Technical Support: common fault detection and treatment for lead-acid
storage battery
Section 1 Detection Procedure for Lead-acid Storage Battery
Inspection of Lead-acid Storage Battery
(1) Outlook inspection: distortion, damage, leakage and contamination
(2) Voltage inspection: measure the total voltage first, and then the voltage of a single battery; inspect whether the connection is in good conditions. If the connection is loosened, please have them well welded. If the voltage of a single battery is found abnormal, the battery should be analyzed for any fault, and the fault found should be settled.
(3) Inspection of the battery safety valve: open the cover first to check whether there are abnormal phenomena, e.g. acid liquor, around the safety valve; open the safety valve with tools and inspect whether there is adhesion, loosening, damage or other phenomena.
(4) Interior inspection of battery: major inspection items include: ①. electrolyte: observe with eyes the dryness & humidity of electrolyte inside the battery, and test the humidity with a wood stick; ②measure the voltage per cell to further judge whether there is short circuit or open circuit; the voltage per cell can be measured by touching the internal bus bar inside the battery with the probe of a multimeter.
(5) Air-tightness inspection for battery: inflate the battery with the barometer device of a hemomanometer to pressure between 30-40Kpa, and observe whether the barometer pressure is stable; or the battery can be inspected in water as well.
(6) Capacity inspection (as per the state standard): discharge the fully-charged battery at the standard hourly rate; the voltage should be 10.50V per battery when discharging is over; during the electric discharge, temperature should be measured and converted. Check whether the capacity reaches the required standard. If not, the battery should be judged as faulted.
Section 2 Common Faults with Lead-acid Storage Battery
1. Battery Leakage
Common phenomena of battery leakage:
① It may be caused by bad sealing between the top cover and the bottom slot, collision or cracking of sealing compound; ②caused by acid liquor leakage from the safety valve; ③caused by acid liquor leakage from the terminal; ④acid liquor from other parts.
Inspection and treatment methods:
Observe the outlook first and find the leaking part. Open the cover and observe whether there is leaking mark around the safety valve; then open the safety valve and inspect whether there is flowing electrolyte inside the battery. If no abnormality is found after the above work is completed, do the air-tightness test (inflate the battery in water and observe whether there is bubble emerging; if bubble emerges, it means there is leakage of acid liquor). Finally, during the battery charging, observe whether there is flowing electrolyte caused; if so, it means it is the cause of leakage. The flowing electrolyte should be exhausted during the battery discharge.
2. Distortion
Fault phenomenon
Battery distortion is not caused suddenly. It is always a process. The battery will enter the high-voltage charging range when it is charged to reach 80% of its capacity. At this moment, oxygen evolves from the anode, reaches the cathode through holes in the baffle, and has the hydrogen and oxygen compound reaction on the cathode:
2Pb+O2+H2=2PbO+H2O+ (other reactions)
PbO+H2SO4=PbSO4+H2O+ (other reactions)
Heat will be generated during the reaction. When the charging capacity reaches 90%, the speed of oxygen generation will increase and hydrogen will be generated at the cathode. Large amount of gas generated makes the internal pressure of battery beyond the pressure to open the valve, so the safety valve will be opened and gas will escape and the battery will finally show loss of water.
2H2O=2H2+O2
As the times of battery circulating increases, moisture will decrease gradually and the battery will result in the following cases finally:
(1) The oxygen “passage” becomes smooth and oxygen generated at the anode will pass the “passage” easily to reach the cathode.
(2) The thermal capacity will be reduced. In the battery, water has the largest thermal capacity. After loss of water, the thermal capacity of battery will be reduced greatly and heat generated will make the battery temperature rise rapidly.
(3) As the superfine glass fiber baffle in the battery shrinks after loss of water, its adherence to the anode or cathode becomes weaker, the internal resistance between them increases, and heat generated during charging and discharging increases as well. After the above process, heat generated inside the battery can only be radiated from the battery slot. If heat radiated is less than heat generated, the temperature will rise, the gassing overpotential of battery will reduce and the gassing amount will increase. Large amount of oxygen at the anode passes the “passage” and reacts at the cathode to give out much heat and make the temperature rise rapidly. Thus, the vicious circulation is formed to cause the “thermal runaway” and distortion.
Fault detection and treatment
If a group of batteries (3) are distorted at the same time, inspect the voltage first. If the voltage is normal basically, measure the voltage per cell to check whether there is short circuit. If not, it means that distortion is caused by “loss runaway” as a result of over-charging. Charging parameters of the charger should be checked specially. If the charger is free of high-voltage over-charging protection or the trickle conversion current is too low, the charger should be replaced.
3. Short Circuit
Fault phenomenon:
Battery voltage drops by the integer times of 2.
Fault detection and treatment:
Measure the battery voltage per cell with the multimeter. The short-circuited battery will be rejected.
