Frequently asked questions (FAQ)

1. What’s the capacity of the battery?

A: The capacity of the VRLA battery means that when the battery is full charged and discharge at some condition to the stated end voltage, the capacity is released out, the unit is Ah. For example, when the battery discharges at 1A current for 1 hour, that’s the 1Ah capacity. If the battery discharge at 4A current for 3 hours to the end voltage, the released capacity is 12Ah.

2. What is EPV(Cut-Off Voltage/End Point Voltage)?

A:EPV is the battery end load voltage in the condition of discharge. Many kinds of standards rule EPV definitely in different discharge rates and temperatures. EPV is different according to different discharge rates: it is low when discharge in high current, contrarily, it is high when discharge in low current.

3. What is the self-discharge rate of batteries?

A: The self-discharge, also known as charge retention capacity, that means when it is in open circuit state, the maintain ability of battery’s storage electricity under certain environmental conditions. During storage time, the rate of capacity loss is called self-discharge rate. It is mainly affected by the manufacture technology, materials, storage conditions and other factors, which is an important parameter to measure the lead-acid battery’s performance.

4. What is discharge hour rate?

A:Discharge hour rate is mean the discharge capacity will decrease according to increase of discharge current under condition that the active substance quantity keep unchange. So the discharge rate should be specified when scale the discharge capacity. Discharge rate include hour rate and current rate. Hour rate(time rate) is the needful time when finished discharge the capacity under a definited current, different VRLA battery have different discharge rate standard; Current rate is also named as double rate, it is meaning that discharge current is the double rate of rating capacity

5. Why the batteries need to be stored for a certain time before delivery?

A: The storage capability is an important parameter for checking the stability of general capability. After a certainperiod storage, the variety of capacity and inner resistance is allowed. And the storage can level off the electrochemistry performance of inner component, so that we can know the extent of self-discharge capability, then pick out the deep cycle batteries with short circuit (caused by fast dropping of OCV) and micro short circuit, so the battery quality can be ensured.

6. What causes battery heat during charging?

A: During the battery charging, a large portion of electrical energy transform to chemical energy, balance energy transform to heat energy and others. Charging battery with heat is a normal phenomenon, but if the surface temperature of the batteries is too high, it should be timely checked the battery charging current and see if it is over the standard or if the internal short-circuit happens.

Amount of heat is little related to electrolyte. If the sealed lead acid battery electrolyte is lower, then the internal resistance will increase and cause warming, leading to the high battery terminal voltage while charging. Cell aging, dry electrolyte, internal short-circuit and so on may also result to battery fever. Chargers cannot be in constant voltage charging while late charging time, it will cause the battery voltage exceeds the allowable values, the battery temperature will rise, even cause the battery bulging and end the battery service life.

7. How can the conversion be made between “watts (W)” and “amp hours (Ah)”?

A: W=I x V = 4I (15 minute rate) = 2CV = 2V

(Ex. SHR1235W = 35/4 = 8.75Ah)

8. What are the concerns when using VRLA batteries in a parallel or a serial series?


  1. Do not mix brands, models and date codes?
  2. No separate discharge then charging in a serial configuration.
  3. Under parallel usage, pay close attention to the differences in voltage in each circuit. 
  4. If the difference in voltage in each circuit is too high, do not charge/discharge as parallel. 
  5. The environment of all circuits must be similar.

9. What is the effect of “floating charge voltage” in relation to battery life?

10. Thermal runaway will happen if a battery is operated under 40-50°C for a long period. How will thermal runaway effect a battery?

A: Thermal runaway in a battery will cause excessive heat generation, battery swelling and result in a dangerous condition. SNB does not recommend the use of our batteries for a long time under a 40° – 50° C (104° – 122°F) environment. The battery should not be used close to a heat source or in a high-temperature application.

11. If a battery fails, what will be the indications?


  1. Lower performance
  2. Low voltage
  3. Cannot charge/recharge
  4. Swelled container
  5. Acid corrosion