Controller showing absorb all the time

Seeing this crop up a fair bit lately and had something similar on my static van setup last summer, so thought it worth sharing what I found.

Running a Victron SmartSolar 100/30 with a 200Ah Fogstar Drift LiFePO4, and I noticed it was sitting in absorb indefinitely — drawing almost nothing from the panels despite decent sun. Turned out the issue was a combination of two things:

1. Absorption voltage set too close to the battery's resting voltage

If your absorption threshold is, say, 14.2V and your battery is already resting at 13.9–14.0V after a light overnight draw, the controller sees it as "nearly full" at first light and immediately enters absorb. With a lithium that barely discharges overnight, this happens constantly. Dropping the absorption time down (or using the adaptive option in VictronConnect) helped enormously.

2. Parasitic loads confusing the tail current detection

Even with everything "off," I had a small inverter on standby drawing ~8W. The MPPT was seeing that as the charge tail current and thinking the battery was full. Proper tail current settings matter — worth checking your Tail current and Max absorption time values in VictronConnect.

Before assuming a fault, I'd check:

• Is your battery genuinely not full? Measure resting voltage with everything disconnected for 10 mins
• What are your absorption voltage and time settings?
• Any parasitic loads running?

A full reset via VictronConnect (not just a disconnect) can also clear stuck state machines on the MPPT firmware.

What controller and battery chemistry are you running? That'll narrow it down considerably.

@MandyRoss ooh yes, had exactly this on my static van last year. Turned out my battery cable runs were way too long and the voltage drop was fooling the controller into thinking the battery hadn't hit absorb voltage yet — so it just... stayed there forever like a confused pensioner.

Worth checking:

• Cable length & gauge — thicker is better, shorter is better
• Victron's charge voltage settings — are they actually correct for Fogstar's spec sheet?
• Temperature compensation — if it's reading ambient wrong it'll chase the wrong target

Stuck a proper battery voltage sense wire directly on my Fogstar terminals and sorted it overnight. The SmartSolar supports remote voltage sensing — massively underused feature that one. 🙌

Yeah this is a classic voltage drop issue but people forget it can also be the BMS throttling charge current on the Fogstar cells when they're cold.

Had it on my motorhome over winter — controller thought it was in absorb for hours because the BMS was quietly limiting current, so voltage stayed high at the controller end.

Worth checking:

• Battery temp (Fogstar drops off below ~5°C)
• Whether you've got the Victron temp sensor actually connected
• MPPT history on the VictronConnect app — look at the charge current graph, if it's flatlining low that's your tell

Nothing to do with cable length in my case. @DustyCaptain's point is valid but rule it out properly before rewiring everything.

Worth adding — if you've ruled out voltage drop and BMS throttling, check your temperature compensation settings in the Victron app. If the controller thinks the battery is colder than it actually is, it'll keep pushing to hit a compensated voltage target that's higher than your actual absorb setpoint.

Had something similar on my garden office setup. The VE.Smart network temperature sensor was reading ambient rather than battery surface temp, so the MPPT was perpetually chasing a moving target.

Also worth double-checking your absorb duration setting. Victron defaults can be quite aggressive for LiFePO4 if you haven't explicitly set a fixed absorb time — mine was sitting in absorb for two hours when it really only needed 20 minutes.

Great thread — this actually sent me down a rabbit hole on my shepherd's hut build last spring.

One thing nobody's mentioned yet: dirty or corroded connections at the battery terminals themselves. I was chasing a "stuck in absorb" ghost for weeks on my SmartSolar 75/15 setup before I pulled the terminal lugs off my Fogstar and found green oxidation underneath. Looked fine from the outside, but was dropping enough voltage to fool the controller into thinking the battery never reached the absorb setpoint properly.

Worth grabbing a multimeter and doing a voltage drop test directly across each connection under load, not just checking cable runs. Even a 0.2V drop per connection adds up fast across a full battery bank.

Cleaned everything back to bare copper, re-crimped, applied some Vaseline — problem gone within two charge cycles.