I found my BMS had shutdown recently due to low voltage but my BMV indicated that I had 72% of my battery capacity remaining. Once I started my engine the battery came back on line within minutes of charging. It appears that my Victron LiFePo4 and the BMV are somehow not synchronized. The battery voltage was below 2.88v while the measured battery usage was only down to 72%. I would expect that the battery should not shut down until 20% as the BMS is set for 80% floor. What parameter am I getting wrong? I would expect much more available power from this 200AH battery??
Have a look at the FAQ section. Plenty of helpful info on shunts and issues like this.
Your battery appears to be flat (the BMV reading is 11.58 V!!)
Charge it! For the first 2–3 hours, use no more than 10–15 A to avoid stressing the cells (otherwise they may swell!!)
Small currents, such as quiescent currents, are not measured!
Your battery is completely flat. In any case, you shouldn’t use anything below 3 volts per cell, so as not to damage the cells. I suspect you programmed the BMV incorrectly. Could you show the settings here?
Thanks for your response. Yes the batteries were flat. I don’t want this to happen. I thought I was at 74%. They shut down in the middle of the night. I’m trying to figure out why so I can avoid this from occurring again.
Thank you, I will look at this section.
The BMV is a monitor, not a BMS, so doesn’t control when the battery shuts down in any way. The BMV “discharge floor” is a setting used to provide the “time remaining” calculation, as detailed in the user and installation manual… and, too, you’ve set that opposite of what you want, if you wanted “time remaining” to calculate based on leaving 20% SOC in the battery, the discharge floor setting should be 20%, not 80%.
Your “charged voltage” is also set too low, meaning the BMV will set itself to 100% SOC far too soon. For that battery, assuming you’re charging it at the recommended voltages, you should have the BMV’s “charged voltage” set to 14.0v
See the BMV user and installation manual here: 7. All features and settings
Justin
Good points
I have adjusted these BMV parameters to hopefully get a more accurate estimate of how much I have used. I still don’t know why I’m going through my usable power so fast. This didn’t happen when I was on a bank of 2 GC lead acid batteries.
Steve
It is because your charged voltage setting in the BMV is at 13.2V, which means with lithium batteries that it is synchronising to 100% before the batteries are full. This should be set 0.1 to 0.2V below absorption, so if you charge at 14.2V set it at 14.0 to 14.1V. This is why you run out of power, you may only be getting the batteries to 50% full. Exceeding 13.2V with a small current is easily done. One of the FAQs I wrote goes into a full explanation.
But the BMV is only a calculator, isn’t it? The BMV has no control of how the battery charges. If there is an error in the charging profile, wouldnt it be in the Multiplus or the Balmar 618 settings?
The issue is that your BMV settings are (or were) wrong, so its calculations were wrong, which means that when you thought your battery was fully charged, it probably wasn’t at all - which means that it didn’t have the stored energy you thought it did, which would explain why the battery shut down before you thought it should.
That said, yes, of course, check all the charge profiles and the entire installation for that matter; where there is one mistake, there are often others.
I appreciate.your suggestions and will check my Multiplus as well as the Balmar settings when I have access to a laptop. The smart battery does tell me when it is fully charged. This being an independent source. It tells me it was fully charged 5 days ago. The question now being was it really fully charged.
The battery does not tell you when it is fully charged; the most it can tell you is its voltage, which is not the same thing. That’s why you put a battery monitor in the system! Please be sure to fully read, understand, and follow all user and installation manuals for your system and/or consult a reputable, experienced Victron systems installer for assistance with your system.
Thanks Justin
Noted