till 2018, cause ... "life", lol. I am glad I oversized back then, though. I just paid my 12 month true up bill about 2 weeks ago, and it was $16 and change. Im basically right on the nose, right now.

 

[arnolddeleon]

I've seen behavior like this before when I was in Advanced/Cost Saving. It seemed to me like the system had decided that it had enough energy in the batteries to ride the peak/off peak. In cost savings mode it seems the system does everything it can to send batteries to the grid. I suspect the system "believed" putting more energy in the batteries wasn't going to help sell more to grid and this avoids the round trip penalty. This is one of the reasons I switched to balanced, to get do as much self consumption as possible while still dealing with time of use.