Lead-acid is the oldest rechargeable battery in existence. It has retained a market share in applications where newer battery chemistries would either be too expensive or the upkeep would be too demanding. There are simply no cost-effective alternatives for such applications as wheelchairs, scooters, golf carts, people movers and UPS systems.

Lead-acid does not lend itself to fast charging. Typical charge time is 8 to 16 hours. The battery must always be stored in a charged state. Leaving the battery in a discharged condition causes sulfation, a condition that makes the battery difficult, if not impossible, to recharge.

 

Unlike nickel-cadmium, the lead-acid does not like deep cycling. A full discharge causes extra strain and each cycle robs the battery of a small amount of capacity. This wear-down characteristic also applies to other battery chemistries in varying degrees. To prevent the battery from being stressed through repetitive deep discharge, a larger battery is recommended.

 

Finding the ideal charge voltage limit is critical. Any voltage level is a compromise. A high voltage limit (above 2.40V/cell) produces good battery performance but shortens the service life due to grid corrosion on the positive plate. The corrosion is permanent. A low voltage (below 2.40V/cell) is safe if charged at a higher temperature but is subject to sulfation on the negative plate.

 

Lead-acid is not subject to memory. Leaving the battery on float charge for a prolonged time does not cause damage. The self-discharge is about 40% per year, one of the best on rechargeable batteries. In comparison, nickel-cadmium self-discharges this amount in three months. Lead-acid is relatively inexpensive to purchase but the operational costs can be more expensive than the nickel-cadmium if full cycles are required on a repetitive basis.

 

The sealed lead-acid battery is rated at a 5-hour discharge or 0.2C. Some batteries are rated at a slow 20-hour discharge. Longer discharge times produce higher capacity readings. The lead-acid performs well on high load currents. During these pulses, discharge rates well in excess of 1C can be drawn.

 

Depending on the depth of discharge and operating temperature, the sealed lead-acid provides 200 to 300 discharge/charge cycles. The primary reason for its relatively short cycle life is grid corrosion of the positive electrode, depletion of the active material and expansion of the positive plates. These changes are most prevalent at higher operating temperatures. Cycling does not prevent or reverse the trend.

 

The optimum operating temperature for the lead-acid battery is 25°C (77°F). As a guideline, every 8°C (15°F) rise in temperature will cut the battery life in half. VRLA, which would last for 10 years at 25°C (77°F), will only be good for 5 years if operated at 33°C (95°F). Theoretically the same battery would endure a little more than one year at a desert temperature of 42°C (107°F).

 

Among modern rechargeable batteries, the lead-acid battery family has the lowest energy density, making it unsuitable for handheld devices that demand compact size. In addition, performance at low temperatures is poor.

 

Invented by the French physician Gaston Planté in 1859, lead-acid was the first rechargeable battery for commercial use. Today, the flooded lead-acid battery holds a domineering position in automobiles, forklifts and large uninterruptible power supply (UPS) systems.

 

During the mid 1970s, researchers developed a maintenance-free lead-acid battery that could operate in any position. The liquid electrolyte was transformed into moistened separators and the enclosure was sealed. Safety valves were added to allow venting of gas during charge and discharge.

 

Driven by different market needs, two lead-acid systems emerged: the small sealed lead-acid (SLA), also known under the brand name of Gelcell, and the large valve-regulated-lead-acid (VRLA). Technically, both batteries are the same. (Engineers may argue that the word 'sealed lead acid' is a misnomer because no rechargeable battery can be totally sealed.)

 

Unlike the flooded lead acid battery, both SLA and VRLA are designed with a low over-voltage potential to prohibit the battery from reaching its gas-generating potential during charge. Excess charging would cause gassing and water depletion. Consequently, these batteries can never be charged to their full potential.

 

In terms of disposal, the lead-acid is less harmful than nickel-cadmium but the high lead content and the electrolyte make the lead-acid environmentally unfriendly.

1. My battery was manufactured by China Battery Company. You don't carry this brand. Can I use a replacement manufactured by another company?
Yes, you may use a substitute as long as the voltage and dimensions are the same. The capacity rating (shown in "ah") may be slightly higher or lower than the original. This is fine and should not affect the unit. There are hundreds of battery manufacturers and many batteries are interchangeable. If you are in doubt, contact our staff.

2. My application calls for the battery to be inserted on its' side. Can this be done with sealed lead acid batteries?
Yes. The batteries can be installed in any orientation.

 

3.Do I need to drain my SLA battery to prevent memory effect?
No. Sealed lead acid batteries do not suffer from memory effect. Draining the battery may result in damage.

4. Do I need to add water to my battery?
No. Sealed lead acid batteries do not require the use of water.

5.What might have caused my battery to fail?
It may have been under-charged or over-charged. Check your charging device periodically to ensure it is working properly. Also, make certain you are using the right chemistry for your application.

 

6. What determines the life of an SLA battery?
Sealed lead acid battery life is determined by many factors. These include temperature, depth and rate of discharge, and the number of charges and discharges(called cycles).

 

7.Can my battery be shipped by air?
Yes. Most sealed lead acid batteries are declared non-hazardous for air shipping. Some exceptions apply.

 

8. I hear lots of talk about float and cycle applications. What is the difference?
A float application requires the battery to be on constant charge with an occasional discharge. Cycle applications charge and discharge the battery on a regular basis.

 

9. What is the difference between a gel cell, an AGM and an SLA battery?
A gel cell or gelled electrolyte is a sealed battery containing semi-solid electrolyte and may also be identified as a sealed lead acid, AGM(absorbed glass mat) or VRLA type battery. AGM batteries are sometimes referred to as starved electrolyte because the fiberglass mat contained within the cell is saturated only 95% with acid and there is no excess liquid. Nearly all AGM batteries are VRLA or valve regulated. VRLA batteries are designed with a valve that allows the battery to keep a slight positive pressure.

 

10. What is a marine or deep cycle battery?
These are actually different types of batteries. The common marine battery is often rated to marine cranking amps. It is designed to offer a quick shot of amperes in a very short time span. These batteries can provide thousands of starts but can usually only withstand 50 or so cycles. A deep cycle battery is designed with the capability of being discharged and charged hundreds of times. Many of these batteries may be totally discharged or drained before they are ever recharged.

 

11.What is the shelf life of an SLA battery?
All sealed lead acid batteries self-discharge. If the capacity loss due to self-discharge is not compensated for by recharging, the battery capacity may become unrecoverable. Temperature also plays a role in determining the shelf life of a battery. Batteries are best stored at 70 degrees F. When batteries are stored in areas where the ambient temperature varies, self-discharge can be greatly increased. Check the batteries every three months or so and charge if necessary.

 

12. I understand that batteries can be put together in series or parallel. What does this mean?
Connecting your batteries in series will generate a higher voltage. The total voltage is the sum of all individual voltages. Connecting the batteries in parallel will increase the capacity or amp hours. When you connect your batteries in a "string" (either in parallel or series) and find a battery that is not charging properly, we suggest that the entire string be replaced.