Questions answered

The starter cranks more slowly than usual, the headlights and dash lights dim while starting, warning lights come on, and on a frosty morning the engine takes two or three tries to start. These signs are not a diagnosis, but they are a reason to measure the voltage.

The nominal voltage of a lead-acid car battery is 12 V. A fully charged, healthy battery at rest usually reads about 12.6–12.7 V. A noticeably lower figure points to undercharging or wear.

While the engine runs, the alternator charges the battery, and for some time after you stop the voltage looks higher than it really is. You get an honest picture after the car has stood for several hours with all loads switched off.

It is corrosion, which worsens the contact and makes starting harder even when the charge is fine. Clean it off carefully, following your vehicle's manual and wearing gloves. If it quickly comes back or you see leaks, have the battery checked by a specialist.

Charging can release hydrogen, which forms an explosive mixture with air. So charge in a well-ventilated place, away from flames and sparks, and strictly following your charger's manual; done that way, it is quite safe.

Yes, but only following the procedure in your vehicle's manual: different cars have their own connection points and restrictions. Mistakes with polarity or sequence can damage the electronics, so don't start without the manual.

In a dry, cool place with no risk of freezing, on a stable surface, away from children, pets, flames and heaters. Charge the battery before storing it, then check the voltage from time to time and top it up as the manual says.

Some charge is lost naturally, which is self-discharge, and some is drawn by the alarm and other onboard systems. If the battery drains noticeably faster than usual, there may be a parasitic drain, and tracking it down is best left to a specialist.

Warning signs: the battery won't hold a charge even after proper charging, loses voltage quickly while parked, or the case has bulged or cracked. For a final verdict, see a specialist who can test the battery under load.

By the specs in your vehicle's manual: capacity, cold cranking amps, polarity, size and mounting. If the car originally came with a special type of battery, such as AGM or EFB, the replacement is usually of the same type.

The cables simply won't reach the right terminals, and if you do manage to connect them the wrong way round, you can damage fuses and electronics. So when choosing a new battery, check the positions of positive and negative against the old one and the manual.

No. Spent lead batteries with electrolyte are hazardous waste; in Russia they are hazard class II under the Federal Waste Classification Catalogue (FKKO) and must not go in household waste. They are taken to collection points, kept upright in transit. Other countries have their own rules and take-back systems.