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Choosing your traction battery and charger Traction batteries - general Choosing your battery Life factors Chargers – general Charging process - general Oxyhydrogen gas – oxygen and hydrogen Topping up Water quality Maintenance Notes


Index ................................................................................................................

1

Choosing your traction battery and charger ...............................................

2

Traction batteries - general .......................................................................... Construction...................................................................................................... Battery size ...................................................................................................... A little battery chemistry .................................................................................. Pause charging................................................................................................. Self-discharge................................................................................................... Cold stores .......................................................................................................

3 3.1 3.1 3.2 3.3 3.4 3.4

Choosing your battery .................................................................................. Standard battery ............................................................................................... Acid circulation battery .................................................................................... CSM (Copper Stretch Metal) battery ................................................................ Construction of a CSM battery ......................................................................... Dryfit battery, VRLA maintenance-free ...........................................................

4 4.1 4.1 4.1 4.2 4.3

Life factors ..................................................................................................... How long does a battery last? .......................................................................... Definition of a cycle ......................................................................................... What affects the life of a battery? ..................................................................... Why is too much current used? ........................................................................ When does a battery sulphate?........................................................................

5 5.1 5.1 5.2 5.2 5.2

Chargers - general ......................................................................................... W charge characteristic .................................................................................... I charge characteristic ...................................................................................... Examples of constant current charging profiles .............................................

6 6.1 6.1 6.2

Charging process - general ..........................................................................

7

Oxyhydrogen gas – oxygen and hydrogen..................................................

8

Topping up ...................................................................................................... Manually ........................................................................................................... Automatically ...................................................................................................

9 9.1 9.2

Water quality ..................................................................................................

10

Maintenance .................................................................................................... Daily ................................................................................................................. Weekly ............................................................................................................. Monthly .............................................................................................................

11 11.1 11.2 11.2

1


Choosing your traction battery and charger The battery is the heart of your truck A healthy heart means good quality of life. An unhealthy heart means poor quality of life. Your doctor gives good advice when he says, “You should use your heart, but not abuse it. You should load your heart, but not overload it.” Replace the word "heart" with the word "battery" and you have some good advice from your battery supplier. Without food and drink, even a genius can’t think Good, sensible dietary habits prolong your life and allow you to be more active. The right current in the right quantities prolongs the life of your battery and allows it to achieve optimal performance throughout its life. Therefore, you should always choose a battery that is big enough for the type of truck and the work for which it is intended. Always use a charger that is correctly dimensioned and gives the battery precisely the right, optimal charge.

Brains and brawn – the right combination of charger and battery makes your life easier

Size (capacity) should not be the only factor that influences your choice of a new battery. The type also plays a very important part in efficient operation and long life.

2


Traction batteries - general Construction A traction battery consists of a number of individual cells, each of 2 volts. For example, a 48volt battery consists of 24 cells connected in series, each with the same capacity (Ah). The cells consist of brown positive filled tubes and grey negative lubricated plates that contain various lead alloys (tubular plate batteries). Unlike starter batteries, which contain positive plates, a truck battery consists of positive tubes. This is because a starter battery has to be able to supply all its current for a short period of time to start a vehicle, while a traction battery has to be able to supply its current over a longer period of time in order to be able to last a full working day. The electrolyte, which causes the electrical tension between the positive and the negative terminals, consists of diluted sulphuric acid. Example A 48-volt/500-Ah battery consists of 24 cells connected in series and enclosed in a painted or Levasint-coated battery case, normally made of iron. Each cell is a 2-volt cell and has a capacity of 500 Ah, which means that, roughly speaking, the battery can supply 100 A nonstop for 5 hours, equivalent to the nominal 5-hour capacity. If, for example, 200 A is consumed per hour, the battery can only operate for around 2 hours and not 2.5 hours, as you might think.

The faster a truck battery’s current is consumed, the lower its useful capacity.

Battery size When a truck works, it consumes current from the battery. The battery is emptied and must then be recharged. We call this discharge and charge process a battery cycle. The more current a piece of work requires, the higher the battery capacity must be unless its lifecycle (life) is reduced. The truck’s battery compartment determines the physical size of the battery. The larger the battery compartment, the more capacity the truck battery can have. The individual cells which make up the battery are therefore produced in many different heights and widths. A large cell volume, which means a lot of active material, produces a high battery capacity. GNB Industrial Power, for example, has more than 150 different cell types in its standard range. Above you can see a small selection of different traction cells that can be combined in the thousands of different battery cases designed for all truck types produced worldwide.

