Correct Way to charge a battery (on-car)

[JC1818]

I remember reading somewhere that you should not charge the battery by simply connecting to the battery terminals as modern cars, inc the V70, have some form of sensor located before the battery, which monitors *something*.

If you connect to the terminals, it bypasses this monitor, thus giving a false reading to the monitoring sensor thing.


If this is the case, what is the correct way to charge a battery, on-car? Or am I talking rubbish?

[Splodger]

good question, was told when jump starting the car to not put both leads direct to the battery. only put the positive on the direct to battery and neutral to the engine mount...worked but weather that is correct I don't know.

[Clan]

Originally Posted by JC1818

I remember reading somewhere that you should not charge the battery by simply connecting to the battery terminals as modern cars, inc the V70, have some form of sensor located before the battery, which monitors *something*.

If you connect to the terminals, it bypasses this monitor, thus giving a false reading to the monitoring sensor thing.


If this is the case, what is the correct way to charge a battery, on-car? Or am I talking rubbish?

You have the right idea , Battery monitors came in after 2010 , in which case connect the red+ clamp to the Battery + terminal and the Black Negative - clamp to the cars body or engine .

[GrantA]

Originally Posted by Clan

You have the right idea , Battery monitors came in after 2010 , in which case connect the red+ clamp to the Battery + terminal and the Black Negative - clamp to the cars body or engine .

Hi Clan, I have one of the C-Tek chargers that I usually use during the winter if the car is left outside for a few days. I normally plug it into the 12V socket in the boot but are you saying on my 2009 (2008 MY) XC70 I could clip it straight onto the battery terminals as my car doesn't have a "Battery monitor"??

[JC1818]

Just read in the owners manual (the one in the car) +ive to battery +ive and -ve from charger to car chassis.

It expressly says not to use -ve battery terminal, something about the infotainment system going all mental otherwise..

[Clan]

Originally Posted by GrantA

Hi Clan, I have one of the C-Tek chargers that I usually use during the winter if the car is left outside for a few days. I normally plug it into the 12V socket in the boot but are you saying on my 2009 (2008 MY) XC70 I could clip it straight onto the battery terminals as my car doesn't have a "Battery monitor"??

Yes straight on the battery if you do not have a monitor that's the usual method ..

[OldEngineer]

If you disconnect the battery earth there is no circuit in the car and you are clear to charge.

Jump leads are a difficult system. You are connecting a remote charged car to your (dead) delicate electronic systems. With both cars off and keys out I move between the cars in a clockwise direction by; Red to dead car positive, Red to live car positive, Black to live car engine block and finally Black to dead car engine block. Then do nothing for 5 minutes until both are settled. Then start the live car followed by the dead car.

[Tannaton]

Originally Posted by OldEngineer

If you disconnect the battery earth there is no circuit in the car and you are clear to charge.

Jump leads are a difficult system. You are connecting a remote charged car to your (dead) delicate electronic systems. With both cars off and keys out I move between the cars in a clockwise direction by; Red to dead car positive, Red to live car positive, Black to live car engine block and finally Black to dead car engine block. Then do nothing for 5 minutes until both are settled. Then start the live car followed by the dead car.

When jump starting - on the "donor" car you should connect the jump leads to the battery only - otherwise the power to start the dead car is going through the engine earth strap of the donor car and there is no need for it to. This could cause problems on that car.

[OldEngineer]

Originally Posted by Tannaton

When jump starting - on the "donor" car you should connect the jump leads to the battery only - otherwise the power to start the dead car is going through the engine earth strap of the donor car and there is no need for it to. This could cause problems on that car.

Really? That's what the earth strap is for. By keeping the earth jump lead on the 'Good' car away from the battery you are preventing any sparks around the battery after it has been through a deep discharge.

[Clan]

Originally Posted by OldEngineer

If you disconnect the battery earth there is no circuit in the car and you are clear to charge.

Jump leads are a difficult system. You are connecting a remote charged car to your (dead) delicate electronic systems. With both cars off and keys out I move between the cars in a clockwise direction by; Red to dead car positive, Red to live car positive, Black to live car engine block and finally Black to dead car engine block. Then do nothing for 5 minutes until both are settled. Then start the live car followed by the dead car.

You must leave the battery connected otherwise the current will not go through the battery monitor , the battery monitor is a mini computer that sends all sorts of interesting charging , State of Charge and usage data to the main computer .