Coping: Prepping Your Battery Supply (Part 1)

There are some damn-fine reasons to mark off a few minutes on a “summer” Friday morning chat to talk for a few minutes about prepping and batteries.

I can speak with some authority because my name somehow shows up on some patents related to battery state-of-charge instruments.

On the surface, this is no big deal, but the more you understand about batteries, the more being a co-holder on software related to battery charge/discharge levels is a very big deal. In other words, people who really know their poop about batteries are few and far between.

But if you read this morning’s discussion (and maybe print it off for further study) you can join the ranks of the battery-wise.

So top up the coffee and I will make this as short and to the point as possible.

Application Note: This discussion is specifically for preppers, ham radio ops participating in field day later this month, and RV’ers as well as boaters.

What is a Battery?

The first concept to master is the terminology of batteries. Because once you understand what the language means (in engineering and software design terms) a lot of misconceptions quickly fall bay the wayside.

Cells: A cell is generally comprised of an anode and a cathode. In between them is an electrolyte. The electrolyte can be dry (semi-dry), wet, or even air (as in zinc-air cells) can be used.

The key concept is that a cell is one collection of parts that uses electrochemistry to store and release energy.

Cells are temperature sensitive.

A typical cell may be fully charged at 2.1 volts per cell if it is hot outside, say 100F. This translates to 12.6 Volts when discussing a 12 Volt automotive, marine, or RV battery.

As the temperature decreases, the individual cells slow down as chemistry works slower (and at higher voltages) as temperature drops.

By the time you get down into the area of 65F, the resting state of a fully charged battery may climb to 2.3 Volts per cell – which is why the auto and deep cycle equipment is based on 13.8 Volts for charging.

Now let’s fast-forward to winter. When it is about 30 F outside, the fully charged cell will need 2.55 Volts per cell. This would put us around 15.3 volts with a properly charged (nominally) 12 Volt battery.

So Much for Cells – What is a Battery?

A battery is a collection of cells. Battery geeks speak in terms of charging and discharging as volts per cell. Humans, just refer to the nominal battery rating – which is good enough for most purposes.

A common battery may have plates made of lead (or lead-antimony for auto use).

What are Majory Battery Types?

Conventional automotive cells are comprises of many thin plates within their 6 cells. On the other hand, a Deep Cycle battery will have often half as many plates, but will deliver more energy over more cycles.

High plate surface area will give maximum terminal voltage under load for a brief period. Auto’s don’t use a lot of power over time. A short burst of power (10 seconds) is usually enough to start a car.

On the other hand, if you are operating an RV and you have an inverter going and there’s a show on satellite, you want a very good deep cycle battery. You want to see the whole movie, right? So power at a modest level (perhaps 500 watts) for as long as possible.

What About Special Cells?

Special needs are best suited to specialized batteries (collections of cells in a container) that have desired characteristics.

If you have a marine application, a Sealed Lead-Acid (SLA) battery is preferred because battery acid and salt water combine to create chlroine. Marine gel cells such as those from West Marine are a great choice if the battery could be “salted.”

If you are bouncing all over hell-and-gone, then Absorbed Glass Matt batteries are superb. Just expect to pay a lot more for them. The seal AGM battery in our old airplane was a $275 item three years ago and I doubt they have gotten cheaper.

Is there One “RIGHT” Battery?

Don’t we wish!

No, there is not. It takes some serious consideration of the battery’s purpose in order to select the best battery.

Sure, SLA-AGM for everything (or gels) may be good, but here is where we get into two critical concepts:

Cost Per Watt-Hour of Storage

A watt is a unit of work. The problem is that in order to find out capacity of a battery, you need an integrating watt-hour meter, of a microprocessor-driven Amp-Hour meter (see the Xantex catalog, I was at one of their acquired companies ack when) for a selection of these. They are precisely what you need in order to accurately determine battery state of charge.

When you are just shopping, look for the best cost per amp-hour or best cost per kilowatt-hour (look to manufacturer spec sheets) and try not to overpay too much.

A couple of examples:

We go to the WallyWorld and find a group 27 sized mixed use battery for our trolling motor. It costs $140. The manufacturer claims it will deliver 100-amp hours.

