January 17, 20232 yr A client has asked me about using a lithium battery with that inverter. Some smaller inverters have issues with lithium batteries because they can't set their low cutoff voltage properly and when discharging the battery is at risk of BMS cutting off - needing a reboot. What's your experience? Edited January 17, 20232 yr by RobM
January 17, 20232 yr 1 hour ago, RobM said: A client has asked me about using a lithium battery with that inverter. Some smaller inverters have issues with lithium batteries because they can't set their low cutoff voltage properly and when discharging the battery is at risk of BMS cutting off - needing a reboot. What's your experience? On that Synapse inverter you definitely are able to change the low voltage cutoff voltage. Picture below shows inverter cutoff voltage set to 12V. This is important as if the lithium battery BMS turns the battery off due to low voltage, then the inverter won't turn on as it needs 12V to power up. The only way to get things working again is to connect an external charger to the battery so that the BMS will turn back on again. Edited January 17, 20232 yr by GreenMan
January 17, 20232 yr 49 minutes ago, GreenMan said: On that Synapse inverter you definitely are able to change the low voltage cutoff voltage. Picture below shows inverter cutoff voltage set to 12V. This is important as if the lithium battery BMS turns the battery off due to low voltage, then the inverter won't turn on as it needs 12V to power up. The only way to get things working again is to connect an external charger to the battery so that the BMS will turn back on again. Just a question. If the battery switched off the power from an external charger should not get past the BMS to charge the battery to get it to switch on. Is this assumption correct?
January 17, 20232 yr The BMS has MOSFETS that turn on/off discharge current and separate MOSFETS that allow current in other direction to charge or not charge. After connecting the external battery charger, once the voltage across the cells has risen to the required voltage the BMS turns on the discharge MOSFETS. The external charger can then be disconnected as the Synapse turns on and it can then supply further charging current to the battery.
January 17, 20232 yr 31 minutes ago, GreenMan said: The BMS has MOSFETS that turn on/off discharge current and separate MOSFETS that allow current in other direction to charge or not charge. After connecting the external battery charger, once the voltage across the cells has risen to the required voltage the BMS turns on the discharge MOSFETS. The external charger can then be disconnected as the Synapse turns on and it can then supply further charging current to the battery. Thank you. I know of a case where even support of a make not mentioned switched off and even if the engineer had means to charge he had to take it in for them to do. The 2 previous times the method advised by support the guy could get the BMS to switch on.
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