Amazon Dash Wand

Amazon is running a promotion where you can buy an Amazon Dash Wand with Alexa for $20, and get a $20 credit on your account when you register it. (So if you are a prime member with free shipping, you get a dash wand for $1.30 in taxes.) It’s basically a handheld wifi enabled barcode scanner with Alexa voice input designed to get you to buy more stuff from Amazon.

The wand arrives in a small blue and black box, and is half white and half black. The black end shrinks to a rubber ring so that you can hang it up on the included sticky hook, and it has magnets hidden inside so you can stick it to your fridge.

 

To install the two AAA batteries (included in the box) the quickstart guide says “Open the Amazon Wand by pulling the two halves apart” when it should really say “Get two strong guys to play tug-of-war with your wand until the two sides pop apart”.

It requires you to have the Amazon app on your phone to pair the Wand with a (2.4 Ghz only) Wifi Network, which also links it to your account. After that, you can use the wand by pressing the button. A red light shines out the end, and if you point it at a barcode, the item will magically appear in your Amazon Shopping cart. (No wonder they are practically giving them away…)  You can also press and hold the button to talk with Alexa, to, for example, add an item to your cart that doesn’t have a barcode by voice.

Amazon music is not supported on the device (I suspect playing music would run the AAA batteries down too quickly, plus the single speaker isn’t exactly high quality), but some other Alexa skills are, so you can check on the weather or play colossal cave (although you have to push and hold the button every time you want to issue a command).  Home control commands (such as HUE lighting) is supported, so this could make a good secondary control device for a smart house. Messaging with Alexa is NOT supported. (Which is a pity, as it’s ALMOST small enough to wear like a  combadge.)

For a teardown, see this link.

Practicalities of On-board solar charging for small EV’s

I’ve been running the numbers on building a small 1-2 person “motorcycle” (3 wheeled) electric vehicle, and was considering adding two 330 watt solar panels to act as the hood and roof/sunshade, which would provide shade for the driver and charging from the sun.

The drive motor I was looking at runs at 96 volts and 95 amps to drive a 325 lb vehicle (with 170lb rider) at 60+ mph. Twelve Nissan leaf modules would provide 96-100 volts at 60 ah for a total storage capacity of 5.7 kWh (giving around a 45 mile range at 60mph, probably close to a 60 mile range at 35mph, an efficiency of  between 83-111 Wh/mile).  This battery pack would weigh 100 lbs, plus BMS/mounting hardware and wiring.

Weight Considerations

Two 330 watt solar panels mounted on the roof/hood would also weigh 100 lbs.This could conceivably be 30% or more of your vehicles weight budget.

With around 6 hours of good solar exposure a day, they would probably provide around 600 watts per hour, or 3.6 kWh of charge (a gain in driving range of between 32-44 per day). They could fully charge my hypothetical 5.7 kWh battery pack in two days.

More batteries?

The alternate way to spend this weight budget is to double the battery pack size. This would give a 11.5 kWh battery pack, giving 90-120 mile range from a single charge. A side benefit is that the extra 100lb of weight could be placed low to the ground, instead of up high on the roof of the vehicle, greatly improving performance on corners.  (Also, the aerodynamic effects upon handling and range of adding a horizontal sail to the top of your vehicle must be considered….)

In my opinion, if you are regularly returning to a home charger, it is more practical to use extra weight allowance for batteries, as opposed to solar panels. Solar panels make the most sense when the vehicle is designed for non-round-trip applications, such as with an RV/Camper or road trip vehicle.

Bigger/Faster charger?

For an “in-town” vehicle, where J1772 (level 2) chargers are readily available, adding a high speed on-board charger (6.6kWh) would allow you to refill a small battery pack in under an hour, and would add less weight than commercial solar panels or extra batteries.  Having an extra 15 lbs of charger instead of an extra 100 lbs of solar panels or batteries would lower your rolling resistance and increase your range and acceleration.

