I am new to micro power grids and learning how to use DC-power storage with AC-powered devices. In researching the topic I have read some unsubstantiated points I want to clarify.

  • Battery: Apparently some DC-to-AC inverters are not compatible with LiFePO4 battery chemistry. Is this the case, and if so, how does that incompatibility arise? Is it safe to assume DC-to-AC inverters can work with LiFePO4 batteries unless they explicitly say so? As an example, this AIMS 1500W inverter has a manual that does not mention battery chemistries, so I assume it can work with LiFePO4 batteries.

  • Fuse: I see some inverters come with the option of a fuse kit for the positive wire between battery and inverter, even when the same inverter has all kinds of protections (including over-voltage, under-voltage, over-load cuttoffs). With all those protections, is a fuse only redundant or does it also offer unique protection?

  • Resistor: This component I am least sure of. Because inverters contain capacitors, connecting them with a battery will tend to spark upon contact. To avoid this being a hazardous spark, adding a resistor in the circuit was recommended. How would such a resistor be sized, and would it be added on the positive wire between battery (or fuse if used) and inverter? Is a resistor only needed for certain types or magnitudes of loads? So far I only plan to power resistive loads of <1000W but I want to understand how the system would need to differ for inductive loads of 1000-3000W continuous, <6000W surge.

  • \$\begingroup\$ "Apparently some DC-to-AC inverters are not compatible with LiFePO4 battery chemistry" Says who? Please quote a source or provide an example. \$\endgroup\$
    – Finbarr
    Jul 12 at 16:16
  • \$\begingroup\$ "To avoid this being a hazardous spark, adding a resistor in the circuit was recommended. " That sounds bogus, too. Provide a link. \$\endgroup\$
    – PMF
    Jul 12 at 16:17
  • \$\begingroup\$ Isn't this a product usage question? Check out how much LiFePo battery voltages differ from lead acid battery. It's possible that the undervoltage protection is rated for lead acid batteries, thus it might draw LiFePo batteries too empty and they degrade fast. So if the inverter does not say which batteries are compatible, you need to check yourself which batteries are compatible. And about the fuse, do you really think it is a good idea to omit a fuse, you are dealing with batteries capable of melting wires with tens to hundreds of amps of short circuit current. Resistor may not apply. \$\endgroup\$
    – Justme
    Jul 12 at 17:14
  • \$\begingroup\$ Source for resister claim: youtu.be/1rxSapfp4Hs?t=1098 and I now see it further elaborated in youtube.com/watch?v=ZlrtmJRfSP8 which I think answers my resistor question. I will try to find the inverter which said it did not work with lithium batteries. Because that didn't meet my needs I didn't save the link. @Justme's explanation about undervoltage makes sense, as I saw undervoltage cutoffs lower than my LiFePO4's needs. I was hoping these conceptual questions could be answered irrespective of specific products or anecdotal sources. \$\endgroup\$
    – cr0
    Jul 12 at 17:16
  • 1
    \$\begingroup\$ The job of a fuse is to protect the cable between the battery and the inverter. If you think there's potential for a short somewhere along the route, or you think the inverter may go short circuit and take more current from the battery than the cable can handle, a fuse will provide protection from the cable overheating and maybe catching fire. \$\endgroup\$
    – Finbarr
    Jul 12 at 18:22

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