Always shows bulk

Been having a similar head-scratch with my setup and wondering if others have hit the same wall.

Running a Victron SmartSolar 100/30 and recently swapped out my old AGM bank for a pair of Fogstar Drift 100Ah LiFePO4s. Ever since the changeover, the controller just sits in Bulk indefinitely — never progresses to Absorption or Float, even when the batteries are clearly well topped up (BMS showing 98-99% on the app).

I've gone through the charge profile settings and dropped the Absorption voltage down to 14.2V and Float to 13.5V as most LiFePO4 guides suggest, but it makes no difference. The MPPT just keeps pumping away on Bulk.

My suspicion is that the default charge algorithm is still calibrated around my old lead acid settings and Victron hasn't "seen" the batteries hit the target voltage properly yet — possibly because the Fogstars' BMS is doing its own balancing and the voltage curve is very flat with LiFePO4?

A couple of questions for the group:

• Has anyone used the lithium preset in VictronConnect vs manually dialling in voltages? Is one more reliable than the other?
• Do I need to set a tail current threshold to help the controller recognise when to transition out of Bulk?
• Could mismatched battery internal resistance across the bank be confusing the MPPT?

Not a critical issue for my emergency backup use case right now, but I'd rather understand what's actually happening than just leave it sat in Bulk indefinitely.

@Clive1978 classic symptom — your SmartSolar doesn't know you've swapped battery chemistry. Go into the VictronConnect app and manually set the charge profile to lithium, or better yet create a custom profile matching Fogstar's recommended voltages (typically 14.2–14.4V absorption, 13.5V float for their Drift cells).

The MPPT will happily sit in bulk indefinitely if the absorption voltage is set higher than your BMS actually allows through. Your BMS is quietly throttling current before the controller ever sees the target voltage, so it never "completes" bulk.

Had identical behaviour when I first fitted my own lithium bank in the motorhome. Once the profile matched reality, it cycled through stages properly within a day.

Worth also checking your battery temperature — Fogstar Drift BMS cuts charge current in cold weather, which compounds the issue.

@SimonKelly has the chemistry mismatch nailed, but worth double-checking one more thing — if you've got the battery temperature sense cable connected (or not connected when it should be), that can also confuse the charge stage detection on LiFePO4.

Also @Clive1978 are you running the Fogstar Drifts with their own BMS communicating to the SmartSolar, or just standalone? Because if the BMS is cutting current mid-charge the MPPT can interpret that as "still charging" and just... stays in bulk forever.

Had almost identical grief with my shepherd's hut setup last summer. Turned out my tail current setting was way too low for the battery capacity — basically the controller never saw the charge current drop enough to trigger absorption. Worth checking that figure in the advanced settings.