Hello, a year ago I received a Radex Lupine purchased on AliExpress that I wanted to use to measure the level of eye protection for my screens. However, they refunded my money because although it works perfectly like any other Radex Lupine, it only works while it is connected to the charger, at the moment you remove the cable it does not measure anything h or the screen turns on, it does not charge either. Because of this I got my money back, however I can still use it and that's great, but I would love to try and fix it and see if you can advise me on how I could fix it.

I have left you some images about a Russian review of the Radex Lupine where they opened it so that you can see what it is like inside and what it contains. since mine works perfectly connected to the electricity but dies as soon as I disconnect it, I suspect that what is defective is the internal battery and that is why it does not charge. Seeing the images that I have given you... do you think it is possible to replace that battery with a similar one? could it be fixed?

Unless you try replacing that battery for the same one you could solder on a AA battery holder. You'd have to find the voltage of the original battery. These are the battery holders (https://www.aliexpress.com/item/4001135566826.html?pdp_npi=2%40dis%21AUD%21AU%20%240.55%21AU%20%240.43%21%21%21%21%21%402101d1af16753006699641034e05ad%2110000014749021342%21btf&_t=pvid:886971af-5479-4caa-bbf3-0b2a6cccdc51&afTraceInfo=4001135566826pcpcBridgePPCxxxxxx1675300670&spm=a2g0o.ppclist.product.mainProduct)
Drill a small hole for the wires on the back an use rubber band to hold it on. Not elegant but could work. Just double check the voltage, you might need a double battery one.

Can you borrow/buy a multimeter? then you can measure if the battery is dead, or if its a poor connection etc

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