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Battery Power
Written By Mark Keitel

 

After attending a few Star Parties I realized that having battery power for my equipment was the only way to go.  If I was only visually observing this may not matter so much to me, but since I am imaging being self contained at night has gotten to be a big deal.  With the influx of people at Star Parties and the number of individuals that now consume power at night has increased to a dramatic proportion.  Not only have the number of go to mounts, and people imaging increased, but so has the number of people that bring other items that plug in.  Here in Florida there is never a night at a Star Party that one will not hear the loud rumble of a hair blower getting the dew off of their optics.  Then the electric blankets on a cold night, or even a plug in electric heater in a pop-up camper.  All in all the drain on these sites has become enormous.  This past WSP2004, there was never a night that the breakers were not tripping from the amount of electric being used, by the people and their equipment.  In comes battery power.  It can be on the inexpensive side up to the very expensive side.  There are now generators that boast a 59db rating at 7.7 yards.  Now that is quiet unless you are wanting to sleep and one is on next to you.  Personally I come to a Star Party to be out in nature and be with friends and fresh air, NOT to smell gasoline from a nearby "quiet" generator.  But that is another issue all together.

Battery power comes in many forms and shapes.  And then you need a charger and then an inverter if you want to convert that power.

 

BATTERIES

BATTERY CARE is your main responsibility with home made electricity. This is the one part of your power system likely to be harmed by neglect or misuse. Lead-acid batteries, the standard in home energy, should not discharge more than 50%. Ideally, they should be recharged to 100% promptly. They can be damaged by undercharging, continued overcharging, or contamination. Do not store batteries without periodic recharging. Continual self discharge when not in use can ruin even a brand new set of batteries. 

DEEP CYCLE lead acid batteries have thicker plates and lead-antimony support grids for years of over 50% deep cycle charge and discharge. Golf cart batteries, the "L-16" and the "L-16HC" industrial batteries are the most common. Surplus industrial batteries may be deep cycle lead-antimony, or pure lead, or may be shallow cycle lead calcium construction.

Auto batteries are shallow cycle only. Cat, automobile, and truck batteries are NOT deep cycle and will not last long in home power systems. These have thinner plates and lead-calcium grids designed for less than 20% discharge and immediate recharge. If an industrial lead-calcium battery is well oversized so that normal cycling uses only the top 20% of battery capacity, lead calcium cells can be used. 

RV/MARINE  This common 12 volt battery is designed about half way between a deep cycle and a shallow cycle, and has medium length of life.

SEALED BATTERIES  Gel or AGM (absorbed glass mat) types damage easily from overcharge, and so should be used with a 3 stage charge control. Sealed batteries can be excellent deep cycle alternative energy batteries, cleaner and safer, but only if charging is precisely controlled. Since water cannot be replaced and hydrometer testing is not possible, they are considered special purpose batteries. 

NICKEL CADMIUM (ALKALINE) BATTERIES: Unlike lead, deep discharge and failure to recharge do not shorten battery life. However, surplus batteries are often overpriced and defective. Cost is much higher than lead acid. Voltage swings higher when charging and lower when using. Charge efficiency (energy charged in versus energy returned to you) is very low. Disposal and recycling can be difficult and costly. Be cautious of buying used alkaline batteries.

Quite a few people have told me that one should discharge a deep cycle battery all the way or at least close to that before charging it.  If one was not to do so then the life of the battery would be shortened.  When I asked these people where they have read this all said they did not know just that it was the way things are.  Doing some research on the subject I found the following information on deep cycle batteries and discharging and charging of them.  The Short and simple is the above is a "Myth"  I have also included information on larger battery banks too.  Not sure if there are any "Tim the Tool Man Taylors" out there, but know that I wanted the information.:

 

A minimum of 4-6 parallel banks of 6 volt batteries are usually needed to absorb "all" the power from the battery charger / inverter and to provide sufficient storage of power. To compute battery capacity for power storage, use 25% of the watt capacity (volts x amps) under normal conditions, and 50% during emergency conditions. The maximum safe charge rate to prevent battery overheating and damage, uses a C/10 charge rate (capacity/10) or 10% of the battery A/H capacity.