3. 1


A little battery chemistry In a new, charged lead/acid tubular plate battery, the plates are "clean", which means that they have been cleaned of acid residue (sulphates), and the acid density is correct, normally 3 1.29 g/cm , also expressed as 1290 g/l. When the battery is being discharged, the lead plates use the free surrounding sulphuric acid to send current out into the system. At the same time, some acid residue remains, the so-called sulphates. The sulphates are deposited on the plates and reduce the area available for the production of current, which finally stops altogether, and the battery is fully discharged and sulphated.

Discharge

Charge

Voltage decreases

Plates sulphate

Density decreases

Plates sulphate

Voltage increases

Sulphates are dissolved

Density increases

Sulphates are dissolved

The plates in a discharged battery are therefore full of acid residue, and the acid density (g/l) has decreased greatly on account of current production. When the battery is then charged, the sulphates are broken down and the acid residue should combine with the very weak acid in the battery. However, the acid residue, which is much heavier than the surrounding liquid, falls to the bottom and is therefore of no benefit to the cleaned plates. So the charger continues with a gassing charge, whereby the current charged is mainly used only to agitate the acid in order to move the heavy acid residue up in the cells and into contact with the somewhat more dilute acid at the top of the battery. When the charger shows that it has finished, the plates are clean and the acid is evenly distributed throughout the battery. When a truck battery is in use, current production takes place where there is least resistance and the distance to the surrounding acid is shortest, i.e. the distance from the surface of the plates. As the surfaces sulphate, current production moves further and further into the plates and finally it stops altogether. The battery is charged in the opposite order.

3. 2


Pause charging If a partially discharged standard battery is pause charged, parts of the plates are cleaned and are ready for use. But the clean plates do not have a very strong acid to work with as the heavy acid residue has fallen to the bottom of the cells. This acid residue is not mixed with the dilute acid until the gas point is reached and the gassing charge starts. Pause charging is fine if the gas point is not reached but the cleaned plates do not work optimally until the acid has reached its correct density again. Therefore, if pause charging is necessary, choose an acid circulation battery, a CSM (Copper Stretch Metal) battery or a charger with chemical acid agitation.

When can you use pause charging? Situations arise in which a battery does not have enough capacity for a full day's work. In order to avoid discharging it more than 80%, it is necessary to use pause charging. The discharge curves of three batteries are shown below. They can all meet the capacity requirements for the day, but only one of them is handled correctly from the point of view of the battery.

Fully charged

Gassing Charging

80%

80% is the correct depth of discharge

Deep discharged Pause

Pause

All three batteries are fully charged at the start of the day and all three have two breaks during the day. One of them is deep-discharged at the end of the day. This is the green one, which was not pause charged. The red battery is pause charged during the first break of the day, with the result that it gasses before it is disconnected from the charger, because more is charged than is taken out. The blue battery is only pause charged during the second break of the day, when the truck driver is certain that the gas limit cannot be reached. Therefore, with a little care and the correct charger, it can sometimes be useful to use pause charging.

3. 3


Self-discharge In addition to its normal discharge, a traction battery also has a so-called self-discharge. There is consumption in both the positive tubes and the negative plates, which just sulphate on their own. On a daily basis, this is of no significance as the regular charges compensate for this discharge. However, if the battery is stored for a period of time, it is clear that the density will decrease. The self-discharge per month is approximately 5-7% of the battery’s capacity but it depends greatly on the battery's age and the ambient temperature. Consequently, it is recommended that a battery be stored in a cold, dry and frost-free room - always fully charged.

Cold stores When a truck battery is used in a cold environment, its capacity decreases, while the voltage and the density increase. This means that cold store batteries must be slightly bigger than normal and the charger and battery indicator must be adjusted according to the actual average temperature. A normally adjusted charger will not be able to charge a cold battery fully, which causes the battery to be sulphated, meaning the capacity decreases further. A CSM battery with an intelligent charger that can compensate for the temperature is best suited for cold operation.

