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Net Work Alan Winstanley This month’s column uncovers a common fault in a popular ‘smart’ charger and examines a USB Power Delivery (PD) adaptor for USB chargers and power banks. We also have a headsup on looming import duty changes. I n t h e l a s t N e t Wo r k c o l u m n (December 2025), I described how I was looking after my sealed lead-acid (SLA) ‘Cyclon’ type lawnmower starting battery, ready for the onset of winter. This winter I’ve used a Sealey Autocharge 100HF compact ‘smart’ charger to float-charge it, nurturing the battery in readiness for the spring mowing season. In between times, my car battery had also been topped up using a popular CTEK MXS 5.0 12V 5A charger during periods of intermittent heavy use. These electronic chargers cost about £80; CTEK has a wide range of connecting leads and under-bonnet adaptors suitable for car and marine use. On a previous car, I even fitted a CTEK connector to the car battery posts, under the clamp nuts, which made routine charging a cinch. Despite my best endeavours, events took a turn for the worse when my car dashboard started flashing up “Stop-start not available”, even though I knew the battery was fully charged. (I always disable stop-start anyway.) I even demonstrated this to the valet who collected the vehicle for service. My dealer shrugged it off and reported that the battery tested OK, but bitter experience told me that the constant error message was a warning sign of imminent battery failure. I’d seen exactly the same thing three years earlier, when the car battery suddenly failed and I was left stranded in town late one evening. It seems that an enhanced flooded battery (EFB) has a lifespan of just 3-5 years and, typically, mine was out of warranty by two weeks. [Editor’s note – we replaced the original battery in our Mazda CX-9 nearly seven years after taking delivery. It seems OEM battery quality is well above that of replacement batteries, even from the original dealer.] With the dealer taking no re- Practical Electronics | May | 2026 sponsibility and only giving the usual vague “It’s up to you” advice, I plumped for a new EFB battery anyway. The ultimate upgrade would be a more costly absorbent glass mat (AGM) type, if you can find the right dimensions and battery post arrangement. It’s probably best to stick to well-known, reputable brands and check online reviews before buying. My CTEK MXS 5 charger then suffered a problem with a jammed, unresponsive Mode selector switch. The switch is a thumb-size pushbutton that is likely to get ‘mashed’ in regular workshop use. My charger was sulking, stuck in motorcycle battery mode. It appears this is a common This selection of 100 tactile switches from Temu costs £2. problem, as CTEK’s own web page suggests “pressing the button a bit firmer and repeat it a few times. If the issue persists, the button is most likely defective. However, please keep in mind that the charger will still work in the selected mode.” CTEK’s remedy was to suggest ‘mashing’ the switch even more! Some users reported that they tried using switch cleaner aerosol, while others resorted to cutting open the front panel and poking the switch internals with a biro. After drilling out a tamper-evident plug, I took my charger apart and discovered that the switch was only a common 6mm PCB tactile pushbutton, of the type found on small electronic gadgets. 3 I was left wondering whether these were the best choice for the job; having lots of thumb pressure bearing down on a tiny switch underneath was maybe not what they were designed for. The old English phrase “spoiling the ship for a ha’porth of tar” sprang to mind. As a possible fix, I’ve just received from Temu a selection box of tactile 6mm buttons with five different actuator sizes (heights), with both DIP and SMD solder terminals. That’s 100 switches for under £2! To make life difficult, CTEK’s pushbutton has a bespokeheight actuator with a tiny recess on top, so I’ll no doubt have to fabricate or adapt something. My next project, then, is to see if I can successfully repair my £80 charger with some solder paste and a membrane switch costing one penny. I’ll let you know if my efforts pay off! Checking out the power Net Work has previously described a range of USB inline monitoring devices, small LCD gadgets that show the voltage, current and other parameters when charging rechargeable products. They are also handy when using USB Power Delivery (PD) compatible products; it’s interesting to see the display ‘handshaking’ as the charging voltage ramps up from a baseline of 5V to deliver more power. My preference is the low-cost Kowsi KWS X-1 USB-C monitor with multi-colour display (see page 63, December 2025 issue), which I use most of the time. It also offers an oscilloscope-type display with a timebase showing voltage and ripple voltage, amongst other factors. As many gadgets and apparatus use the classic 5.5mm DC jack, the Kowsi DC-28 (Net Work, November 2025) works well with ordinary mains adaptors, as used by my 25V rechargeable vacuum cleaner, for example. A short DC extension lead is handy for hooking up the inline monitor, so I can see at a glance the current state of charge and guess when it’s likely to be finished. Not every idea pays off, though – I also tried one with the PSU for my Asus laptop. Some trial and error revealed that my laptop used a DC jack measuring 4.0 × 1.35mm. To complicate matters, there’s a similar 4.0 × 1.7mm type, which didn’t fit. Eventually, I sourced a suitable set of DC adaptors/reducers from 4 AliExpress, but the laptop connections proved dodgy at best, so I gave up on that idea! Another handy gadget that caught my eye is an inline USBC voltage adaptor with a difference: it exploits the principle of PD ‘triggering’ to boost the output voltage from a compatible USB power bank or mains adaptor. The adaptor is equipped with a USBC input lead, a 7-segment display and a standard 5.5mm DC 1m-long output lead. Pushbuttons on the device select the DC output voltage. I tested one using several power banks and obtained 9V and 12V DC outputs. It also worked well with a PD-­ compatible UGREEN mains adaptor; I could derive the advertised options of 5V, 9V, 12V, 15V and 20V from it. Where a USB-C port isn’t available, a USB-C-to-A-type converter can connect