Specialized solar panels

Alternate solar panels (smaller RV style, or thin film flexible solar panels) would weigh slightly less, but the weight savings is not as impressive as you may think. A 330 watt “house style” panel weights 50 lbs, or 0.15 lb per watt. A 100 watt RV panel weights 15 lbs, or the same 0.15 lb per watt. A 72 watt PowerOak flexible panel weights 6.2 lbs, or 0.086 lbs per watt. This is a weight savings of almost 50%, but unfortunately they are much less efficient, so would need more surface area, something in short supply on a motorcycle class EV, plus they cost much more on a per-watt basis.

Custom Alternatives

If you wanted to take the time to fabricate your own solar panels out of individual cells as part of a fiberglass layup, you could conceivably make them weigh less and fit the contour of your vehicle better, possibly integrating them into your vehicles body.  But if they are integrated into the skin of your vehicle you have to worry about solar heat gain. I think it would be better to have them mounted as a “shade” or “2nd skin” just above your vehicles main body with airflow channels between the two.

Cost Considerations

100 lb of 330 watt solar panels (two) cost around $500, while a 100 lb Li-Ion battery pack would cost about $1200-1500 (unless salvaged from a surplus battery pack). So the solar panels could cost less than a larger battery, but would require more work to integrate into the vehicle. A 1.5 to 2kWh charger would be fully adequate for a vehicle with a 5.7 kWh battery pack. You could even have only 110V charging (1kWh) and save the expense and complication of a J1772 inlet, while still being able to recharge a fully used battery pack in six hours. A minimal charger like the ELCON PFC1500 would cost $575.  An Elcon PFC 5000 ( TCCH-84-50 ) could charge at 5 kW, giving a small EV an almost “QuickCharge” charging speeds for around $2000 with J1772 inlet/adapter.

Modular Vehicle

One option would be to mount several solar panels on a trailer (possibly with a 2nd battery pack, and even extra motors) to be used only on longer “road-trips”. It is possible that the trailer could have room to hold 4×8 sheet goods, and/or a sleeping compartment under the solar panels for road trips. If the solar panels could swing up, it could be used for transporting larger furniture or appliances. (Consideration would have to be given to adding a lower gear ratio to the tow vehicle, or including extra motors on the trailer itself for heavier loads.)

LED Headlight power savings for Electric Vehicles

Upgrading the headlights on an EV from incandescent bulbs to LED’s will save some electricity, but it’s such a small amount of electricity compared to what the motor uses to move the EV that it’s probably not worth the effort purely from a range perspective.

My original OEM halogen headlights (together, at high beam) take 130 watts, while the motor takes around 12,000 watts just cruising down the road. So the headlights account for only 1% of the total energy usage.

One burnt out, so I replaced them with LED units that take less power.
Driving around with my high beams on, I’m saving a maximum of 78 watts by replacing both my headlights. 78 / 12000 = just over a 1/2 of one percent energy savings. So that gives me an extra quarter mile of range.

There are other benefits to LED headlights when compared to the OEM halogens. First, they produce more light, which is a safety advantage when driving at night. (I was never happy with the light output from the original headlights, and feel happier driving at night with the LED units.)

If you like the “cool white” color temperature of LED bulbs, you can say it’s an improvement in appearance. (They do make the headlights look more modern, as most newer cars have “cool white” headlights.)

Because the headlights are one of the largest consumers of power on the 12 volt accessory bus, swapping them out would allow you to significantly reduce the size/capacity of your DC-to-DC converter used to keep your 12 volt accessory battery charged.

 

The real power savings come from the addition of DRL, which only take 2.2 watts, compared to driving around with my low beams on.

G-board uses more power than it should, shortening your battery life

The new Google Keyboard application (G-Board / Gboard) works fine, and has a few nice features, such as the ability to search for an animated gif to send when you want to blow through a lot of bandwidth.

You might notice that in the screenshots above, the Gboard power usage is higher than my email client, and even YouTube.  When you take more power than streaming videos, you know you are a power hog.

However, all of these new features come at the expensive of battery life.  As a simple keyboard application, it shouldn’t be using more power than any of the other applications on my phone.  I use the keyboard when sending text messages or email, and for a few search bars, etc…

In my opinion, a keyboard app should never appear in the top power consumers on your phone.

