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January 15, 2011

Hi Folks !
Welcome to the BATTERY BANK
We will cover some different types of batteries, the different wiring configurations
and the interconnection -( battery to battery ) interconnect types.
Starting at the beginning we have the Franklin Leyden Jar.
Old Ben was brilliant and you will note that he interconnects the Jars to increase volts and perhaps amps for his experiments:
The Photo is from the Franklin Historical Society, and what I find amazing is even the case shows superior craftsmanship !!
Let that be a lesson, the more time, effort, and craftsmanship you put into your battery bank, box, shelves, room, the results will be a superior configuration
provide safety, and ease of maintenance. Not to mention, you will have something worth showing off, and perhaps even ease of permitting should you decide to
grid-tie your system and sell excess back to the utility.
Technically, it is a myth that a battery placed on the ground "loses" charge.
It is more likely that the temperature and moisture played havoc with an already weak battery.
The coldest spot in a basement would be the floor/wall intersect, and not a good place for your bank.
It would be better to build a shelf system to raise it up to waist level, and your back will thank you later when maintaining them.
If you are serious about going off-grid, you will need a serious battery bank.
In the UPS and Audit pages you have discovered the method to determine your load.
In the battery bank you will want to consider that load in two variables: Capacity and TIME.
In the Solar Industry they allow for a 20% discharge capacity, meaning you can safely use 20% of the total charge without damaging the batteries.
I prefer to be safe and use a 10% discharge rule. I have stated as such in my previous articles.
It gives a few advantages:
1.) Room for error
2.) Emergency reserve of 10%
3.) Perhaps a longer lifetime for the bank, although I do not have data from my experiments as yet (but I will in 2 years from now)
And so, your bank if built to my rule will have built in extra capacity.
Depending on your ultimate goal, availability, budget, your choice of batteries that make up your bank MAY differ : in capacity, size, and voltages.
I will attempt to cover some common set-up(s) so you can see and think about some options.
For example:
If you plan on charging from solar panels, most panels with the balance of output, performance and price, may require a 24 or 48 volt battery bank.
It would also make sense if you are running your machine shop, or heavy household appliances from your bank. ( inverted loads )
For lower voltage appliances and devices, it will be necessary to have available, or be able to build, step down dc to dc voltage transformers,
by design some charge will be lost as heat so heat sinking, fans and safe placement need to be considered.
Some large street inverters, IE: drawing power from your bank, inverting it to AC and pushing the power thru a second meter to the grid;
these may also require a higher voltage battery bank.
Personally, I am going with 12 volt.
It eliminates the need for dc to dc transformers for most equipment.
The batteries are readily available, and fairly low priced, and charging equipment for cars, solar panels etc are also low priced and available.
I can mix and match regular automobile batteries in a pinch,
to make up secondary banks or replacements when funds are low, and still get some order of performance.
RV, Van, and automobile equipment  has some very sophisticated devices and products, some are VERY COOL !
Car boneyards are very cheap for lights and other devices for creative use.
So, I will lay out most of my dream system in terms of 12 volt, you can up the numbers for your dream system.
MY DREAM battery is this:
From   staab battery is a known company with excellent service and prices.
There is a possibility of us creating a co-op to get a better price so let me know if you are interested.
The Trojan battery is the best battery for solar / off-grid applications, and their MFG standards are superior.
The stats on the battery:
  • Part number: Trojan L16P-AC Deep Cycle Battery
  • weight lbs: 114
  • Volts: 6
  • BCI: 903
  • AH: 420
  • LENGTH (in): 11 5/8
  • width: 7
  • height: 16 3/4
  • Terminal type: automotive post & stud
ON SALE 1_18_2011: $279 Each
From their literature:
With over 80 years of experience, Trojan Battery Company is the worlds leading manufacturer of deep cycle battery technology.
Long-lasting, reliable and clean, users all over the globe know Trojan deep cycle batteries deliver superior power.
Trojans proprietary Maxguard® Advanced Design Separator and exclusive Alpha Plus® paste formulation team up to increase battery life,
extend run time and decrease maintenance.