You should never drain the batteries to zero charge, and by using the formula above, it will give you much longer battery life. (see example below) Divide your total daily energy requirement into 25% of the battery capacity to compute how many days you can safely go without running the generator to charge your system.


 

Trojan L-16 Battery - Cycle Life vs. Depth of Discharge
 Depth of Discharge    10%   20%   30%   40%   50%  60%   70%   80% 
 Number of Cycles  4,200   2,800   2,000   1,500   1,100   900  800  700


Only one "Industrial" HUP (High Utilization Positive) Forklift Battery is needed to absorb the power from the battery charger and to provide sufficient storage of power. To compute battery capacity for power storage, use 50% of the watt capacity under normal conditions, and 80% during emergency conditions. The maximum safe charge rate for industrial batteries, is a C/5 charge rate (capacity/5) or 20% of the battery A/H capacity!

Industrial Forklift Batteries can be cycled much deeper, down to an 80% discharge regularly with up to 2,100 cycles in heavy forklift use! In a "24-7 Power System", if the battery is maintained properly and follows the formula above, it should last 150 - 200% longer than the projected 10 year industrial use.

The only drawback is "initial cost", as they average about 40% more than the $60 6 volt Trojan "Golf Cart" Batteries, or about the 15% less cost than the $150 6 volt Trojan L-16's on an equal "usable" storage basis. But the longterm  "cost per year" is under half the price of the 6 volt batteries, with much less maintenance needed!


 

Battery Price Comparison (20 Amp/hr rating)

 1- Industrial HUP 24v/600A 

  16 - Trojan L-16 24v/1400A 

 24 - Trojan T-105 24v/1,320A 

$2,037 / 10 years = $204 / yr

 $2,400 / 5 years = $480 / yr 

$1,440 / 3 years = $480 / yr


The advantages greatly outweigh any negatives, so all large "24-7 Power Systems" will be sold with "Industrial" HUP Batteries. But due to shipping weight, handling, and delivery problems, all HUP batteries will be sold in multiple 12 volt batteries, wired in series with battery interconnect cables. They have twice the usable storage power (50% vs 25%), and they can be safely recharged at twice the charge rate, which cuts the generator run time in half, much less maintenance is required due to less cells to service, 3 times the cycle life, and under half the cost per year over the longterm!

All "24-7 Power Systems" with "Industrial" HUP Batteries also include, a "DeSulfator" module to eliminate battery sulfation and to further increase battery life, a professional hydrometer, battery cleaning solution, safety gear kit, and 4/0 welding / battery cables with 350 A/H "Anderson SB" cable connector plugs for a "First Class" installation. Optional custom made "Hydrocaps" are also available directly from the manufacture to reduce battery watering and Hydrogen gassing.


 

 

 

CHARGERS

Battery Charging - Remember you must put back the energy you use immediately. If you don't the battery sulfates and that affects performance and longevity. The alternator is a battery charger. It works well if the battery is not deeply discharged. The alternator tends to overcharge batteries that are very low and the overcharge can damage batteries. In fact an engine starting battery on average has only about 10 deep cycles available when recharged by an alternator. Batteries like to be charged in a certain way, especially when they have been deeply discharged. This type of charging is called 3 step regulated charging. Please note that only special SMART CHARGERS using computer technology can perform 3 step charging techniques. You don't find these types of chargers in parts stores and Wal-Marts. The first step is bulk charging where up to 80% of the battery energy capacity is replaced by the charger at the maximum voltage and current amp rating of the charger. When the battery voltage reaches 14.4 volts this begins the absorption charge step. This is where the voltage is held at a constant 14.4 volts and the current (amps) declines until the battery is 98% charged. Next comes the Float Step. This is a regulated voltage of not more than 13.4 volts and usually less than 1 amp of current. This in time will bring the battery to 100% charged or close to it. The float charge will not boil or heat batteries but will maintain the batteries at 100% readiness and prevent cycling during long term inactivity. Some gel cell and AGM batteries may require special settings or chargers.