Since we run the trolling motor slowly, (10 AMPs) we MIGHT get 6 hours of use out of the battery.

I know – you’re thinking “How come I can’t get 10 hours of trolling?

Here’s the problem: At 13.8 volts (battery just off the charger) you might be getting 138 watts of work. But battery manufacturers rate batteries in Amp-Hours for convenience of testing and they don’t think a battery is dead until the voltage with the motor on drops to 10.5 voits. But you see? 10 times 10.5 is only 105 watts of work when you get out into the fully depleted battery area.

But stand by, fellow troller, there’s another gotcha in the wings:

Cycle Life and Depth of Discharge.

Note:  Charging is a temperature dependent art.  Get a charging temp table from your battery manufacturer.

Holy smokes, now what?

Sad truth is that you might be able to get “name plate” service for 100 cycles out of your battery, but if you were just a little gentler on the battery and only used half its capacity, then you might get 2,000 cycles out of it.

The reason has to do with how sulfury crystals are deposited on the battery plates and driven back into solution during charging. (This is how hydrometers work.)

And that gets us to the whole mattery of battery charging and discharging.

Multiple Stage Charging

When a battery is nearly empty (say below 11.4 volts on a 12 Volt system), the battery will (after a minute or so, and an effect called crack of the whip) begin to store energy as fast as you can toss amps into it. This is why big sailboats like the one Elaine and I lived on *(and me for 10 years+) use big computer-controlled charging systems. They charge very quickly with minimal engine run time. Work slick on RV’s, too, espectially if you aren’t going anywhere for a while and you just want to “top off batteries” with an hour or two of engine time.

This is BULK charging.

As the voltage slowly comes up, to about 14.2 volts, that battery wioll charge on a declining current basis until it will accept only 1%, or so, of it’s Amp-Hour rating. I know…


Let’s go back to that 100 Amp=Hour battery we picked up. When we charge it at 14.2 volts, at some point the current going into the battery will drop to 1 amp (1% of the 100 amp hours, eh?). Simple as pie.

This is the ACCEPTANCE charging part of the overall charging profile.

Last, come FLOAT where we kick the voltage down to 13.2 or so, and the battery is charged and not wasting energy from the charger (which would be dissipated as heat anyway). Dloat varies by temperture, too.  Higher when colder.  Lower when hotter.


After a fair number of charge and discharge cycles, and being more necessary as the depth of discharge increases, a liquid cell battery may be equalized.

Over cycling service, not all sulfur crystals are driven back into solution during charging.

To equalize, gradually increase the charging voltage to perhaps 15-15.4 volts, being careful to avoid thermal runaway) and allow the battery to begin to “gas” – it is not boiling.

Always wear eye protection, conduct equalizing in a fresh air environment because the gases released during equalizing are Brown’s gas – an explosive mixture of hydrogen and oxygen.

Optimum Battery Cycling for Field Day (Ham radio or Dry Camping)

Start with fully charged batteries. Run until battery voltage drops to about 11.2 volts under peaks on SSB or CW,

Then charge like hell until the battery voltage comes up to abourt 14.1 volts – kill the generator and make another 1,000 points or finish the movie.

When you’re all done, charge the batteries full, equalize, and try to explain to people who don’t work ham radio contests how being in the rain in a tent doing high speed code with a generator running just outside is fun. (Good luck with that…send in your reports…) I should mention the ham radio “sale” is much harder to dry campers with a cold toddie and a movie going…they use cells phones.

With good care (missing here at times) a battery should last 8 years in deep cycling service.  Mine would go longer but I keep getting too busy to equalize.  My bad.

Next Friday (if I remember) we will do solar panel basics…and maybe a simple load sheet. So dew drop in, as they say (somewhere, but not here).

I think that about covers the basics… There’s a lot more on the site with how to do a load sheet and all that. But you may have some work to do before the weekend starts. Besides, come to think of it, I have another (guess what?)…

Eye Surgery Progress

Off to the big city (Tyler) again this morning – and again Monday – for more eye checks.

