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Battery Basic PART 2


1How to charge deep cycle batteries
There are numerous correct ways to charge the batteries. Typically, charge at C÷10 amperes,  (where C = the 20 hour capacity of the system expressed in Ampere Hours) until the battery voltage rises to 2.583 Volts per cell (i.e. 7.75 volts for a 6V battery). Hold this voltage constant for 2 to 4 hours, and stop charging.

A similar method would be to charge at the following upper limits and terminate the charge when the time limit is reached:

* Charge Current = C÷10 Amperes
* Charge Voltage = 2.583 Volts per Cell
* Charge Time = 10 Hours Battery temperature adjustment: reduce the voltage by 0.028 Volts per Cell for every 10°F above 80°F, increase by the same amount for temperatures below 80°F

What size battery do I need for my application

Determine how many amperes your application needs from the battery and for how long. Multiply the two to obtain Ampere Hours required. Increase this by 20% for a safety cushion, and from our capacity charts, match a battery which will deliver this many AH for the required time, and voltage. Connecting batteries in parallel adds AH, and connecting in series adds the voltage. In either case the energy (WH) storage capability is increased by the amount of energy each additional battery provides.

What is the cycle life of the batteries
Any claims of lasting longer are based on selective data, as a marketing gimmick (i.e. selecting the best of one and worst of the other) and is misleading. Battery life, like anything else, cannot be precisely pre-determined, any more than the life of your car or humans. The actual life out in the field, when operated under identical conditions, is the only valid criteria. One way to differentiate the life and performance is to look at the amount of materials, and the type of materials used in making the product.

Battery Selection

How do I select the right battery for my application?
Proper battery selection may require the assistance of a knowledgeable battery sales/service technician. Please contact us at +65 6741 7123 or email rpt@renewpowers.

What is the difference between a deep cycle battery, a starting battery, and a dual-purpose battery?

A deep cycle battery has the ability to be deeply discharged and charged many times during its service life. It is designed specifically for powering electrical equipment for long periods of time. An automotive or starting battery is designed for brief bursts of high current and cannot withstand more than a few deep discharges before failure. This is why it is unable to start your car if you accidentally leave the lights on more than a couple of times. For applications where both engine starting and light deep cycling are required, a dual-purpose battery is often used. This type of battery is neither a starting nor a deep cycle battery but rather a compromise between the two so it performs both functions adequately.

Can I use my Deep Cycle battery as a starting battery?

Deep cycle batteries can be used for engine starting but starting batteries should not be used for deep cycle applications. A deep cycle battery may have less cranking amps per pound than a starting battery, but in most cases a deep cycle battery is still more than adequate for the purpose of starting an engine.

What are the advantages and disadvantages of gel, AGM, and flooded lead acid deep cycle?
Generally, gel and AGM batteries have about 20% less capacity, cost about two times more, and have a shorter cycle life than comparable flooded lead acid batteries. However, Gel and AGM batteries do not need watering, are safer (no acid spilling out), can be placed in a variety of positions, have a slower self-discharge characteristic, and are more efficient in charging and discharging than flooded batteries (see table below). Gel batteries are more suitable for deep cycling applications whereas AGM batteries are more for light cycling and engine-starting applications.

  Flooded Gel AGM
Charge/Discharge Efficiency 89% 98% 99%
Self discharge rate (per month) 13% 1-3% 1-3%
Finish Voltage 15.3-16.0V 14.1-14.4V 14.1-14.7V
Float charge: 13.2-13.7V 13.4-13.8 13.4-13.8V

What's better? 24 Volt or 48 Volt system?

Higher-voltage systems tend to be more efficient and put a lower load on the batteries. Factors other than the battery enter into the system's overall efficiency.

1 Maintenance

When should I water my flooded batteries?
Water is lost during charging. Therefore, the best time to water your batteries is always at the end of the charge cycle. However, if the electrolyte level is extremely low or the plates are exposed to air, add some water to cover the plates before starting the charge cycle.

How often should I water my flooded batteries?

How often you use your batteries will determine the frequency of watering. For example, the weekend fisherman may find he only needs to water the batteries in his boat once a month. While a maintenance supervisor for a golf course might need to service the batteries in their golf cars every week. Also using batteries in a hot climate may require more frequent watering. It is best to check your new batteries regularly as this will give you a good feel for how often your application will require battery watering. WARNING: A brand new battery may have a low electrolyte level. Charge the battery first and then add water if needed. Adding water to a battery before charging may result in overflow of the electrolyte.

