Suggest device for logging AC current?

baldguyfromblackpool

Dec 18, 2025
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I have a Zappi EV charger which is working fine when I plug my BYD car into it, but when Mrs Baldguy plugs her MG into it, all sorts of crazy happen.

I've been through many menus and manual chapters trying to figure out what's wrong but nothing has worked so far. What I -have- noticed though is that very often when she tries to charge, the lights throughout the house often dim momentarily as if a sudden very high load is being imposed.

It's always very fleeting though, and the normal reporting screens for the car, Zappi and solar/battery system feeding them, have nowhere near enough temporal resolution to show any detail.

I'm looking for some kind of minimally invasive, maybe CT-based logging device, that I could use to record the current draw on the Zappi's single phase feed, and subsequently (or in realtime) display it as a graph, current v time.

I've seen a few full blown oscilloscope/multimeter/loggers costing up into the multiple hundreds of pounds and beyond but really I don't want to spend so much on a device I'll probably only use once. Is there something cheap that would maybe connect to a laptop or phone over WiFi / USB? I'm thinking of a sub £50 budget.

Accuracy probably isn't a paramount concern. Just something that can give me a good clear visual window into what's happening over the course of a few seconds, with the current flow?

In an ideal world a box with a CT clamp on a flying lead, and a big LCD with a continually updated graph display of the last five seconds in 0.25 second samples would be perfect. But to keep cost down, data sent to a laptop that I could then homebrew a graph in python would be ok?
 

Harald Kapp

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Something like this Tuya based meter?
Or this one if you are uncomfortable buying in China.

Unfortunately I couldn't find any information on the temporal resolution of these units.
 

hevans1944

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Jun 21, 2012
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A Mooshimeter will provide a Bluetooth wireless cell phone display. Just had a clamp-on AC current probe.
 

Harald Kapp

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When you follow the sales links from the Mooshimeter website itr looks like it is discontinued. Possibly available used on one of the intenet platforms of your choice. As shown in the ads the original doesn't come with an AC clamp, you'd have to supply that additionally.
 

baldguyfromblackpool

Dec 18, 2025
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Whilst away from the thread I ordered something called a PZEM-004T that sends data out to a com port, planning to read it on a laptop with python.. not sure how fine-grained that will be either. ChatGPT thinks you can poll it about 5–10 times per second (100–200 ms intervals) without issue. I'll order a Tuya one too & see what it's capable of. Thanks
 
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Harald Kapp

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I found some useful information and a datasheet for the PZEM-004T here. But even the datasheet doesn't state the sampling rate :(
 
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