Deficiencies Identified in the Process of Quality Assessment
| Deficiency | Cause | Manufacturer Response |
|---|---|---|
| Failure Modes | ||
| ~20% LED failure rates | Variance in wire diamater to LEDs | New LED provider identified |
| ~25% reduction in light output | Assembler deviated from design specification, using material for diffuser in front of LED array that fogged in the presence of sunlight, leading to very noticible reduction in light output. | Manufacturer instructed to re-instate specified material |
| Batteries overheating | Co-location of batteries with solar panel, resulting in heating during charging | Product redesigned to achieve passive cooling |
| Battery will not charge | Unknown | Unknown |
| Battery will not charge on hand-cranked light | Counterfeit (non-rechargable battery) | Deliberate |
| Battery will not charge on "shake light" | Counterfeit (non-rechargable battery) | Deliberate |
| Short battery life | Use of inferior batteries | Life cycle testing of different suppliers of batteries, change from lead-acid to Ni batteries |
| Internal condensation | High charge rates causing high temperatures, in high humidity areas | Lower charge rates from 0.5-1C to <0.2C and/or conformal coating on circuits for waterproof design |
| Warped solar panels | Thin black plastic frame overheats in sun | Change color, thickness and/or shape of panel frame |
| Reduced light output | Likely failed voltage regulator | TBD |
| Vulnerability to rainwater damage | Electronics short if light left in rain. Light and connections not protected from rainwater that would run down cable connecting it to rooftop PV cell. | TBD |
| Cracked junction of gooseneck and body | Use holding by gooseneck, not lamp body, weak structural joint | Make joint thicker, include instructions on proper handling |
| Sub-optimal Design or Manufacturing | ||
| Non-uniformity of light distribution | Directionality of LEDs | Varied type and location of LEDs and added switching to provide narrow and wide modes of illumination |
| Insufficient operating hours between charges | Battery under-sized | Upgraded to battery with greater capacity |
| Dead circuit | Poor soldering during manufacture | TBD |
| Wiring damage | Wires installed in goosneck with no slack. Repeated adjustment stretches and ultimately breaks wires. | Unknown (slack should be added) |
| Undercharging of battery | Solar cell voltage and batteries mismatched | Unknown |
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