Thinking of making the switch to lithium from lead acid

[aaarneson]

I am looking into the batteries below to replace the batteries I currently have when they start to go bad....they are only about a year old so I am looking into what I may need now.

First question...do I need to make any changes to my current system....in regards to the components?

Second question....How many batteries would I need to match the battery bank I currently have?

Is there anything else I may need to know that may not be obvious?

Simpliphi PHI-3.8-48-60-M 3.8kWh 48 Volt Lithium Ferro Phosphate Battery

Thank you

[raysun]

All your equipment is LiFePo4 ready. SimpliPhi 3.8-48 are used by folks on this forum with good results.
The 415AH lead acid battery is 207AH net usable. They may be drawn down more or less in actual usage, you should be able to determine that. If on OpticsRE, its a trivial exercise.
Phi specifies two battery blocks minimum (to maintain the warranty.) That would be 150AH @ 80% = 120AH usable. Three = 180AH @ 80%. Four = 240AH @ 80%.
Bear in mind LiFePo4 charge efficiency makes a greater percentage of PV harvest available for servicing daytime loads.
Have new battery cables made to parallel connect the blocks to battery bus bars. Its important that the battery block to bus bar cables be electrically identical, and stay that way. I use these folks: https://www.batterycablesusa.com
They are fast, reasonably priced, and good.
A pair of bus bars like these will connect up to 5 blocks: https://www.solar-electric.com/victron- ... cover.html
The pre-connected FlexPower One battery cables are fine for the bus-bar to system connection. No fussing inside the DC cabinet or inverter is necessary. (Except to unplug the Remote Temperature Sensor cable used with the existing battery. LiFePo4 does not want temperature compensated charging.)
Configuring for Phi charging is simple. You can search or ask later for details.
Consider adding solar panels. While not strictly necessary, it can make a big difference to the easy operations LiFePo4 supports. We use a lot of juice, and when we went from VRLA/AGM (efficient lead acid) and 4kW array to LiFePo4 and 7kW (in two arrays) our backup generator went from 8% of our annual power contribution to 1%.

[aaarneson]

Thanks for all of that. So, at a minimum 2 batteries up to 4 would be good?

[raysun]

Thanks for all of that. So, at a minimum 2 batteries up to 4 would be good?

Yes. 2 will maintain warranty requirements, and provide about 6kW of battery power. Four puts you squarely into 12kW usable capacity. We have 6, use about 12-14kW power a day, and usually discharge the battery 35% overnight (leaving 45% more available capacity in the bank.) Another nice thing about these batteries is you can start with 2, and add more blocks as budget permits.

[aaarneson]

That is good to know. I also like the idea of better charging when loading up in the day. "Bear in mind LiFePo4 charge efficiency makes a greater percentage of PV harvest available for servicing daytime loads."

[raysun]

That is good to know. I also like the idea of better charging when loading up in the day. "Bear in mind LiFePo4 charge efficiency makes a greater percentage of PV harvest available for servicing daytime loads."

On the average day my battery is fully charged before 11AM, and I guess we waste fully half the potential PV harvest. I'm thinking of setting up a free roadside charging station for homeless Tesla drivers.