Too low capacity. Voltage drops sharply
Battery low
Recharge the battery.
Charging voltage too low
Check voltage regulator, replace if necessary.
Connection terminals loose or oxidized
Clean the terminals and tighten the clamping bolts. Lubricate the terminals with a thin layer of anti-electrolyte grease or petroleum jelly.
Bad connection on «mass» (-) battery-engine-body
Check the connections, lay a new wire if necessary, tighten the bolted connections. Replace rusted bolts with new ones.
Excessive battery self-discharge due to electrolyte contamination
Replace battery.
Battery sulfation
Charge the battery with a small current. If the power remains low after charging, replace the battery.
The battery has served its time. The active mass of the plates precipitated
Replace battery.
Insufficient battery charging while driving
Faulty alternator, voltage regulator or connecting wires
Check alternator and voltage regulator. Repair or replace if necessary.
The ribbed belt is loose. Faulty belt tensioner
Check belt tensioner. Replace ribbed belt if necessary.
Too many current consumers connected to the on-board network
Install a larger battery or install a more powerful alternator.
Low electrolyte level
Overload, evaporation (especially in summer)
Add distilled water to specified level (with a charged battery).
Electrolyte density too low
Low battery
Charge the battery.
The density of the electrolyte in one cell is significantly lower than in the others
Short circuit compartment. Replace battery
The density of the electrolyte in two adjacent compartments is much lower than in the rest
Short circuit in the on-board electrical network
Check the onboard power supply.