Anyone else had issues with a Renogy 40A MPPT dropping out on the move?

Had exactly this with my Rover Elite last summer — driving up to the Cairngorms with the panel on the roof and the controller just kept cycling off every 20-30 minutes. Thought it was a dodgy unit at first.

Turned out to be a combination of two things:

1. Vibration on the B-roads loosening the Anderson connector at the battery end — just enough resistance to confuse the controller
2. The bulk/absorption voltage creeping too high because I'd set it up for my Fogstar lithiums but hadn't properly locked the profile — it was reverting to a gel setting after power cycles

Once I sorted the connectors with proper ferrules and heat shrink, and confirmed the LiFePO4 profile was actually saving, it's been solid for about 8,000 miles since.

Worth checking:

• All terminal connections, not just the obvious ones
• Whether your charge profile is genuinely persisting after the unit loses power (Renogy's BT app doesn't always reflect what's stored in firmware)
• Temperature — the unit does throttle in high ambient if the heatsink isn't getting airflow

The Renogy kit is decent value but their documentation around lithium profiles is genuinely rubbish. Had to dig through a Reddit thread from 2021 to find the actual register values.

Anyone else found the Bluetooth module causes interference issues? Mine seemed to occasionally cause dropouts before I removed it. Could be coincidence but curious whether others have seen similar.

@BirchRunner mine did the same thing on the A9 — turns out the vibration was rattling the PV terminals loose enough to cause a voltage spike that triggered the protection circuit, tightened everything with a proper torque screwdriver and haven't had a drama since.

Donna1998 · 47 posts

Chiming in here because I had almost the identical problem last spring on a run up to Applecross. Turned out it wasn't the terminals at all in my case — it was the controller overheating. The Rover Elite has a thermal shutdown and mine was mounted in a poorly ventilated cabinet right above the engine bay bulkhead. Moved it to a spot with proper airflow and haven't had a single dropout since.

Worth checking the unit's temperature during one of those cycles if you can — there's a readout on the display. If it's climbing past 45°C while you're moving, ventilation is likely your culprit rather than loose connections. A small 12V fan on a thermostat sorted mine completely for about a fiver off eBay. 🙂

Had this on the boat actually, not a motorhome, but same Rover Elite unit — vibration from the engine was enough to make it throw a wobble. For me it turned out to be the temperature sensor lead. Tiny little connector and it was just... not happy with movement. Unplugged it altogether and the unit stopped cycling.

Worth checking before you start swapping terminals around. Also — are your panel cables long enough that they're not pulling taut when the van flexes? I've seen that cause grief too.

@WayneTaylor is probably right about terminals but I'd look at every single connection systematically, not just PV side.

Really interesting thread — @WayneTaylor and @BayLisa have covered the terminal vibration angle well, so I won't retread that. One thing nobody's mentioned yet though: have you checked whether the controller's dropping out due to thermal protection rather than a connection issue? The Rover Elite can get quite warm tucked inside a habitation space with poor airflow, and on a long motorway run the combination of charging current plus ambient heat can trigger the thermal cutoff. It'll reset itself once it cools down, which would explain that 20-30 minute cycling pattern @BirchRunner described. Worth putting your hand on the unit next time it drops — if it's uncomfortably hot, look at improving ventilation around it or relocating it somewhere cooler before assuming it's a fault. A small 12V fan on a thermal switch sorted mine completely.