The eye is sealed well now…but there is a bit of blood from surgery which is in the VSS (visual saiine solution) by eyes now run on, instead of normal aqueous fluid as was installed at the factory.

To ensure pressure stays down, and to encourage the exchange of the bit of blood in the fluid, I will be on two kinds of drops. These are distinguished as the “blue drops that lower pressure” and the “Green drops that slow the production of fluid but give you a headache in some cases.” Yes, I know that one, now.

My vision was so foggy I was looking for the Ronnie Milsap songbook until it began to clear, about halfway through Thursday’s rant on Break Away Civilizations. (To which I should add Richard Dolan’s outstanding work in the field – oversight, ahem, so to speak.)

I would emphasize to those following along at home that a) none of this began until about five days after I began messing with the feng shui of the office and the ranch.

The second thing is, cataract surgery is nowhere near like what I am going through…so if you are thinking about surgery, go for it.

My problems arose from having one set of surgeries to take out the cataracts back in 1979. Implants were still on the drawing board, so I didn’t get them until 1991. And then they aren’t as good as today (engineered materials, don’t you know) so only one of mine failed, and that after 25 years of all kinds of head-banging adventures. No telling what actually set off the problem, I just know it crescendoed in April of this year.

But no, cataracts of the garden variety t’ain’t no big deal. My case is “special” – and it’s one of the toughest for the month (and maybe quarter) for a specialty practice.

So please don’t let me scare you out of the surgery…it’s great once done. Just – if you can help it – don’t spread out the removal and the implants by over a decade for starters. And don’t jump down off tractors and heft 150 pound hunks of concrete a second later and then stand up quickly. Give your eyes time to equalize a bit.

I’m a great believer in the Theory of Common Sense. Darwin awards as examples, the missing companion volume The Practice of Common Sense is being slowly drafted by people like me.

On the other hand, if you’re not making mistakes, check your pulse.

You may be dead.

A Friday First

Telemarketing slime is getting crude.

I had a call from a telemarketer Friday.

Hello, this is the Windows Technical Support Department calling about your computer…”

Right here I knew is was slime (Microsoft doesn’t act this way or call from blocked numbers) so I “went George” on him.

Cool. I have heard about telephone calls from outfits like yours…calling people and bothering them in order to try to scare money out of them. Go ahead…give me your best shot…let me turn on a recorder, while we’re at it… OK go ahead….”

A moment of silence.

F((( You…” click.

I tried to call back to talk to the empty-pecker’s boss, but like I said, it was a slime call…and it’s a safe bet that unless it’s my son calling on his fancy backwoods SatPhone, its what?

NOT Windows tech support, of that you may be fairly sure.

With that, we have a busy weekend ahead…I’ll be supervising Elaine lifting everything over 10 pounds for another week.

She’s the best damn Chauffer, bartender, philospher, and personal assistant in the world and I am blessed. What the hell did I do to deserve things this good? Next lifetime, maybe a few less eye surgeries, please?

Have a fine weekend and write when you get rich…


Coping: Prepping Your Battery Supply (Part 1) — 17 Comments

  1. Hello again, George. About the eyes: Not to slam flying, but I wouldn’t recommend it for anyone with artificial parts in sensitive organs. The air pressure is below that at sea level (despite cabin ‘pressurization’), and EVERYTHING expands, eyes included – one of the things I always hated about flying, and why I will not go up in a plane again. I always hated feeling ‘stretched’ or ‘inflated’. Stay well.

    Robert in WA State

    • I considered that…and flew with no issues for 5 years…with two lens implants. The one that failed was just one of those getting old things. We expect a few more trips but the plane is listed on…

    • Cell phones us Li-ion batteries. George is speaking of lead-acid batteries. Two different chemistries, two different sets of rules.

  2. If I do make the mistake of answering a number I’m not sure about, it’s easy to tell by less than the whole first sentence of the caller if it is some kind of solicitation. I just speak louder than them and say I do not accept phone solicitation and hang up. If I get phone calls from a number more than once and they leave no message, I block the number. Panasonic sells a landline phone that allows one to block up to 60 numbers.