4. Open Circuit
Fault phenomenon:
The battery cannot be charged or discharged.
Fault detection and treatment:
Measure the battery voltage with the multimeter. If the voltage is 0, no sparkle is produced after ignition, and the battery cannot be charged, then open circuit can be confirmed. The open-circuited battery will be rejected.
5. Reverse Polarity
Fault phenomenon;
Negative value is detected when the battery voltage is measured with the multimeter
Fault detection and treatment:
Discharge the battery to 0v and then charge it fully with the maintenance charger.
6. Irreversible Vitriolization
1. Fault Phenomenon
Electrode vitriolization is a common fault for storage battery. Many batteries fail as a result of the fault. Major phenomena of electrode vitriolization are as follows: the voltage rises quickly during charging, gas evolves early, and the temperature rises rapidly; the voltage drops quickly during discharging and the capacity is small.
2. Fault Detection and Treatment
Causes to irreversible vitriolization of electrode are summed up as follows:
(1) The storage period is too long, the self-discharging rate is high, or the battery is not maintained and charged.
(2) The battery is not charged timely after being discharged.
(3) The battery is at the partial state of charge.
(4) The battery is over-discharged.
(5) The battery dries up or the concentration of electrolyte is too high.
When irreversible vitriolization occurs to the battery, the battery should be recovered according to the degree of vitriolization.
In the case of light vitriolizaition, the battery can be recovered through ordinary activated charging (i.e. equalizing charging) as the following details:
Constant-voltage and limited-current charging: in the first phase, with 0.18C2A the battery is charged to 2.7V per cell for 12-24 hours. The first phase of constant-current electricity: with 0.18C2A the battery is charged to 2.4V per cell; the second phase: with 0.05C2A the battery is charged 5-12 hours.
In the case of serious vitriolization, the battery can only be recovered through charging and discharging with the method of “hydrotherapy”. The details are as follows: feed the battery to the rich liquid state with pure water or dilute sulphuric acid at the density of 1.05g/cm3first, then charge the battery with the current of 0.05-0.018C2A for about 20 hours, exhaust the flowing liquid and take the capacity test. Repeat the above operation until the battery capacity is recovered.
7. Failure of a Single Battery
1. Fault Phenomenon
Equilibrium of storage battery in series connection is a global academic difficulty. There is always the “failed” battery in the course of application. There are various reasons to the problem, involving production, raw materials and application, etc.
2. Fault Detection and Treatment
First, the battery will be maintained and charged generally, and then be discharged at the international corresponding hourly rate. During the course of discharging, measure the battery voltage continuously, select the “failed” battery with inadequate capacity and have it treated. Add the dilute sulphuric acid 1.050 until flowing electrolyte just appears, and then keep charging for 12-15 hours. During charging, ensure the battery temperature is not over 50℃. After charging, leave the battery alone for 0.5-4 hours, and then repeat discharging at the hourly rate. During discharging, measure the voltage per cell. If the discharging time fails to reach the standard or the voltage per cell reaches 1.6V, and the discharging time differs greatly from that of the normal cell, the above charging and discharging procedures should be repeated until it is consistent with the requirement.
If the battery capacity doesn’t increase obviously after the circulation of charging and discharging is repeated, there will be short circuit, serious shedding & softening of active substance or serious irreversible vitriolization etc with the battery generally, the battery cannot be recovered and should be rejected. For the battery that is consistent with requirement and can be used, the flowing electrolyte should be exhausted under the charging condition of constant voltage 15V per battery, the battery surface should be wiped up, the cap valve should be installed, and the panel should be bonded well.
8. Shedding of Active Substance
Fault Phenomenon:
The battery electrolyte becomes muddy and reddish brown.
Fault detection and treatment:
Check whether the battery capacity is normal; the battery with inadequate capacity should be rejected.
9. Quick Voltage Drop for the New Battery
1. Fault Phenomenon
The voltage of the new battery drops quickly when it is started
2. Fault Detection and Treatment
Check whether the voltage displayed on the meter is consistent with the battery capacity.
If the relationship between the voltage displayed on the meter and the battery capacity is inconsistent with the above table, the manufacturer should be required to make relevant adjustment.
Check whether the battery wire connection is reliable or whether there is short circuit, etc. Settle any problem found. Check whether the starting and operating current is too large. If so, the current-limiting value of equipment controller should be adjusted, or the equipment should be inspected and repaired.
Check whether the battery capacity is too low. If so, the battery should be charged and discharged.
10. Failure of Battery Charging
1. Fault Phenomenon
First, check whether the connection of the charging circuit is reliable, check whether contact of wires and plugs are intact, check seriously whether there is the phenomenon of “ignition” arc burning with the sockets and plugs, and check whether the circuit is damaged or opened, etc.