Group Size is one of three terms used to categorize the differences between various batteries.
The three terms (group size, vehicle requirements and power rating) are standard throughout the industry and are
governed by the Battery Council International (BCI).
Simply stated, the group size of a battery will determine if it will physically fit in a particular vehicle.
The term has no relation to how a battery will perform in a particular vehicle.
You will note it is a 6 VOLT battery, as such, 2 will be needed wired in Series to make up a 12 volt "cell"
and then each pair wired to make up the larger bank.
Lets look at other batteries and bank configurations:
This bank appears to be made up of 6 Volt "cells" and wired using a combination of series and parallel to make up a 24 volt system (if I had to guess)
Note the long interconnect to join each set of 8 batteries, also note that the take-off leads are at each end of the bank one positive one negative.
I am not entirely thrilled with it being so low to the ground again as different parts of the bank may be at different temperatures.
It is a pretty setup nonetheless.
Another apparently 6 volt "cell" setup, it appears to be in a nice metal frame.
again note, the take-off leads are on each "end" of the bank, also note the quick disconnect hanging in the upper left corner that
obviously plugs into the connector where the red and black wires terminate.
NOTE: ALL interconnecting wire is the same gauge.
It appears to again use a combination of parallel and series wiring, from left to right-parallel sets of 4, and those wired in series to the next row.
A nice sturdy shelf system, large capacity bank.
You will note these are clear case for easy visual assessment of electrolyte level, note the tubing on the left
probably used to top off the cells.
These too seem to be 6 volt cells.
A possible advantage of this type cell, is from what I have seen, some batteries with the clear case are able
to be TOTALLY rebuilt, including internal plates, an obvious advantage as long as parts are available or you can micky something.
Yet another 6 volt cell setup -are you sensing a theme yet ?
NOTE the nice battery box of plywood and the grey VENT pipe at the back.
the wood lip around the perimeter says there is a cover. a good setup as batteries outgas hydrogen when charging
and hydrogen sulfide gas in general, so a VENT is a MUST.
The only thing wrong I see in this photo is that there is a CHILD present as he fiddles with the cell levels.
Children should not be around these banks, at least without safety gear, rubber gloves and eye protection.
acid splashes, explosions occur. BE SAFE and teach the CHILD to be SAFE !
These are NI-Cad batteries could be 2,4 or 6 volt cells.
I included them here as the interconnect between cells are plates and not wires.
This can be a superior interconnect, as wires loosen in their fittings, and the surface area makes for a great electrical connection.
Just be careful of dis-similar metals, as they WILL corrode.
The only drawback of Ni-Cad cells, (which may have changed with new technology) is that they tend to develop a "memory" over time.
So it is fine if you use and recharge in the same pattern during their life, but go outside of that pattern and performance could drop.
A mistake of discharging more than the 10% could render the bank in a bad performance pattern for the rest of it's lifetime
a very frustrating position.  IE: laptop batteries are typically Ni-Cad.
Oh, and what they don't tell you about the new clown-car electric vehicle LiOn batteries, is THEY can develop a memory
so if you consistently are out of range and deep discharge them, you are in for expensive repairs.
although I would love to get a few paks from the bone yard to experiment with !
They MUST be recycled as they are VERY toxic waste.
I wish I could remember where I got this pic, it is a LARGE battery room in an observatory building on a mountain.
On the member "generator" page, the generator that charges this "room" can be seen.
note the HEAVY wires on top of the bank. This room is the last place you want to be during a thunderstorm !
The battery cells appear to be closed cell gel type as they look to be laid out on their sides, fluid would drip otherwise.
NOTE: the "extra" connections, this is called "cross tied cells" or "massively parallel" it prevents the natural voltage variance between cells in a group.
This last battery bank example appears to be the typical "telco" type battery/cell
You can often buy these used at auctions, for sale rags, or even from the utility itself.
These are typically used in those little telco buildings you see around neighborhoods to repeat/boost line voltage
and keep telco equipment running.
The beauty of these is you can SEE the plates, fluid levels and any debris that may be bridging the plates.
Generally they are totally rebuildable an added advantage.