 

Updating XML Google Maps plugin for newer versions of PHP

If you are using the XML Google Maps wordpress plugin (version 1.14.1 by Patrick Matusz), it has not been updated for a while, and won’t work quite right with newer versions of PHP.

If you are getting the following error message twice at the top of every page in your wordpress blog:
Warning: mysql_get_server_info(): No such file or directory in … on line 10

Change line 10 from:

 

if ( version_compare(mysql_get_server_info(), ‘4.1.0’, ‘>=’) ) {
to:
if ( version_compare($mysqli->server_info, ‘4.1.0’, ‘>=’) ) {

And that will make things work without the error messages.

Curtis 1231c upgrade: Binning Gate Drive Resistors

I am upgrading the power board of my Curtis 1231c DC PWM motor controller. It uses 18 MOSFETs to switch the power, and each MOSFET had a 47 ohm resistor on it’s gate input. The point of such a high resistance was to slow down the switching of the MOSFET’s so that they would all share the current somewhat equally and no single MOSFET would turn completely on before all of the others had a chance to start shouldering the load.

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Comparing Brighthouse Networks (Spectrum) with AT&T U-verse Internet

I’ve moved my SamKnows FCC broadband testing unit from one location to another in the middle of the month. The first location had one of the best home Internet plans available from BrightHouse networks (now Spectrum after the Charter purchase), the “Lighting 200” plan. The new location has the best available AT&T U-Verse plan, limited by the distance from a central office and older wires. AT&T did set me up with a bonded pair (using 2 phone lines, or 4 wires to provide better service).  The U-Verse plan is much slower, on both downlink and uplink, but is perfectly serviceable. The graphs below do show the stark contrast in available bandwidth.

I am going to miss the 24 up / 200 down of BrightHouse, but the 5 up / 30 down on U-Verse is still enough bandwidth for most needs.

The quality of the service has also gone down slightly, with slightly higher rates of packet loss and slightly higher latencies.

The extra 12 ms of latency isn’t much to worry about, but it is a definite change. The jump from almost no packet loss to 0.5 to 1 percent packet loss is annoying, and you can see that even on the worst day Spectrum / BrightHouse  is better than AT&T U-Verse on an average day.

 

Curtis 1231c Power Board desoldering

I desoldered all of the main power components (diodes, MOSFETS, capacitors) from the power board of my failed Curtis 1231c PWM DC motor controller. The plan is to upgrade all of the components to give it higher capacity; while producing less heat. Of course, to replace them, I had to remove the old ones, which took around 6 hours of work with two different soldering irons and a solder sucker.

My advice:
-Heat component legs (diodes/MOSFETS) from the top of the board (side with the component) while you solder-suck from the bottom. Get one leg completely free first, then work on the other. After you suck almost all the solder out, you may still need to re-heat the leg and push it away from the PCB with a small screwdriver so it doesn’t stick to the inside of the hole.
-For the capacitors, don’t be afraid to add a little solder to the smaller leg, and then use a 100 Watt super wide tip soldering iron to heat both legs up at the same time, and pull the capacitor straight out. Suck the solder from each hole individually later once all the components are gone.
-I heartily recommend the Engineers SS-02 Solder Sucker, the silicon tube it uses is great! I did get solder stuck inside the metal tip a few times, but nothing a 5/64th drill couldn’t fix right up.
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AT&T U-Verse not working with Office 365 IMAP or SMTP

Or, how I lost several hours of my life to a tricky and hard to diagnose networking issue.

I recently set up broadband Internet service with AT&T U-Verse. The internet appeared to be working correctly, except that I was not able to send or receive email (via IMAP and SMTP) from my work account, which is hosted by Microsoft on their office365.com platform.

I could send and receive email via IMAP/SMTP with two OTHER email providers, and if I used any other network (Brighthouse, T-Mobile, etc) the outlook 365 email would work just fine.

After calls to AT&T (Internet is working just fine, must be a problem with Office365), and my companies’ helpdesk (sorry, we don’t support Thunderbird or K-9 mail). I finally had to figure out the problem myself.

