Note: this technical information comes from Deltran, manufacturer of the Battery Tender Plus. It is presented here for those who wish to delve deeply into the subject of battery maintenance: Q: How is the Battery Tender Plus battery charger different from a trickle charger?
A: The Battery Tender Plus battery charger delivers 1.25 amperes during bulk charge mode, holds the battery charge voltage constant at 14.4 VDC during absorption charge mode until the battery charge current drops to 0.1 amperes, then automatically switches to a float charge mode. During float charge mode, the output voltage of the Battery Tender Plus battery charger is 13.2 VDC, which is well below the gassing voltage of a lead acid battery. This keeps the battery topped off, while minimizing any detrimental effects. The Battery Tender Plus battery charger is able to perform these complex switching functions because its electronic circuitry is controlled by an on-board microprocessor.
Although they often appear to be a better economic choice for the typical consumer, trickle chargers do not have the advantage of sophisticated electronic control. Therefore, as they allow the value of charge current to trickle down to what appears to be safe levels, the output voltage of the charger rises well above 15 VDC, sometimes even going higher that 16 VDC depending on the charger type and the battery that is connected to it. Either voltage is well above the gassing voltage of a lead acid battery. If the battery remains connected to this high level of voltage for an extended period of time, even less than 1 day, extreme damage can be done to the battery. What appears to be a cost savings for the charger may actually cost several times the charger price in replacement batteries.
Q: What makes the Battery Tender Plus battery charger different from other automatic battery chargers?
A: Many automatic battery chargers turn off when the battery voltage rises or the charge current falls to a preset level. Then after a period of time, when the battery self discharge characteristics have reduced its terminal voltage significantly, sometimes to the point where the battery has given up almost 90% of its stored charge, the charger will turn on and recharge the battery. This type of cycling will dramatically reduce battery life. The Battery Tender Plus battery charger does not turn off. It automatically switches to a safe float voltage level that keeps the battery charged and yet does not do any harm to the battery or cause any reduction in its useful life.
Q: Is the Battery Tender Plus battery charger more expensive than a trickle charger?
A: In simple terms, comparing only the “off-the-shelf,” retail price dollars, it probably is. However, in terms of the total cost of ownership, including the likely dramatic reduction in battery life resulting from using a trickle charger, then the answer is ABSOLUTELY NO. The Battery Tender Plus will more than make up the difference in price by extending the useful life of only one engine start battery. Multiply this savings over the 5-year warranty period and you will save enough in battery cost to more than pay for the Battery Tender Plus.
Q: How long can I leave the Battery Tender Plus connected to a battery?
A: In theory, you can leave the Battery Tender Plus connected to a battery forever. Like they say, “Just plug it in and forget about it!” Practically speaking, it is a good idea to check on the battery at least once a week. Strange things can happen. Sometimes a battery can have a weak cell that won’t show up until the worst possible time. Of course, that time is usually when the battery is connected to a charger. If something goes wrong, then you have to deal with the question of the chicken and the egg. Which came first? Did the battery fail because it was connected to the charger or did the charger fail because it was connected to the battery?
No matter how good a product is, anything can break. With a battery and a charger connected together, it’s a much better idea to be proactive and anticipate problems, however unlikely they may be. In more than 99.9% of cases, nothing will go wrong. That still leaves about 0.1% where something might. A little common sense can go a long way.
Q: How can the Battery Tender Plus--rated at 1.25 amperes--recharge a battery as fast as another charger that is rated at 3 amperes?
A: To recharge a battery, it is necessary to replace the charge that the battery delivered during the last time that it was used. The dimensions or units describing electrical charge are the Coulomb or, more conveniently in the context of battery charging, the amp-hour. The abbreviation for amp-hour is Ah. A battery charger delivers charge (amp-hours) to the battery by using an electrical current (amps) at its output over a period of time (hours). The numerical product of the electrical current and time period is the amount of charge delivered. This is true in a general sense for any charger.
What is not obvious is that for the calculation of charge returned to be valid, the electrical current at the output of the battery charger must be constant during the period of the calculation. This, and the amplitude of the charge current, are the critical features of a battery charger that determine how fast it will recharge a battery.
