Hi.

The car it regards is Skoda Octavia combi 5E5 2013 model. The battery gets low after two to three days. 

1. If i fully charge battery and it show 12.7volt and i turn the Key to on position the voltgae decreases to 12.3 or 12.4 volt. 

If battery is charged to 12.4volt and i turn ignition key to ON, the voltage decreases to 12.0volt or 12.1volt. 

 

2. I used voltmeter in my cars cigarette inlet and measured that it shows only battery voltage when idle to whatever it is at  that poin 12.3volt as exmaple.

 

But when i turn on seat warming the voltage increase to 14.7 volt.

When i turn headlight switch to right to low beam it shows 13.2 volt.

 

3. Only sometimes it charge the battery on idle if needed i think and show 14.7 volt.

When i conencts vcds and measure battery current it show -10Amp taking from battery if engine in not started. Is there anything worng or is it normal?

Can anyone share their knowledge and experience?

 

4. I thought that alternator should not charge battery to as high voltage at 14.7 because it can damage the battery? 

 

5. If there is a setting in VCDS that can bet set to tell alternator to charge battery all the time when battery is low, even if seat warming is on or not or when braking or not it would do the miracle.

 

Kind regards

dreamlearn

 

I think your car has start/stop functionality?

If so it has a charging system that can vary the alternator's output voltage according to system current demand, and need for battery charging.  A controlled (time limited) charge at 14.7 will do no harm.

 

I don't know if a 10 Amp current draw with ignition on is normal, maybe someone with a similar car to yours and VCDS could check? 

 

Is the battery the one it left the factory with?

 

 

 

Edited 28 April, 20206 yr by Wino

Yes. My Car have start/stop function. 
 

No. I put the new AGM battery for a month ago. It is coded to new serial after help here in forum. 
 

yes I hope someone with similar car can read out their values. 

My 2015 1.4TSI charges at 14.7V for the first 10 miles or so after a 2 week period of not being used, the voltage then drops to 13.4V  for most of the rest of the journey.

 

After a week of misuse the battery voltage with the ignition off is around 12.6V.

 

Your voltages all like fine and normal to me.

Ok. I will see what happens in future. I will use it normally and see what happens. Hope it can always be started ☺️

See this picture. It scares me. Nothing is operating. The car just idle and it draw -16amps. 
 

21 hours ago, dreamlearn said:

See this picture. It scares me. Nothing is operating. The car just idle and it draw -16amps.

Ignition off or on?

Ignition is on. Yes. 

2 minutes ago, dreamlearn said:

Ignition is on. Yes. 

There's your answer.

And car is at idle. I noticed that it start charging battery when battery usable amps fall to 41 amp and charge up to 48 amps. 
but actually the batter is 70Ah so I do not really understand why it does not charge fully. If I drive one hour with low beam lights than it charged once to 58Ah but not higher. 
 

this big amp draw, could this be an error in battery? 
 

 

I disconnected the main headlights but still is draw that much amp? 
 

one important thing to ask when battery is coded to 70Ah and car does not charge over 58 Amps. What voila be problem? Or is IT not ment to charge that much 

@PetrolDave Do you know if this Battery usable measurement is for sure correct measured by the Skoda cars? 
I wonder how to have enough amps to not have start problems after if it draws too much amps and car is used for small tours? 
 

My theory was that if the car keeps battery charged at high level most of the time than I do not need to worry about that battery is low. 

3 minutes ago, dreamlearn said:

@PetrolDave Do you know if this Battery usable measurement is for sure correct measured by the Skoda cars?

 

My theory was that if the car keeps battery charged at high level most of the time than I do not need to worry about that battery is low.

I suspect you need to ask Ross-Tech  - they simply display the number measured/calculated/guessed/stored by the VAG software in the module in the car.

 

Overcharging the battery will lead to premature failure, so could be counter productive.

I see. That is a good point. Maybe this is the way this charging and discharging nature is in this car. 
 