Even when no longer suitable for telco use, they can make up a very reliable bank for your purpose.
I would dearly love to get my hands on a bank of twenty or so of these !!
Care should be used in transport of old battery banks, as sulfate deposits that built up over time can be jarred loose
and fall between the plates, and get stuck thereby causing a bridge, short-circuiting the cell, and it's discharge and charging ability.
I would be VERY reluctant to buy a used large bank of closed black-case batteries because you can't SEE.
Forget about a ten year old bank unless they give it away, as you are paying for their replacement bank.
Go new adding the value to YOUR system !
A charger with a de-sulfination cycle is VERY handy when you first set up a used bank
The de-sulfination is actually a pulsed electrical charge that can loosen and break up sulfide deposits and with any luck they
simply fall to the bottom of the case. so NEVER tip a used cell on it's side even if it's a closed sealed type as you will cause the sediments
to shift and could short the plates, it doesn't explode, it just renders the cell useless or weak.
Even the vibration of travel can move stuff around, so a bank that worked when you saw it to purchase
could be shorted by the time you get it set up at your house.
This is what typically happens to power tool batteries, and some of the smaller rechargeable batteries.
You can find video on you tube that shows how to get a little extra life out of them by using an electrical welder to
"spark" across the positive and negative poles of the battery.
You take the ground clamp of the welder and connect to negative, and then take the positive lead of the welder and
QUICKLY spark the positive pole of the battery. this has the effect of a very quick de-sulfinator the juice breaks the sulfur bridge
thereby opening up a good, sort of original, electrical path, you can't hurt an already dead battery,
it often allows them to charge up normally thereafter
You truly CAN cause the battery to explode, so PLEASE wear a good strong set of goggles,
and maybe even put the whole process behind a shield & wear goggles !
I must stress your contact with the welder is a SHORT duration that's why they call it sparking.
considering the cost of a replacement, it's worth a shot to get a little life in the old battery, or when in a pinch.
Then again $30 is cheap considering an emergency room visit and permanent disfiguration
USE your judgment. Be safe.
Other batteries good for banks and large capacity are golf cart batteries, forklift batteries, heavy equipment batteries
often they are VERY beat up but still have some life for our purposes. They are hazardous waste, so some companies
will be glad if you ask for them and their garage would probably have a few hanging around, or ask when they switch out to new
to call you and you will take the old away. IF you see a battery you like, you can always buy it new, but be prepared to PAY
they are not cheap.
Also, these days you may even have to pay a little for used as there is a recycle CORE value to used batteries.
ALWAYS WEAR GLOVES, GOGGLES, APRON when fiddling with batteries.
A story:
I was changing out my car battery one day, simple enough, we all have done it.
I was tormented by mosquitoes and black flies while doing the job.
Something was biting me on the back of the head, I slapped it away and itched the spot.
Later that night my girlfriend was petting my head and a clump of hair came out on her hand.
LOL, she got instantly ill, and I was panicked at first, scrambling for mirrors to see the spot.
Then I remembered my earlier battery change out.
I must have gotten enough acid on my bare hands to eat the hair away where I itched
but it didn't burn my hands due to callous. (Yes, I did wash up before dinner)
So I went around with a perfectly smooth bald spot on the back of my head until it grew back in.
could have been worse, like an eye itch.... THINK and wear protection.....!
You have many options in wiring your bank, it all depends on what your goal is, more voltage, more Amp Hours, or a combination of both:
The basic wiring of either Series or Parallel and resulting combined output(s)
Combined batteries into a bank, in parallel, leading to a load, load distribution center, or breaker panel, the result is longer Amp Hours.
This is how I will have my dream bank, with each "cell" above consisting of (2) 6 volt trojan wired in series to make a 12 volt "cell",
then each of those wired in Parallel for Amp Hour capacity.
Series wiring of a bank to accept voltages from say a 48Volt solar array, or to output to a 48Volt street inverter.
Combining series and parallel to both increase voltage and Amp Hours
Another way to look at it...... this is the same as the above combination.
Cross Tied Wiring, the dotted lines are the SAME gauge wire as all others, and eliminates or reduces the
