Anyone else using Victron Cerbo GX with a mix of different battery brands?

Running a Cerbo GX in my off-grid cabin and it's been solid for monitoring, but I've got a bit of a Frankenstein battery setup — two Fogstar Drift 100Ah LiFePO4s alongside an older Renogy 200Ah AGM I haven't got round to replacing yet. The Cerbo sees everything through a BMV-712 shunt, which works fine for overall capacity tracking, but I'm not fully convinced the state of charge readings are accurate given the different chemistries pulling at different rates.

The main issue is the charge parameters. I've got a Victron Multiplus 24/3000 doing the work and I've had to compromise the absorption voltage down to keep the AGM happy, which probably means the LiFePO4s never quite hit a proper full charge. It's not disastrous but I can see on VRM that the Fogstars are sitting around 95-96% most days rather than a clean 100%.

Has anyone managed a decent workaround for mixed chemistry banks without completely rewiring? I keep thinking the right answer is just to pull the AGM out and be done with it, but it's a free battery and waste not want not. Curious whether a DC-DC isolator between the two banks would actually help here or just add more complexity for marginal gain.

@WattAndrea running something similar on my boat — Cerbo GX with a mix of LiFePO4 and an older AGM bank.

Main thing to watch is the charge profile. The Cerbo itself doesn't care what brands you've got, but your charger/inverter needs to handle both chemistries sensibly. AGM wants a proper absorption stage that'll stress LiFePO4 if they're on the same circuit.

I'd keep them on separate charge sources if possible, or at least wire the AGM to drop off before absorption kicks in properly.

Also worth setting up the battery monitor in VRM based on your dominant bank — the SOC calculations get a bit confused with mixed chemistry otherwise.

The Fogstar Drifts have no comms protocol so the Cerbo won't see them directly anyway, just voltage-based monitoring. Not ideal but workable.

@WattAndrea — been down exactly that road with my static caravan setup.

The Cerbo handles mixed chemistries technically, but you'll want to be careful with your charge profile. The LiFePO4s and that AGM will have very different absorption voltages and float requirements — the Renogy will want around 14.4V absorption, whilst your Fogstar Drifts are happier lower.

What I found worked was configuring the Victron around the most conservative profile to avoid stressing the AGM, accepting slightly undercharged LiFePO4s as a trade-off.

Longer term though, that AGM becomes the weak link. It'll drag the whole bank down once it starts degrading — and you won't necessarily see it coming until something's unhappy.

The Cerbo's DVCC settings are worth digging into if you haven't already. Proper VE.Smart networking changes the picture considerably.

Really interesting thread this — I've got a somewhat similar muddle on my narrowboat actually, though mine's all LiFePO4 (two Fogstar Drifts plus a third one I added later from a different batch).

One thing I'd throw in that hasn't been mentioned yet — have you set up separate battery monitors for each bank in VRM? I think you can assign different battery presets per monitor rather than relying on one global setting, which might help the Cerbo make more sense of the mixed chemistry situation?

Also curious — is the AGM on its own DC bus or are they genuinely in parallel? Because I'd be a bit nervy about that voltage mismatch during charging cycles. The LiFePO4 charge profile is quite different from AGM isn't it...

Has anyone actually spoken to Victron support about mixed chemistry setups? Worth a ticket maybe?