SOC is different to bms control.
CVL and CCL do not come from a shunt.
The batteries have balancing - correct and expected. But now you also have the ve bus bms (and for some systems other models depending on system choice- this is external) is needed. This is different to other manufacturers that have it all in one inside the battery.
The BMS is what is controlling the system. This bms is different as it connects to the ve bus (quattro) not the can like other batteries, that does not mean it is not doing a job. Its just doing it differently.
I know, but what device is doing it? Sometimes it seems to be the quattro, sometimes the smartshunt and if its the quattro and not the smartshunt (as I have set it to) then what is the point of having a choice? I note the smartshunt does indeed not have settings for CCL or CVL so is not actually acting as a BMS. WTF is victron doing? Offering a choice that effectively does not exist.
OK set to “automatic” and the system chose “SMARTSHUNT”! I am guessing that its actually using the settings in the quattro, but who knows? It is all starting to look a bit ad hoc, with stuff added in layers over the years and now nobody really knows exactly what is going on, and probably the original programmers have long since left.
The only good bit is that, according to my installer who rarely uses Victron due cost, the others are much worse!
NB Cvl & ccl could come from a smartshunt, because it could hold the settings as its (a bit) smart.
That is because it is not a Battery Management System. It is a monitor for State of Charge.
The Ve bus, or quattro in your case, with synchronise it’s SOC to the monitor set in the GX, so if the shunt is set than that is what is bases things on.
Note the shunt needs regular charging over a certain voltage to auto synchronise as well. So hovering would also cause drift there as well, as it does on many batteries.
I would NEVER buy a LFP battery without an ACTIVE balancer. But this is not the question. Somebody said that it is not good if a LFP battery is charged full every day. And I doubt this very much. A LFP battery does not lose capacity if it is fully charged every day. When your battery only has a passive balancer then the balancer needs more time to balance.
It is just like with mine. I have a JK Inverter BMS with phenomenally inaccurate current measurement—particularly at low currents—and this inaccurate current measurement results in a phenomenally inaccurate SOC determination. I have also installed a Victron SmartShunt in parallel with the BMS. Here are the readings from both:
BUT why does everyone miss the point I have made from the start?
WHAT SYSTEM sets the full charge voltage and balancing time?
Some say its the BMS (claimed by victron to be the smartshunt), which it clearly is not as no voltages and times are defined there.
Some say its the battery onboard BMS, which doesn’t have such data, just balances and flags fault conditions.
Maybe its the Quattro, but the ability to alter these are limited and changing these does not seem to alter charge profile.
Maybe its the Cerbo but equally so.
Since almost all battery descriptions warn about overcharging and the benefits of not being close to full charge (as in 56V/16 cells) or (or course) excessive discharge I am doubtful if twice daily balancing to 56.8V is a great idea and that doing it once a week is not preferable.
I totally agree that an active balancing if preferable, but not what I have with victron smart Li batteries.
Where though? The product pages all describe all their shunts as a monitor?
The BMS for the Victron battery ranges is described as a Battery Management System.
This is my point, the BMS is a separate item, see the product page. All their batteries say in their respective manual not to use them without the purchase of a one of the BMSs -separately sold -to manage the battery.
All i am hearing is some people don’t know the products, are speaking as if they do, and no one is reading and checking the manuals.
This depends on your installation and how your battery is charged. In an ESS normally the battery has a BMS which communicates with the Cerbo, and in the Victron console → Settings → System Setup → Charge Control you define which device has control. In the Victron console → Settings → System Setup → Batteries → Battery monitor you define the battery monitor. In my system the JK Inverter BMS has control, but the Victron Smartshunt is used as battery monitor.
I am not familiar with Victron batteries and their special BMS, but probably they take the values from VeConfigure:
You clearly did not read my post with a screendump of the remote console for the BMS. I attach another with it set on automatic showing its chosen the smartshunt. Not my idea, victrons.
I’m not disagreeing with you conceptually, but trying to work out what is ACTUALLY being used and how to set it.
Yes, I know, that’s how it worked before the smartshunt was installed although it didn’t actually use the figures I set.
You will note I have posted mine above at the start of the thread for you to read.
Interestingly your absorption and float are not the default values, certainly when originally set up (56.2 and 55V IIRC). Last I tried reducing these, it didn’t actually have any effect. Further you cannot set absorption time (actually balancing time) below 1 hr which is far far too long if done daily.
While that is true, an absorption time longer than necessary has no negative impact.