The effect of the temperature on capacity Acid temperature +30°C

Battery capacity 100%

+20°C

95%

+10°C

90%

0°C

80%

-10°C

70%

-20°C

50%

-30°C

35%

3. 4


Choosing your battery Standard battery The standard lead/acid battery has not changed much since it first came into existence more than 100 years ago. It is the type of battery used most throughout the world and it fully meets the requirements made of a battery designed for normal operating conditions. If, in compliance with the warranty, you use 80% of a battery’s capacity of around 5 operating hours, the equivalent of a normal working day, a standard battery is the correct one to choose. There is no reason to pay for a better or stronger battery if you do not need it.

Acid circulation battery If there is not enough room in the truck for a battery that is big enough for a full day’s work, or if you have less then around 8 hours available for charging, it is often a good idea to choose an acid circulation battery. This is well suited for pause charging and charging in as little as 6 hours. You just have to be aware that, as the battery is too small for the job, it will be exhausted before time. So its life will be somewhat shorter than usual, depending on the level of over-consumption. The advantage of a circulation battery’s “spot charges” is that the heavy acid that normally falls to the bottom is agitated and is immediately sent to the top as a result of the air supply connected to the battery. This type of battery is more expensive than a standard battery and it needs a special charger with an air pump that must be purchased with the battery in most cases. But the alternative would be to buy a replacement battery.

CSM (Copper Stretch Metal) battery Less internal resistance and high, stiff voltage make the CSM battery ideal for hard operation and heavy lifting when you are really in a hurry. The faster current needs to be consumed, the more suitable a CSM battery is. The resistance in a CSM battery’s negative copper grids is 13 times lower than in traditional lead grids, which produces an energy gain of up to 25%. So you get much more energy with the same capacity.

The idea behind the CSM battery The idea behind the CSM battery is based on Ohm’s Law, which basically says that a battery’s voltage loss is equal to current multiplied by internal resistance. The lower the internal resistance, the lower the battery’s voltage loss (heat loss), which now becomes useful energy instead, meaning a longer operating time.

4. 1


CSM batteries and pause charging Due to the low internal resistance of a CSM battery, it supplies and collects current faster, evenly distributed throughout the height and width of the cell. This means that the cell voltage increases faster, with the result that the energy collected during pause charging is higher than for a standard battery. CSM technology was originally developed as a necessity for submarine batteries. Today it has been patented by Exide Technologies. The advantages of CSM batteries are obvious 

Up to 25% more energy and thus a longer operating time than standard batteries.

High constant voltage under hard operation compared with a standard battery, which has a steadily decreasing voltage throughout the course of operation. This decreasing voltage is problematic for the truck’s electronics, which will react by demanding more and more current.

Lower heat generation and thus less damage to the battery throughout its life.

Construction of a CSM battery

1.

Copper Stretch Metal grid

10. Patented terminal

2.

Negative leaded CSM grid

11. Cell cover

3.

Perforated protective casing

12. Flexible screw connection

4.

Separator

13. BFS float

5.

Negative lubricated grid plate

14. BFS plug

6.

Positive lead grid

15. Seal cover

7.

Positive tubular plate

16. Terminal screw

8.

Negative plate assembly, Terminal

17. Gasket

9.

Positive plate assembly, Terminal

4. 2


Dryfit battery – maintenance-free Dryfit batteries are closed, valve-regulated (VRLA), maintenance-free traction batteries with the same dimensions as standard batteries, but the difference is that they have slightly less capacity per volume unit. Moreover, these batteries can only be discharged to around 70%, whereas standard batteries tolerate 80%. This means that the useful capacity of a given truck is much lower than its nominal capacity. So before you choose a Dryfit battery, you must be completely clear about the type of operation for which it will be used and you must know the daily capacity consumption.

The advantages of dryfit 

No topping up with water Saves time and possibly money, as a lack of water shortens a battery’s life.

Lower energy consumption More economical. Less current used for charging as the battery does not require an agitation period.

No acid overflow More economical. No acid in the battery case and on the floor and less cleaning of the battery.

Virtually no gassing Environmentally-friendly. Saves money. Smaller charging room and air extraction.

The disadvantages of dryfit 

Lower discharge depth Less economical as a larger battery is required than for open batteries.

Higher price Less economical as dryfit batteries are generally around 50% more expensive than standard batteries.

