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I have a sump pump system that includes a 12 volt backup sump pump. It is managed by this Pump Spy system: https://www.amazon.com/PumpSpy-PS2000-Battery-Internet-Monitoring/dp/B07N8FY4L9 I have a 200Ah AGM battery. I'm tired of the AGM batteries losing total capacity so quickly. I'm looking at a 200Ah Lithium Iron Phosphate battery. I understand LiFePO4 needs a different charger that supplies 14+ volts. The Pump Spy brains charges the battery (12 volt) and monitors the health. I'd like to keep the Pump Spy monitoring functions working, but charge the LiFePO4 battery to full capacity. I asked, and there is no supported way to disable the Pump Spy charging function. Is there a good way to connect a proper charger without interfering or conflicting with the built in Pump Spy charger? I'd be fine preventing the PumpSpy charger as long as it is still able to monitor. Thanks.

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  • \$\begingroup\$ Unlikely because the Pump Spy because if the Pump Spy is any good, it will know when when the battery isn't properly charging when its trying to charge it and spit an error message. \$\endgroup\$
    – DKNguyen
    May 5, 2021 at 21:33

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3.4V per cell (13.6V on a 4 cell battery) gets you more than 90% charged

3.65V per cell (14.2V on a 4 cell battery) is also acceptable, but only gets another 10% energy into the battery.

You can probably just connect the LiFePo4 battery in place of the lead acid battery and get acceptable performance. staying below 100% charge will probably result in a longer life for the battery.

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  • \$\begingroup\$ Thank you! This is the battery I'm looking at: amazon.com/gp/product/B088RM4W48 The seller answered a similar question with "You can use the lead-aicd battery charger to charge our lithium battery. But we recommend lithium battery charger because on one hand, lead-acid battery charger can only charge our battery to 90% full and might influence our battery performance in long term use. On the other hand, lithium battery charger is designed for our lithium battery and can maximum its performance. And it’s also ok if you use your lead-acid battery charger in a short time." \$\endgroup\$
    – Matthew
    May 6, 2021 at 3:11
  • \$\begingroup\$ If the only real issue is that it charges to 90%, that is fine. \$\endgroup\$
    – Matthew
    May 6, 2021 at 3:11
  • \$\begingroup\$ PumpSpy engineer got back to and said their charger is 13.8V. I think that will be enough for me. It has to be better than the AGM batteries I have where the vendor is overstating their capacity and they lose capacity way to quickly. \$\endgroup\$
    – Matthew
    May 7, 2021 at 16:08

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