The Battery Charge Process

Introduction

Batteries are complex mechanisms that can even fool the experts at
times, so it comes as no surprise that non-technical people have a
hard time understanding the charge process. Ask a typical crowd of
battery users when their batteries are full charged and at least ten
answers will surface.

In both Living on 12 Volts with Ample Power, and Wiring 12 Volts for
Ample Power the authors explain that a battery is fully charged when
the voltage is about 14.4 Volts and current through the battery has
declined to less than 2% of the capacity of the battery in Amp-
hours ...2 Amps for a 100 Ah battery.

That information is substantially correct, however, a more intuitive
feel for the charge process is necessary, not only to understand when
the battery is full, but also to know when the battery is not
behaving normally. It is the intent of this application note to
provide enough information about the charge process so that the
average user can judge how well the batteries are charging.

The Bulk Charge Step

When a charge source is first applied to a well discharged battery,
charge current begins to flow, typically at the maximum rate of the
charge source. If a true 40 Amp charger is connected to an 8D battery
which is completely discharged, about 40 Amps of charge current would
flow for some period of time. Because most of the charge is delivered
at the maximum charger rate, the first step of the charge cycle is
called the bulk charge step. NOTE: During the bulk step, battery
voltage will steadily rise.

The Start of the Absorption Step

At the instant battery voltage has risen to the maximum allowable
voltage of the charge source, current through the battery begins to
decline. This simultaneous event of reaching maximum voltage and the
start of current decline marks the beginning of the absorption step.

For instance, if the 40 Amp charger is set to 14.4 Volts, then when
battery voltage has risen to 14.4 Volts, the charger will now hold
the voltage constant. Current through the battery will begin to
decline. NOTE: The charger, (or alternator), is not limiting the
current at this point. The battery is `absorbing' all it can at the
voltage setpoint.

The End of the Absorption Step

The absorption step should continue until current through the battery
declines to about 2% of battery capacity in Amp-hours as mentioned
above. Without knowing what the current is through the battery, you
can't know when it's full. Just because that fancy charger, (or
inverter/charger), has kicked out to float is no sign that the
battery is full ...there is no charger on the market that measures
battery current!

It's a given, then, that you need to measure battery current to know
when the battery is full. With a battery current meter, you can
discover some very interesting details about the charge process. For
instance, you can discover that once the charger voltage limit is
reached, battery current begins to decline. If the current decline is
rapid, either the batteries are nearly full, or they are NO GOOD! If
the current decline is slow, then either the charge source has more
output than the batteries can reasonably absorb, or the batteries are
NO GOOD! Here's where Amp-hour instrumentation is particularly
valuable.

Given enough time at the absorption voltage, charge current will
decline to a steady-state value, that is, a low current that either
stays constant, or declines very little. At the point where charge
current has gone as low as it is going to, then the batteries are
truly full. While 2% of Ah rating is close, good batteries will reach
a steady state current at less than 1% of Ah rating.

The Float Step

Once a battery is full, a lower voltage should be applied that will
maintain the full charge. Depending on the type of battery, (liquid,
gel), and the age of the battery, 13.4 - 13.8 Volts is appropriate as
a float voltage.

Temperature Compensation

The voltage given above are good only at F, (C). For high
temperatures, voltage will be less. It is important to charge
batteries with temperature compensation. To learn more about this
aspect of charging, refer to page 70 in the revised edition of Wiring
12 Volts for Ample Power.

A Very Common Problem

Your batteries are only four months old. You discharge them until
their voltage is less than 11 Volts and then crank up the engine. The
alternator brings up the voltage to 14.4 Volts very quickly, but the
current begins to decline immediately and in a few minutes is down to
a few Amps. You:

*suspect your voltage regulator and immediately call the factory and
ask for a replacement to be sent out; OR
*realize that something has happened to the batteries because the
alternator and regulator are operating as expected.

Conditioning Batteries

How do batteries that are only four months old die? Perhaps they
weren't broken in properly; maybe they sat deeply discharged for a
few days or more; perhaps they were allowed to self-discharge over
the last four months ...there's plenty of ways to murder batteries.

All batteries that refuse to accept a charge are not necessarily
ready for the scrap heap. Often, a deep discharge followed by a slow
charge will recover lost capacity and charge acceptance. For more
information, refer to Wiring 12 Volts for Ample Power.

Materials Needed for Installation:
Premixed ceramic tile adhesive or premixed thinset
Notched trowel
Small plastic smooth trowel
Ceramic tile spacers (optional); small 1/8” spaces look better with the murals
Sponge (small kitchen sponge works fine)
Rubber float
Grout (un sanded grout is recommended)
Bucket with water

Wood bar for stabilizing bottom row of tiles. If there is not an existing row of tiles on your wall, nail or screw a small wood bar directly below the bottom row of where your mural will be installed. This will prevent the tiles from slipping down during installation and curing.

