26 June, 2014

One AA Plus One AA Doesn't Equal Two AA, Or Does It?

Before we get started with today's lesson in electricity, I have to tell you this bit.

The day started off as usual with a walk with the girls. That went as you would expect. After a shower and breakfast, I made a quick trip into town to get some groceries. Nothing unusual there.

Dianna beat me to the pool this morning, so I made it to the pool about 10:30 AM. Roughly about 11:15, Cecil showed up with my ShopVac motor. Cecil had taken it the day before to see if he could get it working. I plugged it in at the gate to test it.

Oh yeah, it worked! Damn near took my finger off when it fired up. Two things - 1) I forgot to check the on-off button of the motor, and 2) I was holding the part of the motor that would rotate at about a bazillion RPM.

So, I plugged it in and promptly dropped it after it savagely mauled my finger. Dropping it didn't do much other than cause the motor to separate into two parts - both trying to go faster than the other, and with a great deal of sparking and noise. The two parts were still connected by wires. After a mili-second or three (it seemed much longer, believe me), I reached up and yanked the power cord out of the outlet.

After picking up the pieces, I returned to Cecil at the gate, and told him the motor worked fine, but would he mind trying to fix it again? I know he thought something  like Geez, what a loose cannon here. But he was too polite to say anything other than "I'll try and bring it back tomorrow."

I then returned to the pool, stopping first to clean up and bandage my finger. As I returned to the pool, I was telling Dianna what had happened at the gate, and suddenly felt a sharp stinging in my left forearm. I saw some little black bug on my arm, which I promptly whacked, and fished it out of the water. It was one of those microscopic wasps. Stung pretty good for such a small critter too.

As I finished telling Dianna about the episode at the gate, and telling her about the wasp, I got bit on the right thumb by a doctor fly. So, what else could happen now? By the time I was finished telling Dianna of my travails, she reminded me that it was a little past noon, and if I was going to catch any of the game (USA v. Germany in the World Cup) I better get a move on.

Thank God for the break. The way I was being attacked left, right, and center, it was not looking good for me to survive the rest of the pool session, much less the afternoon. So, I went back up to the house and turned on the tube to watch USA lose to Germany, but that was OK, as both sides were advanced to the next phase of the Cup.

Now, what I was really going to write about. If you follow the blog, you know I've been having problems with the weather station. After some time, I finally narrowed the problem cause to one of possible electrical error, which I wrote about several times. Billy had read some of those postings and sent along some amplifying information that I'll pass on to you.

All this technical stuff reminds me of when I was in Radar 'A' School, in the Navy, at Treasure Island. Treasure Island was a cold, bleak, wind, rain, and snow swept lump of rock in the middle of San Francisco Bay - within easy view of Alcatraz, the infamous Federal prison. There were some similarities beyond just being co-located. But, that's another story.

What Billy's bit reminds me about, is one of the instructors at the 'A' School. Of course, they were all Navy Radarmen from the fleet, serving a tour ashore. This particular instructor, Radarman First Class, Petty Officer Fogbound (No lie. That was his actual name.) was usually assigned to us for the afternoon lecture - right after lunch. Anyone who's been in the military knows it's a cardinal sin to doze off during a lecture.

Petty Officer Fogbound's favorite topic was advancing our knowledge of electricity and electronics beyond the basics (which we had just spent 8 weeks in San Diego learning about). his favorite tool or example was a character he called Joe Electron, and every time he mentioned Joe Electron, he would give a thunderous clap to the blackboard, guaranteeing that even the sleepiest of us young sailors in the class would snap to and be alert for the next little while.

You know how names sometimes fit the action. Well Petty Officer Fogbound's lectures were just that - fogbound and as obtuse as could be. Thankfully little Joe Electron (BANG!) frequently came along and jarred us awake.

So, here's Billy's piece on AA batteries. Watch out for Joe Electron...

Billy is a friend of ours, who, with his wife Pam, have lived here in Belize, and in Oregon, for several years now. Billy worked in the battery business for around thirty years, so you might say he has some experience in the field. Billy sent me this information about the various AA battery types after reading my posting of the problems I had been having with my weather station and my amazement at finding out that all AA batteries are not necessarily created equal.

Billy said; "A little insight into rechargeable AA batteries. [First, their voltages]: Alkaline - 1.5V; NiCd - 1.2V; NiMH - 1.2V; and Li-ion - 3.6V."