Because of the many different ways that a battery charger can be constructed and electronically controlled, there are many cases where one charger can have a higher numerical charge current rating and yet not charge a battery as fast as some other charger with a lower current rating. This is unfortunate for the consumer, because there is really no way to tell based on industry standards because those standards define construction and fault protection methods to ensure safety. Those standards do not define a framework that limits how a battery charger’s numerical charge current rating is determined. This is not unlike some of the confusion that exists when attempting to compare a battery’s performance based on its ratings, although the Battery Council International (BCI) clearly defines the tests that must be performed on a battery for it to be rated at a specific number of cranking amps. No such governing body exists to define a similar testing process to control how manufacturers rate the charge current output of a battery charger.
With battery chargers, the electrical current rating alone cannot ensure an accurate estimate of recharge time. Only by looking at the charge current time profiles of two chargers connected to the same size battery, in the same state of charge, can one accurately compare recharge time.
Deltran’s claim that the 1.25 amp Battery Tender Plus will charge a battery in the same amount of time as a typical 3-amp charger is based on the fact that the Battery Tender Plus charge current is very nearly constant during the bulk charge period, while a typical 3 amp charger, configured like so many chargers on the market, is not.
Q: Can I leave the Battery Tender Plus battery charger connected to a battery while I’m using the battery to power another appliance like a radio?
A: Yes, you can leave the Battery Tender Plus connected to a battery even when the battery is being used. As far as the Battery Tender Plus is concerned, the appliance just makes the battery look like it’s not fully charged. The Battery Tender Plus can supply up to its full 1.25 amp current output even while its output voltage is at the lower, float level of 13.2 volts. It is only when the battery voltage drops below somewhere between 12.0 and 12.5 volts that the Battery Tender Plus will reset and begin the full charger cycle. All that means is that when the appliance is no longer being used by the battery, the battery voltage will rise normally and there will be an absorption period of a few hours where the Battery Tender Plus holds the battery voltage at 14.4 volts until the charger current drops to below 0.1 amp, or until 8 hours has elapsed during the absorption charge period. Then the Battery Tender Plus goes back into float mode where its output voltage is constant at only 13.2 volts.
RECHARGING AGM BATTERIES:
The primary difference between the original Battery Tender and the Battery Tender Plus is that the newer model is specifically designed to accommodate the charging requirements of the new, Absorbed Glass Matte (AGM) style batteries. To achieve that goal, it was necessary to modify the absorption charge mode in the following way. The original Battery Tender switches to float mode when the charge current drops to 0.5 amps. The Battery Tender Plus switches to float mode when the charge current drops to 0.1 amps. The result is that for an extended period of time, not to exceed 6 hours, the Battery Tender Plus output voltage will be held at a constant voltage that is significantly higher than the float voltage.
With the original Battery Tender, the switchover at 0.5 amp results in an absorption charge mode length of approximately 1 hour. During this 1-hour period, the battery charge voltage is held constant at a value of approximately 14.3 volts. Because of the slightly higher voltage recharge requirements of AGM batteries, and because AGM batteries require a longer period of constant voltage absorption, the Battery Tender Plus controls the output voltage at 14.4 volts while it waits for either the charge current to decrease to 0.1 amp or for the absorption charge mode control timer to expire. The end result is that the Battery Tender Plus absorption period is longer and at a slightly higher voltage than that for the older Battery Tender.
USING THE BATTERY TENDER PLUS TO RECHARGE LARGER BATTERIES:
The Battery Tender Plus was designed to recharge and maintain batteries commonly used in motorcycles and power sports equipment. The typical size of those batteries is 16 to 20 amp-hours. The cold crank rating of that size battery is typically 250 to 350 CCA (Cold Cranking Amps). If either charger is used on a much larger battery, like a typical car battery rated at 650 to 900 CCA with a capacity rating of 40 to 70 amp-hours, then the time to fully recharge may be very long. Particularly on AGM batteries, the last 5% of recharge is the most difficult to deliver to the battery. That is why it is important to extend the absorption charge period longer than is possible with either charger. Even with the 6 hour safety timer used on the Battery Tender Plus, a larger battery may have the higher, constant absorption voltage removed while the battery is still drawing much more than 0.1 amp. Once either charger switches over to the lower float voltage of 13.2 VDC, the voltage potential available to force the charge current into the battery is very low. By this time, the rest state battery voltage is probably at 12.7 to 12.8 VDC. That leaves only 0.5 to 0.6 VDC to push the current. Near the end of the absorption mode, with the rest state battery voltage at the same levels, the charger voltage is at 14.4 VDC, leaving a voltage potential of 1.7 to 1.8 VDC to push the current into the battery. That’s almost 4 times the push available, compared to what’s available in the float mode. That’s why it takes so much longer to recharge a battery, once the charger switches over to float.
