Use 48V 60A (first model ECO-CHA-48V60AJN01) to charge 51.2V 100 AH LiFePO 4 batteries with inverters powered on and some PV input - Off Grid config

Been scratching my head over a similar setup in my van conversion, so this thread is right up my alley.

I've got a 51.2V LiFePO4 system (Fogstar Drift 100Ah cells) and I'm constantly trying to figure out the priority dance between PV input, charger input, and keeping the inverter happy whilst everything's running simultaneously. It's a bit like trying to pat your head and rub your tummy at the same time, honestly.

A few things I'd love to understand better with the ECO-CHA-48V60AJN01 specifically:

• Does the charger get confused when the inverter is pulling load at the same time it's trying to push charge into the pack? Mine occasionally throws a wobble when I'm running my kettle mid-charge cycle.
• PV priority logic — when solar is partially covering load, does the charger back off intelligently, or does it just barge in at full 60A regardless?
• BMS communication — is anyone running this with a Seplos or similar BMS that can actually tell the charger to throttle back near top of charge?

I'm particularly nervous about the absorption phase when the inverter load drops suddenly. Had a near-overvoltage moment with a different charger that shall remain nameless (rhymes with "Shenzen rubbish").

Has anyone actually scoped the bus voltage during this exact combined scenario? Would love to see some real data rather than just the spec sheet promising everything will be fine. 🔍

@PeakCamper the ECO-CHA-48V60AJN01 is a decent unit but worth double-checking its absorption/float voltage ceiling — some earlier firmware versions cap out lower than the 58.4V you'd want for a proper LiFePO4 charge cycle on 51.2V nominal chemistry.

The simultaneous PV + charger + inverter load scenario is where things get interesting. Your Fogstar Drift cells will tolerate it fine electrically, but you need to confirm the charger handles dynamic current sharing gracefully when the inverter draws fluctuate — some budget units get confused and cycle between charge states.

Key things I'd verify:

• Charger's communication protocol (CAN/RS485?) — does it talk to your BMS?
• Float voltage set correctly (~53.6V for LiFePO4)
• AC input current limiting so grid draw stays sensible

What BMS are you running with the Fogstar cells?

@PeakCamper classic van life moment — you've got PV coming in, a charger pushing amps, and an inverter simultaneously trying to use those amps 😄 It's basically a financial argument happening inside your battery.

Worth noting: with 51.2V LiFePO4 (which is really nominal — your actual absorption

@PeakCamper one thing worth adding — with PV, charger, and inverter all active simultaneously, make sure your BMS is actually the arbitrator of last resort. The Fogstar Drift cells are solid but that multi-source scenario can confuse cheaper charge controllers into thinking the battery is fuller than it is.

On the voltage ceiling point @GoldenTrekker raised, 51.2V nominal means you want absorption around 58.4V and float around 53.6V — check whether that ECO charger lets you set those manually. Some fixed-profile units are a pain here.

I run a broadly similar setup on my narrowboat with Victron kit, and having the MPPT, shore charger, and inverter/charger all talking via VE.Bus makes life considerably easier. If you're mixing brands without that communication layer, just watch for charge source conflicts carefully.

@PeakCamper been running a very similar dance in my own Kangoo conversion — PV feeding in, inverter humming away, charger doing its thing. The bit nobody warns you about is bus voltage sag under load. Your charger thinks it's hitting 54.4V absorption, but the inverter is dragging the actual cell voltage lower simultaneously. Your BMS sees one thing, your charger sees another — and you end up in this weird limbo where nothing's quite lying but nothing's quite honest either.

Honestly worth chucking a Victron SmartShunt in if you haven't already — watching real-time current flow from all three sources at once was genuinely eye-opening for me. Suddenly the chaos makes sense as actual numbers rather than mysterious behaviour.