We recently converted a van for off-grid living. We are beginners with electrics so sorry in advance for incorrect terminology, any help is appreciated!
Our system was working fine previously, battery would drain to about 60-70% overnight with fridge/fan use etc and charge up within a few minutes once the sun has come up. In the last few days, despite us being in the most sun we’ve experienced, it hasn’t done this and often hovers around 40-50% all day even if we’re not using appliances etc. The problem is then it gets to night time and for the first time we ran out of power last night. When it kicked back in this morning it is at 34%, does this indicate there is a problem with the settings or does it auto-shut off at 33% to protect itself?
We have a Multiplus 12/1600/70 inverter with MPPT 100/50 and a 450W solar and a Drift ECO 314Ah 12V leisure battery. There is also an Orion-Tr Smart which is not hooked up due to other concerns with the starter battery.
Attached is a picture of our system and the settings on our MPPT and SmartShunt. We don’t know what most of it means. Any help figuring out what’s changed is appreciated.
Just as a follow up, one of these charts is from today, sitting under the sun the solar is copping about 250W but recharging around ~3% per hour.
On another day, recharging under much less sunny weather from 59% up to full in about 30 minutes. Has something gone wrong with the settings to make this happen, or there is something else we’re not understanding.
I have some bad news for you, you have NEVER been charging your battery to 100% even.on the lower sun days, you have not set your shunt correctly so it has been going to 100% SOC before it was full. Saying you had discharged to 60% and then quickly recharged to 100% is just not physically possible. Increase your charged voltage on the shunt to 14.2V, 0.2V lower than you charge at. This is explained in the attached FAQ.
What is probably happening is you have never been recharging as much as you have been using, the SOC is over reading and you have slowly drained your batteries. You need change the settings then cut back on power use or get at mains hook up to fully recharge or get the Orion sorted to charge from the engine.
Hi pwfarnell, thanks for your help and the detailed FAQ. What you said about the charged voltage definitely makes sense. We have changed the charged voltage to 14.2V.
I’m guessing based on that, that the displayed percentage is now out of sync and that’s why it cut out at around 33%. Is the best way to regain an accurate reading to fully charge to capacity using shore power etc?
pwfarnell already mentioned the charged detection voltage, but for the other shunt settings, they appear to be left on standard values. For LiFePo you want to use the following
Peukert 1.05
Charge efficiency 99%
Discharge floor at 50% is up to you, i think its a bit high, but that doesnt affect the 100% sync. It solely means that the shunt will give an SOC alarm at 50% SOC already, and that the time-to-go calculation is done on 100% to 50% SOC. I usually set that to 20% on LiFePo, so you have 80% that are used for the time-to-go calculation and the alarm is a bit later. But thats personal preference mostly.
On the MPPT, i personally would use the LiFePo preset since its a LiFePo battery, but its an MPPT, the battery is getting a rest at night anyway. But also check the MultiPlus charge settings too.
