Victron IP43 48 volt smart charger to balance LiFePO4 batteries

Been running a Victron IP43 (48V) on my cabin setup for a couple of seasons now and it's decent, but balancing LiFePO4 properly through it is a bit of a faff if you're not careful with the absorption settings.

The key thing most people miss — the IP43 isn't natively BMS-comms aware like the MultiPlus range. So if you're expecting it to "talk" to your Fogstar or whatever cells you're running, it won't. You're relying on a correctly configured charge profile rather than any smart handshake.

What's worked for me:

• Absorption voltage: 56.8V (14.2V per cell equivalent across 16S)
• Float: 54.4V
• Absorption time: fixed at around 20–30 mins rather than adaptive

That combination keeps my pack reasonably balanced without cooking the cells. Proper balancing still happens at the BMS level though — the charger just needs to get you close enough to the top of the curve for the passive balancers to do their thing.

One thing I'd push back on — if your cells are significantly out of balance (say >100mV spread), no charger profile is going to fix that. You need to look at the BMS balancing settings or consider an active balancer.

Anyone else running the IP43 on 48V LiFePO4? Curious whether others are using the VictronConnect app to tweak profiles or just leaving it on the lithium preset. The preset is frankly a bit conservative in my experience.

@PeakExplorer yeah the absorption voltage is the key bit people get wrong. On my static van setup I've got the IP43 absorption set to 57.6V (3.6V/cell × 16 cells) with a pretty short absorption time — like 1hr max. Let the BMS do the actual cell-level balancing rather than relying on the charger.

Worth checking if your BMS has passive or active balancing too. Passive ones need longer sat at top voltage to do their thing, active ones are much quicker.

One thing that helped me was enabling the "tail current" cutoff in VictronConnect — cuts absorption once charge current drops below a set threshold rather than just timing out. Much gentler on the cells long-term.

What BMS are you running with it?

@OffGridDawn curious what absorption voltage you've landed on — there's a lot of conflicting info out there depending on whether your cells are EVE, CATL etc.

On my shepherd's hut build I use a BMS with active balancing which takes a lot of the pressure off the charger itself. The IP43 just needs to not fight the BMS, really. Got mine set fairly conservatively — absorption at 55.2V (3.45V/cell) with a short absorption time, float disabled entirely.

The bigger issue I see people overlook is charge current relative to capacity. Hammering LiFePO4 at high rates near top of charge doesn't help balancing at all — slow the tail end down and let the BMS do its job.

What BMS are you running? That matters more than the charger settings in my experience.

@ExPostie the conflicting info is mostly because cell manufacturers give different specs — Fogstar cells vs EVE vs whatever else all have slightly different sweet spots.

On my motorhome I run 48V LiFePO4 (16S EVE cells) and had a nightmare until I actually talked to the BMS manufacturer rather than just copying random forum settings.

Few things worth knowing:

• Let the BMS handle balancing, not the charger
• Keep absorption short or even disabled if your BMS has active balancing
• Float should basically be off or very low on LiFePO4

Victron's own LiFePO4 presets are honestly a reasonable starting point, people overcomplicate it massively. Connect via VictronConnect and use the lithium template, then tweak from there based on your actual cell specs.

What BMS are you running? That matters more than people realise here.

@OffGridMax is right about the cell variance, but the bit people consistently miss with the IP43 on LiFePO4 is the tail current setting.

Absorption voltage gets all the attention — typically 57.6V (3.6V/cell) for 16S — but if your tail current is too high, the charger exits absorption before cells are properly balanced. I run mine at around 2% of capacity, so on a 200Ah bank that's 4A.

Also worth noting: the IP43 doesn't have a true balancing function — that's your BMS's job. The charger just needs to hold absorption long enough for the BMS to do its work.

On my cabin setup I've got VictronConnect logging the absorption duration — if it's consistently under 10 minutes, something's off upstream. Could be a dodgy cell, could be tail current misconfiguration.

The Victron CCGX/Cerbo integration makes spotting this so much easier.

@DailySolar is teasing us — finish your point about the tail current, that's exactly where most people go wrong.

My setup (garden office + emergency backup, 48V/200Ah EVE cells): I've got absorption set to 55.2V (3.45V/cell) with a tail current cutoff of around 2-3% of capacity configured via VictronConnect. Without that tail current setting dialled in, the IP43 just sits in absorption indefinitely and you're not actually balancing — you're cooking the top end.

The other thing nobody mentions: if your BMS is cutting out before the charger reaches tail current, your absorption voltage might be creeping too close to the BMS overvoltage threshold. Leave yourself some headroom. I've seen people set 3.6V/cell on a BMS with a 3.65V cutoff and then wonder why it keeps tripping.

Check your BMS logs before assuming the charger is the problem.