  3. After putting myself on both State and National “don’t call lists” some years ago, and having the junk calls not cease, I instituted a personal policy of not answering my phone for any unrecognized number out of area, or any number which came up *unknown* on my caller-id. A couple years ago, I began running a Google search on any such numbers (it’s simple: Just enter the 11 digit number. Google will return a number of sites which are Wiki-style clearinghouses for unwanted calls and callers.) I like knowing whether it’s a salesbot, a con man, a PAC or polling organization (hey, ’tis the season), or whatever, that’s trying to phone-spam me, and how-often by each.

    These cold-calls or bot-calls are often made, just to see whether a phone number is active. If the phone is answered, the number is noted, then put on an “active number” list and sold — same as an E-Mail addy which garners a reply.

    Interestingly, I’ve answered two of these spam calls this year, both by ESL callers who spoofed my area code. Playing dumb seems to get the caller frustrated rather quickly, but still leaves me irritated with myself for landing on somebody’s “hot leads phone list.”

    I thought the last of the phreakers went away ten years ago or so, when Mitnick started doing his security spots on TechTV, but apparently not — Something of which to be aware…

  4. Valuable battery charging comments, imo.


    Globally, less than 30 percent of wind capacity is utilized; solar less than 20 percent

    Excess electric energy disposal fee? Your comments please.

  5. Respected guru, Since you did a segment on der spitzen sparken und fusen poppen, may I pick your brain a little? If you were to run a current through your lonesome gold coin and it hopefully is pure, would it warm up from resistance as would a tungsten (ie light bulb filament)fake coin?

  6. My favorite reply to those MS / alarm company / vacation packages calls is saying this: “My fee for you to talk to me is $150 per hour”.
    Typical replies include: they immediately hang up, a few choice curses, or they ask me how (the hell) can I do such a thing? If they still persist I ask them for their credit card number. That one really works!

  7. got an old booster pack that I’ve been abusing for must be 14 years now,
    it’s got a 17 amp hour gel cell in it
    still charges ok
    I just haven’t managed to kill it yet….. ;)

  8. Why all the hysteria over batteries….OK, a little bit of histore sis on why batteries will not retain a full charge after many cycles of recharging….LOL!

  9. I have a number of responses I use for the “Windows support department” or the “computer support division”, or whatever name the scammers decide to use. My normal one is similar to yours. I get a fair bit of amusement out of stringing them along with the “I don’t know anything about computers and my husband isn’t here right now” line if I’m bored and I want to hassle them a bit (I’m in Operating System development and support at a different company so I have the background to make up some pretty interesting “problems” here). I think my favorite is the “Hey I work at Microsoft, too! What group are you in? Maybe I know your boss.” I usually get at least a few seconds of stunned silence on this one because it’s not a scenario they have a canned response for. I might try “I’m Amish, I don’t have a computer” next. I suspect they don’t know that the Amish wouldn’t have a phone either :)

  10. Thanks, George. I’ll pass that cataract advice along to the Mrs.
    BTW I have a great comeback for those “Windows tech support” dialers…..Sorry, I have a MAC. Click!

    • That’s what I did but not until I played dumb for a while and let them try to walk me through a bunch of stuff and then finally said, “Oh, wait a minute… I’m on a Mac…”

  11. Oh, I have gotten that Windows scam before – twice in fact, months apart . . . second time, person asks if I am ‘on my computer as it shows current activity’ – ‘Well,’ I said, ‘I know you aren’t Microsoft – and besides which – you do know about ‘cell-phones’? and I always unplug my computer . . . bye!’ Haven’t been bothered since – I may be ‘old’ but I don’t buy anything from someone ‘cold-calling’. Funny like that.

  12. I used to get those calls; the caller had an Indian accent, which some people find intimidating. I gave her the argument, and finally cast aspersions on her research, as I have Mac.
    Another time, like you, I got the f-bomb, but from a siding company. Taking a cue from Carol Burnett’s “Mama’s Family’ I let them go through the whole spiel, and asked a question or two. At the end, when they wanted an appointment, I told them I’d never put siding on my brick house. Then they asked why I’d let them go through the whole spiel. I told them since they were wasting my time by calling at dinner, I’d waste theirs. They were decidedly not happy.