Checking the status of conventional and low maintenance batteries
1. With an insignificant average annual mileage of the car, it is enough to check the specific gravity of the battery electrolyte in order to determine the level of its charge once every three months. The measurement is made using a standard hydrometer. The test results should be compared with the data in the table below. Please note that the standard measurement should be made at 15°C. In this case, for every 10°С of the temperature drop below the reference point, 0.007 should be subtracted from the electrolyte density reading. The temperature rise for every 10°C above the reference value requires the addition of the same value to the measurement result (0.007).
Ambient temperature above 25°C | Ambient temperature below 25°C |
Battery fully charged | |
1.210÷1.230 | 1.270÷1.290 |
Battery is 70% charged | |
1.170÷1.190 | 1.230÷1.250 |
Battery low | |
1.050÷1.070 | 1.110÷1.130 |
2. If the battery condition is suspicious, first check the density of the electrolyte in each of its cans. A difference in measurement results greater than 0.040 indicates a drop in the electrolyte level or destruction of the lamellae.
3. If the difference in the specific gravity of the electrolyte in different banks exceeds the specified value, the battery must be replaced. Otherwise, the charge level can be restored (see below in this Section).
Checking the status of maintenance-free batteries
4. If your car is equipped with a maintenance-free sealed type battery, there is no need to regularly add electrolyte to the banks. The battery charge level can be determined by the indicator or voltmeter built into its case.
5. Some vehicles use maintenance-free Delco batteries. Such batteries are equipped with a built-in charge level indicator. The indicator is located on the top surface of the battery case and changes its color depending on the level of charge. The green color of the spot in the viewing window of the indicator indicates a high level of charge. Spot darkening (down to black) indicates the need for charging. The light yellow color of the indicator indicates an excessive decrease in the electrolyte level - in this case, further use of the battery is unacceptable and its replacement is required.
6. If a voltmeter is used to check the charge level, connect it between the battery terminals. Compare the measurement result with the requirements of the Specifications at the beginning of the Chapter. The readings taken can be considered reliable only if the measurement was made at least 5 hours after the last charge. Otherwise, you should turn on the headlights of the car for about 30 seconds, then wait another five minutes, and only then start taking readings (don't forget to turn off the headlights). All other onboard electrical consumers must also be turned off during the test (make sure that all car doors, including the tailgate, are tightly closed).
7. If the measurement result is below 12.2V, then the battery is low. The range from 12.2 V to 12.4 V corresponds to the normal battery level.
8. If you need to charge the battery, remove it from the vehicle (see Section Removing and installing the battery) and proceed in accordance with the instructions set out below in this Section.
Charging traditional and low maintenance batteries
Note. The information below should be taken as a general guide to action only. Be sure to read the charger manufacturer's instructions, as well as the recommendations on the label affixed to the battery case.
1. Charge the battery with a current that is about 10% of the battery capacity. So, the charging current of a 55 Ah battery should be 5.5 A. Continue the charging process until the density of the electrolyte stops changing for at least four hours.
2. Alternatively, a 1.5A slow charge can be performed. In this case, the battery can be left connected to the charger overnight.
3. The compilers of this Guide do not recommend resorting to quick methods of restoring the battery charge level in 1 ÷ 2 hours - this practice is fraught with serious damage to the lamellas as a result of their overheating.
4. When charging the battery, make sure that the temperature of the electrolyte does not rise above 37.8°C.
Charging maintenance-free batteries
Note. The information below should be taken as a general guide to action only. Be sure to read the charger manufacturer's instructions, as well as the recommendations on the label affixed to the battery case.
1. Full recovery of the charge level of such batteries takes a little longer than the norms accepted for standard type batteries. In particularly difficult cases, charging can last up to three days.
2. Prepare the DC charger. Set the output voltage of the power supply to a value of 13.9 ÷ 14.9 V. The charge current should not exceed 25 A. With this method of charging, the battery charge level should be restored to a weak (12.5 V) in approximately three hours. Fully charging the battery, as mentioned above, can take much longer.
3. When recovering a completely discharged battery (with output voltage below 12.2V) charging correctly will be entrusted to car service specialists.
Checking the electrolyte level
Warning! The electrolyte inside the battery is a sulfuric acid solution. Perform all work with rubber gloves. When adjusting the electrolyte level, make sure that it does not overflow through the holes in the jars. Wash off spilled electrolyte immediately with clean water. Upon completion of work, rinse the entire battery case with water. Never attempt to pump excess electrolyte out of the jars.
1. Standard models include batteries that do not need to check the electrolyte level. During the operation of the car, the battery may be replaced with a traditional one.
2. Batteries in need of checking and adjusting the electrolyte level can always be distinguished by the presence of removable covers on the upper planes of the cans. The battery case is usually made of translucent plastic, so the electrolyte level can be easily assessed visually -
minimum and maximum level labels. Before attempting to adjust the electrolyte level, make sure that the battery is not of the maintenance-free type (on the case of such batteries there is usually an inscription like Freedom or Maintenance-Free).
3. Check the electrolyte level through the holes of the jars (having removed the covers), or by marks on translucent walls. The electrolyte must completely hide the lamellae. If necessary, make adjustments by topping up the jars with distilled (non-ionized) water. Replace the covers and rinse the battery case with water.