CAUTION: SOME THOUGHTS ON CONTINUOUS USE OF THE BATTERY TENDER and BATTERY TENDER PLUS AUTOMATIC BATTERY CHARGERS: Even though both chargers are designed for continuous use, with features that automatically drop the recharge voltage to safe "float" or "maintenance" levels, common sense dictates that ANY electrical appliance can malfunction. Even with a field failure rate at only a small fraction of a percent, the likelihood that either charger will fail is still not zero. It is a good idea to check the battery and charger at least once a week, just to be safe.
COMPARISION of GENERAL BATTERY CHARGING REQUIREMENTS by TYPE: The maximum recharge voltage is the highest for sealed AGM, and the lowest for sealed GEL, with flooded batteries falling somewhere in between. The exception to this rule is flooded SLI batteries that have antimony added to their lead grids. The highest voltage is delivered during the equalization charge period. Equalization charging will be discussed later. The maximum recharge current is the highest for sealed AGM and sealed GEL, and the lowest for flooded batteries. Most battery manufacturers will specify the maximum recharge current to be a percentage of the amp hour capacity.
For example, many flooded SLI batteries are limited to 10% to 20% of the amp hour capacity. For more specific example, consider a 20 Ah, flooded SLI battery, as you would find in a motorcycle, sports watercraft, or ATV. In this case, the charger should only deliver a maximum charge current of 2 to 4 amps to the battery. On the other hand, sealed AGM batteries are becoming very popular in these SLI applications. Sealed AGM batteries do not usually have the same maximum charge current limitations as flooded batteries. However, some AGM battery manufacturers continue to prefer to make a more conservative recommendation for the maximum charge current.
In this regard, with one more known fact about the majority of commercially available battery chargers, the conservative approach to recommending a maximum charge current is usually not necessary. That fact is that most commercially available battery chargers are not true constant current chargers. What most battery chargers do is one of two things. They either allow the charger output current to immediately taper (reduce in amplitude) in response to an increase in battery voltage, however slight that voltage increase may be, or they maintain a regulated current limit until such time that the battery charger develops sufficient voltage for the charger to switch to a true, constant voltage mode of operation.
The initial period, prior to the constant voltage mode of operation is called the bulk charge period. The constant voltage period is called the absorption charge period. It is during the absorption charge period that the charging requirements for AGM batteries differ most significantly from those for flooded batteries and GEL cells. AGM batteries require a longer period of constant voltage - so long in fact, that the current drawn by AGM batteries is virtually nil for up to several hours at the end of the absorption period. Typically it takes 1 to 2 hours for the battery charge current to drop to a few tenths of an amp at the beginning of the absorption period. After the battery charge current drops to this very low level the AGM battery still requires several more hours with the constant absorption voltage being applied.
The precise electro-chemical requirements for this extended, essentially “zero” current high constant voltage period are debatable. Suffice it to say that a significant body of empirical evidence supports this claim. Without an extended, “zero” current, constant voltage absorption period, the cycle life of AGM batteries is dramatically reduced. The reduction may be by as much as a factor of 2 or 3 to 1. In other words, an AGM battery designed to deliver 400 deep cycles may only deliver 200 or as few as 125 deep cycles if the length of the absorption period is not sufficient. One deep cycle is defined as a battery discharge where the battery capacity is depleted to between zero and 20% of its fully charged value. We could say that the State Of Charge (SOC) of the battery is 0% to 20% after a deep cycle discharge. This is described as a Depth Of Discharge (DOD) between 100% and 80%.
No such lengthy, “zero” current, constant voltage absorption period requirement exits for either flooded SLI or GEL cells. However, both of these battery types do benefit from extended float maintenance charge periods. This is usually referred to a “topping off” the batteries. There is some debate amongst battery and battery charger professionals about the benefits and risks of extended float maintenance charging. The major difference between float maintenance charging and absorption charging is that the float voltage is only a few tenths of a volt above the fully charged, rest state voltage of the battery. This is typically 13.2 to 13.6 volts. This voltage range is below the gassing voltage of the battery. The absorption voltage is about 1 volt higher, 14.2 to 15.0 volts. The absorption voltage range is above the gassing voltage of the battery.
Q: What happens if the AC power is removed from the Battery Tender Plus battery charger while it is connected to a fully charged battery?