the voltage adaptor to traditional-style USB ports instead. These PD adaptors could prove handy for re-purposing a common power bank to supply 9V or 12V DC like a traditional mains adaptor, or you could utilise a PD-compatible mains adaptor to obtain higher voltages (9-20V) for your projects. They are widely available online for under £3. In for the long Haul? Mention the Chinese website Temu to someone and you’ll be greeted either with knowing smiles or hoots of derision. Temu came to Britain quite late in the day and, regardless of one’s opinion about the merchandise offered by some sellers, what’s undeniable is that Temu has grown exponentially to become one of the world’s largest e-commerce platforms. There can be no dispute that Temu’s attention to error-free detail at a granular level, especially on the mobile app, is nothing short of sublime. In my view, it makes rivals such as AliExpress appear very clunky and unvarnished in comparison. AliExpress is clearly rattled, because a survey they sent me was obviously fishing for opinions about Temu. Amazon’s answer to Temu is called “Amazon Haul”. It lists many low-cost items, but there’s just a fraction of the choice offered by Temu. I soon found items on Haul that were three times more expensive than on Temu. Haul is still a work in progress, and how long Amazon bothers with it remains to be seen. As I wrote in earlier columns, substantial savings can be made on Temu if you know what to look for, and such savings are certainly welcome these days. There can be dubious products of questionable quality; reviews can be insightful. I steer clear of most mains-powered products like unbranded or oddly named electric heaters, steamers, irons, power tools, or similar. Apart from the odd duff, lowcost purchase, I remain quite defensive of Temu and think it’s a mistake to write it off. It’s little different from buying through eBay, Amazon, Facebook Marketplace or TikTok Shop, for example. Not every reader agrees, as my mailbox reminds me, but freedom of choice is a good thing and, in my case, every delivery has arrived A USB Power Delivery (PD) adaptor triggers a compatible power bank or USB mains adaptor to provide higher voltages than 5V (20V in this case). Practical Electronics | May | 2026 as expected, with any problems soon rectified. Questions about quality and safety apply to goods imported through other platforms, including Amazon Marketplace and AliExpress. The risk of buying items with fake approvals is ever-present. I sourced a decent-looking digital pen-type soldering iron via AliExpress, and when I plugged it in, the tip literally glowed red hot! It was supposedly CE approved and stamped for 220V AC. A 7000mAh LED rechargeable ceiling light sourced from Amazon had, as I would discover, a Li-ion battery stuck face-down inside – presumably to hide the fact that it was labelled 5000mAh. I couldn’t be bothered returning it. One popular and highly knowledgeable Scottish YouTuber, Big Clive (“the trashiest electronic channel on YouTube”) delights in sourcing sundry and sometimes lethal-looking electronics from China and ripping them apart. His “AliExpress Unbagging Joy” videos entertain his 1.1 million subscribers as he reverse-engineers a variety of ‘tat’ bought online. It’s not all bad, though; sometimes he’s impressed by what he finds. low-value orders. The problem lies in the extra cost of collecting and processing these import duties, which is why I think buyers may eventually see a price hike. In my industry career, I’ve done my fair share of importing and exporting (even driving the forklift!). In the world of shipping, the term ‘brokerage’ covers the work undertaken by import agents to clear loads through customs, sort out the onerous paperwork and collect any import duty before delivering the goods. These admin fees are charged to the importer. At the consumer level, customs clearance fees can make smaller orders almost non-viable. Some years ago, late one Sunday night, I ordered some camera equipment online from B&H Photo in New York. My order enjoyed the fastest logistics turnaround I ever saw: the photo gear arrived at my door early on Wednesday morning, and I gave the courier a cheque for the import fees, the goods having arrived in the UK ‘delivered duty unpaid’ (DDU). The sting in the tail was that my order had been split into two consignments and therefore across two invoices. This attracted two lots of customs fees, which effectively nearly doubled the delivery cost. For now, consumers can enjoy buying low- cost merchandise online under the prevailing de minimis rules. How the new proposals will play out remains to be seen, but they will eventually affect all imports, including printed circuit boards sourced from China. Updating systems to recover customs clearance fees from consumers won’t happen overnight, and financial sources suggest “by 2029” as the likely timetable. One emerging trend is ‘local warehouse’ sales, where independent British-based sellers use the Temu platform to sell merchandise; especially heavier, bulkier lines such as the oil-filled radiator shown in my example. Goods are sold and shipped from within Britain and usually arrive within a day or two. There is plenty of evidence that the ‘local warehouse’ channel is becoming more popular with traders. You can check out the surprisingly wide range of categories on their website, and suppliers can search for “Temu Seller Center” to learn more about selling that way. Join me next time for more Net Work. You can contact the author PE at alan<at>epemag.net The Temu Tax Buying low-cost goods from Chinese platforms exploits the fact that they land in Britain duty-free, although VAT is levied on top. What has gone unreported so far is last year’s Budget announcement by UK Chancellor Rachel Reeves that the de minimis rule for imported goods is planned to be eliminated. The UK duty-free allowance for personal goods is £135 (US $185) and the budget proposals, intended to please British-based businesses and fend off ‘unfair’ foreign competition, would see import duties applied to all shipments regardless of value. Charging a nominal import duty (say 2.5-4%) on ‘Local warehouse’ items are shipped top may not have directly from UK warehouses rather much impact on than China and arrive in a day or two. Practical Electronics | May | 2026 5