Charging a car battery

This applies to a car with stop/start facility. That is one that cuts off the engine when stationary and restarts when prepared to move off.

Other "normal" batteries can be charged with this charger as welll on different settings.

These batteries are called AGM batteries and need special battery chargers for them.

Below is a photo of mine on charge with one of thes special chargers

Not over clear I know but taken in my garage. This particular make (one of the best I have to add) can be set for motor bikes ordinary batteries and AGM batteries depending on the press button setting you make

it works of a series of indication lights telling what stage the charging is at. In the picture it is at stage 4 , there are 8 stages of charge

STEP 1 DESULPHATION
Detects sulphated batteries. Pulsing current and voltage, removes sulphate from the lead
plates of the battery restoring the battery capacity.
STEP 2 SOFT START
Tests if the battery can accept charge. This step prevents that charging proceeds with a
defect battery.
STEP 3 BULK
Charging with maximum current until approximately 80% battery capacity.
STEP 4 ABSORPTION
Charging with declining current to maximize up to 100% battery capacity.
STEP 5 ANALYSE
Tests if the battery can hold charge. Batteries that can not hold charge may need to be
replaced.
STEP 6 RECOND
Choose the Recond program to add the Recond step to the charging process. During the
Recond step voltage increases to create controlled gassing in the battery. Gasing mixes the
battery acid and gives back energy to the battery.
STEP 7 FLOAT
Maintaining the battery voltage at maximum level by providing a constant voltage charge.
STEP 8 PULSE
Maintaining the battery at 95–100% capacity. The charger monitors the battery voltage
and gives a pulse when necessary to keep the battery fully charged.


Not by far the cheapest of battery chargers ( this one around £50) but you get what you pay for
With the cold weather keeping a battery fully charged is advisable

Re: Charging a car battery

You shouldn't need a charger.......unless you leave your lights on by mistake.
If your battery is affected by the cold then it's time fir a new battery not a charger.

Re: Charging a car battery

Tpin
Not quite correct ,sorry .

The air con alone has quite a drain on a battery let alone radios lights etc. A battery is 12volts and the alternator only pumps our around 14.4 volts . The difference being only 2.4 volts being put back into the battery via a regulator to stop over charging. That is if the alternator is up to the task. this in turn can easily be checked via a digital meter.

So just by having the aircon on will alone take up at least most of the 2.4 volts that are trying to keep the battery at it maximum. add to that headlights and say a radio and the battery starts to struggle maintaining power.

The above has not even taken in the battery drain on starting as the starter motor again takes a fair wack out of a battery.


So your submission about needing a new battery really doesn't stack up.
I understand your reasoning, a common mistake often made and causing people to buy when a charge is sufficient

This is why it pays to get a charger as I have which gets the
best power usage and life length by charging correctly

Re: Charging a car battery

Not quite correct, 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.
Like Tpin has already stated, if you have to constantly charge your battery with an external charger then you really need to look at purchasing a new battery.

Re: Charging a car battery

How to check an in an alternator is giving the correct volt output. Again very easy.
put a digital meter across the battery terminals and check the volts the battery has (not alway exactly 12 volts). Turn on the engine and the readout
Should go to about 14.4 volts maybe with a little engine on a faster turnover than idle,

if it doesn't then your alternator is knackered but to those not knowing might well put it down to the battery and pay a lot of money just for the new battery to go flat as before

Re: Charging a car battery

I have a CTEK on my BMW because it is not used very often, it's ideal, the connection wires stay permanently on the battery, you just unplug it and go.

Re: Charging a car battery

When batteries fail nowadays I find they seem to go out like a light.

Re: Charging a car battery

Ern no the amp hr of a battery has nothing to do with charging , it only relates to capacity of the battery. Another common mistake often made and can confuse people.
Many overlook that it might be down to alternator failure

Re: Charging a car battery

A Battery Conditioner is not necessary an a vehicle that is used regularly, they are usually used on summer cars and motorbikes.

Re: Charging a car battery

constant stopping and restarting can drain a battery very quickly so a boost to a battery via a charger is sometimes very necessary. This is why short journeys are a pain. Take a car on a long run and the power is restored to the battery. This is ofen why a car runs better after a long trip against a short one.