Check whether the charger is damaged and whether the charging parameters are consistent with the requirement, i.e. the initial charging current reaches 1.6-2.5A per battery; the maximum charging voltage reaches 14.8-14.9V per battery, the floating charge conversion current reaches 0.3-0.4A per battery, and the floating charge voltage reaches 14.0-14.4V per battery.
Check whether the battery dries up inside, i.e. whether the battery lacks electrolyte seriously.
In addition, check whether there is irreversible vitriolization with the electrode. Vitriolization of electrode can be judged by measuring the terminal voltage variation through charging and discharging. During charging, the battery voltage rises rapidly, and the voltage of some cells is especially high and much higher than the normal value; during discharging, the voltage drops rapidly and the battery doesn’t store electricity or stores a little electricity. Based on the above cases, it can be confirmed that irreversible vitriolization occurs to the battery.
2. Fault Detection and Treatment
First, have the charging circuit be connected firmly. Replace the abnormal charger. Feed the dried battery with pure water or sulfuric acid 1.050, and charge and discharge the battery to recover the battery capacity. If irreversible vitriolization is found, equalizing charging should be carried out to restore the capacity. For maintenance charging after feeding liquid to the dried battery, the maximum current should be controlled to be 1.8A and the battery should be charged for 10-15 hours. The voltage of three batteries had better be kept above 13.4V per battery. If the voltage difference between batteries is over 0.3V, it means that non-synchronous irreversible vitriolization has occurred to the battery. For the battery with irreversible vitriolization, the whole batteries should be replaced or activated.
11. Detection and treatment of the fault that the battery is burned once charged
For detection of the fault, first check whether the battery connection is correct and whether there is reverse polarity; in addition, observe whether poles of the battery charging socket are connected reversely and whether the charger poles are connected reversely, which will cause pole conversion after over-discharging. Then check whether there is short circuit with the battery charging socket or connection wires. The reverse-pole short circuit should be eliminated. For reverse polarity with the charged battery, the battery should be discharged first, then maintained, and charged for 15 -18h with the charger continuously. After the battery voltage is restored to the normal, repeat the discharging inspection for 2-3 times. The battery can be used after the capacity is restored to the normal. The battery with inadequate capacity should be rejected.
12. Detection and treatment of the fault that the electric bike battery fails to store electricity when left alone for a period
(1) First check whether the bike or the power user is turned off, whether the controller meter etc is still at the working state, and whether there is small current discharged (about 30mA-150mA). As a result, the battery will be discharged completely or over-discharged within 1-4 weeks.
(2) Check whether the power source section of equipment is provided with good insulation: for the inspection, have the milli-ampere shift of milliammeter/multi-meter be connected with the battery circuit in series, and then disconnect the switch to see whether there is micro current passing.
(3) Check whether the terminal voltage of battery is consistent and whether there is fault of over-large self-discharging with the self-discharging performance of battery.
(4) When it is stored, the battery should be charged once within 3 months, and the ordinary battery should be charged once every six months to prevent its performance from being affected by self-discharging.
13. Detection and treatment of the fault that the battery fails to be charged
(1) First, check whether the connection of the charging circuit is reliable, check whether contact of wires and plugs are intact, check seriously whether there is the phenomenon of “ignition” arc burning with the sockets and plugs, and check whether the circuit is damaged or opened, etc.
(2) Check whether the charger is damaged and whether the charging parameters are consistent with the requirement.
(3) Finally check whether the battery dries up inside, i.e. whether the battery lacks electrolyte seriously.
(4) In addition, check whether there is irreversible vitriolization with the electrode. Vitriolization of electrode can be judged by measuring the terminal voltage variation through charging and discharging. During charging, the battery voltage rises rapidly, and the voltage of some cells are especially high and much higher than the normal value; during discharging, the voltage drops rapidly and the battery doesn’t store electricity or stores a little electricity. Based on the above cases, it can be confirmed that irreversible vitriolization occurs to the battery.
(5) First, have the charging circuit be connected firmly. Replace the abnormal charger. Feed the dried battery with pure water or sulfuric acid 1.050, and charge and discharge the battery. If irreversible vitriolization is found, equalizing charging should be carried out to restore the capacity. For maintenance charging after feeding liquid to the dried battery, the maximum current should be controlled to be 1.8A and the battery should be charged for 10-15 hours. The voltage of three batteries had better be kept above 13.4V per battery. If the voltage difference between batteries is large, the battery should be discharged to the final voltage before the maintenance charging discharging is carried out. After the battery with irreversible vitriolization is fed with electrolyte (just when the flowing electrolyte appears), it should be charged with the current of 0.05-0.15C2A for about 20h, and then discharged with the current of 1.5A. The final voltage of discharging is 10.5V per battery. Repeat the above operation 1-3 times until irreversible vitriolization is eliminated and the battery capacity is restored to the normal. Then the battery can be used repeatedly after the flowing electrolyte is exhausted and the cap valve etc is installed.
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