4. 3


Life factors How long does a battery last? A battery's life depends entirely on how much it is used every day for however many days it is used. So a battery's life varies from user to user.

A battery’s life in accordance with the IEC 254-1 standard 5-6 years or 1500 cycles in normal operation with one outlet and a discharge depth of max. 80% per day. The life of a dryfit battery is around 1200 cycles, but it may only be discharged to 70-75%.

Definition of a cycle A cycle is a discharge followed by a charge. The more cycles a battery undergoes in a 24-hour period, the shorter its life in terms of time. The best rhythm for a battery is one cycle every 24 hours, which means that the battery must be charged when the day’s work is done and when it has been discharged to max. 80% (dryfit: 70-75%) of its capacity, so that it is fully charged when the next day's work begins.

Over 80% (70-75%) discharge depth constitutes a deep discharge and invalidates the battery warranty.

In principle, pause charging, i.e. an incomplete charge of a partially discharged battery, is a permissible option but it also risks the temperature becoming too high or the gas limit being reached (this counts as 1 cycle). For this reason, pause charging should only be considered if the battery capacity is not sufficient for a full day’s work and you are certain that you will not reach the battery's gas limit.

5. 1


The chart shows the number of cycles a battery contains throughout its life at various discharge depths.

Number of cycles

Discharge depth and life: 80% discharge produces 100% life. 90% discharge produces roughly 75% life.

1500

Discharge depth in%

60%

70%

80%

90%

What affects the life of a battery? Deep discharges: Over-consumption: High temperatures: Overcharging: Undercharging: Maintenance:

Max. 80% depth Max. 80% of capacity Max. 50°C in the acid Burns the battery out Sulphates the battery Incorrect acid level, dirt, faults, etc.

Why is too much current used? Battery too small Driving and lifting at the same time The truck driver thinks he’s a “racing driver” Truck fault (wear, brakes sticking, dirt in wheels) Too much additional equipment Incorrect tyre type, ramp driving, driving surface

When does a battery sulphate? If it is left uncharged If it is not discharged to 80% every now and again, it gets “sluggish” If it is not fully charged If it works at a high temperature If it is topped up with acid The above points are the main reasons why a battery does not last as long as expected. Some of the factors destroy the battery very quickly. Others take slightly longer. However, a common feature of them all is that they can be avoided if you are interested in prolonging your battery’s life.

5. 2


Chargers - general

As it is the battery that keeps the truck going, users often only focus on the battery, ignoring the charger, which is usually regarded as just an expensive but necessary evil. The charger supplies the battery with “fuel�, which, in turn, supplies the truck with energy, just like petrol in a car engine, and who would put 92 Octane fuel in a 98 Octane engine? Incorrectly charging a battery will simply destroy the battery bit by bit, or possibly even very quickly. So it is very important to be quite clear what performance you require of your battery pack now and in the future. Hard operation or normal operation? How much time do you have available for charging? Do you work for a few hours a day or around the clock? These questions should be answered before you buy a charger.

6. 1


Charging process W-characteristic

Two types of charger are available today, “W” constant-effect-chargers and “I” constantcurrent- chargers.

W charge characteristic A constant-effect-charger generally produces the same effect (W) throughout the charging process, which produces a decreasing current characteristic. This means that, as the battery voltage increases, the current decreases until the voltage reaches the gas limit of roughly 2.4 volts per cell (V/c), at which point water begins to divide into oxygen and hydrogen. The current then decreases to roughly 25% of the charger’s rated current value, after which it stabilises until the charging has been completed. This phase is called the gas phase. When the battery is fully charged, the charger stops. Most chargers will then start a maintenance charge which may be either constant current or current pulses that maintain the battery’s voltage level.

Charging process IUI-characteristic

I charge characteristic A constant-current-charger produces the charger’s rated current throughout the bulk charging process until the gas limit of roughly 2.4 V/c has been reached. The charge characteristic varies somewhat after this, depending on battery type. In the graph to the left, the charger continues with constant voltage of 2.4 V/c until the current is so low that the actual gas phase can start.

One of the many advantages of constant-current-chargers is that the battery is generally fully charged when the gas point is reached. This means that the charging time is greatly reduced. These chargers are also based on the microprocessor principle, which means that the charging process is read off continuously and the charging is adjusted in line with the readings. The latest of these chargers are high-frequency (HF) chargers, which cause the battery the least damage.

