Batteries Are Undercharged; Insufficient Solar Supply - Victron energy MPPT 150/70 Manual

To identify reverse PV voltage, watch for these indicators:
• Absence of battery charging with the charge current remaining at zero.
• Excessive heat generated by the solar charger.
• PV voltage reading zero or close to zero.
To verify, use a multimeter to ensure that the positive PV cable is correctly connected to the positive PV terminal and the negative
cable is connected to the negative PV terminal.
WARNING: Certain solar charger models may have PV voltages up to 250Vdc. Voltages exceeding 50V are
generally considered dangerous. Only a qualified technician should handle dangerous voltages.

8.6. Batteries are undercharged

This chapter addresses the issue of undercharged batteries. It explores possible reasons why the solar charger might not be
adequately charging the batteries and provides steps to check or resolve the situation.
Some signs of undercharged batteries include:
• Batteries taking too long to charge.
• Batteries not being fully charged by the end of the day.
• Charge current is less than expected.
Several factors can cause this, such as:
• Insufficient solar supply. Refer to the
• High DC load. Refer to the DC load too high [55]
• Voltage drop in battery cables. Refer to the
• Incorrect temperature compensation setting. Refer to the
• Temperature difference between the solar charger and battery. Refer to the
battery [56] subchapter.
• Battery charge voltages or current settings are too low. Refer to the

8.6.1. Insufficient solar supply

Check if the solar charger reaches the float charge stage each day.
To investigate, check if the solar charger reaches the float charge stage each day. Utilise the VictronConnect app's history tab,
where a histogram displays the daily charging durations in the Bulk, Absorption, and Float stages for the last 30 days. Clicking on
a histogram column provides a breakdown of the charge stages.
You can use the charge times to assess whether the PV array is appropriately sized for your needs.
Reasons for the solar charger not reaching the float stage include:
• An inadequate number of solar panels.
• Excessive DC load.
• PV array issues causing reduced power output.
Page 54
MPPT solar charger manual
Insufficient solar supply [54] subchapter.
subchapter.
Battery cable voltage drop [55]
Temperature compensation setting incorrect [56]
Battery settings too low [52]
subchapter.
subchapter.
Temperature difference between solar charger and
chapter.
Troubleshooting