natural process of depleting some batteries more than others in a large bank (explained further below)
Equalizing the Battery Bank:
Battery banks are made up of individual "cells" which can be a battery that has 2,3,6 cells itself.
When you first set up a bank you want to equalize the charge in all cells in the bank
Start by fully charging each individual cell before wiring together.
You want each cell to be very close to the same voltage before wiring together
If you do not equalize the charge properly before wiring them together
the charge and discharge cycle will be harder on the weaker cells in the bank thereby shortening their life, and weakening the bank.
Once a cell fails the entire bank's performance will be weaker due to the bad cell.
Half of your testing and maintenance time and efforts will be in ensuring that
ALL cells are optimum and replacing weak or failed cells in a bank.
There are few methods to equalize a bank:
Connect the cells in a parallel configuration, leave them in this state for 24 hours,
with no load or other connections, the stronger charged cells will charge the weaker ones
and they will equalize over time. (no external charger)
The second method is to again connect them in parallel configuration, then charge the whole bank at 1.4Volt current.
You need to do a little calculation as you limit the current Amperage to total mA of the bank divided by 40
IE: 4000 mAh battery,  divided by 40 = 100mA current limit
This possibly may be faster method to charge and equalize
then you can rewire the bank to your planned design configuration.
The third method is actually after you equalize the cells in the bank and wire into your
design configuration is to "cross tie" them, also called "massively parallel" wiring.
Generally, from the above picture, you only need the cross tie from positive to positive,
the "extra" negative to negative is not necessary,
but hey if you have extra wire or connection plates why not.
The cross tie allows the stronger cells to again charge the weaker ones, and will equalize the whole bank.
Let the system rest for 24 hours.
Then you can charge and use the bank at will.
This is why, you want to try to purchase all the cells in your bank at the same time, or at least put them all in service at the same time.
So they age together.
It is also why you can pretty much destroy the performance of a bank by adding in a new or old cell in the middle of their lifecycle.
You will either waste the new cell's life or beat up the other cells, in any case the performance will suffer.
This is why, I recommend having two banks, even three and four separate banks.
You can stagger lifecycles of the banks, and be building up a replacement bank as the "old" one is in service.
For example as soon as you build your single dream battery bank, you will want to start gathering cells for the second bank
GREAT if you can get the cells "dry" from the factory or supplier, and add electrolyte when all the cells are on the premises.
simply save  them dry until you are ready to put them in service.
Also why, you will want to wire your load distribution centers to certain limits, and use a quick connection that you can move from bank to bank.
IE: lights and all the low power draw stuff are on one load center,  fridge, furnace, pumps, inverters, etc on a second load center
When the supply bank of the heavy loads of the second load center starts to become unreliable, you can use it for the low power load center
where you can get more life out of the bank and more reliability until it is recycle or rebuild time.
You get the idea,  you will save some $ , effort, and angst in the long run. 
Maintaining your battery bank
The only battery that is maintenance free, are some automobile batteries, and the sealed gel types.
They have their purpose and place, however I would recommend NOT using them for off-grid purposes
They are expensive, and short-lived, require recycling, and overcharging can do a number on their cases even explosions.
Three things are death to a battery: sulfation, HEAT and FREEZING.
SO, you will need to do testing and regular inspection & maintenance on your battery bank.
First off, I have found that a spray can of silicone is VERY useful for protecting connections from corrosion and sulfate buildup.
easy wipe ups too as everything is slippery from the silicone, a paper towel and throw it away.
( I worry about fire with paper towels and chemicals, so I do my cleanups on dump day and bring them to the dump right after)
You will want a battery post tool
  the 4 in one tool
  my favorite, the bottom is a ring wire brush you just slide on and twist, and the top cap comes off
revealing a brush for inside diameter of the terminal connector. you can buy online for 7-10$ OUCH or a couple of bucks
at NAPA, one will last you a lifetime, if you keep it where you can FIND it.


