Battery problems and LiFePO4

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Revlac Guru Joined: 31/12/2016 Location: Australia Posts: 1293	Posted: 10:08am 11 Jan 2024       The DALY active equaliser arrived today, including the Free Gift "wiring harness" that is essential for it work, the wires are going to need extending to suit the batteries in the shed, might get to that next week. I read a few of those complaints in places, plenty of user error, and not just with the BMS but other system parts as well, I know the installation manual I was given was a bit different instruction to another one for the same BMS.   Quote   I configured the BMS to switch off the charge MOS above a lower specified voltage, this voltage should be around 90% of charge, by programming the Solar chargers to run at 1 volt higher, it should cause the batteries to be "SEMI" isolated from the DC supply system, unless pulled down by a big load on the Solar charges or Solar output drops off. Having done this quite a few times because the shed batteries (white plastic cells) get a bit out of whack, manages to take a photo of the inverters usage the charge controller input and the BMS CHG MOS turned off, all kept running without issue apart from the high cell voltage (set well below usual) that triggered the protection mode, there was nothing to pull that cell voltage back down so it could sit there for some time, or until I give the inverter some extra load that the Charge controller Couldn't keep up with because it is so slow to respond to loads, then the cell voltage is pulled back down and the charge MOS is then switched back on. How I see it with the Charge MOS off, the BMS is like a big Diode and the battery is still accessible to the loads when required. Hmm, I wonder if that makes any sense.     Also when the charge mos switches off it reads or triggers 100% SOC, probably some other settings going on, most of them are still set at default. I will say that the other 2 systems on the house that are setup properly haven't had to trigger any safety condition and likely wouldn't for years to come, hopefully.   Quote   If the Charge MOS is off, the coms lead now becomes a Negative connection between BMS Battery Negative connection and the BMS connection to the System (load) negative rail, bypassing the MOS.  What could possibly go wrong! I wonder is s current sensor on the small black wire would pick this up?   Quote   However, one must realize that there remains the possibility a momentary high charge current if the charge MOS reconnects with the Solar charges not loaded down Thats Actually a good point, But I had the idea the other way round, disconnect instead of reconnect.....I'm well past my last cup of coffee and my brains. Edited 2024-01-11 20:45 by Revlac