What is the proper electrolyte level?
Liquid levels should be 1/8 inch below the bottom of the vent well (the plastic tube that extends into the battery). The electrolyte level should not drop below the top of the plates.

Do you ever add acid to a battery?

Under normal operating conditions, you never need to add acid. Only distilled, deionized or approved water should be added to achieve the recommended levels mentioned above. When a battery is shipped in a dry state or accidental spillage occurs, electrolyte should be added to the battery. Once filled, a battery should only need periodic water addition.


What is the proper torque value for my battery connections?


Automotive 50-70 in-lbs
Wingnut 95-105 in-lbs
LPT 95-105 in-lbs
Stud 120-180 in-lbs
LT 100-120 in-lbs>


Button 90 to 100 in-lbs
LT 100-120 in-lbs

WARNING: Do not over tighten terminals. Doing so can result in post breakage, post meltdown, and fire.

Can a battery freeze?
The only way that a battery can freeze is if it is left in a state of partial or complete discharged. As the state of charge in a battery decreases, the electrolyte becomes more like water and the freezing temperature increases. The freezing temperature of the electrolyte in a fully charged battery is -92.0oF. At a 40% state of charge, electrolyte will freeze if the temperature reaches approximately 16.0oF.

Can I reduce my maintenance by not gassing my batteries?
You will reduce the frequency of watering, but will cause a condition known as stratification where the specific gravity of the electrolyte is light at the top of the battery and heavy at the bottom. This condition results in poor performance and reduced battery life.

How can I tell if a battery is bad?
To determine if the battery system is experiencing a problem, fully charge the batteries then shut off the charger and remove all electrical loads. Allow each battery in the system to stand on open-circuit for about one hour. Measure the voltage of each battery. If the battery voltage spread exceeds .15 volts for a 6 volt battery, or .30 volts for a 12 volt battery, a problem is indicated. Battery voltage alone does not confirm a problem. When the voltage spread indicates a problem, confirmation is accomplished by taking electrolyte specific gravity readings using a hydrometer. If the specific gravity readings show a spread greater than .030 (30 points), give the batteries an equalization.

What is used to clean a battery and neutralize the electrolyte?
A solution of baking soda and water. Use 1 lb of baking soda for every gallon of water.


·  New batteries should be given a full charge before use.

·  New batteries need to be cycled several times before reaching full capacity (50 - 125 cycles, depending on type). Usage should be limited during this period.

·  Battery cables should be intact, and the connectors kept tight at all times. Systematic inspection is recommended.

·  Vent caps should be kept in place and tight during vehicle operation and battery charging.

·  Batteries should be kept clean and free of dirt and corrosion at all times.

·  Batteries should be watered after charging unless plates are exposed before charging. If exposed add just enough water to cover plate tops by 1/8". Check acid level after charge. The acid level should be kept 1/4" below the bottom of the fill well in the cell cover.

·  Water used to replenish batteries should be distilled or treated not to exceed 200 T.D.S. (total dissolved per million). Particular care should be taken to avoid metallic contamination (iron).

·  For best battery life, batteries should not be discharged below 80% of their rated capacity. Proper battery sizing will help avoid excessive discharge.

·  Battery chargers should be matched to fully charge batteries in an eight hour period. Defective chargers will damage batteries or severely reduce their performance.

·  Avoid charging at temperatures above 120°F or ambient, whichever is higher.

·  Deep cycle batteries need to be equalized periodically. Equalizing is an extended, low current charge performed after the normal charge cycle. This extra charge helps keep all cells in balance. Actively used batteries should be equalized once per week. Manually timed charges should have the charge time extended approximately 3 hours. Automatically controlled chargers should be unplugged and reconnected after completing a charge.

·  In situations where multiple batteries are connected in series, parallel or series/parallel, replacement battery(s) should be of the same size, age and usage level as the companion batteries. Do not put a new battery in a pack which has 50 or more cycles. Either replace with all new or use a good used battery(s).

·  Periodic battery testing is an important preventative maintenance procedure. Hydrometer readings of each cell (fully charged) gives an indication of balance and true charge level. Imbalance could mean the need for equalizing; is often a sign of improper charging or a bad cell. Voltage checks (open circuit, charged and discharged) can locate a bad battery or weak battery. Load testing will pick out a bad battery when other methods fail. A weak battery will cause premature failure of companion batteries.