10. Battery Do's

11. Battery Don'ts

 

 

Basic Wave Theory

 
The following; 'Phase Conjugation', Holography' and 'Scalar Waves', some common concepts are used, all related to wave movements. Instead of repeating these in three places, some of these common concepts are presented here.

 
PHASE RELATIONSHIPS:

 

Wave movements are described by means of sine curves.

 

A sine curve is in reality a description of a circle, and wave movements can be considered and calculated as circular movements. A sine curve is because of that descriped like a circle through 360o as shown in fig. 1.

 

At the figure the amplitude is measured upwards and the time from left to right.

 

Fig. 1.
 A sine curve represents a circle and like that it is divided into 360o

 

* * * * *

 

If two sine curves with the same frequency occurs, then the distance between for instance their tops will represent a certain part of a complete cycle, this difference is called a phase difference, and is measured in degrees.

 

Because the phase difference is expressed by the difference of the 'starting points' of the two frequencies related to the complete cycle it is self evident, that the two frequencies must be the same, otherwise it will not be possible to tell which frequency to use as a reference.

 

At the first picture of fig. 2 the two curves cross the reference line in a positive direction at the same time. Thus the two curves are in phase, or their phase difference is 0o.

 

At the second picture the red curve crosses the reference line in a positive direction at 0o, and the blue one crosses the same reference line, also in a positive direction at 90o. Thus the red curve is leading the blue one by 90o, or the blue one is lagging the red one by 90o.

 

Fig. 2.
 The difference between two waves with the same frequency has a certain phase relationship which is expressed in degrees.
At the third picture the two curves cross the reference line simultaneously, but into opposite directions. This is called that they are in opposite or counter phase. Or expressed in a different way then the blue curve crosses the reference line in a positive direction 180o after the red one. Thus there is a phase difference of 180o.

 

Finally the blue curve crosses the reference line in a positive direction 270o after the red one, or 90o before the red one. In other words, the blue curve leads the red one by 90o, or the red one lags the blue by 90o.

 

* * * * *

 

If the two curves represent the same unit, for instance voltages, then they will create a third sine curve, the individual points of which represent the sum of the instant values of the two curves. If the value of the red curve at a certain moment is 4 volts, and the value of the blue curve at the same moment is 3 volts, then the total voltage will be 7 volts at that moment. On fig. 3 fig. 2 is repeated, but with the total value expressed as a green sine curve.

 

Fig.3.
 The sum of the red and the blue curve is showh by the green curve.
An important thing is made clear by the above mentioned curves; the amplitude of the sum is greatest when the two basic curves are in phase and least, when these are in opposite phase. The amplitude of the sum is reduced more and more the greater the phase difference is.

 

* * * * *

STANDING WAVES:

 

Until now we have been looking at how two waves moving in the same direction add forming a third wave.

 

Now we will look upon how waves of the same frequency moving in opposite directions behave.

 

As shown at fig. 3, then the two waves can be added forming a third one.

 

But where the two waves in fig. 3 moved in the same direction, why the sum wave also moved in the same direction, then it is a different matter with waves moving in opposite directions. But we still consider waves of the same frequency.

 

Because the waves moves towards each other, the phase will change continuously, but this in such a way, that the sum all the time will have its maximums and minimums in the same place, and will cross the reference line in the same points.

 

Thus where the resulting wave before followed the original waves, then it will now be 'lapping' to and fro in the same places. This is called standing waves and is shown in fig. 4.

 

Fig.4.
 Standing waves. The red wave is moving towards the right and the blue one is moving towards the left, whereas their resultant wave, the green one does not move. Its amplitude is changing, but all the time it crosses the reference line in the same points. This is a standing wave.
If we imagine it to be a couple of wires between which a standing wave signal appears as a voltage, and we want to measure that voltage, then the result will differ according to the points, between which we measure. If we measure in the points where the wave crosses the wires, at point '0' at fig 5., then we will measure nothing, because the voltage there will always be zero volts. Equidistant between these points at point 'm' at fig. 5, we will measure the maximum value being the double of each of the single voltages. In any other random point we will measure a value in between these two values. As is apparent from the figure, then the zero-value is the best defined point of the curve. If we find two adjacent zero-points and measure the distance between these, then we will have half the wavelength.

