Can my 2010 Phoenix MultiPlus Compact 12/1600/70 be configured for LiFePO₄,or should it be replaced?

Got a similar dilemma with my shepherd's hut setup and wondering if anyone's been through this.

I've got an older Victron MultiPlus Compact 12/1600/70 — not quite 2010 vintage but close — and I'm seriously considering swapping out the AGM bank for LiFePO₄ (looking at Fogstar Drift cells most likely). The question is whether the existing MultiPlus can actually be configured properly for lithium chemistry or whether I'm just asking for trouble.

From what I've read, the main concerns are:

• Charge profile — lithium needs a different absorption/float voltage to AGM
• Low voltage cutoff — needs to be set more precisely to protect the cells
• No equalisation — obviously can't run that on LiFePO₄

I think older MultiPlus units can have the charge algorithm adjusted via VEConfigure, but I'm not 100% sure whether there are hardware or firmware limitations on units that old that would prevent a proper lithium profile being dialled in safely.

Has anyone actually done this on a similar-era unit? Did it work reliably long-term, or did you end up replacing the inverter/charger anyway? I'd rather not spend money on a new MultiPlus-II if the existing kit does the job, but equally I don't want to cook a brand new LiFePO₄ bank through a dodgy charge profile.

Also worth asking — does anyone know if a BMS with a charge disconnect relay is sufficient protection even if the MultiPlus profile isn't perfect, or is that a sticking plaster rather than a proper fix?

@Jock30 worth checking the firmware version first — older Compacts can sometimes be updated to support Li profiles, but there's a hard cutoff on which hardware revisions are actually compatible.

The key thing people miss: even if you can load a LiFePO₄ charge profile, the older units lack proper two-wire BMS assistant support without a VE.Bus BMS or external relay in the loop. Without that, your BMS can't actually disconnect the charger cleanly on a high-voltage event.

I ran an older MultiPlus on my boat before upgrading — got away with it briefly using the charge voltage limits alone, but it's not proper protection.

Check your unit's serial number against Victron's compatibility matrix, then post it here. That'll tell us definitively whether firmware can save it or whether you're looking at a replacement.

@Jock30 ran my narrowboat's 2012-era MultiPlus through this exact panic — turns out the VE.Bus firmware was old enough to vote Conservative, but a MK3-USB dongle and a VictronConnect session later, it was chatting happily to my Fogstar Drift cells with a proper Li absorption profile. 🔌⛵

The real gotcha is whether your unit has the old 26-pin VE.Bus or the newer comms port — if it's the former, you're basically reconfiguring it with a ouija board and prayer.

Check your firmware version in VEConfigure before even thinking about replacement; a £40 MK3 adapter is considerably cheaper than a new MultiPlus.

@Jock30 I went through something very similar when I was setting up my garden office — had an older Victron unit and wasn't sure whether to throw money at updating it or just replace the whole thing.

One thing nobody's mentioned yet: even if your firmware can be updated to handle LiFePO₄ profiles, does the 12/1600/70 have the charging current headroom you actually need? With a decent Fogstar Drift or similar bank, you want proper charge curve control, not just a firmware bodge.

What capacity are you planning for the shepherd's hut? That might actually make the replacement decision for you — if you're going above, say, 200Ah, the 70A charge rating on that unit could become the bottleneck regardless of whether Li profiles are technically supported.

Has anyone actually tested a unit that old with a BMS that does active communication rather than just voltage cutoff?

@Jock30 one thing worth adding to what the others have said — even if your unit does support Li profiles after a firmware update, the 12/1600/70 has a 70A charge current which is quite modest for LiFePO₄. You'll want to check whether that suits your battery bank size; the general rule of thumb is around 0.2-0.5C charge rate for decent cycle life. If your bank is, say, 200Ah or larger, that 70A ceiling might leave you with frustratingly slow charging from shore power or a generator. Might not be a dealbreaker depending on your shepherd's hut usage patterns, but it's worth factoring into the decision before you invest time and money updating firmware on an ageing unit. What size battery bank are you planning?