·  Always use a matched voltage charger and battery pack system. An undersized charger will never get the job done, no matter how long you let it run. An oversized charger will cause excess gassing and heat; this situation could cause explosions or other damage.

·  As batteries age, their maintenance requirements change. This means longer charging time and/or higher finish rate (higher amperage at the end of the charge). Usually older batteries need to be watered more often. And, their capacity decreases.

·  Lead acid batteries should be brought up to full charge at the earliest opportunity. Avoid continuously operating batteries in a partially charged condition. This will shorten their life and reduce their capacity.

·  Extreme temperatures can substantially affect battery performance and charging. Cold reduces battery capacity and retards charging. Heat increases water usage and can result in overcharging. Very high temperatures can cause "thermal run-away" which may lead to an explosion or fire. If extreme temperature is an unavoidable part of an application, consult a battery/charger specialist about ways to deal with the problem.

·  Inactivity can be extremely harmful to all lead acid batteries. If seasonal use is anticipated, we recommend the following:
a. Completely charge the battery before storing.
b. Remove all electrical connections from the battery, including series/parallel connectors.
c. Store the battery in as cool a place as possible. However, do not store in a location which will
consistently be below 32
°F. Batteries will discharge when stored, the lower the temperature the
lower the self discharge.
d. When not in use, boost every two month




1 Charging

How can a battery's state of charge be accurately measured?
The state of charge of a lead acid battery is most accurately determined by measuring the specific gravity of the electrolyte. This is done with a hydrometer. Battery voltage also indicates the level of charge when measured in an open circuit condition. This should be done with a voltmeter. For an accurate voltage reading, the battery should also be allowed to rest for a period sufficient to let the voltage stabilize.

When do I need to perform an equalization charge (only for flooded batteries)?
Equalizing should be performed when a battery is first purchased (called a freshening charge) and on a regular basis as needed. How often this might occur with your battery will vary depending on your application. You will need to monitor your battery voltage and specific gravity to determine when equalization is needed. For example, it is time to equalize if the measured specific gravity values are below manufacturer's recommended values after charging (recommended value for Trojan Deep Cycle batteries is 1.277 +/- .007 at 80o F). Equalizing is also required if the specific gravity value of any individual cell varies 30 points or more. Reduced performance can also be an indicator that equalizing is necessary. Equalization should also be performed when individual battery voltages in a battery pack range greater than 0.15 volts for 6 volt batteries or 0.30 volts for 12 volt batteries.

Does my deep cycle battery develop a memory?

Lead acid batteries do not develop any type of memory. This means that you do not have to deep discharge or completely discharge a battery before recharging it. For optimum life and performance, we generally recommend a discharge of 20 to 50% of the battery’s rated capacity even though the battery is capable of being cycled to 80%.

Do batteries self-discharge when not in use?
All batteries, regardless of their chemistry, self-discharge. The rate of self-discharge depends on the type of battery, the age of the battery, and the storage temperature the batteries are exposed to. As an estimate, Trojan batteries self-discharge approximately 4% per week at 80o F.

What type of charger should I buy?
An automatic charger offers the greatest convenience. Just plug the battery into the charger and the charger does the rest. Manual chargers, although equally effective at charging batteries, require a greater level of attention. Generally speaking, automatic chargers are priced higher than manual chargers.

What size charger should I buy?

A properly sized charger takes into account battery capacity and the time interval between charges. In applications where cycling is infrequent, such as weekend RV users, or infrequent or seasonal trolling motor usage, a charger with an output current rating between 10 and 13% of the battery's rated 20-hour capacity will suffice. In applications where battery recharge must be accomplished within 8 to 10 hours, a three stage, automatic charger, rated at 20% of the battery capacity, may be required.

•Example: A good charging rate for a battery with a 20-hr capacity of 225 amp-hr is about 22 to 29 amps. You can of course go slightly higher or lower depending on what is available on the market.


How does temperature affect the performance of my batteries?
At higher temperatures (above 77oF) battery capacity generally increases, usually at the cost of battery life. Higher temperatures also increase the self-discharge characteristic. Colder temperatures (below 77oF) will lower battery capacity and prolong battery life. Cooler temperatures will slow self-discharge. Therefore, operating batteries at temperatures at or slightly below 77oF will optimize both performance and life.

How do I determine my battery capacity when it is colder/hotter?

Battery capacity is basically a linear relationship. A good rule of thumb is that for every 15oF above 77oF, capacity is increased by 10% and for every 15oF below 77oF, capacity is reduced by 10%.

