My Multiplus switches between charging state prematurely. It will change from bulk to absorption between 85% and 88% (SOC), but I have the bulk state set at 90% (SOC) (see image 1 below). From absorption to float between 90% to 95% (SOC) (see image 2 below). I always thought the float state would be 2 amps or less. Can someone tell what is going?
The way I read this feature,
When the charger transitions from bulk to absorb, the state of charge is reset to 90%. (or whatever value is programmed)
Hi Z. Klim is onto it. Your Multi is just following a charge algorithm determined by V, unless of course you have some special high-level kit installed.
I note you have 'DC Power' enabled in the GX. If you actually have dc loads, then the SOC determined in the Multi (the VEConfig thing) would be worthless, as you'd need a BMV to pick the dc up. The Multi can't see dc loads that aren't going through it.
With no dc real loads that dc box will just be trying to balance the screen out, and with varying sample times will just flick about and be meaningless.
Your A in Float shown is typical. It should taper after a while, perhaps to < 2A, and with your 217Ah bank, down there could be considered pretty much 100% SOC, for all practical purposes.
If your SOC doesn't show that, then you need to tune it so it does. And once you've managed to do that, you may well just choose to return to watching V's and A's anyway.. :)
As far as I know the current MultiPlus chargers still follow the logic in this whitepaper for absorption phase duration;
https://www.victronenergy.com/upload/documents/Adaptive_charging_how_it_works.pdf
That is that that the absorption phase duration will be 5x the duration of the bulk phase.
There is no measurement of charge tail current to end the absorption phase with a MultiPlus charger.
If your not getting enough charge into the batteries, you could try to reduce the max charge current a little as a workaround - that will lead to a longer bulk time, the battery will be charged to a higher SOC % when it enters absorption phase and the absorption phase will be proportionally longer.
In terms of SOC% monitoring, the MultiPlus inbuilt battery monitor has limitations, so purchase a dedicated BMV if you have a need for more accuracy.
