I need to report on this. We all know that Pylontech batteries starts acting out after 2,5-3 years. You will receive constant alarms every time the battery reaches 100%.
In some cases and if left for too long, the damage will be irreversible and the brick would have to be replaced. So far so good with the claims as Pylontech is honoring their warranty’s without any exception (Not true! as CNBM is the only Pylontech importer that is looking for excuses to honor the warranty). The more reputable importers will even offer a refund instead of a replacement. The refunds is normally enough to replace the bank with a freedom Won slightly bigger than the original Pylon bank.
Victron was blamed to contribute to this high voltage issue, but imo because they are one of few, if not the only brand that will report the error messages received from the BMS.
From what I could gather is that Victron worked very very hard to develop a new “Charging Algorithm” for the Pylons and I have tested it on a few problematic sites with great results.
In short, it looks at the highest cell voltage and works its magic based on this value. The alarms stop on day one and the pack voltage drops. Over the next few days the pack voltage will gradually increase to reach 100% again.
You will need the following to implement this in your own system.
1: Firmware on the batteries that will report Lowest and Highest cell values.
2: For now the latest Beta/Candidate release on the GX device. This will also be included
in the latest 3.50 stable release in the next few days.
I would strongly recommend that if you are running a Victron System with Pylontech batteries to install the above. It will save you a lot of trouble in the future.
I have been testing this for about a month and it works well. 100% SOC isn’t reached immediately but this is not an issue. Charged voltage (52.4 is also a lot lower than the previous settings (Pylontech recommended))
Mine have also started giving warnings once or twice a month. 2 of the batteries were purchased in 2019, the other 2021.
I don’t have the correct firmware for the cell values, which leaves me wondering if they would honour the warranty if I do change firmware and it doesn’t resolve this? My issue is not currently the warnings but more around lifespan of the existing pack and possible “irreversible” damage that has already occurred.
Knew this balancing thing will evolve. It is all software driven.
Cell exceeds a certain level, do something with the charging to give the balancer time to balance without affecting overall system performance too much.
How to balance in the best way, JK seems to be next level with this new 5th generation one.
And NEEY with its 4th generation active balancer.
I imagine the mainstream battery suppliers will probably follow in due course.
Till then, do as Jaco posted. Will help a hell-of-a-lot today for Pylontech users. Respect.
There is a pretty new battery on the market. Ran into a few of them on installs I have inherited. They dont do well at all in parallel and I am used to removing the worst one and returning it for a fix/replacement and after reinstalling that one, I remove the second one and have that one replaced. Did it on a site last week and contacted the supplier to find out where I could drop the battery. They asked me to put it back, they will send a technician to verify system settings and to connect an active balancer to the cells. Will leave it there for 2 months and then remove it again. Asked them why? “Because we believe in our product” and if used correctly and setup was done correctly it should not go out of balance.
First battery company I know of that does this, still not convincing enough to start installing them.
You were going on about voltage deltas last time we spoke… This is a lot simpler. This looks at the voltage of the highest cell, and if it exceeds 3.485V it starts to penalise the charge voltage until it all evens out. So either you end up with a battery that is perfectly balanced with all the cells at exactly 3.485V… or (more likely), you end up with a battery that is 99% full with one cell around 3.5V and the rest just below it.
Some tests we were running on batteries with an imbalance in the field (one of our trusted resellers/installers did the tests) showed very good results. By putting the system in Keep Batteries Charged for a few days, and watching the cell voltage chart, you could visibly see it improve over the course of a few days.
Edit: Why 3.485V? Because I am freaking allergic to charging LFP cells over 3.5V, especially when the battery raises high voltage warnings just 0.05V later at 3.55V. I wanted it just high enough that 100% can be reached and the balancer works properly.
Theoretically this shoiuld then work for any lithium that reports its minimum and maximum cell voltage. This new Algorithm should work on other manufacturers as well. I have just decided to test this on a BSL site. Will report back. I will also start testing on a Freedom Won site.
Well, it is only applied to 15-cell Pylontech batteries right now. The ideal is still that the BMS does this work (not us). And quite a few of them do this properly these days, eg BYD (Flex, Premium) and FreedomWon (Lite, not eTower).
PoTAto POtato … go left around the obstacle, or right … same thing at the end of the day … action is required.
Balancer can only get one so far UNLESS you have amps balancing, not mA, like i.e. a NEEY or some such. Ps. See there is a 10a NEEY out.
I’m just super happy it is in motion now.
Hope it becomes standard that one day, irrespective of BMS make, that if the Venus/Cerbo sees individual cell volts, do something if volts go above 3.485v.
Personally I prefer 3.45 - even better, make it a user setting one day under DVCC … hint hint.
I don’t think I’ve ever really figured out what they mean with the 0101, 0102, 0103. Is it actually just pointing to the battery module? So in the screenshot’s instance the highest and lowest cell were in battery module 1?
The spec says it is a free-form ascii representation of the module and the cell. How the manufacturer chooses to indicate it, is up to them. In this case it looks like it just tells you in what module the cell is.
To visually see it, go to VRM, Advanced tab, add a custom chart. Select “System” as the Device, and “Effective charge voltage” as the parameter.
Then notice how this voltage is pulled down when the battery gets closed to full, to make sure the highest cell is kept down.
In practice you will see the battery stops charging around 52.2V (that is what I see in most systems), and 99% SOC, and then after some time it will reset to 100%.
This is a lot simpler. This looks at the voltage of the highest cell, and if it exceeds 3.485V it starts to penalise the charge voltage until it all evens out. So either you end up with a battery that is perfectly balanced with all the cells at exactly 3.485V… or (more likely), you end up with a battery that is 99% full with one cell around 3.5V and the rest just below it.