I bought a 2nd-hand (but new-in-box) Kenwood radio that requires USB-C @ 9 volt 1.5A. It did not come with the original charger, so I bought a separate universal USB-C charger (145 watt, full range of voltages incl. 9v 3A). The charger is not Kenwood, but it should work, no? Because we have standards, right?
I plugged it in and LCD was dead for like the first 45min. Then it started to show the 3-stage charging indicator. The device would never power on. I assumed it had to be well charged, but then saw in the manual that it’s expected to function while it charges. It never got fully charged and the display eventually simply went off.
Day 2:
I plugged it in again and it was again dead for like 30 min before it started charging for hours. LCD went off again. Never made charging progress and never powered on.
Day 3:
I plugged it in and the LCD was off, as usual. But this time it stayed off. It no longer shows a charging indicator even when plugged in overnight. I wonder if the charger killed the radio (or the internal battery).
I went to a retail shop that has the same model radio on display. The display model had no juice but I plugged it in and it instantly indicated it was charging and also instantly powered on. Then I noticed the stock factory PSU is strictly 9v. WTF?
Is that compliant? USB PD chargers are supposed to default to 5v until the device asks for more. There is a handshake process, per the spec.
The handshake is important
If a device needs 12v, for example, you cannot just take a 12v PSU and solder a USB-C connector to it. It will fry things because the device expects to start with 5v and negotiate for 12v.
So WTF is Kenwood doing making a USB-C PSU that is strictly 9v? Did they actually just hardwire a 9v PSU to USB-C connector and build a device that skips the USB PD handshake?
The manual says: only use the Kenwood PSU that is made for the device. When I read that shit, I thought: yeah yeah, the usual liability bullshit. They want us to be loyal and only use their products. But now I wonder if they did something seriously obscure to where it’s in fact true that only their 9v PSU will work – and yet it does not seem to be sold separately.
Crappy design?
It’s certainly indisputably a crappy design that the radio has an internal battery that (according to the manual) must never be replaced by the consumer. But the more interesting question is whether it’s a crappy design to produce a USB-C charger that is 9v-only. As well as whether it is a crappy design to produce a radio that requires a non-universal non-PD-compliant power source with a USB-C connector.
I brought the dodgy radio into the store and plugged it into the Kenwood OEM PSU. It’s still dead, which I suppose is concrete proof that the radio is toast.
Dead battery was my 1st theory, but it’s questionable. I fiddled with a healthy demo unit (same model) at the store. The battery ran out of juice and the machine shut down. I plugged it in and hit the power button and it instantly turned on. So it can apparently run directly off the USB-C as the battery charges (and the manual says as much). But the one I have never powers on, even when connected to power.
There’s a wide voltage difference between “I’m dead, charge me” and “I’m so dead any half competent charging circuitry will refuse to charge me lest I combust”.
If it’s fuggered, you’ve got nothing to lose by opening it up and seeing how hard replacing the (probably 18650 Li-Ion) cell(s) will be.
Good chance they’ve got solder tabs spot welded onto the cells, but that’s not a showstopper, you can buy em that way if you don’t know anyone with a spot welder.