 

Fig. 5.
 Measurements at different points of the wire will give different results.
* * * * *

 
TYPES OF WAVES

 

The waves may oscillate in different ways. There are longitudinal and transverse oscillations.

 

When the oscillations take place in only one medium, for instance sound waves in the air, then you will have longitudinal oscillations as shown in fig. 6. The oscillations move from the left to the right, but each particle only moves a very little distance parallel to the wave motion. As the direction of the movements of the particles is parallel to that of the wave, they are called longitudinal oscillations.

 

Fig. 6.
 You get longitudinal oscillations when the direction of movement of each particle is parallel to that of the wave.
If one media oscillates in another one, as for instance radio waves, where electrons move in the ether, we will get transverse oscillations, i. e. waves where each particle moves perpendicular to the direction of the wave.

 

Fig. 7.
 You get transverse oscillations when the direction of movement of each particle is perpendicular to that of the wave.
Transverse oscillations can be expressed by means of two longitudinal oscillations as shown in fig. 8. If you watch the purple particle, then you will notice, that apart from moving left to right, then the two longitudinal waves are also phase shifted 180o, creating an up/down movement, too. As the purple particle is a part of both, its movements are circular. It is not because moves perpendicular to any of the waves, but exactly because it is part of two waves; one going up/down, and one going left/right, then the particle itself must also move both up/down and left/right.

 

Fig. 8.
 Transverse oscillations can be expressed by means of two longitudinal oscillations.
A closer view at fig. 8 reveals, that the concentrations and dilutions move from the left towards the right, but not up and down. Vertically you see no contrations on the middle. Vertically, thus, it corresponds to a standing wave with the zero-point at the middle. If we watch the wave perpendicularly to the longitudinal oscillations, then we will get it symbolized as in fig. 9 as a seesaw, which simultaneously explains the transverse movements of the transverse oscillating particle.

 

Fig. 9.
 The phaseshift of the two longitudinal oscillations makes it look like a seesaw when viewed along the direction of movement.

 

Electrical Waveform Output

A quality consideration that can be important in some applications is the output waveform of the UPS. This refers to the shape of the alternating current signal produced by the UPS. The quality and cost of the inverter that is within the UPS is the primary determinant of the shape of the AC signal that is produced by most UPSes, especially ones on the lower end. The ideal situation is for the UPS to produce a clean output waveform that is close to what would be produced by the electrical utility, but this is not always the case.

There are three main waveform types produced by Inverters and UPSes:

  • Sine Wave: This is the best waveform, as it is the shape of an (ideal) AC electrical signal from the wall. The highest quality Inverts and UPS supplies, produce a true sine wave output, which requires fairly expensive components in the inverter. This is especially important for online UPSes, since their loads are always running off the inverter. True sine waves are normally found only in higher-end models.
  • Square Wave: The least desirable output waveform type, a square wave is sort of a "flattened-out" version of a sine wave. Instead of the voltage smoothly increasing from the negative maximum to the positive maximum and back again, it shifts suddenly from negative to positive, stays there for half a cycle, and then jumps to full negative and stays there for half a cycle, then repeats. Cheaper inverters are designed produce a square wave output primarily because the components required to do this are cheap. It wouldn't surprise you to learn that some equipment doesn't really like running on a square wave (it may be more surprising to learn that many types of equipment will run on it!) There are several reasons why square waves cause problems. For starters, the peak voltage of a square wave is substantially lower than the peak voltage of a sine wave, which causes issues with some types of equipment. In addition, while a sine wave has a single frequency in it--60 Hz in North America--a square wave contains many higher frequencies as well, called harmonics, which can cause buzzing or other problems with some equipment. Square wave output is found only in the cheapest equipment and should be avoided if possible.
  • Modified Square Wave: This waveform is a compromise between the sine wave and the square wave. The positive and negative pulses of the square wave are thinned, separated and made taller, so the peak voltage is much closer to that of a sine wave, and the overall shape of the wave more closely resembles that of a sine wave. At the same time, the cost of the circuitry to produce a modified square wave output is much closer to the cost of a square wave's circuitry than that of a sine wave unit. (In fact, you can create a modified square wave by adding together two square waves that are shifted in phase slightly from each other.) Many fewer pieces of equipment have problems with modified square wave power than with straight square wave. Modified square wave output is used on many lower- to middle-range Inverters and UPSes, and is also sometimes called "stepped approximation to a sine wave", "pulse-width modified square wave", or even "modified sine wave". The last term is marketing cutesy-speak, since the output form isn't really a sine wave, modified or otherwise.

