jameshowison
New Member
- Joined
- Jul 30, 2021
- Messages
- 184
My first time charging LiFePo. Using the Jakiper server rack battery, charging with a Victron Multiplus II 48/3000.
I'm a bit confused about a number of things. I've tried this on the two batteries I have, similar results. No communication between the batteries and the inverter/charger.
When the batteries stop taking current, the Victron shows "absorption" (and eventually "float") on the LED, an amp-meter shows 0 through the cables, and the terminals at the battery show 57.4. The BMS, though, shows an OVP state, reports "PackV" at 54.53V. Individual cells show the range of 3.4V (3376mV min to 3428 max). The unit shows State of Charge as full (well, it's just four LEDs, all 4 are lit up). If I change to discharge (unplug from the grid and add a load to the inverter) then all performs well (and the inverter runs for approximately the length I'd expect, given the draw of the little heater I plugged in).
Perhaps I misunderstand, but does the OVP error/state mean that the BMS cut off charging due to something being in too high a state? But shouldn't that only happen if a cell reached 3.7V (3700 mV)? Once OVP kicks in, does that mean that the BMS is not attempting to balance?
Why is the battery showing PackV at 54.53 when 100% would be more like 58? OTOH I understand that the LiFePo curve is very steep at the end, so 54V is 99% charged (using this chart here: https://diysolarforum.com/threads/lifepo4-24v-voltage-chart.22388/). About 10 minutes later the battery still shows OVP but now shows PackV of 54.06V (with a min cell of 3357, most around 3360, max at 3389). Bms status still shows OVP.
Is this all normal? Or a bit strange? Perhaps OVP kicks in because one cell hits 3.7, but by the time I look at it (maybe 20 minutes later) things have balanced down?
Settings details:
Victron settings changed (via usb and Victron Connect app on a Mac) to match recommended settings for the Jakiper battery. ie absorption 57.6v with a float voltage at 55.2. I am using a "Fixed curve" with an absorption time of 1hour. My understanding is that the absorption phase for a LiFePo battery is primarily for balancing, which is why that is set to 1hour. Charge current is set to 20A (Jakiper recommended) but I've also set to 25A and confirmed that the current through the wires changes. So I'm confident that the Victron settings are being changed.
Jakiper manual shows recommended charge voltage of 58.4v. BMS "Charge Cut-Off Voltage" of > 59.2V (3.7 V/cell) and balancing voltage of > 54.4V (3.4 V/Cell). In a youtube video, though, they did recommend 56V as charge voltage.
I do not currently have a shunt in the system (I have a Victron SmartShunt but not hooked up yet).
I'm a bit confused about a number of things. I've tried this on the two batteries I have, similar results. No communication between the batteries and the inverter/charger.
When the batteries stop taking current, the Victron shows "absorption" (and eventually "float") on the LED, an amp-meter shows 0 through the cables, and the terminals at the battery show 57.4. The BMS, though, shows an OVP state, reports "PackV" at 54.53V. Individual cells show the range of 3.4V (3376mV min to 3428 max). The unit shows State of Charge as full (well, it's just four LEDs, all 4 are lit up). If I change to discharge (unplug from the grid and add a load to the inverter) then all performs well (and the inverter runs for approximately the length I'd expect, given the draw of the little heater I plugged in).
Perhaps I misunderstand, but does the OVP error/state mean that the BMS cut off charging due to something being in too high a state? But shouldn't that only happen if a cell reached 3.7V (3700 mV)? Once OVP kicks in, does that mean that the BMS is not attempting to balance?
Why is the battery showing PackV at 54.53 when 100% would be more like 58? OTOH I understand that the LiFePo curve is very steep at the end, so 54V is 99% charged (using this chart here: https://diysolarforum.com/threads/lifepo4-24v-voltage-chart.22388/). About 10 minutes later the battery still shows OVP but now shows PackV of 54.06V (with a min cell of 3357, most around 3360, max at 3389). Bms status still shows OVP.
Is this all normal? Or a bit strange? Perhaps OVP kicks in because one cell hits 3.7, but by the time I look at it (maybe 20 minutes later) things have balanced down?
Settings details:
Victron settings changed (via usb and Victron Connect app on a Mac) to match recommended settings for the Jakiper battery. ie absorption 57.6v with a float voltage at 55.2. I am using a "Fixed curve" with an absorption time of 1hour. My understanding is that the absorption phase for a LiFePo battery is primarily for balancing, which is why that is set to 1hour. Charge current is set to 20A (Jakiper recommended) but I've also set to 25A and confirmed that the current through the wires changes. So I'm confident that the Victron settings are being changed.
Jakiper manual shows recommended charge voltage of 58.4v. BMS "Charge Cut-Off Voltage" of > 59.2V (3.7 V/cell) and balancing voltage of > 54.4V (3.4 V/Cell). In a youtube video, though, they did recommend 56V as charge voltage.
I do not currently have a shunt in the system (I have a Victron SmartShunt but not hooked up yet).