Pre Installation - Lay out your mural on a flat surface. The mural tiles are numbered on the back. - Make sure the installation surface is clean and free of wallpaper, grease etc. Installation - Start with the bottom row of tiles. If there is not an existing row of tiles, backsplash or support on your wall, nail or screw a small straight wood bar directly below the bottom row of where your mural will be installed. Use a level to make sure the wood bar is straight and level. This will prevent the tiles from slipping down during installation and curing. (If you have an extra day for your project, install the bottom row of tiles first and let them set 24 hours before proceeding.) 1. Adhering the Tiles to the Wall - Starting with the bottom row, spread a thin layer of premixed thinset on the wall then use a notched trowel to make valleys in the thinset. - Butter the back of the tile with thinset then use the notched trowel to create valleys in the adhesive. -
Press the tile firmly into place. (Note: Put a moderate amount of adhesive on the tile, but not so much that it oozes out the sides.) - Immediately wipe off any thinset that get onto the front of the mural tile and do no let any thinset dry on the front of your mural. Wipe any excess off with a wet sponge. - If you are using spacers, place 1/8” spacers between the tiles (spacers also help prevent to prevent slipping). - Make sure you clean off any adhesive that gets on to the front of the tiles! Keep a bucket of water and sponge close by. 2. Curing - Once you have glued all the tiles to the wall, let them cure 24 hours before grouting. 3. Grouting - Start with a small section (12 tiles or so). - Remove all tile spacers. - Dampen the tiles with water and a clean sponge (small kitchen sponge works well). - Apply just enough grout to fill the spaces (joints) between the tiles. Do not cover the entire surface of the mural with grout.

Use a small flat plastic trowel to place grout on the end of the float.) - Holding the rubber float at a 45 degree angle, push the grout into the spaces between the tiles until they are filled. - Remove excess grout using the edge of the float at a 90 degree angle. - Clean any excess grout off the tiles using a clean sponge and clean water, avoiding the grout lines. - For smooth joints: use the end of your finger. or for a textured rustic look: take the sponge and pat the grout lines. It’s a great look with the tumbled stone. - Clean the tiles with the edge of the sponge until they look clean! (Not hazy.) - If there is haze, you can remove it several hours later. Cutting Tiles - Some installations may require cutting of tiles. You can cut tiles with a wet saw. The sharper the blade the cleaner the cut.

We did our time as nomads in a couple Winnies. We still have a Tioga
and a Chinook. We raised two welps without death or major crime.

In our experience the real problem with a baby is heat. If you have
good heat you can make do while you deal with the rest.

We have found no small scale solar anywhere near effective for space
heating up here above the 40th parallel. The woman who does will be
the one Bill Gates goes to for a loan.

We have 3 Toyo heaters in our trailer and would strongly advise you
not to use them in the same air space as your child. We use them only
in emergencies. In an emergency we evacuate the child ASAP.

We used to flip an old cast iron skillet over a burner to heat up in
the morning but again that is not good for baby.

If you can put in the fireboard and do a safe job the wood stoves
built for wall tents work great but they are scary as hell. Don't put
one between you and the door.

We have slept in tents with a box of hot rocks and been very
comfortable and safe. Not real eco friendly but if you have a back for
it we recommend it. It works and is safe for baby if hard on Dad.
Don't use river rock.

Our Winnies had combo heater/reefer units made by Electrolux and were
very safe and function-able so you might be willing to pay for the fuel
if you don't want to adapt. There is a small danger to baby but
nothing near Toyo's and the rest.

A propane fridge is an oxymoron as far as we are concerned. We
frequently go over a hundred F.
We use to this day coolers and ice in an adaptation cycle.
If you do the maths you will be able to decide if it is worth it to
you. For us solar powered cold creation is not cost effective at small
scales any where it gets hot.
We used/use the fridge for mouse proof storage.

We have and still use semi daily a "turkey" cooker propane stove. It
boils up a big pot of water in less time than a cup of tea. You will
want more hot water now. We paid $28 for it at a hardware store and a
propane tank gives us baths and wash water for about 40 days. With a
baby probably about 30.

We use the sawdust bucket method from the Humanure guy. We didn't mean
to. We were just using it while we built our composting toilet. It
works so well we just kept using it. It is by far the best way to go.

