Bulk/Absorption Time Excessive - Adaptive Charging

I have a Victron M.P.P.T 100|30 with 140W panel on the P.V side. Collectively they are charging a 600Ah Victron Li.Fe.Po Smart Battery Bank installed on a boat, with no 120VAC shore power taken on. The M.P.P.T is configured for Li.Fe.Po and is setup for adaptive charge profile.

The issue I am seeing that concerns me is that the absorption time each day is approximately 2hrs even though the batteries never drop below 13.3V during the evening. The vessel is unattended and has no loads and so never drops below 13.3V and 99% SoC. This is obviously outside the 2hrs per month recommendation for lightly loaded system, as stated in the Victron Smart Battery Manual. I also see that the charge current off the M.P.P.T during absorption is approximately 1.8A when in Absorption, with approximately 1.3A of that value going into the bank as reported by the B.M.V.

Question: Why is the M.P.P.T holding itself into Absorption that long and how do I stop this behavior. According to the manual, if the battery voltage doesn’t drop below 12.6V the maximum absorption time should be 1hr (x1/6 Multiplier). So that’s no happening to begin with. And the tail current is 1.3A which is way below the usual 2% tail current switch most chargers have for switch to float.

If somebody can please make some recommendations I’d appreciate it? Thanks in advance for your help.

Matt

I need more info to better advise e.g.; what are the other components and models in your system: BMS, Cerbo, MPPT, etc.
That said, it is general practice to set charging absorption profile to Fixed rather than Adaptive. In fact MPPTs select this as a default.

Go into expert settings on the MPPT, swap to fixed absorption and reduce to say 10mins. The manual provides a detailed description of each setting.

I assume you are not using a Lynx BMS, if you are then the changes need making in there.

Hey pwfarnell. Thanks for that feedback and manual. That was going to be by next course of action but wanted to check to make sure I wasn’t having a brain fart and missing something. Thanks again…

Hey CharlieJ, thanks for the reply. It sounds like moving to expert mode and adjusting the settings is what’s best. But to answer your question, it’s an MPPT 100|30 connected to a Cerbo GX via VEDirect. And a Victron BMS v2 connected via VEBus on the Cerbo side. Thank you again.