Quattro 12/5000/120 charge current limit

Been scratching my head over this one and wondered if others have hit the same wall.

Running a Quattro 12/5000/120 here and trying to nail down the optimal AC charge current limit when paired with a bank of Victron lithium batteries. I've got four of the Victron 12.8V 200Ah Smart Lithium units wired in parallel, so roughly 800Ah total at 12V.

My question is really about how aggressive you can realistically push the AC-side charge current without causing grief — either to the batteries themselves or to the Quattro's internals. The manual gives you a range but doesn't really tell you where the sweet spot is in practice.

A few specific things I'm unsure about:

• Does the MPPT solar input effectively "share" the charge burden, meaning you can back off the AC limit somewhat?
• Has anyone found that setting the AC limit too high causes the Quattro to run hot, particularly in a confined install space?
• I've got mine set at 100A currently — feels conservative but I don't want to damage anything while I'm still learning the setup

I'm also using VRM and VE.Configure to monitor everything, but the charge current interaction between shore power and solar still confuses me a bit in terms of how Victron prioritises them.

Anyone running a similar 12V high-capacity setup who's dialled this in properly? Would be useful to know what charge current limits people are actually using day-to-day rather than just what's theoretically possible on paper.

Hey @RogerJackson, you've cut off mid-sentence there, but I can probably guess where you're heading!

The 120A figure in the model name is your max DC charge current, but what trips most people up is working backwards from your AC input to figure out your practical ceiling. The Quattro's charger efficiency sits around 93-94%, so factor that in when you're calculating.

What battery chemistry are you running? That makes a massive difference to where you actually want to set the limit, regardless of what the inverter can theoretically push. LiFePO4 cells in particular can be fussy about bulk charge rates depending on your BMS settings.

Also worth checking your AC input current limit in VEConfig isn't inadvertently throttling the charger before it even reaches the battery limit. Caught me out once!

Great thread, even if it did get cut off in two places! 😄

@RogerJackson if you're asking about limiting AC charge current to protect your battery bank, the key thing with the 12/5000/120 is that the 120A refers to the DC charge current, not AC input. People often mix these up and end up either undercharging or hammering their batteries.

What battery chemistry are you running? That makes a massive difference to where you'd want to set the limit in VEConfigure. LiFePO4 owners often find they need to be quite conservative initially while monitoring cell balance, whereas AGM users tend to have more headroom.

Also worth checking your AC input current limit separately — that's the one throttling your inverter/charger on the grid or genny side. The two settings interact in ways that catch people out!

Great thread @RogerJackson - looks like the forum gremlins got both you and @Foggy80 mid-sentence! 😄

One thing worth mentioning that I don't think's been covered yet: don't forget the AC input current limit on the Quattro affects both the charger and any loads running simultaneously. So if you've got, say, a 16A shore power hookup, you need to account for your AC loads first before deciding what's left for charging. Victron's PowerAssist will handle the balancing, but setting your charge amps too ambitiously on a limited supply can cause nuisance tripping.

What battery chemistry are you running? LiFePO4 or lead-acid? That'll make a significant difference to the recommended charge current ceiling and whether your BMS has anything to say about it too.

Forum gremlins have now claimed three posts in a row — at this rate the actual answer to @RogerJackson's question will remain a mystery until 2031.

On the narrowboat I run my Quattro with the AC input current limit set conservatively via VE.Configure, because marina shore power pedestals here in the UK are notoriously flakey and tripping the bollard at 0200hrs earns you enemies fast. Worth remembering the Quattro's charger limit and the AC input limit are two separate settings that confuse absolutely everyone the first time.

My Victron setup on the narrowboat has eaten more mid-sentences than a tunnel eats phone signal — starting to think the forum software runs on a 100Ah LiFePO4 that's been DVCC-limited to 3%.

Right, let me actually answer the question before the gremlins get me too —

On the Quattro 12/5000/120, the AC input current limit feeds the charger and any loads simultaneously. People get tripped up thinking the 120A charge current is what you set on the AC side — it's not, that's the DC output.

For AC input limit, work backwards:

• Loads first, remainder goes to charging
• Charger efficiency ≈ 85-90%, so factor that in

My Quattro 5kVA paired with a Fogstar lithium bank — I run 16A AC input, leaves headroom for loads without tripping the supply.

VEConfigure is your friend here, not guesswork. Set it properly and the Quattro handles the balancing automatically.

What's your battery bank capacity @RogerJackson? Changes the calc significantly.