Sverige
A Brit in Sweden
@909 I suggest reconsidering whether you need a BMS, if you ever plan to run your battery down to the low voltage cutoff point of the inverter and rely on that to protect your battery from over discharge. It cannot, as the inverter doesn’t see the individual cell voltages in the way the B6 charger can.
Based on below screenshots the low voltage cutoff on that Bestek inverter can be as low as 10V (designed with a lead acid battery in mind). Although you may imagine your Lithium cells to be 2.5/2.5/2.5/2.5V each when that happens, grab a multimeter or hook up your B6 charger in balance mode with a super low charging rate of 0.1A so you can see the cell voltages either during or immediately after a low voltage cutoff event and I bet you’re going to be shocked to see at least one of your cells under 2V, which will quickly ruin that cell over a few cycles as it will no longer stay in balance with the rest of the pack from the internal damage which starts to occur.
The reason is those lithium cells are never fully in balance and never identical in capacity and that small difference between cells becomes a big voltage difference when they run out of energy to provide because they’ve been run down below 2.75V, where they are basically empty.
A $50 80A BMS like a Daly or any other brand will watch the voltage of every cell and cut the power before your inverter over discharges one or more cells, ruining your expensive new battery. It’s up to you.
Based on below screenshots the low voltage cutoff on that Bestek inverter can be as low as 10V (designed with a lead acid battery in mind). Although you may imagine your Lithium cells to be 2.5/2.5/2.5/2.5V each when that happens, grab a multimeter or hook up your B6 charger in balance mode with a super low charging rate of 0.1A so you can see the cell voltages either during or immediately after a low voltage cutoff event and I bet you’re going to be shocked to see at least one of your cells under 2V, which will quickly ruin that cell over a few cycles as it will no longer stay in balance with the rest of the pack from the internal damage which starts to occur.
The reason is those lithium cells are never fully in balance and never identical in capacity and that small difference between cells becomes a big voltage difference when they run out of energy to provide because they’ve been run down below 2.75V, where they are basically empty.
A $50 80A BMS like a Daly or any other brand will watch the voltage of every cell and cut the power before your inverter over discharges one or more cells, ruining your expensive new battery. It’s up to you.