Overkill Solar iOS App - Possible Short Circuit Protection Incompatibilities with newer JBD BMS's

Been running a JBD BMS on my van build for about 18 months now — 200Ah LiFePO4 from Fogstar paired with one of the older 100A JBD units — and I've had zero issues with Overkill Solar's iOS app reading the short circuit protection parameters correctly.

But here's where it gets interesting. A mate of mine picked up a newer JBD unit (one of the revised 150A versions from late 2023) and when he tried configuring short circuit protection through Overkill's app, the values weren't sticking properly. He'd set a trip threshold, it'd appear to save, then reconnect and find it had reverted — or worse, saved something entirely different.

He eventually had to use the Xiaoxiang BMS app instead, which read and wrote the parameters without any drama.

My suspicion is that JBD quietly revised their register mapping on the newer hardware revisions without updating anyone downstream. Wouldn't be the first time a Chinese manufacturer has done exactly that. Overkill Solar's app is brilliant for the older units but it seems like they're playing catch-up.

A few questions worth chewing over:

• Has anyone confirmed which specific firmware versions on newer JBD units are causing this?
• Is it purely a short circuit config issue or are other protection parameters affected too?
• Has Overkill Solar acknowledged this anywhere officially?

The practical concern here isn't just app compatibility — if protection settings aren't saving correctly, you could think your BMS is configured safely when it isn't. That's not a theoretical risk I'd be comfortable with, especially in a van where a thermal event is rather more personal than in a shed.

Worth getting to the bottom of properly.

Has anyone tested whether this affects the short circuit protection trigger threshold specifically, or is it more general communication drop-outs with the newer JBD firmware versions?

Asking because I'm about to pull the trigger on a second battery for my garden office setup and was looking at a newer 150A JBD unit. I'd been planning to use Overkill to monitor it alongside my existing Victron MPPT — if the app's reading cell voltages incorrectly on newer hardware that could genuinely throw off my charging decisions.

@SussexVanLifer — when you say "older 100A JBD unit", do you know what firmware version you're on? Wondering if there's a specific cutoff point where the incompatibilities started appearing, or whether it's purely a hardware revision thing.

@Smithy98 from what I've seen with my garden office setup, the short circuit threshold gets misread by the app and shows a value that'd make your hair curl — mine reported something absurd like 400A on a 60A BMS, so I'd trust the raw BMS registers over whatever Overkill's iOS app is cheerfully displaying at you.

@NorfolkVanLifer interesting you're seeing that on a garden office setup — same here. What I've found is the misread threshold isn't just a display glitch; if you're relying on the app to confirm your SCP settings are correct before commissioning, you could be flying blind.

I verified mine with a proper bench test rather than trusting the app readout. The actual BMS triggered fine at the right point, but the app was showing a completely different value.

Worth noting: this seems worse on the newer JBD firmware versions. My older unit (flashed maybe 2 years ago) reads consistently. The newer JBD app on Android doesn't have the same issue in my experience — might be worth cross-referencing readings between both if you've got an Android device handy.

@FormerMariner24 when you say the threshold is being misread — are you able to clarify whether the displayed value in the app is wrong whilst the BMS is still triggering at the correct threshold physically, or whether the miscommunication is actually causing the BMS to behave differently in practice?

That distinction seems fairly critical before anyone starts adjusting settings based on what the app reports. On my van build I've not pushed mine to short circuit territory obviously, but I'd want to know if this is purely a cosmetic display issue or something with real-world consequences for protection behaviour.

Also — what firmware versions are people seeing this on? The JBD units aren't always consistent with versioning nomenclature and I suspect that's muddying the waters when comparing experiences across different builds.