When a Rich Solar MPPT charge controller finds a problem, it shows a short code on the screen, flashes its backlight and changes the pattern of its LED bars. This guide explains each code, what usually causes it and how to fix it. It also covers the most common reason a controller shows no code at all but still won't charge: a lithium battery whose BMS has switched off.
Which controllers this covers
The codes below come from Rich Solar's user manual for its RS-MPPT40P 40A MPPT controller. The BRAVO 30 is model RS-MPPT30P from the same P series, and both list the same battery types (Crystal, GEL, AGM, WET, Calcium, LCO, LFP and LTO). The wall-mount BRAVO 40 lists the same battery types too. If you own a BRAVO 50 or BRAVO 60, compare the codes on your screen with your manual. If you own a flush-mount BRAVO PRO, a BRAVO 50 DC, one of the 20A, 30A, 40A or 60A MPPT controllers without the BRAVO name, or a PWM controller, check the code list in your own manual, because it may differ.
Error codes at a glance
| Code | What it means | Backlight | Usual cause |
|---|---|---|---|
| No code, panel icon flashing | Solar input weak (under 15V) | On | Dawn, dusk, heavy cloud or shade, or a loose panel connection |
| P-01 | Solar panel connected in reverse | Flashing | Panel positive and negative swapped |
| P-02 | Solar panel over-voltage (over 95V) | Flashing | Too many panels in series, especially on a cold morning |
| b-01 | Solar connected but battery disconnected | Flashing | Blown fuse, open breaker or switch, loose cable, or a battery whose BMS has shut off |
| b-02 | Battery connected in reverse | Flashing | Battery positive and negative swapped |
| b-03 | Battery over-voltage (over 17V) | Flashing | Another charger pushing the voltage too high, or a system voltage mismatch |
| b-04 | Battery temperature over 65°C (149°F) | Flashing | Hot battery compartment, or a temperature sensor reading wrong |
| OTP | Controller over-temperature protection | Flashing | Controller has no airflow or is mounted somewhere hot |
Codes and thresholds from Rich Solar's RS-MPPT40P manual. The fixes below are our advice.
Solar-side codes
Panel icon flashing, no code: solar input weak
The controller sees less than 15V from the panels. That's normal at dawn, at dusk and under heavy cloud, and it clears when the sun gets stronger. If it shows in full sun, check the MC4 connectors, any inline fuse or breaker on the panel side and the panel cable for damage. Shade on part of one panel can drag a whole string down.
P-01: solar panel reverse connection
The panel leads are on the wrong terminals. Cover the panels or open the panel-side breaker so no current is flowing, then swap the positive and negative leads at the controller. Rich Solar lists reverse-polarity protection on both the solar and battery sides, so a reversed panel usually does no harm, but don't leave it that way.
P-02: solar over-voltage (over 95V)
The panels are producing more voltage than the controller accepts. Add up the open-circuit voltage (Voc) of every panel wired in series. Voc rises as panels get colder, so an array that reads safely in summer can trip on a frosty morning. Three MEGA 100 panels in series total 68.4V and leave margin. Two 24V MEGA 200 PRO panels in series total 87V, which is too close on a cold day. Rewire some panels in parallel, or move to a controller with a higher voltage limit such as Rich Solar's 60A MPPT (150V). Disconnect the panels straight away; sustained over-voltage can damage the controller.
Battery-side codes
b-01: solar connected, battery disconnected
The controller has panel power but can't see the battery. Work outward from the controller:
- Check the fuse or breaker between the controller and the battery, and any battery disconnect switch.
- Check both battery cables for loose or corroded lugs.
- Measure the voltage at the controller's battery terminals with a meter.
- If the battery is lithium and reads near 0V, its BMS has probably switched it off. See waking a lithium battery below.
When you reconnect, connect the battery to the controller before the panels. The controller uses the battery to detect whether it's on a 12V or 24V system.
b-02: battery reverse connection
The battery cables are on the wrong terminals. Disconnect the panels first, then the battery, and reconnect the battery the right way round, positive to positive. Check the fuse afterwards.
b-03: battery over-voltage (over 17V)
The battery terminals read over 17V, which is too high for any 12V battery. Measure the battery with a meter. If it really is high, another charger is overcharging it: switch off the converter, DC-DC charger and any other solar controller one at a time to find it, and check its battery-type setting. If you've connected a 24V battery to a controller that started up on a 12V battery, disconnect the panels and battery and reconnect the battery first so the controller detects the system voltage again.
b-04: battery temperature over 65°C (149°F)
The controller has stopped charging because the battery is too hot. This reading comes from the optional battery temperature sensor. If the battery compartment really is that hot, ventilate it before charging again. If the battery feels cool, check that the sensor is fastened to the battery and its cable isn't damaged.
OTP: controller over-temperature
The controller is protecting itself from heat. Rich Solar's controllers reduce charging current as they warm up; OTP means that wasn't enough. Mount the controller vertically on a non-flammable surface with space above and below for air, away from the battery and out of direct sun, and keep the fins clear. In a closed cabinet, add a vent or a small fan.
Reading the LED bars when there's no error
The RS-MPPT40P has a green system light, a blue charging light and four white battery bars. In normal charging:
| Stage | Green | Blue | White bars |
|---|---|---|---|
| Soft start | On | Flashing | First bar flashing |
| Bulk charge | On | On | First bar on, second flashing |
| Absorption / equalization | On | On | Three on, fourth flashing |
| Float | On | Off | All four on |
A lithium battery doesn't float the way lead-acid does. After absorption the controller stops charging it, and restarts bulk when the voltage drops (13.3V for an LFP battery, per the manual). A full lithium battery showing no charging current is normal.
No code, but it won't charge a lithium battery
If a lithium battery has been run flat, its BMS switches the battery off to protect it, and it can read near 0V. Rich Solar's controller checks the battery voltage and periodically sends a signal to the battery terminals to wake the BMS. If that doesn't work, the manual describes a manual wake-up: press and hold the BATT / – button for 3 seconds. The LED bar on the display rotates while it tries. If the battery still won't wake, try a mains lithium charger that lists a BMS wake-up or 0V charging function, or contact the battery's maker. Our answer on charging a lithium battery the BMS has shut off covers the same problem on another brand.
Other reasons a controller shows no fault but no charge:
- Cold battery. LiFePO4 batteries won't accept a charge below 32°F. An ALPHA LITE has no heater and waits until it warms up; a standard ALPHA warms itself. See ALPHA LITE vs ALPHA vs PRO.
- Wrong battery type. Set the controller to LFP for a LiFePO4 battery such as a Rich Solar ALPHA.
- Battery already full. See the lithium note above.
- Undersized wiring or a tripped breaker between the panels and the controller.
Our general RV solar not charging guide walks through the whole system.
Check it from your phone
BRAVO MPPT controllers have Bluetooth built in and show their status in the RICH SOLAR app (Rich Solar's BRAVO 40 and BRAVO 60 listings name the Smart Life app). The 20A to 60A MPPT controllers without the BRAVO name need the BT-1 module. See which Rich Solar controllers need the BT-1.
Still stuck?
Note the code, the LED pattern, your panel wiring (series or parallel, and how many panels) and your battery type, then call Rich Solar support on 1-800-831-9889 (Monday to Friday, 9 a.m. to 5 p.m. Pacific), or contact us if you bought the controller from RV Parts Giant. If the controller needs replacing, compare models in Rich Solar BRAVO charge controllers: which model? or browse the Rich Solar range.
Shop all Rich Solar charge controllers.