A: If the battery is fully charged, then the Battery Tender Plus battery charger’s green light will be on. Once the AC power is removed from the Battery Tender Plus battery charger, the green light will go out and the charger will not have any effect on the battery. The Battery Tender Plus battery charger is protected from reverse current, so it will not discharge the battery. Of course, like we said earlier when discussing nominal voltage mismatches between a battery and a charger, the battery will not be recharged either.
When AC power is restored to the Battery Tender Plus battery charger, it will restart its charge cycle. The sequence of events should go something like this. The red light will come on for a few minutes. Then the green light will start flashing while the red light stays on. The next thing that happens is what may confuse some people who use the Battery Tender Plus battery charger. Remember, the battery was fully charged, so you may ask, “Why doesn’t the green light just come right back on?”
The reason that the green light doesn’t come on immediately is that when the charger first comes on, the battery is sitting there, fully charged, at a voltage of about 12.9 volts. The charger immediately tries to bring the battery voltage up to about 14.5 volts. This takes a finite amount of time, although it should only be a few minutes if the battery is fully charged. Then, when the battery reaches 14.5 volts, the charger will hold it there until one of two things happen. Either the battery charge current will drop to less than 0.1 amp (from an initial value of 1.25 amps) or, if the current does not drop below 0.1 amp, then the charger will hold the battery voltage at 14.5 volts for 6 to 8 hours.
There are a couple of reasons why the battery current may not drop below 0.1 amp. First, on a larger battery, like an automotive SLI battery, the internal losses of the battery may consume more than 0.1 amp. Second, if the vehicle or the system that the battery is connected to has appliances that consume electricity, then that consumption of electricity, coupled with the battery internal losses may very likely exceed the 0.1 amp limit. This second cause is very common and its result is that the Battery Tender Plus battery charger’s timer circuits will be fully engaged. So it will take 6 to 8 hours for the green light to come on. Fortunately, the Battery Tender Plus has the ability to continue to supply its full current even after it has switched over to the lower, float, maintenance charge voltage of 13.2 volts. When the charger turns the green light back on, it also drops its output voltage to this float, maintenance charge level of 13.2 volts.
Note: It only takes a momentary AC power outage to cause the Battery Tender Plus battery charger to reset.
Q: What is Temperature Compensation and how important is it?
A: While a battery is being charged, it is important that the charger absorption and float, maintenance voltages closely match the recommendations of the battery manufacturer. The absorption voltage match is important for quick charging. The float, maintenance voltage match is important for long term, storage charging.
Batteries are sensitive to temperature. Recall the number of TV ads showing how tough a battery is when it can start a vehicle in sub-zero temperatures. Cold temperatures tend to reduce a battery’s ability to deliver current to a load. High temperatures not only increase a battery’s ability to deliver current to a load, but also increase a battery’s internal losses. Temperature compensation is a way to change a charger’s output voltage to maintain optimum compatibility with the battery’s charging requirements. The way it works is that the charger senses the ambient temperature. Then it increases the charge voltage when it is cold and decreases the charge voltage when it is hot. Typical values for temperature compensation for a lead acid battery are minus 0.0025 to minus 0.004 volts per degree Centigrade per 2-volt cell. For a 12-volt battery, that would be minus 0.015 volts to minus 0.024 volts per °C. The reference temperature requiring zero charge voltage compensation is 25 °C or 77 °F.
How important is temperature compensation? Like with most everything else about batteries, it depends on the application. For industrial, critical load, standby power applications, where the batteries may be connected to a live charger for a number of years, then temperature compensation can have a significant influence on battery life. In many consumer applications like SLI, deep cycle marine, etc., temperature compensation will increase long-term battery performance, but it is probably not essential in all applications. Where it is most beneficial is in helping to minimize the negative impact of a battery’s self-discharge characteristics in high temperature environments. Deltran Battery Tender Plus Battery Chargers overcome the negative impact of high temperature on battery performance.
The self-discharge rate of a battery is directly dependent upon the ambient temperature of the battery environment. At higher temperatures, the chemical reaction rates that determine self-discharge will also increase.
When a battery sits idle, its self-discharge characteristics will reduce its ability to deliver power on its next use. If the battery either sits long enough, or if the ambient temperature rises high enough, then the battery may become fully discharged. In fact, it is possible for the battery to be over-discharged to the point where it cannot be recovered.