  A very fancy unbreakable hydrometer from this site:
They also have complete turn key solutions, testing equipment and lots of DREAM pages, just going thru the site you will learn a lot. a favorite 2V flooded cell they carry. NOTE the very safe interconnect !
Just a note on battery sites: there are a LOT of them, most online sites are like online solar sites.
They appear to be "helpful" and will want to contact you for specifics, basically so they can up-sell you.
Your best bet is to be educated and certain of what type, capacity and number of cells you want for your bank.
Tell them your purpose and ask about their interconnect options, and ask for a price and shipping quote.
No BS, if they won't answer, move on.
I find it helpful to pretend to be a pro installer and looking for future volume quotes, you can easily see just how bad their markup is.
Technically I am not off base or lying, I DO recommend to many people, including you, so if they are honest with me I will drive business to them.
Often I will ask for a quote telling them I am building a model home, to be used to sell more. In that I am NOT lying.
When I get this pad done, I will conduct open houses to show others the how's and why's of what they are seeing.
Specific gravity is the ratio of the weight of a solution (Sulfuric Acid in the case of a flooded battery)
to the weight of an equal volume of water at a specified temperature.
The measurement is taken usually by use of a hydrometer.
Typically an automotive battery has a specific gravity of 1.260
In general for flooded cell batteries, the specific gravity of the electrolyte indicates the state of charge at a certain temperature.
Specific gravity CANNOT tell the battery's capacity.
During discharge the specific gravity decreases linearly with the amp hours discharged as illustrated in the chart below:
So, the specific gravity is an approximate indication of the charge state of a cell.
As the battery discharges, the specific gravity approaches that of water -a fact to remember.
The sloping line in the discharge side of the chart can be expressed by the equation:
specific gravity = single cell open circuit voltage - 0.845
single cell open circuit voltage = specific gravity + 0.845
You COULD fiddle with the specific gravity of a battery for a PURPOSE.
However, you really need to know what you are doing, and have a good digital hydrometer, and only then based
on many consultations with the battery manufacturer. Here's some reasons why you would adjust:

