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.
I don’t think the charger fried your gear.
If it had, it would have also fried the display unit you tried it on.
USB-PD defaults to 5V until a negotiation takes place to establish voltage and current limits. In order to have caused damage, negotiation would have to have established voltage greater than 9V.
Plenty of USB-C chargers do not supply the full range of voltages that are possible through USB-PD. For example, the Nintendo Switch’s charger is limited to 15V because that is the most the switch supports. Lots of inexpensive “phone chargers” top out at 12V.
It’s more likely that you received a defective unit.
If the USB-PD PSU that you bought was correctly supplying 5V prior to any kind of negotiation, then how was it possible to damage the radio that’s expecting a 9V supply? Did they wire the polarity incorrectly?
It’s possible that it’s just the battery that needs replacing, and because it’s dead it doesn’t meet the minimum supply voltage to power the radio while it’s charging. You might want to try that before giving up on it.
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.
That sounds horrible. You’re right about everything.
It sounds like they wanted to just use a 9V input with no USB circuitry, but they slapped on a USB-C connector on it because e.g. European regulators require all rechargeable devices to use USB-C. But obviously that’s not compliant, not with USB specs and not with the regulations.
@NeatNit @evenwicht Not unusual. Cheap devices like these light do not conform to the USB spec and are missing 2 resistors signaling the power demand. USB-C chargers won’t work in this case, as they only output voltage, if they detect a device. You need a USB-A charger with a A-to-C-cable. Yes, it sucks, but the seller saved 0.2 Cents during production :/.
USB-C chargers won’t work in this case, as they only output voltage, if they detect a device.
Note that the first 2 times I attached a universal USB-C charger to the radio, it gave a charging animation (though after ~30-45 min wait). So I am struggling to work out how that happened. Did the charger give up after waiting a long time and say “fuck it, will give some arbitrary power”?
You need a USB-A charger with a A-to-C-cable.
My universal charger has both USB-A and USB-C ports. I tried the USB-C port first (thus usb-c→usb-c). Then at one point I tried usb-a→usb-c. I was expecting usb-A to behave the same because the charger specifies the same range of voltages for both ports. The only difference is the max current is a little higher on the usb-c.
What’s the model of radio, and if you have it, the official charger?
Does the device (actually, both devices- radio and charger) say it’s USB (logo, etc), or does it just look like a USB-C connector? Kenwood (now part of JVC) is pretty big. They’re unlikely to use the logo if not compliant.
Also, you mentioned plugging the display unit to power. Was that to an official charger, or to your own charger? Is it possible that your charger is bad? A lot of cheap, generic ones (anything from Amazon or AliExpress) can damage electronics.
It’s also entirely possible that your unit was defective before you even opened the box. Missing the charger means it probably wasn’t just unsold inventory.
The seller had a few of these same radios, new in box, but all missing the chargers. My thought was either the seller sold them separately or the chargers were stolen and so whatever retail store had them could not sell them and they ended up on the street market. But after seeing that the OEM chargers are strictly 9v, they seem worthless without the radio. Unless it’s just a shitty label. Maybe the OEM charger is proper USB PD, but they only wrote 9v on the label. I can only speculate.
The universal charger I have could also be dodgy. It was from a 2nd-hand shop. But afaik it’s fine.
Since I don’t have the OEM charger, I cannot see how it is marked. I just recall it was only marked 9v.
(edit) it’s also possible that the OEM chargers are poor quality and have short lives… maybe the retailer opened boxes just to replace broken chargers for customers under warranty, which would also result in radios without chargers.