Thanks a lot friends for help 😀

I don't know how accurate this information from batteryuniversity.com is (I don't know of any reason to doubt it), but the last two paragraphs before the coloured tables are interesting.

 

"As with all gelled and sealed units, AGM batteries are sensitive to overcharging. A charge to 2.40V/cell (and higher) is fine; however, the float charge should be reduced to between 2.25 and 2.30V/cell (summer temperatures may require lower voltages). Automotive charging systems for flooded lead acid often have a fixed float voltage setting of 14.40V (2.40V/cell); a direct replacement with a sealed unit could overcharge the battery on a long drive. (See BU-403: Charging Lead Acid.)

AGM and other sealed batteries do not like heat and should be installed away from the engine compartment. Manufacturers recommend halting charge if the battery core reaches 49°C (120°F). Table 1 spells out the advantages and limitations of AGM."

 

So although you can charge AGMs faster and at a higher voltage than 'wet'/flooded lead acid batteries, they are likely to be damaged if this charging voltage is maintained once the battery is fully charged (the point at which the 'float voltage' should be applied). The last sentence of the first paragraph is saying that an AGM battery that is charged as if it were a 'wet' one will be overcharged by a 14.4V alternator output.

So retrofitting an AGM to a car without the appropriate alternator control may be bad news for the battery's long-term life. Also, modifying the existing charging system in a car with an AGM, to a fixed voltage 14.4V alternator output will be similarly risky, potentially, if journeys are long and the battery gets to full state of charge.

 

Both paragraphs mention heat and reducing charging rates/voltages, this might be another reason to not fully charge an AGM battery in a car (under-bonnet installations particularly), in fact it might be the main reason, despite claims by VAG that the charging to less than full is to leave room for regenerative alternator behaviours and such 'marketing friendly' claims.

Edited 29 April, 20206 yr by Wino

As that car has stop/start it will also have "regenerative braking/recuperative energy recovery" to make use of wasted energy and reduce fuel usage, along with that comes the grand idea to never bother/waste energy charging the battery up fully, I seem to remember that the intention is to keep it only 60+% charged - enough to make sure that the car, in normal use, will be able to start from cold.

To someone used to wanting/liking their car battery to end up fully charged it can be a bit annoying, but that is how things are I'm afraid.

@Wino, it sounds like the OP reprogrammed the battery charge management section in probably the BCM to take account of the replacement battery technology, so that bit about overcharging should not be an issue.

16 minutes ago, rum4mo said:

As that car has stop/start it will also have "regenerative braking/recuperative energy recovery" to make use of wasted energy and reduce fuel usage

 

Marketing ploy and/or emissions type-testing 'dodge', surely? How much time in the average journey are you actually likely to be recuperating anything? Nowhere near long enough to fully charge a battery from 80% SOC (the figure I've seen bandied about), I'll bet; maybe enough to add 0.1%?.  I just don't believe that's the real reason.  That's why I posted what I did.

 

9 minutes ago, rum4mo said:

that bit about overcharging should not be an issue.

That was more of a general observation about why the system won't/doesn't fully charge an AGM battery, and why tinkering with the charging system of one with an AGM battery might not be advisable; nor fitting an AGM to a car not suited to one.

Edited 29 April, 20206 yr by Wino

2 minutes ago, Wino said:

 

Marketing ploy and/or emissions type-testing 'dodge', surely? How much time in the average journey are you actually likely to be recuperating anything? Nowhere near long enough to fully charge a battery from 80% SOC (the figure I've seen bandied about), I'll bet; maybe enough to add 0.1%?.  I just don't believe that's the real reason.  That's why I posted what I did.

 

That was more of a general observation about why the system won't/doesn't fully charge an AGM battery, and why tinkering with the charging system of one with an AGM battery might not be advisable; nor fitting an AGM to a car not suited to one.

 

I was just pointing out that the charging systems on these newer cars do come with the flexibility to swop battery size and technology as and when you want to and still work as intended.

OK, fair enough, it just sounded like you'd possibly 'bought into' VAG's marketing more than I feel is justified. 