6. 2


Examples of constant-current-charge curves

2100 HFP high-frequency for open tubular plate batteries - IWa charging profile Constant current until the battery is almost charged. Then decreasing current until the voltage has become constant for a given period of time. 10 min. maintenance charging every 6 hours.

2100 HFP high-frequency for closed dryfit tubular plate batteries - IUIU charging profile Constant current until the voltage reaches 2.35 V/c. Then constant voltage until the current has decreased to 10% of the nominal value. Then constant current until the battery is fully charged. Constant maintenance charging so that the cell voltage does not fall below 2.3 V/c.

The above are just two examples of charging profiles for an open battery and a closed battery. However, the battery suppliers’ prescribed curves may be different so it is a good idea to check the profile for any existing charger if it is subsequently connected to a new battery.

6. 3


Charging process - general Bulk charge The charging time is from when the charger is started until the gas point at approximately 2.4 Volts per cell is reached. A constant-current-charger charges up to 20% more than a standard effect-charger during this phase.

Gassing charge The charging time from when the gas point is reached until the charge is finished varies from charger to charger. Some gas phase times are a percentage of the main charge time and others are controlled by the microprocessor's program.

Maintenance charge When the battery has been fully charged, most chargers continue with some form of maintenance charging to counteract the battery's self-discharge.

Equalising charge Some chargers are programmed to continue charging with a weak current for a number of hours in order to adjust any cells that have too low voltage.

Always remember to switch the charger off or press the pause button each time the battery is disconnected from or connected to the charger If the charging connectors are disconnected live, sparking may occur.

7


Oxyhydrogen gas – oxygen and hydrogen A battery that is disconnected from the charger before the charging process is finished will usually emit gas. A battery that is fully charged with the cover closed will take a long time to emit its gases. This means that the air around the battery is full of hydrogen gases that explode on contact with the slightest spark. A battery that explodes will most probably burst the cell covers and expel acid out into the surrounding area. If there is anyone nearby, they will be hit by the acid. In the event of an accident, the acid can be adequately neutralised with plenty of running water, followed by an immediate visit to a hospital accident and emergency department.

NB! Avoid cigarettes, sparks and open flames near the battery

Your eyes are most at risk, so you should always use protective goggles. There must be an eyewash bottle near the charger.

8


Topping up When a battery gases, water disappears and not acid. This means that the acid concentration increases in the remaining liquid and the plates are no longer covered. This causes the battery to “die” very quickly. To avoid this, it is necessary to top up with water occasionally, but only with demineralised water. Water can be added in many different ways, for example: Manually 

A simple water bag with a hose and a gate valve.

A watering can with a standard spout.

A watering can with a self-stopping spout.

An inflatable “HandyFil” with a filling tube and manual water cock.

But never use equipment in which the water can come into contact with metal as otherwise it will immediately be ionised.

AccuPub with LED filling gun Still manual, but the easiest method on the market. The AccuPub consists of a filling trolley that pumps the water out through an optical filling gun. When each cell reaches the correct liquid level, the filling gun automatically shuts off the water supply. Using various spacers, the AccuPub can be used for all cell types. 

No overflow of water or destructive acid.

Always uniform, equal acid level in all cells after each top-up.

Stops topping up itself when the cell is full.

No extra accessories or equipment on the batteries.

Can be used for all makes of battery by just replacing the spacer.

9. 1


Automatically Manual topping up is time-consuming. Therefore, several different automatic systems are available today that can make life easier for the people who look after batteries on a daily basis. Automatic topping up takes place via cell plugs on hoses that are connected to a central, mobile or permanently installed water supply. Automatic topping-up plugs shut off the water when the cells are full.

Indicator cylinder Valve cylinder Water cylinder Gassing cylinder The picture shows

4 cells with the BFSsystem mounted

T cylinder for water connection

The picture shows the structure of a BFS plug All cells in the battery have level-regulating plugs that are connected to each other via plastic hoses. The entire system ends in a quick-acting coupling that must be connected to a suitable water supply. The three known systems available on the market today work in different ways. However, the principle of the plugs and the hose connection is a common feature.

