Lithium batteries and microwave use

12thgenusa wrote:
. . . My specific question is, are the characteristics of lithium batteries sufficiently different from FLAs that 200 Amp hours of lithium batteries with at least a 200 amp BMS will operate the microwave without voltage sag causing inverter under-volt alarm or shutdown?

Should be, is not a helpful answer.

Here's a lifepo4 C rate discharge curve at 25c (77f) that may help you better understand the voltage drop that occurs while powering a microwave with a lifepo4 battery. Multiply the voltage in the graph by 4 for a 12v lifepo4 battery. Smaller .7cf microwaves will draw approx. .5c using a 200ah lifepo4 battery. The average microwave will draw .6c - .75c.

As a lot of folks have already confirmed, a 200ah lifepo4 battery with a 200a continuous rating will power a microwave. The only thing that can derail your plan is voltage drop due to the use of too small of cabling. As long as the voltage drop between the battery terminals and the input to the inverter remains below 2% (at 150a) you should be able to access almost the full ah capacity of the battery. Inverters typically start experiencing low voltage alarms (and cut-off) when the input voltage drops below 11v. Assuming less than 2% voltage drop, you should be able to power a microwave with a 150a draw down to 5-10% SOC with a 200ah lifepo4 battery before the inverter low-voltage alarm activates. This equates to a bit more than an hour of runtime.

We use a 200ah lifepo4 battery to power our 11k BTU a/c unit (and small microwave). They both draw roughly the same current (105-110a via inverter). While powering the a/c, we've inadvertently discharged the lifepo4 down to low-voltage cut-off (2.7v at cell level or 10.8v overall) many, many times. After two years of doing so, we've never experienced an inverter low-voltage alarm or shutdown.