Is a phone thermal camera good enough for checking a Victron system?

Been thinking about picking up one of those phone attachment thermal cameras for checking over the DC side of my motorhome setup — mainly terminals, fuses, busbars and connections under load.

Anyone actually used one for this kind of thing? The Topdon IRS and the FLIR One seem to come up a lot, but they're not cheap for what they are. There are also some cheaper knockoffs floating about on Amazon that I'm a bit suspicious of.

My main use case would be:

• Battery terminals on my Fogstar 200Ah lithium
• The Victron SmartShunt connections
• Blade fuses and ANL fuse holder
• Busbar connections when the inverter's pulling decent current

I imagine even a basic 160x120 resolution unit would flag up a dodgy connection that's running warm — you don't really need surgical precision for that, do you?

What I'm less sure about is whether the cheaper phone-based options give you enough temperature accuracy to actually trust the readings, or whether you'd be better off just saving up for a proper handheld unit like a Fluke or similar.

Anyone running one of these regularly on their van or off-grid setup? Curious whether it's become a genuinely useful bit of kit or just a novelty that collects dust after the first check.

@RobJones85 yes, absolutely worth having. I use a FLIR One on the narrowboat regularly — brilliant for spotting a dodgy terminal before it becomes a proper problem. Caught a warm 500A fuse holder last summer that looked fine visually but was reading 15°C above ambient under load. Turned out the lug crimping was poor.

The phone attachments won't match a dedicated Fluke or FLIR E-series unit, but for DIY monitoring of busbars, battery terminals and Victron shunts they're more than adequate.

Few practical tips:

• Always check under load (not idle)
• Shiny terminals can fool the emissivity reading — a bit of black electrical tape helps
• Do a baseline scan when everything's known-good, so you've got something to compare against

For the money (£150–£200 for a decent FLIR One) it's a no-brainer.

@RobJones85 welcome to the forum — good first question, straight to the point.

One thing worth knowing: resolution on phone attachments like the FLIR One is fairly low (around 80×60 or 160×120 pixels on the cheaper units). Fine for spotting a genuinely hot terminal, but you can miss a subtly warm connection if the surrounding thermal mass is large — think big copper busbars or a Lynx distributor.

Practical tip: load the system properly before scanning. Faults that are invisible at 10A become obvious at 80A+. I do mine with the EV charger running flat out — that's when the dodgy connections reveal themselves.

Also check both sides of every fuse. A significant temperature differential across a fuse that isn't blown is telling you something.

Worth the £150-200 for peace of mind alone, honestly.

@RobJones85 got one of those Seek Compact jobs rattling round my motorhome glove box — found a terminal on my Fogstar battery that was running warm enough to fry an egg before it became a proper problem, so yes, 10/10 would recommend over finding out the hard way.

@RobJones85 worked on vehicles professionally for years before going off-grid — thermal cameras are genuinely useful but don't expect them to catch everything cold.

Run your system under proper load first, ideally 80%+ draw for 10-15 mins before scanning. Caught a loose bolt on my lynx distributor that way — looked fine visually but showed up orange straight away.

Also worth checking:

• Fuse holders — these run warm even when fine, so learn your baseline
• Battery terminals — especially on Fogstar cells, the busbars can mask heat underneath
• Inverter DC input cables — often overlooked

The cheap Topdon or InfiRay units off Amazon do the job for this kind of work. Doesn't need to be a FLIR.

Just don't bother scanning AC stuff unless you actually know what you're doing — different ballgame.

Used mine to "check" my cabin connections, mainly found that my Victron MPPT was fine but the mug of tea I'd left on top of it was stone cold — priorities.