The BFS system The BFS system is the most widely used system. A BFS water trolley or a water container in a high place which can provide a pressure of between 0.3 and 2 bar (min. 3 m height) is required as the water supply source. If you only have a few batteries, the simplest solution is a standard 25litre water container with a hose and a quick-acting coupling. If you need to top up a lot of batteries, you are advised to use a mobile water trolley.

9. 2


The Aqua Jet system The Aqua-Jet system is the fastest topping-up system on the market and works at high pressure. The battery cells are connected by hoses in this system. An external water supply and a pump that can create the right pressure in the tank are also required. When the topping-up tank is full and pressurised, the hose system is connected to it and the battery is ready for use in less than 30 seconds.

The Autofil system The Autofil system also has the battery cells connected by hoses, and has an external toppingup trolley or a wall-mounted box that tops up the battery using negative pressure, unlike the other systems. The Autofil system, which used to be very popular, is in the process of disappearing from the market.

The following applies to all systems: Only top up with demineralised water.

9. 3


Water quality mS - microSiemens Normal tap water is usually around 250 microSiemens. Demineralised water is at 0-5 mS. However, if it is placed in clear containers, its mS value will gradually increase so much that it cannot be used for batteries. This is because of the liberation of salts by bacteria. As a result, it is advisable to use coloured containers or dark rooms if the water is to be stored for an extended period of time. If the water comes into contact with metal, for example taps, pipes or topping-up heads, the water’s value increases to 50-60 mS, which is unacceptable. The water should preferably not exceed 10 mS and must never exceed 20 mS. If you have a lot of batteries and use a lot of water, it may be worth buying your own demineralisation system.

10


Maintenance Prevention is better than cure Make sure at all times that your battery is "in good health". Visible defects and deficiencies must be remedied immediately to avoid subsequent high repair costs which could easily have been avoided. A defective cable will result in unnecessarily high current. Dirty, damp cell covers will result in leak current and drain current from the battery. Acid overflow will reduce the battery's capacity and break down the battery case. Too little liquid in the cells will sulphate and damage the battery. All of the above can be avoided by spending a few minutes a day on the battery. If you check your battery and remedy any faults in time, you will prolong its life. In addition to the battery care mentioned above, there are a few things that must be done every day, every week and every month.

Daily

Morning – When you start work Check that the charger has finished charging the battery. The green light must be on.

Evening – When you stop work Drive the truck close enough to the charger that the battery connector and the charger connector can easily reach each other.

Turn the ignition key and switch off the current. Switch off the charger or press the pause button.

Disconnect the battery connector and the charger connector. Do not pull the cables.

Open the battery cover so that the gases can escape during charging.

Connect the charger connector to the battery connector. Wipe the battery and close the battery cover. Connect the battery connector to the truck and drive off. Switch on the charger if it has a switch.

Check that the charger starts before leaving it. The red light must be on. Some chargers have a yellow light.

11. 1


Maintenance

Weekly

Check (every Friday, for instance) that the acid level is above the lead plates and separators before charging the battery. If the acid level is too low, top it up with demineralised water so that the acid just covers the plates but is no higher. If you charge a battery with an acid level that is too high, the acid will overflow down into the battery case. If this happens too frequently, the battery will require acid adjustment. If you charge a battery with exposed plates, the battery will gradually be ruined. Then check the acid level mid-week after charging when the battery is idle. If the acid level is too low, top it up with demineralised battery water until the acid is 1-2 centimetres above the plates. If you pour too much water into the cells, they will “boil over” the next time the battery is charged. Always use approved demineralised battery water. Check the cell connections, cable terminals and connectors. Any defects must be remedied immediately. Ensure that the cell plugs are closed. Then wash the battery with a brush and hot water and wipe it dry. Use protective goggles.

NB! Top up with water to the correct level after charging has finished.

Monthly

Measure the temperature in the centre cell of the battery when the battery is fully charged and idle. The temperature must not exceed 50°C but will normally be around 30°C. Then measure the density or voltage in the cells and note the maximum and minimum values. If the difference between these values is too great, the battery must undergo an equalising charge to equalise the cells, depending on the age of the battery. The table below shows the relationship between density and voltage. The values increase as the temperature decreases. 30°C is the nominal value.

Temp.

Density

Volt

0°C

1.31

2.15

15°C

1.30

2.14

30°C

1.29

2.13

45°C

1.28

2.12

11. 2


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