Xantrex Technology 120 VAC/60 Battery Care And Maintenance, Page 104, Technical Information

TECHNICAL INFORMATION

BATTERY CARE AND MAINTENANCE

If you have read the battery charger mode section of this manual, you already have a good idea of the stages of battery charging that combine to promote fast charging and ensure long battery life. Basically, there are five charger-related considerations to properly care for your batteries.

•Charge Rate - The maximum safe charge rate is related to the size and type of your batteries. Standard vented lead acid batteries (with battery caps) can be charged at a high rate - equal to their capacity. Small batteries may require a lower charge rate. Check with the battery manufacturer. Adjust the MAX CHARGE AMPS AC setting to control the charging rate.

•Bulk Voltage - This is the maximum voltage the batteries reach during the normal charging process. Gel cell batteries are usually set to a lower value, while non-sealed batteries are set to the higher. Adjust the SET BULK VOLTS DC setting to control the battery voltage during the BULK and ABSORPTION stages.

•Float Voltage - The batteries experience less gassing if they are maintained at a lower voltage than the voltage at which they are charged. Adjust the FLOAT VOLTS DC setting to control the battery voltage.

•Temperature Compensation - Temperature affects the optimum voltage values for the bulk and float charging stages. The Battery Temperature Sensor (BTS) automatically fine-tunes these voltages for you.

•Equalization (Non-Sealed Batteries Only) - Many experts recommend that batteries be "equalized" (A fancy term for over-charged) every month or two. However, a leading battery manufacturer recommends equalizing only when low or wide ranging specific gravity (± 0.015) are detected after fully charging a battery. Since the individual battery cells are not exactly identical, some may still have sulfate on their plates after a complete charge cycle. On the other hand, if the batteries never received a full charge, all plates will have sulfate left on them. If the sulfate remains on the plates for an extended period of time, it will harden and seal off a percentage of the plate area, reducing the capacity of the battery. By equalizing the batteries, the entire sulfate is removed from the plates. Additionally, the gassing that result stirs up the electrolyte which tends to stratify. Stratification concentrates the sulfuric acid in the bottom of the cell while the top becomes watery. This corrodes the plates. Equalization is accomplished by charging batteries above a voltage of 2.6 VDC per cell. This is over 15 VDC for a 12 VDC system, 30 for a 24 VDC system and 60 for a 48 VDC system.

Since equalizing is basically overcharging the battery, which can be harmful to battery's life and performance, it is done only when required.

CAUTION: Equalization should be done only with standard electrolyte batteries. If you have sealed or gel cell batteries, check first with the battery manufacturer before equalizing. DC loads should be disconnected before equalization to protect them from damage by the high battery voltage involved.

Table 6, Battery Charging: Charging Setpoints

TYPICAL BULK AND FLOAT SETPOINTS FOR COMMON BATTERY TYPES

Battery Type

Sealed Gel

Lead Acid battery

A.G.M.

Lead Acid battery

Maintenance-Free RV/Marine Lead Calcium Battery

Deep-Cycle, Liquid Electrolyte Lead Antimony Battery

NiCad or NiFe Alkaline Battery* (using 10 cells in series)

Bulk Volts

14.1VDC BULK

14.4VDC BULK

14.4VDC BULK

14.6VDC BULK

16.0VDC BULK

Float Volts

13.6VDC FLOAT

13.4VDC FLOAT

13.4VDC FLOAT

13.4VDC FLOAT

14.5VDC FLOAT

Equalizing Charge Process

Not Recommended - Consult manufacturer

Charge to 15.5 VDC or as per manufacturer

Not Recommended - Consult manufacturer

Charge to 15.8 VDC or as per manufacturer

Consult manufacturer

Note: Values shown are for 12-volt systems. For 24-volt systems, multiply the settings shown by two. For 48-volt systems, multiply the settings shown by four. These settings are guidelines, refer to your battery manufacturer for specific settings.

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 2001 Xantrex Technology, Inc.	Telephone: 360/435-8826	SW Series Inverter/Charger
5916 - 195th Street N. E.	Fax: 360/435-2229	Part No. 2031-5
Arlington, WA 98223	www.traceengineering.com	Rev. C: February 2001