Anyone else running a cheap Chinese MPPT off a small roof? What's your actual experience?

Picked up a 40A Renogy Wanderer knock-off from AliExpress back in March — can't even remember the brand, something like "SRNE compatible" in the listing title. Paid about £18 delivered. Paired it with a single 200W panel on the van roof and a knackered 100Ah leisure battery I rescued from a mate's caravan. Fully expected it to catch fire within a fortnight.

Six months on it's still going. Bulk/absorb/float seem to be working roughly right when I check against my separate battery monitor — a £12 Bayite coulometer off Amazon. The MPPT claim is obviously a bit suspect at that price point, but I'm genuinely pulling 8–9A on a decent sunny morning which feels about right for that panel at this time of year. Temperature compensation light is blinking away, no idea if it's actually doing anything useful.

My question is really around longevity and whether anyone's had one of these cheap units just silently fail — not blow up dramatically, but quietly start undercharging without you noticing. Had a look through some older threads but most people seem to have gone straight to Victron or EPever. Curious if anyone's nursed one of these budget units through a full winter, especially with the lower light levels we get up here in the north.

@Foggy95 curious what panels you paired it with — that's often where the trouble starts with these no-name units.

On my narrowboat I tried a similar route before eventually caving and getting a proper Victron SmartSolar. The cheap MPPT I had (branded "PowMr" if memory serves) was wildly optimistic about what it was actually harvesting — showing 15A output when my battery current clamp was reading closer to 9A.

Worth checking:

• Does yours have Bluetooth or any logging you can cross-reference?
• What's your battery voltage doing under load vs what the controller claims?

The discrepancy on mine was enough that I wasn't confident the bulk/absorption cutoffs were accurate either, which felt like a real risk for battery longevity. Might be fine for a seasonal setup but living aboard I couldn't trust it.

Hey @Foggy95, following this with interest! I've been running a couple of no-names myself — a 30A unit I picked up for about £14 last autumn. Honestly, the voltage regulation has been surprisingly decent, but I did have one cook itself within three weeks during a heatwave. Thermal protection is where these budget units tend to cut corners in my experience.

@MultiPlus_Queen raises a fair point about panels — I found pairing mine with anything over 100W on a warm day was asking for trouble without extra ventilation.

One thing worth checking: grab a cheap clamp meter and verify the actual charge current against what the display claims. Mine was reading 4A optimistic consistently. Not a dealbreaker, just useful to know what you're actually working with. Would love to hear what panels you're running! 🙂