power options for charging smartphones in the field july 2011 cody winn east africa coffee...
TRANSCRIPT
Power Options for Charging Smartphones in the Field
July 2011
Cody WinnEast Africa Coffee Initiative
SUMMARY
TNS East Africa CI is evaluating the feasibility of deploying smartphones with applications for use in the field. The phones and applications can have significant benefits, and 98% of Rwanda is covered by mobile internet, but the biggest concern is the lack of power for recharging the phones.
Very few wetmills are connected to the electricity grid. Wetmill employees generally walk some distance to the nearest mobile charging station in a village, drop their phone, and pick it up at the end of the day. This is not a feasible option if they are expected to use the smartphone throughout the day.
This presentation outlines a number options for charging smartphones in the field. There is no clear product that will work successfully – field studies should be done before moving forward with this project.
Generators
Details
Some wetmills were provided with generators for powering equipment
Concerns
Generators frequently broke down and had to be returned, and are not reliable
Generator charge fluctuates, and thus is not recommended for electronics because it can fry the battery
More expensive generators with an AVR (automatic voltage regulator) or with an additional battery for charge storage would be required
Recommendation
Not a viable option, too unreliable for electronics
Solar panel + Powertank
Details
Create a kit from a solar panel plus a power storage battery (by itself, a small solar panel generates 125-500 mA of power, which is not enough to switch a smartphone into charging mode)
Sample battery: Swisscharger Powertank L
Includes multiple outputs and adaptors to charge light, radio, phone, etc
Cost
$40 (Powertank) + solar panel cost
Concerns
Would need to assemble a kit from different parts – may be support requirements
Any solar solution will require strong sunlight, so no charging can be done at night or during rains, a significant concern as the harvest is during the rainy season.
Field studies and online reviews show disappointing results using solar to charge smartphones. The power generated from solar is often not enough to meet the daily battery consumption of a smartphone
Recommendation
Probably better to use a product that combines both (see next slides). Field testing should be done with any candidate solar products to evaluate performance.
d.light s250
Details
Already used at wetmills for night lights
Solar panel + battery embedded within a light
Includes phone charger connection
Cost
$60
Concerns
Not strong enough to keep a smartphone charged if needed for regular use – solar power stored per day is less than an Android phone needs to recharge
Concerns about life of battery
Other considerations
d.light is continuously doing R&D and will come out with stronger, cheaper products over time
Recommendation
Not a viable option now, but company’s products should be monitored for 2012 season
Fenix ReadySet
Details
Can take charge input from solar panel, stationary bicycle, or grid
Low-maintenance, optimizes battery efficiency through software, will last 3 years
Can charge multiple phones, lights, radio, etc
Grameen Uganda has deployed these into the field for 4 months and is happy with results so far
Cost
$150 retail, possibly cheaper for large purchase or NGO use
Concerns
Very expensive - it is not a charge generator in itself, solar panel is also required
Other considerations
A bicycle can generate significantly more power than solar (100x per same unit cost). Wetmills have expressed opposition to biking for power but it could be an efficient option.
Recommendation
Discuss minimum cost of product + solar panel with Fenix. Re-think whether wetmills could hire day laborers to pedal a bike and charge a battery.
Solio Classic Hybrid, PowerCurve
Details
Similar products: solar panel + internal Li-ion battery
Claim to fully charge in one day of sunlight but online reviews say this doesn’t often happen
Various outputs for charging phone, light, radio, etc but only can charge one device at a time
Cost
$40-$90
Concerns
Online reviews of use of these products to charge smartphones are not positive– eg: “When fully charged from the wall the battery pack would only take my phone from 10% up to about 40%. Since it takes so long to charge in the sun, this rate of charge is unsustainable”Will only charge a smartphone up to about 75% full but some reviews say 60% is more common
Recommendation
Unlikely to be sufficient, but can try to get demo products to field test the performance
Solio Classic
PowerCurve
Great Lakes Energy – reseller of 2 solar products
Details
Solar re-seller based in Kigali, recommend 2 products:
Greenlight Planet Sun King Pro
Trony Sundial
Both are similar to d.light – solar panel + battery embedded within a light - but newer and better
Battery should last multiple years
Cost
$70 each
Concerns
Initial field test of a Trony Sundial charging a Huawei Ideos phone was not positive
After charging the battery for 1.5 days in fairly strong sunlight, the battery only intermittently charged the phone – the phone wouldn’t recognize the charger 100% of the time. Even while successfully charging, the phone battery only increased 7% in one hour.
As with all solar products, performance in rainy season is a significant concern
Other considerations
Could replace the d.light for nightlight use as well
Great Lakes also sells a larger but similar Philips product for $140
Recommendation
Continue talking to Great Lakes and do more field testing on their products