Schematic representation of one cycle of a sine wave, square wave, and modified square wave
output. The area under each curve is the same, so they each carry the same amount of power.

 

 

 

Now there are units that come self contained battery / charger/ inverter all together in one nice package.  I have used two such self contained units before.

1) Century Portable Electric Power model BPIP-99
    This unit has a charger, inverter, (2) 17 amp batteries inside.  A 300 watt inverter with two grounded plugs onboard.  also one cigarette lighter adaptors. Very
     nice unit and was great when I was not imaging.  Worked all night long with my  mount.  As my power requirements increased this battery was no longer
     enough. This battery is rated for 300 watts (2.3 amps)  12volt output 20amps
  

2) xPower 600 Indoor / Outdoor Generator  made by Xantrex
    This unit called a generator though it has NO engine.  40 amp-hr AGM sealed Non-Spillable, Lead Acid battery. 600 watt inverter 115vac 60Hz continuous
    power.  It has two grounded plugs on the  inverter. Has one cigarette lighter adaptors.  Also has a power switch for the A/C outlets and battery status light 
    bar.  Nice thing about this is it is on wheels. I still have two of these little gems.  Xantrex no longer makes these from what I can figure out.  They make a larger version now a xPower 1500    
    http://www.xantrex.com/products/product.asp?did=126


 Now all this is great and wonderful.  What about the equipment that is sensitive to energy spikes that an normal inverter can not control?  The Xantrex does a very good job at this, though it is on the lines of what is called a modified Sine Wave Inverter.  What is really needed is called a Sine Wave Inverter.  These now tend to get expensive, though there are going to save the equipment that you spent thousands of dollars on.  There are different manufactures of Sine Wave Inverters however I decided to get one made by Xantrex.  I had such a great experience with their xPower 600 that I decided to also go with their Sine Wave Inverter.  Another thing to consider on Inverters, that is if you are putting together your own system.  Do you want to go with 12 or 24 volts.  24 volts will give you a longer run time, and you will need to have more batteries.  I chose the 24volt system since this was also going to be used in my home since living in the Hurricane capital of the World this unit will be used.  In fact as soon as I finished putting this together and I built the cart for it.  Two days later we were hit with Hurricane Jeanne.  Being without power for 105 hours this system got a nice work-out.  I did not use the Sine Wave Inverter on my Refrigerator, instead I used a generator that was being used for other things too.  Due to the use of "Dirty Power" the Refrigerator was a casualty of this storm. 

With the below set-up once can run a 6amp draw for 43 hours or 5 nights at 8 hours per night. And still have some left over to view a movie on your laptop. This is without recharging. The following calculations were done by someone allot smarter than I on this

The specs on a group 31 battery. It is called a 225 amp
battery but it really delivers 130 amp/hours for 20 hours. That is a big difference.
130 x 20 = 2600 then you multiply that by 24 volts and you get 62400 watts. you take 50% of that an your get 31200. divide that by 120 volts and I get 260 amp hours.
You could run you 120 volt, 6 amp telescope for 43 hours.

 

Current Battery Power Set-up: