Power for an outdoor project

[GeeTwo]

Oh - a sitting bench, not a work bench. That's a horse of a different color.

Have you considered burying wires (suitably deep and moisture resistant) from "the gallery" to "the bench" to carry the electricity? This would open up a wide variety of options, from solar to a wall-wart.

Your power needs may even be small enough to pull a trick out of Tesla's bag and transmit the power wirelessly from the gallery to an antenna above the bench but below the canopy of the tree.

Edit: Overhead wires (routed mostly along a branch headed toward the gallery and down the trunk) are also worth considering.

[DonRotolo]

I was thinking the same, but the 12 volt variety of wires. Go to Home Depot or Lowe's and look at their wired lighting section: It's junk but you'll get the idea.

Run some #12 wire underground from a convenient window to the bench area. Put a waterproof electrical box (the kind for outdoor receptacles) on a pipe sunk a little into the ground, and a set of Powerpoles inside. Unplug to move the bench, plug in in the morning. Leave extra wire so you can replace the powerpoles once a year...

Batteries are a last resort, if there is AC power within 100 feet of the bench, run low voltage out to it. Very small likelihood someone's gonna mess with the wires.

Arm detection: Maybe some ultrasonics too, maybe for leg position?

[Foster]

I'm pretty good with the feature creep on ultrasonics, but not on now needing to get a building permit, digging around in walls and maybe a short trench to run wires. The building is commercial space, so it's conduit for the AC. Low voltage is easier, but will need plastic flex to meet local code.

But I'm sensing a clue train (*) here, I had come trying to get some ideas on best practices on battery power for an outdoor project. but I'm getting lots of cycle back to AC power. Should I go back and say "Sorry, this isn't going to fly since I don't have a reliable power source. Battery is a short term, you'll get bored with changing the battery packs and the bench will die."? I'd like the project to fly, but don't want to see hours sunk into something that isn't going to be really viable.

Thanks

(*) Clue train reference is from a person that used to walk up to me and go "Clue train now departing to Smartville. All Aboard" and hand me what ever document she had to prove that I was being stupid.

[pilleya]

So if your power usage is 6a/h per day ( at 12V) and you are wanting minimum battery changes/maintenance surely larger batteries would be better.

Is there anything which makes large lead-acid batteries unsuitable for this purpose?

A large sealed lead acid battery/marine battery ( let’s say 60a/h) should be able to power the bench for more than a week before needing a battery change.

Because of the relatively high weight of the battery (probably 20kg) you could have a high-amperage battery charger already attached to the battery and simply need to run a power cord to the bench to plug in and charge with when possible or when the gallery is closed etc. You could even use two batteries in parallel if you have the space. Although the battery(s) would be bulky and heavy this has benefits, if you attach it to the bench securely enough (in a nice looking weather-proof enclosure) the 20-40kg of battery weight, is going to make someone seriously reconsider trying to steal or move the bench.

If you have battery charger permanently attached to the battery the people at the gallery would simply have to run an AC power cable to it occasionally, and potentially click a switch to change it from operation to charging.