Covered Topics

Please see the list of the topics I've covered. It's located near the bottom of the page. Thanks for stopping in!!

Sunday, May 22, 2016

Solar Power Plus Off-Grid Battery System: Putting It All Together

Readers familiar with my Off-Grid Mobile Battery cart will remember my writing about my plans to use solar panels to recharge the batteries. Reference Off-Grid Mobile Power Supply and Mobile Battery Cart Update for full background information. Over the past few months I have obtained a pair of brand new 100 watt solar panels from a supplier on eBay. I recently ordered the second panel and got it in the mail this week. I took advantage of the sunny weather and a breather from work today to test the panel "live" with the battery cart.

These 100 Watt panels each come with a pair of 10-15 foot long 14 mm cables and a charge controller. That is NOT a bad deal for $140 apiece!! Even ignoring the cost of the cables and controller, that comes to $1.40 per watt. Additional panels can be purchased without the controller for closer to $125. That said, any solar power system needs a charge controller to ensure the batteries aren't overcharged during full sun.

I figured I'd need about 300 - 400 Watts worth of solar panel capacity to really handle these 220 ampere hour batteries. As of now I have a pair of 100 Watt solar panels, though I'm just testing the one I got this week.

To run a quick test, I temporarily connected the whole mess up to the battery cart with some alligator clips, then arranged the panel on my front porch with the cables running through the front doorway back into my living room. I believe the charge controller may have issues, as it was only allowing about 2.5 amperes through even with a heavy load connected to the battery and a terminal voltage of 12.58 volts. I disconnected the charge controller and just connected the panel straight and got plenty of current, as the meters in the photo reveal. The orange meter is reading the current in amperes; the gray one is reading the voltage. At one point I did see the rated 5 amps these panels produce. Clearly, I need to address the charge controller issue, because at 4+ amps for ONE panel with a battery voltage of 15 volts, I'd quickly cook these batteries if I ran without one for long!

Stay tuned for future testing of the system with both panels : )

Thursday, January 21, 2016

A Real-Life Example of Why Materials Quality Is Important

Last Summer, I replaced both of the front stabilizer links in my pickup truck. At that time, the rubber bushings were disintegrating. One of the links had actually broken due to hitting a particularly large pothole. I thought, barring another large pothole, this would be the last time I'd be dealing with that for at least a couple years. Alas, that was not the case.

A couple days ago, I was driving and heard a clunk, followed by some pinging noises. Upon looking in the rear-view mirror, I noticed a rod-shaped item bouncing in the roadway and thought I must have driven over some trash in the road. A few minutes later, I heard more noises and saw more objects rolling around in the road behind me. I also noticed the handling was suddenly really "loose". Then I realized these were coming off my truck and were NOT stuff already in the road. I pulled off at the nearest gas station and, upon peering under my vehicle, found the situation shown in the stitched photo of both the left and right front suspension. Note the missing parts in the right-hand side of the picture v.s. the left. Fortunately the part that broke was NOT a life-or-death critical component - but this was unnerving nonetheless. Also extremely annoying is the fact I had replaced these parts less than 7,000 miles/6 months ago - and certainly did NOT plan on doing this in 15 degree weather.

While I bought these parts at a legitimate auto parts store, my guess is there was a flaw in the metal - perhaps a void - that created a weak spot which just happened to fail at that time.

The following day, I showed these pictures in class to my Applied Engineering students as an object lesson in why manufacturing quality is important and the possible real-life consequences of product failures. Judging from their reactions, I think the point was made and got across to one and all.

Friday, January 1, 2016

Portable Battery Supply

Readers of this blog will no doubt remember the "Mobile Battery Cart" - indeed the post before this one is a short update on that. For some time I have been thinking of a portable unit I could take in the car, on a bike/motorcycle, or even pack in a suitcase for travel. Hardened Power Systems makes a particularly elegant system they call their "Juice Box" that is built into a US Army ammo can and is waterproof when the lid is closed. It features a 30 amp-hour lithium ion battery, digital voltmeter, USB output ports, Anderson power pole connectors, an integral power inverter as well as a 12 volt "lighter" socket. It's a sweet system - the main issue with this is at $580 it is well beyond my budget. But ... all is not lost.

At the battery shop where I work part-time, we recently scrapped out a small "MAC" type (NOT related to Macintosh computers) battery charger. The case was quite pitted with oxidation and even though it was otherwise in good condition, the boss said it wasn't worth keeping. So I asked for it, explaining what I wanted to do with it, and he kindly gave it to me. See the top photo. It has a handle on the top and plenty of room inside for two 12 volt/7 or 9 amp-hour SLA or AGM type batteries. There is room inside for a low voltage cutout board like I built into the mobile battery cart, a digital panel-mount voltmeter from eBay, a solar charge controller and perhaps a small power inverter in the 100-200 watt range.

