I build my first RV (Van Life Ford Transit) and I have 2 x 440 watts solar panels connected serially (90 volts) to a Victron MPPT 150-100 to a Redodo 410ah 12 volts battery. I also installed a 500a Victron shunt.
I’m traveling in the USA, Mexico and central America in my van, so mostly sunny warm and hot weather. During my first 4 months trip, the battery was very powerful and I never ran out of power despite using an 1500 watts air fryer 45 minutes a day. But in the second trip (5 months between them), the battery runs out of power pretty much every day.
So I contacted Redodo’s support with a brief description of the system and issue. They reply with a lot of technical questions that I answered. Of course they told me to contact Victron to verify the MPPT calibration parameters. Actually, in the battery section of the MPPT, VictronConnect app, these are the actual settings:
Max charge current : 100a
battery preset : User define
Expert mode : Off
Absorption voltage : 14.6
Float voltage : 13.90
Automatic equalization : disabled
Temperature compensation : disabled
Low temperature cut-off : 5C
My question : I don’t know exactly know how to calibration parameters or to set parameter in this section of the app. Any pointers or videos on that topic to help me understand what I need to do to optimize the MPPT charging parameters for a Redodo 410ah battery ?
I’m new to these kind of systems but I’m 40 years experienced DIY electrical engineer so I can understand complex concepts.
Your absorption and float are high, you should not be charging at 14.6V, 14.4V is better, 14.2V will be ample, Victron’s current batteries charge at 14.0V. However, you need to know what voltage the balancer activates at to make sure you do activate balancing. Float should be around 13.5V, you may well have been keeping your batteries at too high a voltage which is not good.
Secondly, have you checked that the cells are balanced and that it is not just one cell limiting charge or discharge as an unbalanced pack will show low capacity as the unbalanced cell stops charging or discharging early. Hopefully you have Bluetooth enabled batteries.
Additionally, you are in hot climate area, high temperature reduces battery life.
Personally I charge all my batteries at 55.2V with absorb for 1-2 hours then float at 54.4V. That includes four redodo 12V 100Ah in series, so that would be 13.8V and 13.6V for you. This way theres very little chance they will encounter a high cell voltage bms disconnect.