Deltran Battery Tender Plus battery chargers overcome the negative impact of higher ambient temperature and battery self-discharge in two ways. First, the Battery Tender Plus applies a safe, float/maintenance voltage level to the battery to overcome its internal losses and counteract the self-discharge phenomena. Second, the Battery Tender Plus automatically compensates the amplitude of its charge voltages for changes in ambient temperature. It reduces the amplitude of the float/maintenance voltage as the ambient temperature increases and it increases the amplitude of the charge voltages in colder temperatures. In mathematical terms, this type of compensation scheme is called a "Negative Temperature Coefficient".
The temperature compensation ratio employed by the Battery Tender Plus battery chargers is approximately minus 3.67 millivolts per battery cell per degree Centigrade of temperature rise above 25 °C. Stated another way, the output voltage of the Deltran Battery Tender Plus will drop 0.022 volts, or 22 millivolts, for every degree Centigrade temperature rise, when it is connected to a 12-volt battery.
In the event that the temperature would rise enough so that the Battery Tender Plus voltage output drops below what would be considered a normal operating voltage for a 12 volt battery, then the Battery Tender Plus automatically disconnects itself from the battery via an internal solid state mechanism, affording an extra measure of safety in a very high temperature environment.
Q: What is Float / Maintenance Charging? Is it really necessary?
A: Historical Background: Charging batteries in a float/maintenance mode has been standard practice for decades when batteries have been used for standby power applications, such as telecommunications, UPS (Uninterruptible Power Supply), and emergency lighting. Also, the U.S. military has invested literally billions of dollars in developing standby battery charger systems for uses in countless weapon systems: ships, aircraft, ground vehicles, etc. The simple definition of float/maintenance charging is that voltage is continuously applied to the battery terminals. The amplitude of that voltage varies between 0.2 volts and 0.6 volts above the rest state voltage of the battery when it is fully charged. The purpose of continuous float/maintenance mode charging is to maintain the battery in a fully charged condition so that when it is called into service, it will be able to deliver its full charge capacity. Until recently, the most commonly used battery chemistry in sophisticated military weapons systems has been NiCd, rather than lead acid. Nevertheless, the concept of continuous float/maintenance charging has been around for a long time.
In the early 1990’s, engineers and product managers at Deltran corporation successfully applied this same battery charging concept to engine start batteries. The original Battery Tender battery charger was marketed for use in the motorcycle industry. After many years of continued success, the Deltran charger product offering was expanded to include many higher-powered chargers, in different physical packages, both portable and permanently mounted, and with different output charge voltage and output charge current configurations. The Battery Tender Plus is an improved version of the original product. The design is optimized for use with sealed, gas-recombinant, absorbed glass matte, lead acid batteries. It has been on the market since 1999.
Technical Discussion Categories: There are basically 2 categories of technical issues that need to be discussed when debating the merits of float/maintenance charging. 1) What observable characteristics of the battery support and detract from using continuous, float/maintenance charging? 2) What observable characteristics of battery chargers support and detract from using continuous, float/maintenance charging?
1) A. Battery Voltage vs. SOC: In the first category, batteries develop a voltage that indicates how much charge is available for use. The relationship between battery terminal voltage and State Of Charge (SOC) is reasonably linear. For a 12-volt, lead acid battery, that relationship is defined by a 1.5-volt change in terminal voltage that represents the entire SOC range from 0% to 100%. Also, that voltage must be measured when the battery is in a state of rest (the battery terminals are open-circuited), neither being charged nor discharged. A fully charged 12-volt battery will have a terminal voltage of approximately 12.9 volts and a fully discharged (0% SOC) battery will measure 11.4 volts at its terminals. Therefore, a change of 0.15 volts represents a 10% SOC difference.
1) B. Internal Battery Losses: All lead-acid batteries develop and store charge as a result of an internal chemical reaction. There are 2 primary internal loss mechanisms. The first is a result of the chemical interaction between the internal battery elements. That interaction is continuous and it is affected by temperature. It is also affected by whether the battery is being charged, discharged, or in a state of rest. In all 3 situations, the battery terminal voltage will change. In one sense, the battery is never truly in a state of rest, rather, its terminals are connected either to a charger (being charged), or to a load (being discharged) or the battery terminals not connected to anything (the terminals are open-circuited, or in a "state of rest").