I thought that perhaps the issue was with the IP address I had from AT&T (perhaps Microsoft’s servers had blacklisted it for some reason, although I could still access the web based Office365 cloud with no problems), so I turned on my VPN software to tunnel all of my traffic through the work network (and get a new IP address).

Even with a new IP address via the VPN software, I still had the problem!
(BUT, if I used my t-mobile phone mobile hotspot, and THEN turned on the VPN, everything worked just fine). However, I was able to ping the smtp server just fine, so it wasn’t a network routing issue.

So the problem was definitely a symptom of the U-verse network. And if a tunneling VPN wasn’t fixing it, it had to be a packet problem (the tunneling VPN would get my packets out of the local network, but not change them).

The solution:
So I found the MTU (maximum transmit unit) on my modem, which defaulted to 1500 (usually a safe number) and changed it down to 1472. Problem solved: Suddenly I was able to communicate with the Microsoft IMAP servers.

I did this with the online web interface for the modem. Settings -> Broadband -> Link Configuration, changed “Upstream MTU” to 1472 (from the default of 1500).

I found that I also had to disable IPv6 on my modem to be able to send email via SMTP.

My best guess is that Microsoft may be running IPv6 inside their server farm, but tunneling it over IPv4 connections, which means that any 1500 byte packets are too big to be tunneled. (And they are not supporting packet fragmentation correctly.)

So by artificially limiting my packets to 1472 on the sending end, it allowed them to make it all the way to the SMTP/IMAP servers.

[I’d like to point out that the other two email providers I use on a regular basis did not have this issue, so it is probably something specific to the Microsoft Cloud.]

So, now I can get back to work. I pity the casual user who doesn’t have a background in computer networking…..of course, they probably all use the Outlook application, which hopefully doesn’t have this issue.

Curtis 1231c diodes: Diotec DR7506FR vs TSR2402R

I am looking to replace the MOSFETS, diodes, and capacitors in my Curtis 1231c with upgraded components. I unsoldered one of the existing TSR2402R (7103 K) diodes from the power board and tested it with my Fluke meter and bench power supply.

Here are my results:
Power Supply providing 3.2A, forward voltage drop: 0.776 volts
Power Supply providing 2.0A, forward voltage drop: 0.737 volts
Power Supply providing 1.0A, forward voltage drop: 0.697 volts
Fluke Diode Setting: 0.351 vdc

Average time for the button temperature to raise from 25 °C to 50 °C with a 3.2A current: 45 seconds

The replacement parts I purchased were from DIOTEC, specifically their DR7506FR model (the R at the end means “Reverse Polarity”, making them an exact drop in replacement in form factor and polarity). They were marked: “DT110  DR7506FR” plus a diode schematic. Here are my results for the upgraded component:

Power Supply providing 3.2A, forward voltage drop: 0.754 volts
Power Supply providing 2.0A, forward voltage drop: 0.700 volts
Power Supply providing 1.0A, forward voltage drop: 0.646 volts
Fluke Diode Setting: 0.399 vdc

Average time for the button temperature to raise from 25 °C to 50°C with a 3.2A current: 47.5 seconds

Of course, the original diode I’m measuring had been in use for many years (I estimate ~750 hours of driving time given the 22K miles) and was heated up as part of the soldering and unsoldering process, while the DR7506FR I tested was brand new straight from the manufacturer. After I unsolder a few more diodes I’ll check them to make sure their readings are similar. (I’ll probably also test a few other DR7506FR diodes from the bag as well.)

Of all the measurements, the temperature rise time measurement was the least scientific, as I was using an inexpensive non-contact IR thermometer and attempting to point it at a small button in each diode, waving it back and forth to find the hottest temperature. I took 4 measurements on each diode (alternating to let the other one cool down) and averaged them together. In general, the readings from the DR7506FR were longer than from the original TSR2402R with one exception. If I throw out that pair of readings, the averages would be 46 seconds vs 50 seconds. Given that the measured forward voltage drop for the DR7506FR was lower for any real amperage readings, it dissipating less power and taking longer to rise to 50 °C appears to be reasonable.