The JK Inverter BMS sets the SOC to 100% after one hour of absorption time (i.e., one hour after reaching 55.2V). The SmartShunt sets the SOC to 100% after reaching 55.2V, AND after the charging current has dropped to (in my case) 2% of the nominal capacity, AND after a further 3 minutes.
Since the SmartShunt serves as my battery monitor, the SOC is set to 100% based on its specific settings. However, the JK BMS retains control over the charging process; consequently, it continues charging—via the absorption phase—at a near-zero current until, approximately 30 minutes after the SmartShunt, the SOC on the JK BMS also jumps from 99% to 100%. This arrangement is perfectly fine and entails no disadvantages whatsoever—neither for me nor for the battery.
I am aware of all of this, but that’s NOT what victron devices are SAYING. That’s why I am posting. There is little point repeatedly stating that BMS, which is in fact a combination of things, battery protection and charging regime specifically, is not directly related to SOC% because that is not the question.
as I said before, cell safety reporting and (crude) balancing electronics reside in the Victron smart lithium battery. This is non-adjustable (and indeed has no need of adjustment). We surely all agree on this.
The cerbo reports that BMS is managed by the smartshunt. That is just a fact and its probably wrong, but there you go. If the smartshunt had details of charge voltages (balancing and float) and balancing times or (even better) used bluetooth to read the cell voltages and stop when balanced then, via the various bus and cerbo, it could work as a (very good) BMS. However I do not belive the smartshunt to be (part of) the BMS, no matter what the Cerbo claims.
When charging from the grid I think the Quattro settings are in control as I can stop balancing from happening Mon-Sat by setting charge levels to 95%, and Sunday it balances as its set to charge at 100%. This works as per manual.
The MPPT will always start a sunny day by going into full 100% charge and balancing. Every sunny day (and if the repeat time is short more than once a day). The MPPT is described as “controlled externally”, probably by the Quattro. HOWEVER I think this control is only partial, or at least is not very smart as it seems to pick the default (57V and 1hr) smartlithium charging profile every day. There is no way to setup this device from the Remote Console, oddly I think it is possible if the quattro is not connected, from distant memory, perhaps I should try bluetooth?
So the question still is, how to stop the MPPT from doing a total rebalance at high voltage every day, which is not needed or wanted. I will disagree with posters that state repeatedly charging to full balancing capacity has no effect on battery life as this is stated as a problem with Li batteries all over the web. Its a second order life reduction, but why have this when its not needed and its very wasteful of energy?
Please show these statements in the web. I have not yet seen only one. I am very certain that charging an LFP battery to its cutoff voltage every single day—and keeping it there until it is truly full (i.e., until the charging current has dropped close to zero)—has absolutely no negative effect on its lifespan or capacity.
However, one can indeed find a great many reports online—and my own experiences with the JK Inverter BMS corroborate this—describing instances where a BMS with poor current measurement quickly arrives at an extremely inaccurate SOC, precisely due to inadequate cell balancing; if additional protective measures are lacking, this can lead to the deep discharge of individual cells and cause genuine damage to the battery.
Well I only did one search which came up with lots of near identical results. Just search “should I fully charge my lifepo battery every day”. Not something worth discussing further.
Search assist précis as:
"Charging LiFePO4 Batteries
Daily Charging RecommendationsYes, you can fully charge your LiFePO4 battery every day. However, for optimal longevity, it is advisable to follow the 80/20 rule:
Charge to 80% for daily use.
Charge to 100% only when necessary, such as before a long trip or when you need the full capacity.
Benefits of the 80/20 Rule? Following the 80/20 rule helps to:
Reduce stress on the battery.
Prolong the overall lifespan of the battery.
When to Charge to 100%? You should consider charging to 100% in the following situations:
Preparing for extended use or trips.
Ensuring maximum available power for emergencies.
By adhering to these guidelines, you can maintain the health and efficiency of your LiFePO4 battery while still having access to its full capacity when needed."
Love the AI post you should probably edit it to be more. Human. but anyway.
The bms already uses the cell in the 80/20 range. If you chrck the actual voltage range of a cell vs what the bms permits.
The perpetual lie on the internet is what has been regurgitated all overnis what you havebposted above.
I’ve been using Zn-Br flow batteries for the last five years, which like 0-100% every day. They are no longer available, so I’ll be adding LiFePO₄ in a couple of weeks to enlarge my ESS. I’ll need to work out a way to keep dis/charging the Zn-Br flow batteries to 0-100%, but limit the LiFePO₄ batteries to 20-80%.
