Cerbo GX showing wrong battery % — anyone else had this with Fogstar Drift cells?

Finally got my 280Ah LiFePO4 bank wired up on the cabin (4 x Fogstar Drift 100Ah cells, 12V), connected to a Victron SmartShunt 500A and feeding into the Cerbo GX. Everything comms fine over VE.Direct, no errors showing.

Problem is the state of charge reads wildly wrong after the first discharge cycle — sitting at what feels like 80% actual capacity but the Cerbo is showing 47%. I've set the battery capacity to 280Ah in VE.Configure and the charge voltage tail is set to 14.2V on the Multiplus, so it should be syncing the 100% point properly.

Has anyone gone through the SmartShunt calibration process specifically with Fogstar cells? I'm wondering if the Peukert exponent and charge efficiency factor defaults are just off for these, or whether I need to do a proper full discharge/charge cycle to let the shunt learn. The Victron defaults feel like they were written for AGM.

What settings are people actually running for LiFePO4 on the SmartShunt — particularly the charge efficiency and tail current %?

PanelRuss | 847 posts

@Cerbo_Queen nice setup! One thing worth checking — have you told the SmartShunt the correct charged voltage and tail current for LiFePO4? It defaults to lead-acid parameters out of the box, which absolutely wrecks the SOC calculation. In VictronConnect, set your charged voltage to around 13.5V and tail current to about 4% (roughly 11A on your bank). Also make sure "Battery capacity" matches your actual 280Ah. The Cerbo just displays whatever the ShuntShunt tells it, so if the shunt's confused, the percentage will be all over the place. Once you've tweaked those figures, do a proper full charge cycle and let it sync to 100% — after that it should track really accurately. Fogstar Drift cells are solid, so I'd wager it's purely a parameter issue rather than anything hardware-related. 👍