How do I account for temperature when taking my gravity readings?
Temperature will affect specific gravity readings. As temperature increases, the electrolyte solution expands and as temperature decreases the electrolyte solution contracts. As a result, it is a good practice to temperature correct specific gravity readings. Here are the relationships Trojan recommends using:
For every ten degrees above 80oF add 3 points to the hydrometer reading.

•Example: @ 90oF the hydrometer reads: 1.250 The actual reading: 1.250 + .003 = 1.253
For every ten degrees below 80oF subtract 3 points from the hydrometer reading.

@ 70oF the hydrometer reads: 1.250 The actual reading: 1.250 - .003 = 1.247

How do I account for temperature when taking my voltage readings?
Temperature will affect voltage readings. As temperature increases, voltage decreases. Conversely, as temperature decreases, voltage increases. Here are the relationships Trojan recommends using:
For every 10 degrees below 80oF, add .028 volt per cell to the charger voltage setting.

•Example: A 12 volt battery @ 70oF. The recommended charging voltage (@ 80oF) is 14.60 volts. The adjusted charging voltage is 14.60 +(6 cells * .028vpc) = 14.77 volts.

For every 10 degrees above 80oF, subtract .028 volt per cell to the charger voltage setting.

•Example: A 12 volt battery @ 90oF. The recommended charging voltage (@ 80oF) is 14.60 volts. The adjusted charging voltage is 14.60 -(6 cells * .028vpc) = 14.43 volts.

Is there a maximum temperature for charging my batteries?
When charging lead acid batteries, the temperature should not exceed 120oF. At this point the battery should be taken off charge and allowed to cool before resuming the charge process.


Are lead acid batteries recyclable?
Lead acid batteries are 100% recyclable. Lead is the most recycled metal in the world today. All the lead purchased by Trojan Battery Company for grid and small parts casting is recycled lead. The plastic containers and covers of old batteries are neutralized, reground and used in the manufacture of new battery cases. The electrolyte can be processed for recycled waste water uses. In some cases, the electrolyte is cleaned and reprocessed and sold as battery grade electrolyte. In other instances, the sulfate content is removed as Ammonia Sulfate and used in fertilizers. The separators are often used as a fuel source for the recycling process.

Where do I recycle my old batteries?

Old batteries may be returned to the battery retailer, automotive service station, a battery manufacturer or other authorized collection centers for recycling. If you are not sure where to take your spent batteries, call your local Trojan dealer for assistance.



What are some common myths associated with batteries?
• Half of a non-buffered aspirin in each cell and then a fast charge breaks up sulfation and extends battery life- Aspirin forms ascetic acid which attacks the positive grid and active material.

• Storing a battery on concrete will discharge it quicker- Long ago, when battery cases were made out of natural rubber, this was true. Now, however, battery cases are made of polypropylene or other modern materials that allow a battery to be stored anywhere. A battery’s rate of discharge is affected by its construction, its age, and the ambient temperature. The main issue with storing on concrete is that if the battery leaks, the concrete will be damaged.

Why do manufacturers use different alloys in their batteries (lead-calcium, lead-antimony, lead-selenium, etc.)?

The composition of the plate grid alloy can have a major effect on operating characteristics, such as behavior on float charging and cycle life. Older lead-antimony designs have good cycling capability but require frequent water additions, particularly towards the end of life, due to antimony migration between the plates. Cells with lead-calcium alloys require far less watering, but tend to have a poor cycle life. Lead-selenium alloys are actually low-antimony types with the addition of selenium as a hardening agent. Such alloys promote good cycling capability, while maintaining a constant and fairly low level of water consumption. Many variants on these alloy types are commercially available.

How do you read the date codes on the batteries?
Positive Terminal- Manufacturing Date. This code indicates the actual date when mechanical assembly of the battery was completed. At this point, electrolyte has not been added to the battery and formation charging has not taken place. LETTER stands for the month and could be anything from A to L (A=January, B=February, C=March, and so on),; NUMBER stands for the date.

Negative Terminal- Shipping Date. This code indicates the month and year when the battery was shipped out of our factory. LETTER stands for the month (see below); NUMBER is the last digit of the year.

•Example: A battery with “I26” stamped on the positive terminal and “J2” on the negative. “I26” means that the battery was assembled, without electrolyte, on September 26th. “J2” means that it was shipped from our factory around October of 2002.