The second photo shows it open with two AGM type batteries sitting inside. Note the rust and corrosion on the inside metal transformer support rails as well as on the "feet". I'll sand and treat those areas with rust remover solution, then I'll sand the whole box with fine grit sandpaper, then paint it inside and out with car engine enamel. I've used that before on past projects and gotten excellent results in terms of looks and durability. Obviously I'll need a front panel made of aluminum or plastic to cover the holes in the existing panel.

Some 5-way binding posts on the front panel might be useful, too.

Once built, my 5-watt solar panel should be able to keep this charged when traveling or during emergencies. A unit like this could charge cell phones, maintain LED lighting, or power my VHF radio and/or a portable shortwave radio for considerable time on a charge. While it is NOT a "juice box", it will serve the purpose well enough for me - and at a fraction of the price. I'll try to post updates of this project as it proceeds.

I hope this gives readers some ideas for solving their own portable or backup power issues. Please feel free to write back with your own ideas!!

Mobile Battery Cart - Update

Those of you who have read my June 2015 post about the mobile battery cart will remember the Deka marine battery and the unpainted plywood lid. Since then I have painted the lid to match the rest of the unit and have replaced the Deka battery with two new 6 volt/220 ampere-hour golf cart batteries, purchased from the battery company I work for part-time. The batteries are both contained in ABS battery boxes so they are out of sight and any leakage that might occur will be contained. Having the batteries NOT readily visible is important, lest my landlord or, in the event of some emergency - firemen or EMTs, see them and get upset. Given the way this unit is constructed, it looks clean, organized and purposeful. One would NOT walk up to this and say "why do you have car batteries in your house?" Yes, it's clearly some sort of electrical device, BUT it's NOT scary looking.

Note that since the golf cart type batteries are taller than a marine or car type battery, they will not fit inside the standard ABS battery boxes available at big-box stores like Wal-Mart or at auto parts places - you'll probably need to get them at a battery company as I did. Mine cost me between $7 and $8 apiece. The batteries - made by USA battery - will run between $130-$170 apiece, typically. USA battery uses really hokey "quick release" type battery caps that inevitably leak; since I bought my batteries at a battery shop I was able to get GOOD LEGITIMATE screw-type retrofit battery caps at nominal cost. They're well worth the investment.

This system can provide about 2400 watt-hours of electrical storage - PLENTY for operating lights, amateur and shortwave radios, etc. in an emergency. Given about 300 watts of solar panel capacity, it could provide sustainable "off grid" operation.

Amateur (Ham) Radio and The December 2015 Tornadoes in Texas

By now, most to the country has heard about the December 2015 tornadoes in Northern Texas as well as the flooding in Missouri and Mississippi. During that one evening, there was a swarm of 11 tornadoes in the Dallas/Fort Worth area. These caused major damage in Garland, as well as Rowlett and Sunnyvale, Texas. I personally know several folks in Texas who lived within a few miles of Garland and Rockwell, where most of the tornado action occurred.

One couple, who are friends of mine and live in the Dallas/Fort Worth area, recently got their amateur (ham) radio licenses. They each bought themselves a Baofeng UV-5RV2+ model VHF handheld radio and had these tuned to one of the local RACES (Radio Amateur Civil Emergency Service) frequencies. On the night of the tornadoes, they had both their TV as well as their VHF radio going and were monitoring the situation. On their VHF radio, they heard "boots on the ground" reports of where the tornadoes were sighted and/or touching down as it was happening; the TV reports lagged significantly behind. Using amateur radio, they were thus able to monitor the situation closely and know whether or not they were in danger at any given time. As one person I know who was affiliated with Skywarn has told me, often the TV reports will come AFTER the storm has come and gone.

On this blog I have stated in other posts how useful amateur (ham) radio can be during a civil emergency. Amateur radio can operate under conditions that wipe out both landline and cellular communications. Having access to amateur radio can mean the difference between having news, information, as well as emergency communications available - or not.

For those who want to make sensible preparations for any number of different emergency scenarios, acquiring an amateur radio license, or at the very least, the equipment to monitor those frequencies, would be a worthwhile investment to make for 2016. The radio shown in the photo above can be bought new for under $40; the kit included the radio, the lithium-ion battery, a "drop-in" style desktop charger, and a stubby antenna. You will definitely want to get the better antenna - the one provided with the radio is almost worthless. The upgrade antenna - a Nagoya NA-771 model - as well as a 12 volt car adapter, together will cost an additional $15 or $20.

The larger battery will likewise cost a few more dollars, but clearly this simple setup is well within the doable range for many people. I recently got my brother the radio, the antenna, as well as the 12 volt car adapter, on eBay for a grand total of under $70.

For those with more money to work with, one can get an Icom or Yaesu brand 2-meter handheld VHF radio for between $160 and $200. I personally own the Yaesu FT-270 and find it to be a superbly constructed and quite rugged 2-meter radio.