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Choosing a right battery charger is important to lead acid batteries, because a proper battery charger not only protects batteries from overcharging but also prolongs battery life. On the other hand, using a wrong battery charger to charge batteries may result in the following consequences: a too-large battery charger will have negative influences on the battery’s lifespan; a too-small battery charger will require long charging time. So, how should the right battery charger be chosen, the following will help make an appropriate selection.

Charger Category

There are two basic types of battery charger: 2-STAGE and 3-STAGE chargers. The 2-STAGE chargers are developed for frequently/fast charging applications, such as portable equipment, electric scooter, electric motorcycle, etc. The 3-STAGE chargers are for fixed/cyclic charging purposes, suitable for UPS, emergency lighting equipment, etc.

Limit on Battery Charging

A high charging current could damage the battery or shorten its life. As a result, battery manufactures have strict instructions on how high a charging current is allowed. A normal recommendation is that the charge rate should be between 10% and 30% of the battery’s capacity, i.e. a 20 Ah (ampere-hour) battery should be charged by 2 ~ 6A.

Selection

Follow the steps below when selecting a battery charger.

Step 1: Identify the capacity of the battery you need to charge

a.

Battery’s voltage and capacity can be found on the battery label located on the top or side of the battery. (If you are unable to find this information, please contact the manufacturer.)

b.

When multiple batteries are used,Batteries in series: total VBat = NxVBat (volts)

total CPBat = CPBat (Ah)

Batteries in parallel: total VBat = VBat (volts)

total CPBat = NxCPBat (Ah)

(Suppose VBat is battery voltage, CPBat is battery capacity, and N is number of batteries)

Step 2: Identify the charger type you need in your application

a.

For recharging a discharged battery to a normal condition: 2-STAGE charger.

b.

For maintaining a fully charged battery or charging a battery operated along with loads: 3-STAGE charger. (Green-colored region)
Step 3: Check the table
This is MW’s suggestion. It’s highly recommended to consult your battery manufacturer for the limitation of the max charging current.

Stage

Model name

12V

24V

48V

2

GC120-12/24/48

40-100Ah

20-65Ah

10-35Ah

2

GC160-12/24/48

60-160Ah

30-90Ah

15-45Ah

2

GC220-12/24/48

80-200Ah

40-125Ah

20-65Ah

3

PA-120-13/27/54

24-72Ah

14-43Ah

7-22Ah

3

PB-120-13/27/54

24-72Ah

14-43Ah

7-22Ah

3

PB-230-12/24/48

50-160Ah

24-80Ah

12-40Ah

3

PB-300-12/24/48

60-200Ah

30-100Ah

15-50Ah

3

PB-360-12/24/48

80-240Ah

40-125Ah

20-65Ah

2/3

PB-600-12/24/48*

135-400Ah

70-210Ah

35-105Ah

2/3

PB-1000-12/24/48*

200-600Ah

120-350Ah

60-175Ah

*PB-600 and PB-1000 can also be utilized as a 2-STAGE charger.

Example: Two lead-acid batteries in parallel are used in an UPS application, how to choose a suitable charger for charging them?

Specification of the batteries

Battery voltage

12V

Battery capacity

80Ah

1) The voltage is 12V; the capacity is 80×2 = 160Ah.2) 3-STAGE charger is suitable for UPS applications.

3) Referring to the table, PB-230-12/PB-300-12/PB-360-12/
PB-600-12 can be selected for charging these batteries.
And, the larger the charger, the shorter the charging time.

Conclusion

Choosing the right battery charger can ensure that batteries are charged efficiently and accurately. Moreover, the right one can also reduce the charging time without damaging or overcharging them.

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