Anyone else running a cheap Chinese MPPT controller long-term? Sharing my 18-month results

I picked up a Renogy Wanderer clone off AliExpress about 18 months ago — paid around £14 delivered. Paired it with a single 100W panel on the roof of my Transit and a secondhand 100Ah leisure battery I got off Facebook Marketplace for £30. Total spend on the whole charging setup was under £60, which felt almost too good to be true at the time.

Honestly? It's still going. The controller reads a bit optimistically on the state of charge display — it'll claim 100% when the battery is clearly not full — but the actual charging function seems fine. I'm getting around 40-45Ah into the battery on a decent sunny day in summer, which seems about right for a 100W panel with some shading losses from the roof vent. The load terminals gave up after about three months but I wasn't using those anyway.

What I have noticed is it runs quite warm, warmer than I'd expect, and I've no idea if it's actually doing proper MPPT or just acting like a PWM unit with fancy labelling. I haven't got a decent enough meter to test the input vs output properly. It's never cooked the battery as far as I can tell — resting voltage sits around 12.7V most mornings which seems healthy enough.

Has anyone actually bench-tested one of these budget units to see if the MPPT tracking is genuine? And is the heat a red flag I should be worried about, or just par for the course with cheap kit?

Chopper62 | Posts: 847

@KeithScott81 cracking little experiment mate, interested to see your results. I ran a similar £12 unit for about 14 months on my shed setup before it finally packed in — but honestly for that price I wasn't complaining. The fan bearing went first, then it started misreporting battery voltage by about 0.4V which was causing some overcharging concerns.

One thing I'd watch with these clones is the temperature compensation — many of them advertise it but the sensor either isn't connected properly or the coefficient is way off. Worth checking your battery temperature on a cold morning vs what the controller reckons.

What charge profile is yours set to? Some of these units default to sealed/AGM settings which isn't ideal if you're running a flooded leisure battery. Small adjustment but makes a difference long-term.

£14 controller on a van build is either genius or a cry for help — after 18 months I'm genuinely unsure which. 🤔

Squib79 | Posts: 1,243

@KeithScott81 solid results for 18 months, fair play. I've had mixed luck with the cheap Chinese units — lost one after about eight months when it decided to stop bulk charging properly and was just floating the battery permanently. Took me ages to diagnose why my battery felt sluggish.

That said, my current one (paid about £18, so living the high life 😄) has been absolutely fine for nearly two years on a shed setup. I think there's a genuine lottery element to these things — same board design, wildly inconsistent QC.

Main thing I'd say to anyone considering it: keep an eye on your battery voltage regularly, especially in the first few weeks. You'll spot any dodgy charging behaviour early before it does damage. What controller temps are you seeing on yours, @KeithScott81?

MuddySkipper | Posts: 134

@KeithScott81 interesting data point — what's your method for actually verifying the controller is doing what it claims? That's always been my hesitation with the unbranded units.

I ask because on my garden office build I nearly went the cheap route but ended up with a Victron 75/15 partly because the VictronConnect app gives me logging I can actually interrogate. Without that visibility, how do you know the absorption/float voltages are accurate rather than just trusting the LEDs?

Genuine question — if the cheap unit is hitting the right charge curve consistently, the £14 vs £60+ argument becomes pretty compelling for a low-stakes van setup. But what are you measuring it against?