Troubleshooting A USB Charging Problem

Anker Powerdrive 2

I use my old Moto G5+ smartphone and OSMAnd+ for navigation, mounted to my handlebars with a RAM mount and powered via the Tracer’s onboard AUX/’cigar lighter’ socket through a USB converter (USB Power Delivery specs). Over the last 6 months or so I noticed my phone would be very slowly losing battery charge despite saying it was charging and I wondered if this was due to a failing battery in the old phone or something else, perhaps some application on the phone using more energy than the charger itself could provide. Finally I decided I needed to actually investigate and troubleshoot this USB charging problem and see if I could get it sorted out – there’s not much point having a navigation system if it runs out of power.

There are plenty of ways I could test this, such as with my Extech 330 multimeter on the AUX socket itself, but for the sake of invasive simplicity I started with a phone app called Ampere to measure the phone’s (claimed) electrical usage, and then the amount of power the phone was actually receiving. There’s plenty of variables here, but I hoped it would be close enough to suggest where the issue was.

With the usual apps running, which is pared down to a minimum as this phone is only for maps, but includes location and GPS, the app says the phone is using ~350-450mA. However, when on charge from the bike, it says it’s only receiving around 250mA in. That explains why it says it’s charging, but it’s not enough to prevent the battery charge level from dropping.

Next thought – is there a problem with the bike’s AUX electrical output? I decided that was unlikely since my experience with bike electrics was that they tended to work or not work, rather than send out consistently reduced amounts of power – and I was certainly hoping that wasn’t the answer if only because I really don’t like troubleshooting bike electrics.

PowerDrive2 image courtesy of Anker

The weak link then could be the AUX -> USB adapter so I replaced the old Sanwa one with a new Anker PowerDrive 2, which has a 24W / 4.8A rating. The bike itself should be fine with this, as my basic maths says the socket is 12V and I know the fuse rating for that AUX circuit is 2A, so that should be 24W max. Upon testing with the same Anker cable I’d been using before, the phone was now receiving a fairly steady ~750mA. This obviously is enough to charge the phone and as an older micro-USB device, it’s around what I’d expect. Why did the old Sanwa adapter start maxing out at 250mA? No idea, but I suspect whatever detects/negotiates best voltage just wasn’t working correctly – perhaps the infamous motorcycle vibration finally got it? Pure speculation.

The main point though is the Anker adapter works fine, so I don’t need to worry about my navi needing its own charging battery on longer trips.

This isn’t the best way to troubleshoot this as I mentioned – a multimeter on the AUX circuit is a basic step you’d want to be doing, if only to check there isn’t some larger, hidden issue with the bike’s electrics, and certainly something I’ll be checking, but I wanted to see how far I could get without access to real tools. The measuring app – and there are quite a few in the Play store – I’d say is a very rough indicator, but that’s all I needed in this case to see whether things were close, and the issue with a phone is that the usage voltage is constantly changing so you’re only ever going to get a range, but at least with a phone running very few apps, that’s a little more consistent than a daily driver phone.

I don’t really want to get into the wit n’ wisdom of using a phone as navigation device here as it’s apparently somewhat divisive. For me, it means I could use a couple of navigation apps (e.g. OSMAnd or Google Maps) and because that’s all it does, it doesn’t overheat or struggle to keep up – and I’m not in the uncharted wildernesses. Of course it doesn’t have a SIM but you can load apps on via wi-fi still, so I can load music and podcasts on there if needed, run the Cardo comms app, the GoPro quick app for controlling the camera if I mount it behind me, and I can still make emergency calls on it if need be. It’s not fully waterproof, but it’s been fine in a downpour or two and I have a plastic cover for it for when things get bad. I wouldn’t use my daily phone for this, again, the vibrations seem to break cameras (and not just Apple ones, but anecdotally most modern phone cameras with physical image stabilization features) and I suspect the phones too eventually. I’d like to get something like a Garmin, but here in Japan they’re 2x the US price, which seems a bit of a markup.

Given the amount of time I use it though, I find the old phone navigation device works pretty well though – just don’t forget the quality of USB adapter and cables you use!