Higher Gravity =

Lower Gravity =

More capacity

Less capacity

Shorter life

Longer life

Higher momentary discharge rates

Lower momentary discharge rates

Less adaptable to "floating: operation

More adaptable to "floating" operation

More standing loss

Less standing loss

Generally though, the MFG takes these properties into consideration in the DESIGN of a battery,
so your purchase of the right battery for the right job is important !
So, using the equations above, you can now perform periodic inspections and tests of your battery bank.
Develop a routine, keep a log, AND spreadsheet, the data is fun to collate over time.
Periodic inspection should be performed on the battery bank.
Inspection should include Daily visual check as well as in depth Weekly and Monthly inspections.
Establish a pilot cell for each "battery/cell".
The pilot cells provide a quick overview on the electrical and physical conditions of the battery and should be reviewed during Monthly inspections
A Pilot cell is a Selected cell of a storage battery whose temperature, voltage, and specific gravity are assumed to indicate the condition of the entire battery.
You perform a hydrometer test on your pilot cell, and calculate the state of charge for the rest of the battery.
Generally in commercial applications when state of charge drops below 80% capacity during inspections,
(when the bank is fully charged), it is time to replace the cell.
In addition to the inspection, electrical measurements should be recorded periodically on the battery bank.
Readings should be performed on a Quarterly and Annual basis.
The Quarterly readings should include individual cell and bank voltages, electrolyte and ambient temperatures.
The Annual readings should also include the Intercell resistance's of all connections.  (requires a special test meter)
A relatively new procedure that may be included is the recording of Internal cell resistance or impedance. (requires a special test meter)
With experience, you may be able to identify suspect cells using  internal cell measurements that voltage and specific gravity readings alone could not.
In the case of a sealed or valve regulated battery,  this information can be critical in the identification of weak units.
Annual readings on your flooded cells and Quarterly readings on sealed batteries will provide useful information on the condition of your battery bank.
The true measure of the condition of your battery is how it performs under load.
Industry standards recommend the replacement of a battery when it reaches 80% of its rated capacity.
Load testing is the only accepted way to determine where the battery is on the capacity vs. time curve for the particular cell or unit.
The best method of performing a battery load test is to monitor each individual cell or unit during the discharge.
Weak or bad cells can be easily identified and scheduled for replacement.
In addition, load testing the battery can verify the integrity of the DC conduction path.
Thermographic scanning could be performed during the discharge.
(EXPENSIVE infrared equipment although there are simple hand held 'thermometers")
In the case of a UPS battery, consideration should be given to incorporating the load test into a functional test procedure of the system.
You can use a simple meter:
or better yet a relatively inexpensive ammeter that uses wired shunts between the load and the meter.
over time you can mark the meter with how much capacity you have left for that particular load.
You may want several set up to measure for specific loads.
you can even use a volt meter in a similar way.
There are many meter types out there, and some specific load test meters.
Some good some bad, some cheap and some very expensive. The sky is the limit.
I'd say start cheap, and build up when you can afford it.
A load test can be quite sophisticated and difficult, I find it best to use the ammeter and shunt with a load, then develop your own
"scale" as to how much capacity you have left. Of course this is MUCH more accurate if you kept other measurements when the bank
was brand new, and you establish a baseline to work from !!
All data should be maintained for review and to track the performance of the battery and bank over time.
Establishing benchmark data will greatly enhance your success in the maintenance of a reliable system.
Consideration should be given to installing diagnostic equipment to record discharges and help evaluate the battery under load.  (hour/run meters etc)
This may be a simple "hit" monitor that records overall voltage, current and the duration of the discharge or
a system that can track the performance of each cell.
If you are or have moved loads off-grid to your bank, include the current electrical rate $ so you can perform periodic cost benefit ratio's
It will also help you justify the expense of adding or replacing a battery bank by considering the cost of going back on grid -
during low capacity or failure of the bank
NOT to mention you will have cool data to show friends and family in how smaht you are in building the thing in the first place !!
Maintenance issues:
During weekly inspections you will want to check and maintain your individual batteries and  the bank itself.
1.) you most likely will have other equipment to charge the bank, solar, windmills, generators etc.
    Besides these you will want to have a "regular" charger of which there are many types:
What about quick charging?
The quick answer is: don't. here's why: only the surface area of the battery plates can be quick charged.
A lower current charges the battery more uniformly.
Trickle Charger: 
This is the charger a consumer - as opposed to a battery retailer or garage - will usually have.
It charges the battery at a fixed rate.
Different ampere-hour batteries have different charge rates.
For most automotive starting batteries, charge them at 1/10 of the rated ampere-hour values.
Battery voltage increases with the amount of charge.
Charging voltage should not exceed 14v to 15v for lead-antimony batteries, or 15v to 16v for maintenance free, low maintenance and sealed types.
Find the charging time for a completely discharged battery by multiplying the ampere-hour rating by 1.3.
Test the battery during charging, and continue charging until all cells are gassing.
Use either a voltmeter (or multimeter) or hydrometer.
The specific gravity of the electrolyte in all cells in a fully-charged battery should come to at least 1.265 in a conventional battery.
During charging, check the electrolyte level periodically and add water - only distilled water- to keep the electrolyte level up to the line.
If the battery becomes hot to the touch, stop charging, Resume after it has cooled.
Note that permanently sealed batteries -  generally can be tested only with a voltmeter or multimeter.
These batteries are fully charged when the voltage peaks and then begins to fall - as high as 17v, for example, on the Maintenance-Free battery.
Do not hook a battery to a trickle charger and leave it unchecked for longer than overnight.
After about eight hours maximum, careful monitoring is required.
Caps need to be replaced tightly after charging's done.
Taper charger:
Similar to the trickle charger, the taper charger charges at a fixed voltage.
As the battery's voltage increases with the amount of charge, the current drops accordingly.
A drawback of both the taper and trickle chargers is speed...they don't have it.
It can take days to bring a discharged battery up to 100%.
Here, too, check batteries for overheating as they charge.
Constant Current Charger:
A professional-quality charger, the constant-current makes charging simple.
It maintains a constant supply of current to the battery at all levels of charging.
You select the charging current.
As the battery voltage increases with the amount of charge,
this type charger automatically increases the charging voltage to maintain the current output.
Pulse Charger:
This is the state of the art in charger technology. The pulse charger monitors the voltage constantly during charging and standby modes.
When battery voltage reaches a specified low level, the pulse charger then delivers a full battery charge.
Then when the battery gets to the specified high voltage, it automatically drops the charge.
High Rate Charger:
Not to for use with small engine starting batteries. They force a high current into the battery, which can lead to overheating and plate damage.

