Real world "on the road" charging experiences

[freiston]

I did a little test today regarding charging electrical items and would like to share the results.

I was wondering what thread to tag it on to but decided to start a new thread because I thought it might be a useful thing to have people's experiences handy in one thread without arguments for and against various power sources - just data that others can use to make informed decisions.

I'm hoping that the thread won't go off topic and that people can add their experiences - I hope that any posts made will be based only on real-life "field" data and experiences and will contain at least some quantifiable data, some description of the conditions and possibly some anecdote too. There's plenty of threads discussing the various merits of different methods/set-ups - but I would like this to stick to people's experiences with some sort of data.

Today, I cycled 18 miles out to a pub over 1¾ hours. I had my Garmin Edge 530 mounted to my handlebar and used it to navigate - screen on all the time.

The battery was reported as 34% when I started. I plugged it into my Cycle2Charge V3, powered by my Kasai IC-KD1F dynamo hub - charging directly rather than to a buffer battery (I usually only charge directly to a powerbank). I switched my lights off. I tried to see what speeds the charging stopped/started but this was difficult because a) the speed reported by the 530 isn't exactly instantaneous and accurate, b) when I slowed or speeded up suddenly, I was usually concentrating on the road not the 530, and c) I have my screen configured to show the map on the approach to junctions/turnings and don't have the speed showing on the map screen - so most of the time that I was hitting the critical speed, the speed wasn't shown on the screen.

Saying that, I reckon the cut in-out speed was about 6 mph.

The route had a lot of narrow road with blind bends and a lot of up and down though not many long up or down stretches - so not many opportunities to go fast (not that I do anyway). The temperature was warm - the 530 reported an average of 19°C. Though I suspect the 25°C maximum was due to the bike being in the house before the ride began.

At the end of the ride, the battery was reported at 77%.

For reference, here are the ride stats:

[OutdoorOasis]

Thanks for sharing your detailed test results! It's great to see real-life data on how the Cycle2Charge V3 performs with a dynamo hub. Noting the cut in-out speed around 6 mph is especially useful.

[edocaster]

Very interesting. The Edge's battery is possibly 750-1000mAh, while the charging time could be called 1h45m, or possibly down to 1h30m if you drastically discount slow climbs or any stops. That gives an average charging rate of between 200 and 300mA (assuming the percentages map linearly to the charge). Probably add another 50-100mA to account for the Edge draining while in use too.

Now, while these are not impressive numbers, charging depends on the source and the device. It's probable that the Edge defaulted to a low rate. Dynamo chargers do need to decide when they start outputting anything, and if they start too early while the bike is slow, the negotiated charging rate is low.

[2_i]

I have a Bike Harvester with two cold-weather 18650 batteries inside, totaling 7000mAh. The Harvester is connected to a SON dynamo that keeps the batteries full and makes it a power bank. In practice, the pace of charging for any device I need to top up does not depend on how I am riding, or even at all, or whether I have lights on.

[freiston]

I have a Bike Harvester with two cold-weather 18650 batteries inside, totaling 7000mAh. The Harvester is connected to a SON dynamo that keeps the batteries full and makes it a power bank. In practice, the pace of charging for any device I need to top up does not depend on how I am riding, or even at all, or whether I have lights on.

Interesting. I had to look up "Bike Harvester". Caveat: my understanding of electronics is very rudimentary and I didn't really follow the technical blurb.

So when you say in practice . . . does not depend . . . , do you mean because the Bike Harvester acts as a reservoir/buffer between the dynamo and the device being charged, providing stable power and there's enough power being topped up to the reserve so that any draw of power from the reserve does not deplete it enough to cause issues? If so, what sort of devices are you charging, do you charge on the go or when off the bike, and do you ever charge multiple devices simultaneously?

[edocaster]

Because the Bike Harvester has two 18650 batteries inside, the ultimate device to be charged never gets to see the variable nature of the dynamo's output. I mentioned this in another comment, but by having the buffer battery built in, rather than a separate USB-charged power pack, means the cells can be charged with less in the way of 'protocols' compared to USB, without wrong handshakes and non-optimal charge rates.

It seems that if the charge isn't getting used up enough, the charger disconnects further charging of the batteries when full to avoid overcharging. On the opposite end, in theory the battery can be depleted faster than it can be charged, and it will eventually go into 'sleep' mode when flat, but the batteries are so large that would only happen if continuously charging something very large (e.g. another power bank).

[2_i]

Yes, the batteries act as a buffer. For someone touring, it can also be important that the Harvester can be charged with a USB AC adapter through another port. On my bike, I typically have other electronics than just the phone that can be topped up from the Harvester: a horn, an MP3 player, a small radio, and a Bluetooth adapter. I have not yet charged two devices simultaneously, but I do not see why this could not be done with a splitter - I usually concentrate on the device that is most in need.