[greenclub] POMCube iCan - a bit more control

[Allen, Bryan L (393F)]

Ongoing beta test of POMCube iCan:

I disconnected the iCan in early September after having charged it and then performing the shutdown procedure; we were going on vacation for most of that month, and I didn’t want this unpredictable device with 2+ KwH storage to have the run of the house. :-) Additionally, to reduce power usage while we were gone and to increase security, we turned off or disconnected various electrical devices, including our WiFi router (which with its connection box to our DSL consumes in total about 10 watts continuously.) The iCan depends on having internet connectivity to operate, like all “smart” devices. I’m pretty much become convinced that’s… not so smart.

Over our vacation we were notified that an update to the PeakShaver app (necessary for all interaction with the iCan) would soon be made, but that it initially wouldn’t be compatible with iOS 10. So I waited until early October to reconnect and reactivate the iCan.

The new features in the app and the associated onboard software (which I believe gets updated remotely from the POMCube servers) primarily have to do with having more control over when the iCan charges and discharges, and at what power setting. Though still with some rough edges and unexpected behavior, the changes are a big improvement in operability.

There are some quirks in how the controls work that I won’t go into here, but one I’ll mention is that the ability to schedule when the iCan should go to “standby” mode, neither charging or discharging, seems not to work. Charge and discharge power, and startup time of a charge or discharge, does work.

I’m using our TPlink ‘smartplug’ to impose standby modes; I can schedule times to connect and disconnect the iCan. A slight benefit of this is that when the iCan is disconnected, its constant 11-watt power consumption isn’t being seen by the house. But not so fast! When the iCan is disconnected but not completely deactivated, it still uses at least 11 watts, draining its battery, so disconnecting it from the wall is not the gain it might initially seem to be; it’ll just use extra power to charge itself once reconnected.

Attached is a recent daily plot showing the iCan in action, charging at 200 watts from 10 PM to 7 AM, and discharging at 200 watts from 9 AM to 5 PM. The burst of power use at 6 PM was from some microwave cooking and a bit of vacuuming.

 

This looks pretty good, but I can’t help but think there’s a better way to do this. More about that “better way” in a few weeks, I hope. A hint: I have an ulterior motive in starting the discharge at 9 AM rather than starting it at 2 PM, when there would be slightly more economic benefit.

The iCan seems to have lost its networked connection to the electrical meter and thus its ability to auto-sense what the appropriate discharge load is so as to not waste energy by running the meter backwards (otherwise known as “powering the neighbor’s air conditioner") but this was something that, before the software upgrade, was intermittent at best and did not seem to work properly even when the app reported what the house load was.

Even with the better control over the device, it’s still nowhere close to being an economic benefit to us given its purchase cost combined with the Time Of Use rate structure for SCE. A fifteen to 20-year payoff with a device that has a battery life of seven years is not a win!

Environmentally, it’s still worse than nothing, as you have to use more power than you would have used without the device due to charging and discharging losses. These losses are unavoidable due to the universe we live in. 

It still impresses guests as the World’s Largest Toothbrush Charger!

—
Bryan L Allen   bryan....@jpl.nasa.gov
Section 393F   MRO eeDAT, RTO, & GDS
Jet Propulsion Laboratory (818) 393-4163
Cell: (818) 298-8408 Text paging: 81829...@mms.att.net