The second primary internal loss mechanism is due to the physical interconnections between the chemically interacting elements and the electrically conductive paths to the battery terminals. This second loss mechanism is usually called the internal resistance of the battery. When the battery terminals are open-circuited, that is, not connected to either a battery charger or a load, only the internal chemical losses influence the battery terminal voltage. When the battery is being either charged or discharged, both the chemical losses and the internal battery resistance influence the battery terminal voltage. The simplest battery model for electrical circuit analysis is an ideal battery in series with a resistor. The voltage of the ideal battery is the open circuit voltage that represents SOC. The value of the series resistance is the battery internal resistance, typically measured on a fully charged battery at a frequency of 1000 Hertz. That resistance value is usually in the 5 to 10 milliohm range. More sophisticated battery models account for the fact that the internal resistance is not constant over the range of SOC. Even more sophisticated models include a complex impedance (some combination of resistance, inductance, and capacitance) in parallel with the ideal battery. For example, because of the construction of lead acid batteries, the equivalent electrical capacitance is in the range of several tens of thousands of Farads. For this reason, specifying a ripple component of output voltage on a battery charger when it is connected to a battery is somewhat futile because of the tremendous voltage-filtering characteristic of the battery’s equivalent electrical capacitance.
Since the internal resistance of the battery is very small, its impact on the value of voltage measured at the battery terminals is only significant during high rate (lots of current) discharges and charges. When the battery is being discharged, the battery terminal voltage is less than its open circuit value. Conversely, when the battery is being charged, its terminal voltage is more than its open circuit value. The difference between the voltages is calculated by the product of the charge or discharge current and the internal resistance. In float/maintenance charging situations, the charge current is usually very small, so that the difference between the open circuit voltage and the actual battery terminal voltage is also small.
2) A. Battery Charger Output Voltage vs. AC Line Voltage (Output Voltage Regulation): This one aspect of Power Supply (battery charger) Line Regulation is very important because the output voltage of the battery charger must be in a certain range, and it must not deviate significantly from that range, otherwise a battery can be overcharged, or it can be undercharged. Fortunately, in the United States, the national AC power grid, the AC power distribution system, is very stable. Therefore, battery charger line regulation characteristics have less impact than they would when the AC power, particularly the AC line voltage varies significantly. In general, one could say that the simpler the construction of a battery charger, the more likely it is to have larger percentage line regulation characteristics. The larger the percentage, the more the output voltage will vary with the AC line voltage.
2) B. Battery Charger Output Voltage vs. Temperature (Temperature Compensation): This battery charger characteristic probably has more influence on the battery than line regulation. Even if a battery is kept at its ideal float voltage, and it that ideal voltage is compensated properly for temperature, an increase of only 7 °C to10 °C can cut the battery life in half, assuming that the higher temperature remained for the entire observation period. Short-term fluctuations in temperature have little impact on battery life, unless the temperatures are extreme. In general, cold is good, hot is bad, very cold is better (but too cold can be worse), and very hot is worse. At the extreme cold end, bad things can happen as well, but those bad things are just dramatic reductions in the battery performance. At the extreme hot end, while the battery is charging, it can emit dangerous gasses. The ideal temperature compensation range for lead acid batteries is typically in the range of 2.5 to 4.0 millivolts per 2-volt cell, per degree Centigrade. The temperature compensation coefficient is also negative, meaning that the change in charging voltage is in the opposite sense as the change in temperature. If the temperature goes up, the charging voltage comes down and vice-versa.
Arguments For and Against Continuous Float/Maintenance Charging: From the preliminary background on batteries and chargers, positions can be taken for or against continuous float charging. The main argument against continuous float charging is that the battery will: a) be undercharged, or b) be overcharged, and/or c) be permanently damaged as a result of a) or b). The main argument for continuous float charging one of convenience, in that it is better to have the battery fully charged when you need to use it. An automatic, well-regulated, temperature-compensated charger can keep the battery fully charged and at the same time minimize the risks of long-term damage to the battery due to either under-charging or over-charging. The alternative is to let the battery internal losses run their course, which for most batteries means that they are fully discharged within a few months. If you forget to recharge them periodically, and they become severely over-discharged, even due to only internal losses, the plates will become severely sulfated. For many batteries, that means that they are permanently damaged.
Recommendations for Using the Battery Tender Plus in Continuous Float Mode Charging: The line regulation characteristics of the Battery Tender Plus are excellent; less than 1% for line voltage between 115 VAC and 125 VAC. This charger is temperature compensated and it has a special charging algorithm optimized for sealed, gas-recombinant, AGM, lead acid batteries. Numerous motorcycle owners have reported to Deltran over the years that their batteries have lasted 3 years or more. Before using the Battery Tender charger, they would have to replace their batteries as often as every 6 months.
Cart: 0 items
