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Goldenvodka

If a car is idling, does it charge the battery

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2nd Gear

A quick question here for the experts in this forum.

Idle the car to keep the battery healthy or really need to drive it around the blocks.

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Supersonic (edited)
7 minutes ago, Goldenvodka said:

A quick question here for the experts in this forum.

Idle the car to keep the battery healthy or really need to drive it around the blocks.

yes its charging, and must charge..

when idling the rpm is lower, so for most car the charging is lower , if u drive around it confirm charge more and faster.

Edited by Beregond
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Moderator
20 minutes ago, Goldenvodka said:

A quick question here for the experts in this forum.

Idle the car to keep the battery healthy or really need to drive it around the blocks.

basically, the car engine will charge the alternator and it will charge the battery.

This is a good video about the alternator. 🙂

 

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2nd Gear

Looks like at least need to idle at least 20minutes if lazy to drive around the blocks.

 

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Supersonic
5 minutes ago, Thaiyotakamli said:

Drive expressway best charge alot 

find your favourite food drive to tabao come back, can park 1 week at least😁

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Turbocharged

FYI a dying battery will also cause slightly higher fuel consumption. As the alternator has to work more to top off the battery that cannot hold charge. 
IMHO, just buy those quick battery testers to check state of charge, state of health, internal resistance and voltage. Can tell you easily how the battery is. 

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5th Gear

i have looked after a neighbour's car when they were away for a few months.

originally i only regularly start and idle for 20 minutes (including rev to 2000/3000rpm for short periods) until the temperature gauge reaches operating temperature where the needle gets to the mid point of the gauge ..

reason is that i try not to drive other people's car in case accident etc

but after about a month the battery becomes noticeably weaker .. cranking longer to start ..

its not an old car, only about less than a year old so battery should be ok ..

then one day, crank but couldnt start .. called AA .. thought need to change battery .. but AA man says battery still good but never run ..

so he help me jump start and tell me drive for 10-20 min once a week .. i did that and the battery/starting etc all back to perfect ..

so somehow idling alone over longer periods does not fully and properly charge the battery ..

no doubting any engineer or someone who can explain otherwise that idle alone will be sufficient for recharging battery but just sharing true life experience.

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6th Gear

Is it many WFH, so car left unused for too long?

Go for a relaxing drive on weekends. Charge and destress at the same time.

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25 minutes ago, Didu said:

Is it many WFH, so car left unused for too long?

Go for a relaxing drive on weekends. Charge and destress at the same time.

Agtee

 

 roads damn empty liao

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Supersonic

I think it is good to use a battery maintainer in times like this. It will be easy if you live on landed property. 

In hdb or condo you will have to remove the battery, bring it home and hook up with the battery maintainer.

Quote

A battery maintainer will keep the battery charged AND extend its life. ... When the battery is fully charged, the maintainer will switch over to float mode to maintain the battery at full charge. That means the battery maintainer will only charge the battery when it drops below a certain voltage

I actually have one of this. Can be used on AGM battery.

https://www.autoguide.com/blog/wp-content/uploads//2019/10/noco-genius-g3500.jpg

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5th Gear
1 hour ago, Didu said:

Is it many WFH, so car left unused for too long?

Go for a relaxing drive on weekends. Charge and destress at the same time.

especially CB last year!

drive 20-30 min .. good for the mind 😄

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Supersonic (edited)

As a battery seller, this is my opinion. 

Battery charge depends on alternator voltage. The higher the voltage, the faster the battery charge, but heats up more as well.

Example, I go to a car with a really flat battery, I measure with a DC clampmeter, after jumpstarting the car, the highest it will go is around 50~60A for the first few minutes. As the battery is being charged, the current drops to 20A ~ +, and continues charging. It will go down to a certain lower level. Now this is all due to the alternator voltage level.

A car whether moving or stationary has an alternator putting out more or less the same charging voltage. Alternator is belt driven by engine, so you would think, the faster the engine runs, (like when you go for a drive), the voltage will be higher. This is not true, bcuz the alternator has electronic control on voltage regulation. So the alternator, if it's putting out 14V at idle, it will more or less put out 14V at 6000rpm. Since the charging voltage does not change, charging the battery will take about the same time.

If you want the flat battery to charge a lot faster, you would have to raise the alternator voltage (if that's possible) to say 15.8V which is the max, before the battery overheats and crack.

The alternator capacity also depends on your car. The big cars may have 120A capability, while the smaller car may have 80A. If the battery is drawing a lot of current, the alternator is then limited by its capacity.