Additionally, some chargers have a de-sulfination cycle that you can run weekly to avoid lead sulfate deposits.
In ALL cases check the manual for your battery and charger, so that you KNOW the best method to charge the battery.
2.) Charging
Under "normal" circumstances a MFG will recommend charging when the battery reaches 80% of capacity (20% discharged)  NOT before.
Most modern batteries are designed with a lifetime of 1500 charge cycles or more.
If your draw is less than the the 20% discharge rate, then only charge when needed, so pay attention to capacity remaining under load.
That will spread out your charge cycles and prolong the life of the bank.
Some chargers have "weekend" "equalize" or "weekly" selections that equalize and part of the de-sulfination cycle, it is recommended to set your charger
for this mode every 5-10 charge cycles to keep your bank healthy.
Performing this type charge cycle too often will shorten the life of your bank.
3.) Charging under solar, wind, hydro using a charge controller.
    While too often, or overcharging, damages the bank, and even "topping" off the charge counts as a short cycle 
    A charge controller will trickle produced power to the bank as it is generated.
If you select the trojan battery (my DREAM battery) it is made to handle this type of charging and a good match for the system..
I recommend a "Morningstar" brand charge controller as it is the most sophisticated, has many options including rs232 interface for computer tracking
and has simple to sophisticated capacity metering depending on the model.
They also have a built in diversion zone to transfer incoming power to another bank, load, or street inverter when the primary bank is fully charged.
Other than that you can see the inherent issues with "renewable" power, as even short charge cycles COUNT as one cycle in the life of a battery !!!
(reason 999 that wind turbines are unreliable)
Always follow the mfg directions for watering, get familiar with the water level line and NEVER overfill.
ALWAYS use distilled water, as any other water will introduce contaminants in the form of minerals and metals in solution, in the water.
USE your hydrometer as you will not always fill to the line with water, sometimes it will be the recommended electrolyte,
totally dependent on reaching the optimum specific gravity for your cell / battery.
In general new batteries require watering every 10 charges, and reconditioned batteries every 5 charges.
as part of your weekly inspection you want to check the water level of 2 or three cells to insure proper levels.
make double sure you know where your level line is and again do not overfill as that space is required for gasses during charging
and could cause a spill during charging if overfilled.
If a battery ever overflows, take a few minutes to rinse it with water immediately afterwards (baking soda optional) to
prevent corrosion on top of and beneath the battery.
Use enough water to thoroughly dilute the spilled acid to the extent that it is not harmful to the environment.
The spilled acid is both highly conductive and corrosive.
If not rinsed away, the conductivity can cause the battery to discharge itself, even while it is not in use, and generate addition heat during recharge.
Over time, acid left on top of the battery will form clumps of conductive white corrosion.
If it is allowed to accumulate, it can dramatically shorten the life of the battery and
make checking and adding water an unpleasant experience which you will tend to avoid, as well as cause obvious safety concerns.
Acid vapors escape during charge, and residue will develop around the vent cap area even under normal circumstances.
it is recommended that batteries be rinsed every spring and fall (or as needed), to remove the acid residue from the battery.


