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Makes you wonder- there isn't that much juice in a 9V battery- why not replace the battery with a NiCad and a solar panel? As long as your unit isn't in comple

Makes you wonder- there isn't that much juice in a 9V battery- why not replace the battery with a NiCad and a solar panel? As long as your unit isn't in complete darkness it seems like it'd get enough light to run the logic if the panel was big enough. I'd put one on kickstarter but they don't sell Americium to just anybody. Yeah, they require Americium to work.

brudgers 14y ago
High reliability and continuous standby are primary considerations. The more components one adds to the system the harder these are to achieve. Best practice is to use the battery only for backup and grid power for the primary source. It would be hard to achieve similar life safety protection in the scheme you propose (i.e. it would not meet current US building and fire codes for new construction in most jurisdictions and would not meet similar requirements for existing in many places).
- mchannon 14y ago
  While I can agree that a convoluted system has more points of failure, it would only add one more component to the system, could still chirp when its battery was low, and would eliminate some situations where no one heard it chirp and it was just dead. Grid power would be ideal but most homeowners don't have conveniently-located wall sockets for this purpose. I suppose there's nothing stopping from me taking an off-the-shelf unit, installing a NiMH 9V, and adding the panel.
  - brudgers 14y ago
    "Hard wiring" means running conductors to the service panel or subpanel. Plugging in to a recepticle outlet is not hard wiring. In addition, solar panels have their own increasingly complex electrical requirements due to the unique life safety risks they present, i.e. they cannot be readily deenergized during daylight hours. In situations involving emergency response personnel, pulling the service meter or throwing a main breaker does not eliminate the risk of electrocution. Likewise, during routine building repairs and maintenance portions of the electrical service are likely to remain live.
    - mchannon 14y ago
      Thanks (?) for the vocabulary lesson on hard wiring, but I never used the phrase. A 9V battery can't be readily deenergized during daylight hours either. At a storage capacity of 5 kWh and a lifespan in service of approx. 360 days, we can guesstimate a daily power consumption of ~14 watt-hours. If placed outdoors in the midwest, the solar panel would need to be about the size of a DVD. There's often little in terms of light that hits a smoke detector but between natural and artificial light there's more hours of light hitting it. I'd estimate a typical household could get by with something twice the size. Dunno about you, but I think there's more to fear from a 9V battery than a solar panel that size, esp. with the whole thing comfortably sitting on the wall.
      - brudgers 14y ago
        I used the term "hardwiring." Since your post mentioned wall sockets, it appeared there was miscommunication regarding what is required by the NEC. If the idea is to create solar powered smoke detectors as a market disruptor, then it's a non-starter because they do not meet current code requirements for primary and secondary power supplies. In an alternative case, homebrew electrical installations are why building permits are required and construction by intuition is why building codes have existed since the time of Hammurabi. Few homes have one smoke detector and thus using one larger panel has some attractiveness. With surplus capacity, why not throw some LED lighting on the circuit? Etc. etc. down to the turtle.
        mchannon 14y ago
        The NEC has a nice big book I can consult when in doubt. While one may or may not plug in a smoke detector, the point I was making was that the wiring and junction box were not in a convenient location for the typical homeowner. The NEC also doesn't regulate portable, battery-powered devices. If I'm concerned about fire safety then I can get UL, TÜV, or similar safety certification for insurance purposes. Most solar battery powered nicknacks carry no such certification nor do they need any to be sold legally. Thanks for the vivid account, but some of us choose not to believe that everything novel is a slippery slope toward the bronze age.

brudgers 14y ago

High reliability and continuous standby are primary considerations. The more components one adds to the system the harder these are to achieve. Best practice is to use the battery only for backup and grid power for the primary source. It would be hard to achieve similar life safety protection in the scheme you propose (i.e. it would not meet current US building and fire codes for new construction in most jurisdictions and would not meet similar requirements for existing in many places).

mchannon 14y ago
While I can agree that a convoluted system has more points of failure, it would only add one more component to the system, could still chirp when its battery was low, and would eliminate some situations where no one heard it chirp and it was just dead. Grid power would be ideal but most homeowners don't have conveniently-located wall sockets for this purpose. I suppose there's nothing stopping from me taking an off-the-shelf unit, installing a NiMH 9V, and adding the panel.
- brudgers 14y ago
  "Hard wiring" means running conductors to the service panel or subpanel. Plugging in to a recepticle outlet is not hard wiring. In addition, solar panels have their own increasingly complex electrical requirements due to the unique life safety risks they present, i.e. they cannot be readily deenergized during daylight hours. In situations involving emergency response personnel, pulling the service meter or throwing a main breaker does not eliminate the risk of electrocution. Likewise, during routine building repairs and maintenance portions of the electrical service are likely to remain live.
  - mchannon 14y ago
    Thanks (?) for the vocabulary lesson on hard wiring, but I never used the phrase. A 9V battery can't be readily deenergized during daylight hours either. At a storage capacity of 5 kWh and a lifespan in service of approx. 360 days, we can guesstimate a daily power consumption of ~14 watt-hours. If placed outdoors in the midwest, the solar panel would need to be about the size of a DVD. There's often little in terms of light that hits a smoke detector but between natural and artificial light there's more hours of light hitting it. I'd estimate a typical household could get by with something twice the size. Dunno about you, but I think there's more to fear from a 9V battery than a solar panel that size, esp. with the whole thing comfortably sitting on the wall.
    - brudgers 14y ago
      I used the term "hardwiring." Since your post mentioned wall sockets, it appeared there was miscommunication regarding what is required by the NEC. If the idea is to create solar powered smoke detectors as a market disruptor, then it's a non-starter because they do not meet current code requirements for primary and secondary power supplies. In an alternative case, homebrew electrical installations are why building permits are required and construction by intuition is why building codes have existed since the time of Hammurabi. Few homes have one smoke detector and thus using one larger panel has some attractiveness. With surplus capacity, why not throw some LED lighting on the circuit? Etc. etc. down to the turtle.
      - mchannon 14y ago
        The NEC has a nice big book I can consult when in doubt. While one may or may not plug in a smoke detector, the point I was making was that the wiring and junction box were not in a convenient location for the typical homeowner. The NEC also doesn't regulate portable, battery-powered devices. If I'm concerned about fire safety then I can get UL, TÜV, or similar safety certification for insurance purposes. Most solar battery powered nicknacks carry no such certification nor do they need any to be sold legally. Thanks for the vivid account, but some of us choose not to believe that everything novel is a slippery slope toward the bronze age.