Car battery charger how long

How Long Should You Charge a Dead Car Battery? | Meineke

Frequent short trips, with constant stopping and starting, make your battery work very hard, especially in winter when heater, headlights, heated windows and wipers may be working most of the time.

Eventually, because more current is being drained from the battery than the alternator can put back, the battery will not have enough power left to turn the starter motor. A battery in that state of discharge is said to be flat.

A flat battery can be avoided if you have a battery charger - a relatively cheap, but worthwhile accessory.

It uses mains current to replace the battery's lost charge through positive and negative leads that clip to the corresponding battery posts.

A typical battery charger, fitted with a charge gauge(ammeter).Clip the red positive(+) charger lead to thepositive (+) terminal.The high andlowcharging-rateswitch.The ammetergauge shows therate of charge.Clip the black negative (-)charger lead to thenegative (-) terminal.Make sure that thecrocodile clips are fixedsecurely and not liableto be knocked off byaccident.If the charging rate is muchmore than 4 amps, take offthe cell caps or coveringtrough to assist the gas toescape.

How to charge a battery

An average car battery has a capacity of around 48 amp hours which means that, fully charged, it delivers 1 amp for 48 hours, 2 amps for 24 hours, 8 amps for 6 hours and so on.

A basic charger usually charges at around 2 amps - and so needs 24 hours to deliver the 48 amps needed to fully charge a flat, 48 amp hour battery.

But there is a wide range of chargers with different charge rates on the market - from 2 to 10 amps. The higher the charge output, the faster a flat battery is recharged. Fast charging, however, is undesirable as it can buckle the battery plates.

The loads imposed on your battery may be gauged from the amount of current used by the various electrical components: headlights take about 8 to 10 amps, a heated rear window about the same.

Theoretically, a fully charged battery, without taking in current from the generator, should work the starter for about ten minutes, or the headlights for eight hours, and a heated rear window for 12 hours. As the battery nears full discharge, the lights gradually grow dimmer and finally go out altogether.

There are also causes other than short trips and cold weather which can affect the state of your battery. Failure is more common on cars equipped with a dynamo rather than an alternator, because the alternator produces more electricity and charges better at low engine speeds (See How the charging system works).

The answer in all these cases is frequent testing with a hydrometer (See Checking the batteries) to see how much capacity is left in the battery, and using a battery charger to top up its charge when necessary.

Connecting a battery charger

Some batteries have a one-piece cell-cap cover fitting in a central trough.

Always check the electrolyte level before connecting the battery to the charger. Top up if necessary (See Checking the batteries) and clean the battery posts.

If there is a power point handy, the battery can be left in the car, so long as the charge rate is only 3 or 4 amps.

However, if the car has an alternator, disconnect the battery terminals beforehand: otherwise some alternators - generally the older type - can be damaged.

Midland Midland GXT1000VP4 36-Mile 50-Channel FRS/GMRS Two-Way Radio (Pair) (Black/Silver)
Wireless (Midland)
  • 50 Channels with Up to 36-Mile range communication in open areas with little or no obstruction,120V Charger.
  • NOAA/All Hazard Weather Channels with Alert and Weather Scan
  • 142 Privacy Codes,Frequency Band: 462.550 - 467.7125MHz
  • Vibrate Alert. 9 Levels of VOX for Hands Free Operation
Motorola Motorola MH230R 23-Mile Range 22-Channel FRS/GMRS Two-Way Radio (Pair)
Speakers (Motorola)
  • 10-hour alkaline or 8-hour rechargeable battery life
  • 11 weather channels (7 NOAA) with alert features
  • 22 channels each with 121 privacy codes for superior interference protection
  • Pair of two-way radios with up to 23 mile range
  • Includes: 2 radios, 2 belt clips, 1 dual drop-in charger, 1 charging adaptor, 2 NiMH rechargeable battery packs, Available in yellow
Fisher Price Power Wheels 6-Volt Rechargeable Replacement Battery
Toy (Fisher Price)
  • 6V 9.5 Amp/Hr rechargeable battery;Built-in thermal fuse included ;Ford Lil F-150-6V, Power Wheels Lil Dune Racer-6V
  • Refer to the instruction manual for battery specifications on your particular Power Wheels vehicle
  • Use only with approved Power Wheels vehicles that have a 6V 9.5 Amp/Hr battery system
  • Red Power Wheels 6V (9.5 Amp/Hr) rechargeable battery is compatible with all of the following model types: Power Wheels
  • Item is hazmat hence it is non-returnable
Tech Armor Apple Certified Lightning Cable by Tech Armor - 2FT White - Tough-Braided Extra-Strong Jacket - Sync/Charge iPhone & iPad - 2-Year Warranty
Personal Computer (Tech Armor)
  • Compatible Model(s): All USB Lightning Charged Small Electronics [Apple iPhone 6 / 6S / 5 / 5C / 5S / SE, Apple iPod Touch (Gen 5), Apple iPad Air / Air 2 / Pro...
  • WHAT ARE TECH ARMOR BRAIDED LIGHTNING CABLES . Tech Armor Braided Lightning Cables are made with highest quality components, including nitrogen injected, skin...
  • HOW DO TECH ARMOR BRAIDED LIGHTNING CABLES WORK . Never contend with tangled chords again. Braided Lightning Cable Jackets are mess and no stress anti tangle material...
  • WHY BUY TECH ARMOR BRAIDED LIGHTNING CABLES . Tech Armor is THE trusted online resource for screen protection. If you only accept the BEST to protect your iphone...
  • Backed by Tech Armor No Hassle Replacements. (PLEASE CONTINUE READING BELOW)
Tactical Flashlight Torch - 18650 Battery and Charger Included, Outlite E6 High-Powered LED Flash Light, Rechargeable Tac Light, Water Resistant Handheld Flashlight, Zoomable and 5 Modes
Home Improvement (outlite)
  • LONG LASTING: Energy-efficient high-powered rechargeable flashlight is environment-friendly and cost-efficient. LED torch bulbs last more than 100, hours. 100% satisfaction...
  • 5 LIGHT MODES: Adjustable focus flashlight range for different usage, stretching to adjust 5 Modes, high brightness; Medium brightness; low brightness; Strobe (intermittent...
  • PORTABLE USE: Handheld flash light is small enough to fit into your pocket size, handbag, or car compartment, so you can take it wherever, whenever.
  • RECHARGEABLE:The tactical strobe flashlight is powered by 1pc 18650 Lithium-ion Battery with built-in protection (included) or 3pcs Battery (not included). A bonus...
  • HIGH-POWER: Outlite tactical flashlight is made from air-craft Grade light aluminum and can withstand extremes of temperatures, from freezing to boiling. This waterproof...

Related posts: