– Battery is old and worn out
– Weather is cold that has increased self-discharge rate
– Battery is new but abused
– Car battery suffered from excessive vibrations and bumps on bad roads
– Battery plates are shorted
– Car alternator / generator is bad that caused overcharging, undercharging of battery and damaged it
– Battery suffered from excessive heat while car was overheated
– UPS / Power inverter has got faulty charger that overcharged and damaged the battery
– You topped up flooded or wet cell lead acid batteries with tap water
– Deep discharged the batteries that caused loss of actual capacity
– Your batteries are of poor quality
– If your battery is very old you should consider changing that. Check with the manufacturer or user manual what average life does your batteries offer. If you are near their end of life it’s the time to change them.
– If you live at a place where weather often gets too cold and temperatures goes below zero, expect your car, generator, UPS or power inverter batteries to suffer. They could lose charge if not used for few days. In cold winter days frequently charge them to make sure they got enough charge when you need it.
– You bought new batteries but abused them like deep discharged them, drove your car excessively on rough roads. These things can badly damaged the batteries. Battery plates may go lose and short causing instant death of battery or battery would stop holding charge. You should consider changing such battery.
– Car alternator stops charging battery once it reaches specified voltage. If the alternator is bad, it will overcharge the battery and damage it in no time. Additionally if alternator is giving low voltage that would cause battery to partially charge or do not charge at all. In both cases, fix your car alternator.
– Did your car badly overheated? If it happened, the massive heat could have damaged the battery too. If this unfortunate thing happened to you may need to change the battery too along with other repairs.
– If you are using UPS or a Power inverter and its charger has gone bad like not cutting off charging, charging battery abnormally slow or charging it at very high voltage that could damage even new battery and it would stop giving good backup. Get your UPS or power inverter fixed.
– Never top up your flooded lead acid batteries with tap water. If you were previously then stop now. Minerals present in tap water can get stuck to battery plates and reduce the capacity or cause the batteries to not hold the charge for long period of time. Always use distilled water to top up flooded batteries. Distilled water can be prepared at home or may be bought from shops. It’s not expensive though.
– Never deep discharge any battery. No matter what type of battery it is, lead acid, lithium ion polymer, nickle cadmium etc deep discharging them could damage them with sulfation. Stop using battery once your observe that battery is excessively getting down. Charge that to maintain battery capacity and prolong battery life.
– Did you save money and bought some cheap batteries? Such batteries are made from poor quality lead and can die in no time. These could also fail to hold charge, may have high self-discharge rate or other problems. Invest your money in better quality batteries.