I’ve just installed a Multiplus 12/3000/120-32 230V inverter/charger in our caravan. Everything appears to be working with the Multiplus charging light on, initially the bulk charge light on and after a few hours that switched to absorption where it has sitting now for 2 days. I have a smartshunt and a VE Bus smart dongle for monitoring, and the ATG LiFePo4 150A has a Bluetooth BMS.
The VE Bus dongle shows the battery voltage at 13.36V:
I’m not familiar with the Overkill Solar app but I would have thought either the arrows under ‘charge’ or ‘discharge’ would be coloured to show the power flow but both are I believe not doing anything.
These are the settings on the MultiPlus and Battery:
Thanks for the suggestions, I will check those out but you hit a key point there with programming the inverter. I was under the impression that the Bluetooth dongle would do this but that appears not the case. Looking at one of the screenshots it seems the inverter output is very low - I guess that needs to be set according to the battery specs.
So I ordered a MK3-USB to sort that out to start with.
An update to this, it is now all working correctly. The issue was a loose connection from the 300A fuse (positive) to the busbar. My own fault!
voltage across the battery terminals was 13.27V, between shunt (negative) and fuse 13.27V but at the MultiPlus battery terminals it only showed 0.66V. Checked the connection from fire to busbar, I could still hand tighten the nut. Once that was properly fastened, the voltage showed as 13.27V at the MultiPlus as well. Turned it on, and now there was charge going into the battery.
Checked the inverter too by switching the 240V off. Works great!
Charged voltage appears to be a bit high. Usually thats set to absorption -0.2V, so i would expect 14.2V or thereabouts.
Otherwise it would mean you charge to 14.8V which in turn is a bit high.
Peukert seems to be on standard value, but with LiFePo you can expect it to be around 1.05. You can measure and calculate it for your own battery, to be more precise. Instructions in the shunt manual
Sounds like you sorted out your main problem but those settings in your battery monitor look like the default for AGM possibly. Definitely not suitable settings for lithium.
Charged voltage should be .2 below your absorption charge setting in your chargers. So 14.00 if you are charging at 14.2
Thank you both. The settings came from the manual that came with the battery. When it was fully charged according to the battery BMS, the voltage was 14.2V.
I’ve changed the charged voltage to 14.2V and charger voltage to 14.4V
