coulomb wrote: ↑Thu, 21 Apr 2022, 15:11
Dahhan wrote: ↑Thu, 21 Apr 2022, 12:46
Welcome to the forum.
Thanks a lot for your help and excuse me for using too many quotes. I stumbled upon this fix using Raspberry Pi for continuous monitoring:
I might have the same problem with my inverter ...
Yes, the premature bugs are proudly provided on every factory Voltronic firmware, even the most recent models like yours. When owners complain to resellers, they are told that there is no such problem, it all works just fine.
I can't even discuss it with the vendor (it just went above his head) and my electrician doesn't seem to care that much (it's no big deal to him as long as the inverter's fan in running then everything is just fine)
- Inverter: AXPERT KING II 5KW from Renovo
I'm not familiar with the Removo branding, but it appears to be genuine enough. Do you have a small sticker with the manufacturing date of year 2021 and month 10? They might have given up on those stickers now.
My inverter was manufacture on September, 2021
Option 2: 60A
That seems very low. With two 200 Ah lithium battery modules in parallel, you presumably have effectively one 400 Ah battery, so usually these would be able to be charged at about C/2 or 200 A max. It might be confusing the firmware having such a low limit. I would set this up to near the maximum your model will allow, though that might only be 80 A or so, due to the way the higher voltage Solar Charge Controllers work.
It's now summer where I live and I like to charge with low amperage as I have about 13 hours of sun, But now I cranked it to 80A (Total and Utility) as my battery circuit breaker doesn't allow any higher value and I don't want to pay for a new one:
http://unimarines.com/index.php?route=p ... ct_id=216
Option 26: 57.6v (3.6v each cell)
Option 27: 54.4 (3.4v each cell)
Those are very high voltages. I know the manufacturer recommends them, but that's so that the capacity figures can be achieved, and the manufacturer doesn't care about longevity of your battery. I use 55.2 V and 53.7 V for my 16S LFP battery, carefully chosen by user Weber on this forum. You could go a little higher than my figures perhaps.
You are absolutely right. I used those values to fight back this float voltage bug. We usually have 2 hours of utility electricity daily and sometimes every 2 days, so I figured I use 57.6v to balance to batteries together and top balance the cells inside each individual battery.
After researching a lot about this topic (bulk, absorb & float voltages) I can say that values you're using are the best IMHO:
I finally went with 56v (3.5v each cell to harness the 2 hours of utility) for bulk / absorb, and 53.6v (3.35v each cell) for float with 120 min of absorb time (After seeing the 2 videos I thought it'd be the best for my case).
I note that 12 x 540 = 6,480 W, which is technically 8% more than you are allowed to connect. I don't believe that this should be a problem, although the Isc of two strings is also a little over the 27 A limit (13.9 x 2 = 27.8 A, or 3% over. Imp just squeaks under the limit, so I guess that this is OK. Though it's possible that the SCC firmware might be on the verge of de-rating the charge current a lot of the time. I might be able to deduce something from some SCC firmware recently acquired. But I've been quite busy of late.
I think that I'd never see a 100% outcome from my solar panels, so I figured I oversize them:
1. When the inverter is charging from solar the voltage never exceeds the float voltage value (54.4v) and the charging LED indicator on the front panel never blinks nor stabilize (as it's finished charging and is on float) (pic 6), but when charging from AC it works as normal going to 57.6v for 10 minutes and the stabilizing at 54.4v and at the same time the charging LED on the panel blinks when charging and stabilize when on float (pic 7).
"Normal" premature float bug behaviour is to start in bulk stage (LED blinking) until the battery voltage reaches no more than half a volt under the bulk/absorb voltage setting. So this is not classic premature float behaviour. That might make it harder to fix (by patchers or even by Voltronic themselves).
Then again, I'm not familiar with how the inverter-charger behaves when in timed absorb mode. I would expect it to be much the same, except for the condition for transitioning from bulk/absorb to float stages.
Please excuse me for asking about it again, but I need to be 100% sure as I understood that by setting option 32 to 120 min in my case I force the inverter to stay about the bulk voltage (56v + or - 0.5v) for 120min whatever is the power generated by solar panels (even less than 1/5). I here quote from your comments:
https://powerforum.co.za/topic/9495-axp ... settings/
When it comes to deciding whether to exit bulk charging and enter the float stage, they use the wrong threshold for battery voltage. The threshold should be 0.5 V less than the bulk/absorb setting; they use 0.5 V below the float setting. So a passing cloud could easily cause the battery voltage to fall to say 0.4 V below the float voltage setting, with the current below 1/5 of the maximum charge current setting (setting 02). This could be when the battery is only say 65% charged; if it happens for long enough, the bulk/absorb charge is terminated and the battery voltage falls to the float voltage. At this voltage, the battery could take days to get to 100% SOC, so the battery is chronically undercharged. Not every day, but most days that have some clouds.
If instead the threshold was the absorb voltage less 0.5 V, then this would not happen at 65% SOC, but could only happen at about 99% SOC or higher, which is obviously what you want. Why they can't see this error is beyond me; it's been there from the beginning.
I have no experience with this, since I use patched firmware. No patched firmware is available for your model, unfortunately. What I've been suggesting (and have had no feedback about) is to use the timed absorb feature (setting 32, "Bulk charging time"). That swaps one bug (premature float) for another (time under the cloud is counted the same as time in the sun), but it seems to me (without actually trying it) to be the "least worst" of the two bugs. The idea is to put setting 32 to something like 90 minutes (adjust with experience), so that even though the inverter will decide to praogress from bulk to absorb stages too early, it will be forced to stay in the absorb stage (aiming for the higher battery voltage, setting 26) for at least 90 minutes every day. Due to the factory firmware bug, it could be 90 minutes of shade/cloud/rain/snow, but at least it will be aiming for the higher voltage for longer.
Is there a firmware update available for my inverter (KING II), as a see one available for KING:
No, since no 50.xx firmware update file has been seen. If you can get one from your supplier, even if it doesn't fix the problem, then I could fix at least the classic premature float bug. I note that Weber and I don't have a commitment to patch your model, since it's a higher voltage SCC model.
Your answer is probably no, but do you think I can extract the firmware my self using a BIOS flasher like this:
2. When the inverter is charging and reaches about 55.2v sometimes the light starts to flicker (it's most noticeable on the fridge lamp).
This is presumably when charging from utility, since it's over the 54.4 V float voltage setting. My guess is that with the bus voltage fluctuating with solar insolation, the battery voltage might occasionally over-shoot the target voltage, and the battery's BMS (even though you don't communicate with it) might be disconnecting internal MOSFETs in an effort to protect the cells from over-voltage. By using a bulk/absorb setting of 55.2 V or perhaps 55.1 V, you might side-step this problem.
I believe this is the case
[ Edited Coulomb: fixed the worst of the quoting problems. ]