Lithium Iron Phosphate battery charging from engine alternators

[AllanS]

Hi, I have arranged four 280 A-hr LiFePO4 batteries into a 24V "generator" battery bank. These are wired into my main circuit panel as the generator output via a 3000W inverter to provide 120V house power. The batteries can currently be charged via solar panels (900W total) as well as from shore power. This system works very well currently, no problems to solve here.

However, my wife and I are going to be cruising the ICW for a couple months, and while the sun MAY shine frequently and we will frequent marina slips with shore power, I want some extra insurance that I can keep my LiFePO4 batteries charged for overnights when we are at anchor or on a mooring. I have been contemplating adding a couple Victron Orion 12V to 24V DC-DC converters to my house batteries/alternators to provide a third source of changing, from the engines' alternator output. I've read that these DC-DC converters sense when the input voltage (house battery) exceeds 13.8V, and then output 24+ V as output. The largest capacity outputs up to 15A, but they can be run in parallel with two or more units.

Anyone out there tried using this DC-DC converter? If so, did it work well, and how would I connect two of them in parallel, one from each alternator?

Thanks!

 

[dtfeld]

I built a panel with a couple Victron Orion 25A 24-12 V DC-DC converters to allow my 24v inverter battery (I’ll call it my House battery) to maintain my starboard and port batteries while at anchor and hoping to extend my “off grid” capabilities, but I have not had a chance to install and test yet…winter project. I’m still working out the on/off logic as well.

I don’t see why what you propose will not work, and Victron stuff is top notch.

 

[AllanS]

Thanks, DT, I think I'm going to go for it. Get two Orion 12/24V 15A units from Victron, wire one between the port house (12V) batteries and the lithium batteries (24V), and the other between the starboard house batteries (12V) and the lithium batteries. I plan to incorporate 60A fuses on the input side (12V) and 30A fuses on the output side (24V). I'm leaning towards the Bluetooth models, where I can set the start/stop input voltages and monitor the system via the Victron Connect app.
Questions I have:
1. Does it matter where I connect to the 12V input power? Can it be either directly on the 12V battery or should it be at the alternator? It shouldn't matter, right?
2. What inline fuses work best for this application? What are the ones in your photo?

 

[Pgeee]

Out of interest when you say wired into generator output, do you mean you wired into an existing generator circuit

Dc to dc setups apparently have a loss factor in terms of lost energy, but only purists care I think