Cheaper, but Not Cheap
Billionaire Elon Musk — of Tesla Motors, SolarCity, and SpaceX fame — is known for generating
intriguing, long-shot business models and finding
backers for them, and they just keep on coming. His
latest offering — a product spinoff from Tesla Motors —
is the Powerwall home battery
( www.teslamotors.com/powerwall) which stores
electricity from your home solar panel array in a
compact and easily installed package. As noted by the
company, "The average home uses more electricity in
the morning and evening than during the day when
solar energy is plentiful. Without a home battery,
excess solar energy is often sold to the power
company and purchased back in the evening. This
mismatch adds demand on power plants and increases
carbon emissions. Powerwall bridges this gap between renewable energy supply and demand."
On the positive side, because the lithium-ion battery is enclosed in an outdoor-rated enclosure, it doesn't take
up space in your garage or basement. Plus, it includes a liquid thermal management system, a battery
management system, and a smart DC-DC converter for controlling power flow. Perhaps most interesting is that a
10 k Wh unit sells for $3,500, which puts the cost at $350/k Wh of storage. This is significantly better than
competing systems which tend to run you closer to $500/k Wh. So, does it make financial sense to install one?
Well, consider that the $3,500 price doesn't include the inverter, installation costs, or possible required upgrades
to the home electrical system. Plus, the maximum continuous power draw is only 2,000W, which won't even run
two hair dryers at the same time. The bottom line is that a plain old generator is still much cheaper for backup
power. Prices are expected to drop dramatically over the next few years, though, so things might become more
favorable. If you want a serious analysis now, try out the return-on-investment calculator at
www.catalyticengineering.com/the-berlin-powerwall/#more-605. ▲
■ The Tesla Powerwall on an outdoor mounting.
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Easy Cable Tracing
It can be a real problem when you have a bunch of wires in the house, office, car, or other location, and
need to figure out where they go and to what (if
anything) they are connected. That's when you need
something like Platinum Tools' new TP150 Tone and
Probe set, designed to simplify cable tracing. As
explained by product manager George Jang, "With the
Platinum Tools Tone and Probe set's steady tone, push-to-scan button, and a clear loudspeaker, you can quickly
trace and identify cable locations on jacks or
through walls."
The probe features a pushbutton that
activates tone scanning, and its tapered tip is
designed to allow easy penetration of cable
bundles. The tone generator includes a slide
switch for selection of tone/off/cont modes,
with the continuity mode used to determine if
a wire is broken. It includes alligator clips to
test wire pairs and an RJ11 connector for data
and phone lines. For about $25, you get both
the tone generator and probe, plus a carrying
case, 9V batteries, and user instructions. ▲
CIRCUITS and DEVICES
■ Platinum Tools' TP150 Tone and Probe set.
8 October 2015