Diapers will be a problem. Washing them in the woods is no more eco
friendly than composting disposables. You can save a lot of time
composting. We gave up and used disposables and froze them in bags in
the winter and dumpstered them when we went to town. We composted them
and even tried to burn them. There just wasn't an easy way to deal
with it.

Grandpa used to say
"The surest way to get rid of your wife is to move her to the woods".

In our experience if you want to keep sane and married you need to
make sure you have SPARE rain shelter, heat, something hot to drink, a
hot wash up and clean underwear. In that order.
Everything else is extra and negotiable.

Make your man get you a REALLY comfortable chair that rocks and one of
the soft tummy carriers so you can free up your hands.
Make him deal with the diaper disposal.
If he loves you he will buy you a big wash tub and care for baby while
you have a hot soak twice a week.
Get a good tent you can stand in, a tarp big enough to cover the tent,
a 100' nylon cord, a good stout knife, a cot to keep you and baby off
the ground, a cold weather bag and a space blanket. Practice putting
the tent up with baby on your tummy. You need to know you can do it alone.
Get a double burner propane stove and lantern and a case of those
little propane bottles.
Get a half dozen NEW five gallon buckets with proper lids and put
clean dry SPARE underwear and baby clothes/towels/blankets/diapers in.
Fill one with paper plates and disposable forks and the like and
another with instant drinks and tinned food.
Don't leave out stuff, don't cheap out because you think you will
never use it.
Put the stove, lantern, tarp, tent, propane, line, knife and a roll of
trash bags in a big plastic tote box.

This is all EXTRA. You don't use it except in emergencies.
It is a $250 insurance policy for your domestic tranquillity. If you
never need it good on you. If like us you find the woods throw you a
few unexpected parties you will be happier. As in less unhappy.

After all these years we still have our bucket full of plastic forks
and such. We have raided it once or twice. We still have the stove(s)
and lantern and tent. We added an air mattress two years ago. We
switch out the propane canisters every year when we go camping
elsewhere and we have changed out the food but we still keep our
"Spares". We have only had to use the stuff a few times in all these
years but they have made the difference between living in the woods
and visiting.

Hope something in there helps you. If you want to know how we do our
coolers let us know. We wish you all the joy we have had with our
sprouts in the woods.

The choice depends upon the power source you have available. If you
are at home getting power from the power grid (power from the local
power company), the 110V bulb is the best choice. 110V bulbs don't
require a transformer to convert from 110 to 12 volts and heavier
wire to minimize voltage drop. Your home is already wired for 110V
devices.

If you are in your RV and power is supplied by a 12 volt battery, you
would need an expensive inverter to provide 110V. There is loss in
the inverter, and available power is limited as compared to your
home. Your RV is probably wired for 12V lighting, and it's tough
making wiring changes is much of your RV.

It's easier and cheaper to use light bulbs that use the voltage
provided by your power source.

If you are planning to live off the grid (providing all power
yourself), there are many things to consider. It's probably best to
get a book on this subject to understand the tradeoffs.

Resealing Solar PV Frames

If you clean the surfaces carefully silicone might be a good
choice for resealing the frame. I suggest you use a good grade
of marine silicone, and make sure it is approved for use with the
frame material.

Silicone often fails and then you have a mess worse than you
started with. The way of preventing that is using quality
silicone that is approved for the application.


Also consider if you need to provide some ventilation as well as
weep holes on the back, bottom of the panels, and that the panels
don't get splashes up from the mounting surface into such holes.

I've noticed that in certain climates a lot of moist air gets
sucked into panels as the evening turns cold, condenses, and
accumulates over time. If there is air circulation the daytime
heat should evaporate the moisture back out.

In Valdez on oil spill response barges we HAVE to be response ready
24/7. So, we run dual John Deere/SDMO gensets. Every 3 days we swap
gensets. Every 500 hours we do an oil/filter change and air filter
change per manufacturer's. Every 2 hours at a minimum we inspect the
engine space and fill up the day tank, verifying genset gauges.

We also have a third genset in a separate space, which is run once a
week in cold weather, and an emergency genset for certain lights and
all radios, and a backup portable emergency generator.

The main genny's run our electric heat, all the deck lights, block
heaters for equipment hydraulic packages, and MOST importantly, the
heaters for the water and MSD tank. (Marine Sanitation Device)

Engines are a fair amount of work!! :)

I was thinking of encasing the dryer tube inside a larger aluminium duct.
You used to be able to get 7" aluminium vent duct for range hoods.
I also thought about dumping the dryer vent into the 7" duct and
running that down the side of my garage. by the time the air hit the
end most of the heat would be transferred out of the pipe.

Thinking a larger box on the inlet side with a screen to capture
lint. and a trap and drain in the low point of the duct if needed to
drain off the moisture.