  • Never over fill. It will cause overflow on the next charge. Acid loss shortens run time, generates more heat, and requires shop service to correct.
  • Never make a habit of giving short charges. Each short charge constitutes a “cycle” and over time will significantly affect the performance and life of the battery. It also causes excess heat that will make the battery less efficient than not charging at all. It’s better to let a battery rest and cool during use breaks.
  • Never interrupt a charge cycle if it is avoidable. It is recommended that once a charge cycle is initiated, it be allowed complete.
  • Never allow a battery to sit discharged for more than a few days to avoid “sulfation”. If it becomes necessary to store a battery for any period of time, charge it prior, and once every 3 to 6 months thereafter to avoid damage.
  • Never allow a battery to go completely dead (unusable). It will take over 72 hours of continuous charging to bring back to full charge, and may require shop service to restore full charge.
  • Never continue to use an overheating battery.
  • If a battery ever radiates excessive heat during use or charging or emits a strong sulfur smell, discontinue use and call for service.
  • Never allow sparks or flame near a charging battery. Batteries produce explosive hydrogen gas while charging, which could cause an explosion resulting in injury or death.


Never over discharge a battery:

  • Deep discharging will harm the battery and cause electrical components to run excessively hot. Significant damage can result.
  • Deep discharging can easily increase the recharge time outside your charger’s range to recover, causing the battery to be only partially charged for the next day.
  • Most automatic chargers must sense a minimum battery voltage to activate and turn on. If the battery is below the threshold voltage, you will not be able to recharge the battery.
  • If you don’t have a working discharge indicator, I recommend installing at least a simple “passive” discharge indicator. They are available for about $75.
  • A discharged battery, since it's specific gravity is near that of water, is subject to freezing aka death.
Be it a room, a shelf, or a box, you want it kept at a temp of 70'F or lower. But not too low. as that effects the performance as well.
A range from say 50'F to 70'F we could say is optimum.
You also want low humidity, the water vapor can condense and mix with chemicals causing corrosion, and even contribute to standing discharge rates.
You definitely want a means to vent. you can simply have passive piping but that can back draft cold air in the winter.
Active fans are better, but I highly advise wither building a circuit that both periodically vents the room, or at least comes on BEFORE charging
UNLESS the fan is rated explosion-proof and shielded !
You do NOT want to have the room in an area where there is a Forced Hot Air heating system (FHA) 
as the outgas byproducts of the bank can be dragged thru the house !
Caution with metal
Keep the room clean as well as the batteries, have safety equipment and  emergency eye wash and wipes available.
It may not be a bad Idea to have the safety Material Data Safety Sheets (MSDS) available and posted in the room or box cover.
In the event of fire, dry chemical, water, water fog, and halon are good extinguishing methods for lead-acid types.
There are MANY different types of batteries as there are applications.
You want to fit the battery to the task, and  the predicted run time to the battery capacity.
OVER building capacity is better than under building as the extra demand will inevitably lead to deeper discharge.
Sometimes it may be better to start with a bank of deep cycle automotive batteries, say 4.
Make the mistakes on a cheap system, consult with a supplier with a good reputation.
then build out an expensive high performance bank.

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