September 28, 20232 yr I have a customer with an Axpert 5kVA Inverter Charger, 12 x 410W Solar Panels, and he has just bought a 5.2kW Deye Lithium Ion battery. I set it up using typical Bulk and Float Voltage settings, but it looks like the battery is only about 50% when fully charged. On the battery it says the voltage range is 43.2V to 57.6V, do I use the 57.6V as the Bulk Charging Voltage, and the 43.2V as the cut-off voltage? Your help will be greatly appreciated, I have tried googling the settings but they don't seem to exist.
September 29, 20232 yr On the battery it says the voltage range is 43.2V to 57.6V, do I use the 57.6V as the Bulk Charging Voltage, and the 43.2V as the cut-off voltage? That probably means it's a 16S LFP battery (16 X 3.60 = 57.6 V). But 3.6 V is an absolute maximum voltage; don't use that. Similarly, 43.2 V is 2.7 V per cell, close to cell death. I would use 56.0 V for bulk, perhaps 55.0 V for float (for longevity; personally I use 53.7 V), and 48.0 V for cut-off (mainly because you usually can't choose any higher than that). Edited September 29, 20232 yr by Coulomb
September 29, 20232 yr Author That probably means it's a 16S LFP battery (16 X 3.60 = 57.6 V). But 3.6 V is an absolute maximum voltage; don't use that. Similarly, 43.2 V is 2.7 V per cell, close to cell death. I would use 56.0 V for bulk, perhaps 55.0 V for float (for longevity; personally I use 53.7 V), and 48.0 V for cut-off (mainly because you usually can't choose any higher than that). I use similar voltages with my Pylontech batteries, but the charge indicator on the battery is only going up to 3 out of 6 lights. That is why I am tempted to increase the bulk charge voltage to 57V and the float voltage to 56.6V, I also use 48V as the cutoff voltage which usually is close to the 20% limit too.
September 29, 20232 yr I use similar voltages with my Pylontech batteries, but the charge indicator on the battery is only going up to 3 out of 6 lights. As far as I know, Pylontech batteries are always 15S, so absolute max voltage for them is 3.60 x 15 = 54.0 V. Any more than that, and the BMS will disconnect, which can't be a good thing. If you're mostly charging from solar, then you might be getting bitten by the premature float bug. That would explain the low state of charge.
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