What is three-stage charging of lead-acid battery?

1.What is three-stage charging of lead-acid battery?

The charging method of lead-acid battery should be divided into three stages, namely, constant current charging-constant voltage charging-trickle charging.

Constant current charging stage: 1.7A current, charging to 13.4V cut-off.

Constant voltage charging stage: 14.7V (single battery), charging time 3 hours, cut-off current 0.35A A.

Trickle charging stage: 13.9V (single battery), when the charging current is less than 100mA, it is considered fully charged.

2.Why should lead-acid batteries be charged by three-stage charging method?

At the beginning of charging, the battery has a strong acceptance ability, so we can take advantage of this feature. High current charging can make the battery get enough electricity quickly to save time and electricity. When the battery is charged to a certain degree, to prevent the voltage from exceeding the limit value, it should be automatically transferred and limited to a constant voltage value, so as to limit the voltage from continue rising, and prevent the voltage from exceeding the end of charging and damaging the battery plate. But after this charge, due to the inhomogeneity of the materials on the battery plate, some of the materials can’t be completely reduced. If these materials are in sulfide state for a long time, they may become permanent lead sulfate which can no longer be reduced, and the capacity of the battery will be damaged and gradually reduced. Therefore, at the end of charging, trickle charging is needed to reduce a small amount of sulfide hidden in the deep inside as much as possible, make the charging level of the plates in one battery uniform from inside to outside, and the plates of several batteries can be uniform as much as possible.

3.What happens when the charger can't keep constant voltage?

If you use a charger that can't keep constant voltage, the battery will be damaged by charging. Because it can't keep absolutely constant voltage, the voltage will exceeds the specified cut-off charging voltage at the later stage, the plate material overheat ,deform, expand and then fall off, and the electrolyte will be decomposed, water will evaporate, and the concentration will increase, which will further excessively corrode the plate and aggravate vulcanization. Some unqualified chargers, because they can't keep constant voltage, the charge voltage of 36V battery pack exceeds 45V, even reaches 50V. According to regulations, the cut-off charging voltage of 36V battery is 41.4V, and the maximum voltage cannot exceed 43.2V, that is, the voltage of single battery cannot exceed 2.4V.In addition, the charger may lose the constant voltage function during use, thus increasing the charging voltage, which is very unfavorable to the battery life.

4.Why is the charging display abnormal?

After the battery is fully charged, the charger should have a display, usually turning red light into green light, and some are green to yellow, indicating that the battery is basically full. If the LED is not bright or without changing color when the battery is fully charge, the reason is mostly the LED itself or the circuit problem. When some chargers charge a certain battery, the indicator light does not change color for a long time. In this case, the constant voltage value of the charger is too high, which is not match with this battery, a matching charger must be replaced, otherwise, it will cause overcharge, overheating, and cause to battery deformed and expanded.

5.Why can't the battery be fully charged?

The charger works for a period of time and stops automatically without current and voltage, which might be the circuit problem, virtual solder point, poor contact or component failure, etc. It could be normal at normal temperature, but begins to appear when the temperature rises. This phenomenon sometimes appears gradually, sometimes suddenly. The battery can't be charged or not fully charged, which will damage the battery. Check and repair in time to make the charger return to normal.

6.Why do some chargers charged unstable or keep charging?

Charged unstable may belong to the same fault as cannot be fully charged, which is poor line contact.

The charging without automatic stop phenomenon and the unstable constant voltage is the same serious problems, which are much more serious than the above two problems. If you don't pay attention, it may damage the battery.

However, the above phenomenon is not common, and most chargers will not or do not often have similar problems. This kind of charger is not only rare, but also a relatively old one that has been used for many years. The correct way to use the charger is that at the later stage of charging, although most of it has been charged, a small amount of sulfurized substances on the plate are not completely reduced. At this time, let the charger continue to charge for 1-2h to achieve the purpose of complete reduction. When the current is only 50mA or less on the 200mA ammeter of the instrument panel and remains unchanged for a long time, you can unplug the power supply. For those with positive pulse repair function, after unplugging the power supply, it is not necessary to remove the connecting wire between the charger and the battery, so that the pulse can continuously impact the sulfide crystal and realize active material reduction the for the plates.