"When multiple batteries are used, you must know the voltage of the device to know whether the batteries are series or parallel. For instance, three Alkaline AA batteries in series are 4.5 volts; and in parallel they are 1.5 volts."

"You can replace Alkaline batteries with NiCd or NiMH batteries in most devices. Due to different charging characteristics you must use the proper charger for each rechargeable [battery] chemistry. Just remember, in batteries, the amount of voltage you get from a cell depends on the chemistry."

"An easy example is lead acid. A lead acid cell is 2.1 volts. A 12-Volt car battery is actually six - 2.1-Volt cells hooked together in series, in a container or case. A 6-Volt Alkaline battery is actually four - 1.5 Alkaline cells in series. A common 6-volt Alkaline lantern battery is really four - D-cell batteries in series, in a case."

"Replacing two NiCd or NiMH batteries with two Li-ion batteries would not be possible. In fact you could ruin the device. Also NiCd and NiMH batteries must be cycled down [discharged] completely before recharging for the longest total life. Li-ion batteries will last longer if they are not totally discharged before recharging."

"Most chargers operate on a timer principle, but some actually measure the charging current and shut off when the battery is charged, thus preventing overcharge or undercharge."

"Some other useful information: you will only get the capacity (amount of energy) of the weakest cell in a series. Kind of like links in a chain. That's why you should always replace all the batteries in a device at the same time."

"And one last thing comes to mind. Sometimes the current draw on a device is so low or the circumstance of its use is such it doesn't make sense to use a rechargeable battery. In fact sometimes it makes more sense to use the cheapest battery you can get. A good example is a smoke detector. They have a very low current draw, but also they should be replaced every year, no matter what battery you use, so why get an expensive battery? I gained a lot of happy customers when they came in expecting to spend $10.00 and left spending $1.99. Also when a battery says Super Heavy Duty don't think it has more capacity than Alkaline. It doesn't , but that is the battery I would use in my smoke detector if I was prudent and changed them every year, if I didn't change them. than I would use alkaline as super heavy duty are more prone to corrosion with age. That's the lesson for the day." 

Thanks Billy. That helps me to understand why my weather station has been kaput for a while now. Hopefully as soon as I get some Li-ion rechargeable AA batteries, I'll be back in business.

I don't think Joe Electron surprised us once, did he?


JRinSC said...

You would have liked my sub. We were nuclear but had a "back up" battery. Had 126 cells, each of which weighed 1,100 lbs. Wonder how they were wired together? I remember that we ran a "trickle discharge" of 5 amps which was to prolonge the life of the battery. Thankfully we never had to rely on it in any serious way.

Good post -- I learned some stuff.


Dave Rider said...

Hi Julian,

With a battery that size, you guys must have really hated having that rabbit running around pounding on that drum 24/7.

This "learning stuff" you speak of. We'll have to blame Billy for providing that.

Glad you liked the post. I learned some stuff too. For such dinky things, I never knew AA batteries could be so complicated.


JRinSC said...

Hey Dave,

Have you lost all your batteries? Or did someone "borrow" your laptop? Or worse yet -- you've forgotten all of us up here in Obamaland?

Seriously, hope there really isn't a problem and you're weathering your hot summer in the pool all day! It's hitting the high 90's most days up here in the Upstate!


Anonymous said...

Hi. I am Beth Walsh and would like some help. We are planning on coming to Belize next winter and want to stay in Corozal. Need some suggestion for places to stay in your town that is beach front and reasonable. We live in southern Calif.and have followed your blog for[removed by admin]

Dave Rider said...

Hi Julian,
I know, I know. I'm overdue on postings.

I'll have one or two up today. Some new and some old toys - more breakages to report; freeking aints are driving us to distraction; Redone RO system is working... That sort of stuff is what I'm working on.
Thank God we have a pool - That's our A/C. We're in it every day, and almost all day too. We're averaging mid-nineties temp and humidity. We use machetes to cut a path through the air just to walk.


Hi Beth,
I modified your comment so your email didn't get posted. I'll send along some info to your email. BTW, for those who want to contact us, so you don't have to expose your email to the world, there is a way to email us from the Blog without knowing our email address - look on the right-hand column where it says 'You Can Send Us Email' - just hit the link underneath that and fire away. I'll try to make that link more obvious.
Thanks for writing. I'm so glad you like the Blog.
I'm working on trying to make almost a thousand postings into some sort of book. We'll see how that goes.