Meine beiden Solarregler zeigen "Float" an, obwohl nur 160 Ah von 200 Ah geladen sind

Got a puzzling one here that I'm hoping someone can help me get my head around.

Running two separate MPPTs on my system — a Victron SmartSolar 100/20 and a 100/30 — because I've got two different panel arrays on the roof that couldn't sensibly be combined into one string. Both controllers are set up through VictronConnect and share the same charge profile for my 200Ah lithium bank (Fogstar Drift cells).

The problem is that both units are showing Float status, but according to my battery monitor I'm only sitting at around 160Ah — so roughly 80% state of charge. That's nowhere near where I'd expect Float to kick in.

A few things I'm wondering:

• Could the two MPPTs be "competing" somehow and confusing each other's charge state detection?
• Is this a voltage-based Float trigger rather than capacity-based, and if so, could a surface charge on the cells be fooling them?
• Would networking them via VE.Smart Networking actually fix this, or is it just for temperature/voltage sharing?

I haven't got a Cerbo GX in the setup — just running the two controllers independently with Bluetooth monitoring. Wondering if that's part of the problem honestly.

Has anyone seen this behaviour before with dual MPPTs on the same bank? The batteries aren't full and the controllers seem to have just... given up charging early. Losing usable capacity daily because of it and it's becoming a real issue heading into autumn.

Hey @Mike1980, classic float issue this one! Your MPPTs are hitting float based on voltage, not actual state of charge — they don't actually "know" how full your battery is, they just see the terminal voltage reach the absorption threshold and work from there.

Couple of things worth checking:

• Are both controllers configured with identical charge profiles? Mismatched settings can cause one to drag the other into float prematurely via the bus voltage
• What battery chemistry are you running? If your absorption voltage is set a touch low, it'll cut short before the batteries are properly topped up
• Have you got any significant load running during charging? That can mask the real voltage and fool the controllers

The Victron app lets you check absorption time logs — worth having a look at how long they're actually spending in absorption before dropping to float. 👍

Good question from @Mike1980 — worth adding that this is especially common in vans where your battery temp drops overnight. Cold batteries show a higher resting voltage, so your MPPTs can incorrectly read "full" even earlier than usual.

Have you got a Victron BMV battery monitor or similar shunt-based SOC tracker? That's the only way to actually know your real charge state rather than relying on voltage alone. My setup in the van was doing exactly this until I added a BMV-712 — game changer.

Also worth checking — are both your MPPTs synced via VE.Smart Networking? If they're not talking to each other and sharing battery sense data, they'll both be making independent voltage decisions which compounds the problem.

Both MPPTs are making their float decision independently based on absorb voltage threshold being hit — not based on actual capacity restored. 160Ah from 200Ah is actually pretty typical; bulk/absorb only gets you so far before voltage rises prematurely, especially if your charge current is relatively high compared to battery size.

What absorption time are you running? If it's too short, you'll consistently end up undercharged. With Victron kit you can either extend absorb time manually or use the adaptive absorption feature — it scales duration based on how long bulk took.

Also worth checking both MPPTs have identical absorption voltage settings. If they're even slightly out of sync, one will pull the other into float prematurely via the battery bus voltage. Happened on my own setup before I locked them both down properly through VictronConnect.

Had this exact same thing on my motorhome setup. The fix that worked for me was connecting both MPPTs via VE.Direct to a Cerbo GX — lets you set a proper networked charge algorithm so they're not making independent decisions.

Also worth checking your absorb voltage setting is actually correct for your battery chemistry. I had mine slightly high on a Fogstar lithium pack and it was tripping into float way too early.

If you're not running a GX device, at minimum sync the settings between both controllers manually — same absorb voltage, same absorb duration.

@Harry1965 has the right idea with VE.Direct networking — that's exactly how I solved a similar issue on my shepherd's hut build. Once both controllers are on the same network with one set as master, they synchronise charge states properly rather than each making their own float decision.

Worth checking your absorption voltage setting too. If it's slightly low (common default on some units), the battery hits that threshold well before it's actually full. I run mine at 14.4V for a 12V LiFePO4 system — bumping it up a few tenths made a noticeable difference to my actual state of charge.

Also, what battery type are you running? Flooded, AGM, or lithium? Makes a difference to what absorption voltage you should be targeting.