hello all I am replacing my boat’s lead acid house batteries with one 12volt 314 amp hour lifepo4 battery. I would like to install a inverter charger too. I’ve been considering the Victron Multiplus 12v 3000 va or Multiplus II 12v 3000va. not sure which one yet. I’ll be using SOK 12v 314 ah or Wattcycle 12v 314 ah battery. Both batteries are smart batteries. The SOK battery has direct connections for Victron equipment. My 3 engine batteries will remain lead acid. What other components are needed to make it all work ?
You will need a GX device, probably a Cerbo GX between the batteries and the Multiplus so that the batteries can control charging and stop discharging if needed.
See the battery compatibility link below.
If you go to the Victron Multiplus product page, click on downloads then one option is system schematics, this gives you example system designs for various cases. This applies to all products.
One battery might not be sufficient for the 3000VA model. Ensure the BMS is capable of the load (including peak loads). I have one 300Ah battery connected to the 2000VA Phoenix model and would say that is the maximum current for the 200A BMS.
You will need a DC DC Charger to keep the LFP happy. Do not connect the alternator directly, or via a battery isolation device. I recommend an Orion XS 1400 or latest 50 model (to avoid VHF interference).
Here is the battery info, The SOK 12V 314Ah LiFePO4 battery features a robust BMS designed for high-power applications, featuring a maximum continuous discharge current of 200A and a peak discharge current of 800A for roughly 7.5 seconds. The recommended charge current is 150A, with a maximum charge current of 200A. I am technically inclined but lithium batteries and inverter chargers are new for me. I would like to a inverter charger that has at least 2k watts of power. It will only be used for short periods of time. Mainly for the coffee maker.
2000W, assume 90% efficiency, input at 12V means 2222W / 12V = 185A so you are right on the limit with the chosen battery and have no leeway if there are other concurrent demands. Some coffee makers can give the inverter a hard time and draw a higher DC current than simple calculations as above suggest. This is the trouble with batteries with inbuilt BMS like this at 12V, the power limits is set by the BMS not the cells. 12V is hard on systems when you want high power, 24V is better. On my boat I have the Multiplus 12V 3000VA inverter charger with 600Ah of batteries and a 500A continuous rated BMS, a bit more capacity than I need, but I know that the system is robust.