I don't think it would be too much trouble to maintain and a pretty
easy to install.

just thinking out loud.

Sandwich a pieces of 0.01 stainless steel between two fender washers.
Clap it down and drill a matching cut a center hole in the 0.010
stainless steel.
Bolt the three pieces together, remove clamps, turn the outside diameter
on a lathe.
Remove from lathe clamp the edges of the three pieces, remove bolt.
Cut inside diameter, remove clamps, separate the three pieces.

One would go from DC to 400 Hz back to DC. I would agree, it would not make a heck of a
lot of sense to go to 400 Hz, and then try to get it back to 60 Hz.
In fact, it would make no sense at all. I was just wondering if there
would be any significant advantage to convert DC to 400 Hz and a higher
voltage for a "long distance" transmission line from PV panels off to a
relatively far off battery bank.

Those transformers were from junked
Jet planes, and we were told that it was more efficient and took
lighter weight wiring and everything else to go to 400 Hz electricity
at higher voltages, and then convert down if lower voltage DC was
needed. Back then, solid state electronics were not all that common in
jets. It was just out of the Boat Anchor Tube Rigs days.

Seems like we are always looking for the cheapest, most reliable,
longest lasting solutions, and I was bringing up 400 Hz just for
thinking purposes. :-) We are always stuck with Ohm's Law, and any way
of moving electrical energy has some trade off. Higher voltages,
smaller wires. But up and then back down always takes some of our
energy. Same, I would imagine, with going from DC to AC, and then back
to DC. No free lunches. But the cost of good copper wire is getting
astronomical. :-(

OK, the BZ Products charge controller installation manual says "You
can charge a 12 volt battery from a 24 to 48 volt solar input." Does
this mean that that I can wire the HF panels in series? Parallel means
12v from each panel? 24v would be 2 panels in series? 48v would be 4
panels in series? Is this right? Is there an advantage to wiring
these panels in 24 or 48 volt configurations? It does seem to me that
the wire from the panels is pretty light weight. The installation
manual also says that the MPPT250 charge controller can take up to 12
gauge wire so thanks Steve. How should I wire these panels?

I have lawn lights for which I have made several sets of seasonal
covers.

One set is simply those plastic pumpkin candy buckets. When I
was using incandescent in the beginning they were great, nice and
orange.

I switched to little 8 LED replacement lamps for substantial
power savings and then they looked like dark pumpkins with 8
blue/white dots around the middle.

I made tubes of plain white
paper and dropped them in the pumpkins to diffuse the light and it
also made the colour much nicer. Same thing for my santa covers. I
will try the Easter eggs soon to see if it helps them also.

TIP:

Maybe try
plain white paper inside the plastic tube?

Product Details
Twenty Five Amp MPPT Current Boosting Solar Charge Controller
The MPPT 250 is a fully automatic, current boosting, 25 amp solar
control. The MPPT 250 incorporates an advanced microprocessor design
that brings outstanding performance and many new features to the
medium power systems. Standard features include digital volt and amp
meter. A 15 amp low voltage disconnect. Battery temperature sensor.
Auxiliary battery trickle charger. Solar inputs of up to 50 volts
(open circuit) may be used to charge a 12 volt battery. Up to 30%
current boost is possible. Ideal for campers, recreational vehicles
and small cabin systems. Up to 250 watt solar input.

MPPT 250 Standard Features:

• Current boosting • Digital volt and amp meter
• 12 Volt operation • 25 Amp charge current
• PWM float control • Fully automatic operation
• Easy installation • Low voltage disconnect
• Five year warranty • Auxiliary battery charger included
• Flush mount • Battery temperature sensor standard

I believe it can handle higher voltages. If so would series wiring be
better and how many in series shouldI go? Would 6 pairs of two works
better on the thin wiring that comes with these Harbor Freight panels?
What would be the optimum wiring arrangement? Thanks again!

I installed these panels last summer. I started out with 3 just to
try them out and the project kind of got away from me! They were a
pretty good deal what with sales and discount coupons and I just kept
adding too it till I had 12 total. I really haven't had the coach out
in the field to really try them out as far as durability.

I know
there are better solar panels out there but these were cheap and they
do work for my purposes. I am just looking for advise to make sure I
have the system optimized for what I have. Can anyone answer my
question about series verses parallel wiring...

does it make any
difference? I Wonder?

They look like good batteries for a small installation, such as
an uninterruptible power supply for a computer / office.

Probably too small to consider for a full solar system such as a
cabin or house.

I modified a small APC UPS with a dead battery to use a battery
like that externally. It works great and gives me extended
backup time for the electronics.