Anyone else running a cheap AliExpress MPPT alongside a name-brand one? Curious how you're getting on

I picked up a no-name 40A MPPT off AliExpress back in March for about £18 delivered — yes, eighteen quid — mostly just to see if it would survive more than a week. Chucked it on a second 100W panel I had spare, feeding into my 100Ah lithium leisure battery alongside my Victron 75/15. Figured the Victron would do the heavy lifting and the cheapo one would either contribute something useful or blow up spectacularly.

Surprisingly it's still going four months later. The stated specs are obviously optimistic (claims 40A but I'm seeing maybe 5-6A out of it on a good day, which is about right for the panel), and the Bluetooth "app" is genuinely baffling — three screens, none of them in proper English, one just says "WORK MODE: YES." But the absorption and float voltages are holding steady at 14.2V and 13.6V, which I set manually and they've stayed put even after a power cycle, so that's something.

What I can't work out is whether it's worth keeping in the mix or whether I should just wire that second panel directly into the Victron and be done with it. The 75/15 can handle both panels combined (about 17.5V Voc each, so 35V in series — well within the 75V limit), and I'd lose the faff of monitoring two controllers. Has anyone actually done a proper side-by-side comparison of one of these budget units versus running everything through a single decent MPPT?

@MPPT_Fan ha, tempting fate with that one! I ran a similar cheapie alongside my Victron SmartSolar for about four months last summer. Honest verdict — it worked, but the voltage reporting was all over the place and I reckon it was clipping the tail end of my absorption charge. Pulled it when I noticed my Fogstar lithium cells weren't hitting full SOC consistently.

For a lead-acid bank where precision doesn't matter as much, probably fine. Wouldn't trust one with lithium though — the charge profile accuracy just isn't there.

Curious what battery chemistry you're running? That'd change my view on whether £18 is a bargain or a false economy tbh.

Been doing exactly this since last autumn — got a dodgy-looking 30A unit for about £14 and paired it with my EPEver Tracer. Honestly the cheap one has surprised me, still ticking along on a 200W panel feeding a leisure battery in the shed.

That said, I wouldn't trust it on anything critical. The EPEver handles my main house bank without question, but the AliExpress one does a reasonable job on the shed setup where if it packs in I've lost nothing important.

One thing I'd flag @MPPT_Fan — keep an eye on the temperature. Mine runs noticeably hotter than the EPEver and I ended up mounting it with a bit more breathing room after it got warm enough to worry me on a sunny July afternoon. Worth checking yours isn't cooking itself quietly!

Running this exact setup in my static caravan — paired a £22 AliExpress 20A unit with my Victron SmartSolar 100/30. The cheap one handles a dedicated 200W panel feeding a secondary Fogstar battery, keeps it topped up without touching my main bank.

Main thing I noticed: the cheap unit's voltage readings are wildly optimistic compared to what the Victron's actually seeing. Like 0.4-0.6V out on the display. Fine if you're not relying on its numbers for anything critical.

Also worth checking the actual charge profile it's running — mine claimed "AGM" mode but was clearly pushing slightly high absorption voltage. Verified it with a proper multimeter before I trusted it near the batteries.

For £22 doing a secondary job with no critical load attached? Can't really argue with it. Wouldn't run my whole system on one though.