If you want to fully charge a flat battery it takes time. It will charge quite fast for the first few minutes and then level off and slows down. But alternator is not build to fully charge a battery, but maintain about 80~90% or so of the charge. If you really want to fully charge a battery to 100%, it will take many hours, which is not possible, when you're driving a car normally.

 

Edited by Kb27
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5th Gear
44 minutes ago, Kb27 said:

As a battery seller, this is my opinion. 

Battery charge depends on alternator voltage. The higher the voltage, the faster the battery charge, but heats up more as well.

Example, I go to a car with a really flat battery, I measure with a DC clampmeter, after jumpstarting the car, the highest it will go is around 50~60A for the first few minutes. As the battery is being charged, the current drops to 20A ~ +, and continues charging. It will go down to a certain lower level. Now this is all due to the alternator voltage level.

A car whether moving or stationary has an alternator putting out more or less the same charging voltage. Alternator is belt driven by engine, so you would think, the faster the engine runs, (like when you go for a drive), the voltage will be higher. This is not true, bcuz the alternator has electronic control on voltage regulation. So the alternator, if it's putting out 14V at idle, it will more or less put out 14V at 6000rpm. Since the charging voltage does not change, charging the battery will take about the same time.

If you want the flat battery to charge a lot faster, you would have to raise the alternator voltage (if that's possible) to say 15.8V which is the max, before the battery overheats and crack.

The alternator capacity also depends on your car. The big cars may have 120A capability, while the smaller car may have 80A. If the battery is drawing a lot of current, the alternator is then limited by its capacity.

If you want to fully charge a flat battery it takes time. It will charge quite fast for the first few minutes and then level off and slows down. But alternator is not build to fully charge a battery, but maintain about 80~90% or so of the charge. If you really want to fully charge a battery to 100%, it will take many hours, which is not possible, when you're driving a car normally.

 

Wow! What an insight!

I used to think that when vehicle is idling, I can rev up the engine to charge a battery faster.

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Supersonic
10 minutes ago, DOBIEMKZ said:

Wow! What an insight!

I used to think that when vehicle is idling, I can rev up the engine to charge a battery faster.

Actually, nowadays smart alternators from luxury cars like Mercedes, will put out 13.3V normally.

If it sense the current load is high, like from a depleted battery, it will push the voltage to go higher to charge faster and when it detects a lower load, it will alter the voltage downwards.

This also reduce the stress on the battery. A lower voltage charge slower, but stays cooler and the battery should last longer.

This is different from old-style "dumb" alternator which puts out fixed voltage, regardless the electrical load.

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6th Gear
4 hours ago, Mooose said:

i have looked after a neighbour's car when they were away for a few months.

originally i only regularly start and idle for 20 minutes (including rev to 2000/3000rpm for short periods) until the temperature gauge reaches operating temperature where the needle gets to the mid point of the gauge ..

reason is that i try not to drive other people's car in case accident etc

but after about a month the battery becomes noticeably weaker .. cranking longer to start ..

its not an old car, only about less than a year old so battery should be ok ..

then one day, crank but couldnt start .. called AA .. thought need to change battery .. but AA man says battery still good but never run ..

so he help me jump start and tell me drive for 10-20 min once a week .. i did that and the battery/starting etc all back to perfect ..

so somehow idling alone over longer periods does not fully and properly charge the battery ..

no doubting any engineer or someone who can explain otherwise that idle alone will be sufficient for recharging battery but just sharing true life experience.

Every cold start draws down the capacity of the battery greatly.

Idling thereafter for 10 minutes may not be sufficient to charge the battery to a higher level of charge before the cold crank

So possibly, you could start every week, but drive and for 30 minutes like normal should be a better way.

Then again, quality of batteries these days are dropping.

The simple math : 10 year COE / lifespan of battery

COE  / 3.  years = 3.3 => 4 battery changes

COE / 2.5 years => 4 battery changes

The cost is the same... no point holding out on battery changes only to be stuck in office or some outdoor carpark at an inopportune time.

The same goes for tires.

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3rd Gear (edited)
5 hours ago, Didu said:

Is it many WFH, so car left unused for too long?

Go for a relaxing drive on weekends. Charge and destress at the same time.

Drive for pleasure and it helps to release pressure...😊

Edited by Cephas
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Hypersonic

If never use car just use a wall charger to charge up the battery.

Helps if you live in landed property.

A bit of a hassle if you need to take out the battery and bring it to your condo.

That will fully charge the battery

:D

image.thumb.png.af8eed93dc076bbff0e9b20b6e0137e7.png

 

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