@TheTerribleTriplet was this DC ripple caused by the Daly cutting of? If so that’s not good at all!
I wanted to look up the specs for the Daly 60A as @johanpre44 is using. The dumb one. But I couldn’t find it on Ali anymore. Think they discontinued them and that would for for a reasson one would say.
Agreed. But cells shouldn’t do that presuming they where (top)balanced before. If they do, the question is what makes them go out of balance. This can only happen after a loooong period of use without any balancing at all. If it happens after a few cycles already it means the cells are not matched well enough in terms of internal resistance and/or SoH.
3.65v cutoff … the cells NEVER got balanced ever by that stupidly low balancing current.
YES!!! The supplier said he had no problems ever anywhere else, but me. Methinks he sold me cells that may not have been balanced, as I bought some of his limited edition 150ah cells and me being new to lithium banks at the time, I did not know how to check … even though I could not check as by the time one has checked 16 cells with a voltmeter on an operating system, the cell/s that shot out would have “settled” a bit.
Really? As I recall, the BMS had two settings, and the highest one was something like 53.5V or something like that. Low for a 16-cell battery. Way too low.
For stability you want a BMS that gives you big margins. One of the best ones I’ve seen recently (the BSLBATT battery) has a static charge voltage of 54.5V. It allows you to push all the way to 59.2V without disconnecting (that is 3.7V per cell). If you go over that, it opens the charge FET. You can push all the way to 61V (and I did, in testing) and all that happens is the battery sits at 59V while the DC bus is at a higher voltage.
Now of course this condition is still not ideal. You can still get a DC ripple, because the battery is not really holding things down as much as before… but the battery remains halfway-connected. If a large load starts at this point, the battery can still discharge. Stability. With your hard-contactor BMS… the power goes out when a large load starts and the voltage bottoms out.
No settings I could access. Sealed unit with no ports.
The doc’s said 3.65v with 30mA balancing vs the new one that can do 160mA and I can increase the 3.65v cutoff up to where I want to go … but I rather go Phil’s idea of 3.4v, or 3.37v and 18 cells.
Just be very careful to check compatibility of the BMS you intend to get with your Growatt Inverter. I had a Growatt for a short amount of time and it didn’t seem to really like to communicate with BMSes.
Interesting. Here in the countries where we have netmetering more or less, batteries or not common at all. Everything is grid-tied so Voltronic isn’t that well known. Growatt however is and the fact that Growatt is using there (good) name to sell Voltronics does say something about Voltronic. Voltronic, as I understood is not the favorite on this forum since the bleu stuff from my country is the best…
I will play around with the settings (already set the bulk charge and float charge to 54.4). Just not sure if the Cell balancing will happen at less than 55V (spec for BMS states balancing happens at 3.5V per cell).
Unfortunately my Multimeter only has 2 digit precision, any suggestions on a good budget option with 3 digit precision? Think I will manually measure all the cells to see if they have the same voltage (plus or minus a couple of millivolts). I don’t think the BMS have disconnected the battery at all since my inverter never switched off and on a couple of times in a short time.
I believe that the inside of most Chinese inverters are similar (Voltronic/Axpert/Growatt/Must), Growatt is apparently one of the better ones. Victron/Deye are very different beasts and much better quality (at a crazy price).
Other thing to add and what some people is misreading is, internal resistance, and this can play a role with a cell that can under charge or overcharge and run away. Some bms , like mine you can adjust the ohm settings per cell so that bms can adjust the things it needs to do. Here some more reading info internal resistance. https://www.evs27.org/download.php?f=papers/EVS27-2790292.pdf There some more info on google about all this stuff
I had the 5kVA version of that inverter and I’ve been following threads about it on another forum. There’s quite a bit of troubleshooting on it available if you just search for it, but yeah, doesn’t seem to be consistently resolved though.
First things first. Put them all in parallel and charge them up to 3,65V until Amperage drops to 0. Do not go over that voltage! Maybe a better (safer) voltage to do so is 3,55 and let them absorb to 0A. Then they are in balance. If you don’t have a charger that can do that let the Growatt charge them till the Daly shuts them off and after that disconnect the cells, parallel them and let them and let them rest for a day. They will now be pretty well balanced as well.
You can do simple measurement in advance to see how well your cells are balanced. Charge them till Daly cutoff. Take your multimeter and check voltage per cell (2 digit precision is ok for this). After that report it here and most of us can tell you wether it is within reasonable values or not.
I’m not sure. Can’t the King blend power and properly talk to Pylontech BMS? That Growatt I had was really only meant to be used with LA batteries and does not blend power.
