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Energy budget

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Energy budget

Old 09-17-20, 09:12 AM
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Energy budget

[motivated by recent thread on solar panels].

Curious as to how many Wh/day people use. I'll read energy budgets with interest. (not being able to tour for the past year or so, I don't have a precise idea of what is our budget. In a pinch (smartwatch + minimal use of LED lights), probably as low as 1 Wh/day. Otherwise, probably something like 20 Wh/day (2 phones a few hours/day),
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Old 09-17-20, 03:58 PM
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Power from dynohub and USB charger. I try to be self sustainable on power, as hunting for outlets in restaurants and campsites is a hassle.

By component, these are all guesses:
  • I think I get two days out of my GPS with a pair of AA NiMH batteries from full to empty, that is probably 3.6 watt hours per day.
  • Probably about 10 days on my headlamp (for my head), single AA battery, so assume 0.4 watt hours per day. I usually tour in June or July, thus long days and short nights, do not need much light in the tent.
  • Phone, usually off or airplane mode, use maybe 20 percent of a battery per day for checking e-mail and weather forecasts on wifi. Battery is 7.8 watt hours, so probably 1.6 watt hours per day. Note: When I have toured in foreign countries, I did not have a local sim card, so it becomes a wifi only device.
  • Taillights (two), usually use one in blink mode, charge them up once a week, powered by a pair or AAA NiMH, so 2 watt hours per week or 0.3 watt hours per day. In fog, use both but usually only use one at a time.
  • Camera battery is 4.4 watt hours, probably get 5 days out of a battery. Thus about 0.9 watt hours per day.

That totals up to 3.6+0.4+1.6+0.3+0.9 = 6.8 watt hours per day.

To charge up my AA batteries in the GPS, I charge that while rolling by hooking up my GPS to the powerbank that functions as a pass through cache battery while it is being charged from the hub. And if I charge my phone, charge that while rolling from the powerbank, using it as a pass through cache battery. But charge the AA or AAA batteries in my headlamp or taillights by transferring power from powerbank to a NiMH battery charger that is powered by USB, do that in the campsite. Camera batteries, use a Lenmar Li Ion battery charger, USB powered, do that in the campsite.

I suspect that there is a loss of maybe 20 percent from transferring power from power bank to the device or in cable losses, etc. So, add 25 percent, 6.8 X 1.25 = need 8.5 watt hours per day.

On a previous thread recently, I estimated that I get somewhere between 5 and 12 watt hours per day out of my dynohub (SP PV8) and USB charger (Sinewave Revolution). My powerbank has a capacity of 44 watt hours.

In the photo I have a small powerbank and a big one, but did not use the small one on last tour, only the big one. And the headlight (for my head) in the photo is not the one I used on my last tour, the one in the photo takes four AAA batteries but I used one that takes a single AA battery.

Touring, I rarely use a headlamp on the bike. Did not use one on my last several tours, the one in the photo (red and black, to the right of the GPS) has no internal battery, powered by USB cable from the powerbank. Brought it just in case I needed it for a tunnel or for an evening trip to the pub, attaches to the handlebar with an elastic, stored in handlebar bag. Since I do not have a headlight wired to the dynohub, that means that the dynohub is used solely for USB power for charging devices.

Heart rate monitor not shown in photo, but that runs on coin type batteries, as is the luggage scale (lower right in photo), thus not included in the energy budget.
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Old 09-17-20, 09:03 PM
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I usually stay in the midwest/ high plains area. Signal is good. I listen to non-stop Pandora music throughout the day. My dynamo hub keeps up but that's about it.
No intermediate battery. Just an I-Phone 8 to navigate, which is nice but not used too much. Charging at county park picnic areas at night.
Don't over think it....
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Old 09-18-20, 03:41 AM
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Not sure anymore. Use to get monthly electric bills but for now . . .

2 LED light bulbs at 5W each 24x7.
PC 10W 24x7.
eBike 8-10W a mile traveling 7 mph, with store round trips 1-4 miles.
Electric AC, heat, water heater, microwave, frig & misc room lights ???
Phone, bike equipment, music, cameras, etc. --- Jackery 160 Portable Power Station.
Grid power plant generation from XCEL ENERGY wind turbines.
I do receive land transport once a month.

Now if only I had a earthship by a bicycle capital with lush vegetation and water ways to call home. My goodness it sounds like MN & WI.
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Old 09-18-20, 07:39 AM
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I'm in the "in a pinch" category, I don't even carry a spare set of batteries for my lights, which I only use in poor visibility/hazardous conditions. They last so long with LEDs, often an entire season now that I'm not commuting in the dark. My phone stays off unless I need it, and I charge it every week with house power somewhere. Pretty old school, I guess, and not very helpful.
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Old 09-18-20, 09:27 AM
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Itís a good thought exercise Iím wrestling with for various self-supported camping disciplines.

Conspicuity taillight and camp flashlight are good for ~150hrs runtime assuming I donít use it as a night-riding headlight (rare), so itís really just my phablet. With conservative battery mgt. (antennae mostly off except wifi, pre-downloaded maps/media, dim screen), 1w-h charge is worth ~1hr Screen-On-Time.

I figure 2 w-h/SOT will cover me for minimal travel needs (digital paper maps, photos, with limited check-in calls/texts/email, weather/tourist research, hopefully on wifi). Then double that to 4 w-h/SOT for minimal entertainment (book reading, movie, games, and limited surfing). Anything over that shifts toward luxury: more GPS use, turn-by-turn, extra cellular data usage, more SOT, brighter screen, etc.

As an ultralight backpacker, I have pretty equivalent Power Bank and Solar systems: ~4oz for 5Ah PB (~15wh output) or 5w S; and double that to ~8oz for 10Ah PB (~33wh output) or 10w S. Of course, can mix/match both S and PB as necessary, and S breaks-even to PB at 3-4 hours of direct, stationary, cloudless charging. If I were out west with more certain sunlight, Iíd probably go all solar.
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