Garret mentions that the power company in Boulder, Colorado is prophylactically ("You're screwed," get it?) shutting down power due to forecasted high winds. This brings to mind my current obsession, batteries.

I think electricity essentially created modernity. To be sure, much of it happened before Faraday and Maxwell (and Volta!), but electricity was the accelerant that facilitated the explosion of modernity and the human population, chiefly through the expansion of information bandwidth, but through all its other uses as well.

I love batteries, but "it's complicated."

We have two Tesla Powerwalls installed and together with ~7KW of solar panels on the roof, we're ~86% self-sufficient in electricity and 100% carbon-neutral in home energy consumption. (We produced more electricity than we consume and export the surplus to FPL. To date, that surplus has also been greater than the amount we consume from FPL when solar+battery can't meet our demand.)

For nearly all of our replaceable battery-operated devices, i.e. the ones using standard AAA, AA, C and D cells, I've switched to rechargeable nickel metal hydride batteries. I use C-cell shaped shells (C-cells C-shells down by... Never mind.)

But lately I've been looking at these "solar generators," and considering what utility they may represent for us, well, me mostly.

We operate the Powerwalls in a 20% reserve capacity, as recommended by Tesla. Now, I don't know if this is a good faith recommendation as a "best practice," or a fancy way of hiding battery performance issues. Ostensibly, the Powerwalls are warrantied for 10 years to maintain at least 80% capacity. There are "optimal" ways to use batteries that prolong their useful life, and I'm not sure if our demand cycle is "optimal." I do know that air conditioning the garage (which didn't significantly increase our overall energy consumption), is likely the best thing I could have done to prolong their useful life. It often got over 110°F in the garage. I began by insulating the garage door which got sun all afternoon and essentially became a heating element radiating into the space. That helped by several degrees, but it was still hot. We installed the mini-split and then insulated the ceiling above the garage. That was more expensive than it should have been because insulation companies don't like to do "small" jobs. The garage is quite comfortable now, year-round.

In any event, I think there may be an occasion when our solar+storage solution might be insufficient and the grid unavailable. One way to improve the situation would be to reduce the load on the Powerwalls. I'd open circuit breakers in non-essential rooms, leaving just the HVAC, garage and kitchen energized (for the refrigerator). I'd probably also raise the thermostat to 78°F (cooling), where we normally keep it at 77°F.

Mitzi is heading to San Diego in a week to spend two weeks with her new grandson. I will take the opportunity to play with the power and gather some data on household loads with all rooms offline except the kitchen.

But in that scenario, it would also be useful to be able to continue to use the internet and wifi. So I'd need a power supply for that.

I bought a Bluetti EB3A Portable Power Station. I have a combined cable modem/wifi router device. It takes a 12v DC input from a wall-wart, and I'll want to see about doing a direct DC connection (a matter of the right cable connector) and avoid the inverter-to-rectifier losses. With wifi enabled, I'll be able to monitor the level of the Powerwalls and the load they're seeing.

I may lower the thermostat to simulate the higher temperatures and increased loads during the summer months. Hopefully, six to eight hours should be sufficient to give me some idea of how much energy just those loads use.

I know it'll just be "some idea," because in the summer the stucco radiates heat into the house perhaps as much as it radiates it into space. The AC runs all through the night. That's another effect of altering the composition of the atmosphere, where higher concentrations of greenhouse gases, to include water vapor, impede radiative cooling at night.

But I'll at least have some idea. I've also ordered a Kill-a-Watt power measuring device (the 4400, not the fancy new one that supposedly computes costs), so I can get some more granular data on things like the toaster oven, the TV, the devices in my office and so on.

I figure the EB3A will be useful at my workbench, and I'm planning to take it with me to the garden to run the glue gun so I can glue the string lattice I placed between two garden poles for our sugar snap peas and pole beans. It's tied to them now, but they're metal poles with enamel paint, so I expect them to slide down as weight gets added. I used it the other night to charge my 14" M3 MBP while I was using it on the couch. It's lightweight at about 10lbs and has a carry handle, so it's like having an outlet wherever you want one for loads up to 600W. (Not sure how much the glue gun takes, but I guess I'll find out.)

Anyway, might be smart to look into batteries. We're all preppers now.

Originally posted at Nice Marmot 09:58 Sunday, 7 April 2024