As you say, the battery management in cars with start/stop probably can cope with whatever it is paired with, given suitable coding of itself.

On 28/04/2020 at 18:39, dreamlearn said:

See this picture. It scares me. Nothing is operating. The car just idle and it draw -16amps. 
 

Just popped in to point out a few thoughts as to what I think is "likely".

 

Current consumption with ignition on, engine idling.

 

Electronics on modern Skodas take a lot of current, many modules, infotainment never off even if you turned it off, drls on, glowplugs can work for a couple of minutes after cold start, injectors, many solenoids, fuel pick up pump, coolant secondary run on pump, aux air pump, turbo electric actuator, aux electric heater, electric steering, radar units, dash etc etc. Lots of amps taken even when little is apparently turned on.

 

The charging system will try to save energy when there is enough SOC in the battery and voltage is sufficiently high, and turns the alternator down, but this also depends on what the engine is doing, idling, accelerating under load, we don't know the algorithm exactly, only a few software people will know.

 

You might find if you turn on the headlights, rear windscreen heater etc that the car will start charging.

 

Try it and see.

 

Secondly, dont assume that "Useable battery charge" is directly related to SOC or charge left in the battery. I would expect that like many battery systems, the last 20% of battery capacity is reserved. Once you get down to that level, battery damage is likely and its doubtful if you'd start the car without issues.

 

Likewise, a buffer of 10% or so may be reserved at the top end, e.g. to stop danger of overcharging during recuperation if SOC has got out of whack.

 

So that display is probably only the battery charge thats available to actively use. Hope you understand what I'm getting at.

 

So in short,I think what your pic shows is probably nothing to worry about.

 

 

1 hour ago, xman said:

Just popped in to point out a few thoughts as to what I think is "likely".

 

Current consumption with ignition on, engine idling.

 

Electronics on modern Skodas take a lot of current, many modules, infotainment never off even if you turned it off, drls on, glowplugs can work for a couple of minutes after cold start, injectors, many solenoids, fuel pick up pump, coolant secondary run on pump, aux air pump, turbo electric actuator, aux electric heater, electric steering, radar units, dash etc etc. Lots of amps taken even when little is apparently turned on.

 

The charging system will try to save energy when there is enough SOC in the battery and voltage is sufficiently high, and turns the alternator down, but this also depends on what the engine is doing, idling, accelerating under load, we don't know the algorithm exactly, only a few software people will know.

 

You might find if you turn on the headlights, rear windscreen heater etc that the car will start charging.

 

Try it and see.

 

Secondly, dont assume that "Useable battery charge" is directly related to SOC or charge left in the battery. I would expect that like many battery systems, the last 20% of battery capacity is reserved. Once you get down to that level, battery damage is likely and its doubtful if you'd start the car without issues.

 

Likewise, a buffer of 10% or so may be reserved at the top end, e.g. to stop danger of overcharging during recuperation if SOC has got out of whack.

 

So that display is probably only the battery charge thats available to actively use. Hope you understand what I'm getting at.

 

So in short,I think what your pic shows is probably nothing to worry about.

 

 

 

Now i got a lot of good explanation from @rum4mo @Wino @xman

 

Well I was out a tour and just bought a Ctek MX5.0 charger beacuse i have a daily small journey of 4-5 minutes one way. Ctek MX5.0 is also good for AGM and start stop battery as the Ctek have written on packing. Since i earlier had starting and cranking issues so i now decided to have enough battery charged. This is a brand new battery and if it works fine with charger connected, it would be fine for me.

 

And yes now i understand why it draw so much amp since so many components are running at same time.  

Thanks to all of you.

Edited 29 April, 20206 yr by dreamlearn

27 minutes ago, dreamlearn said:

 

Now i got a lot of good explanation from @rum4mo @Wino @xman

 

Well I was out a tour and just bought a Ctek MX5.0 charger beacuse i have a daily small journey of 4-5 minutes one way. Ctek MX5.0 is also good for AGM and start stop battery as the Ctek have written on packing. Since i earlier had starting and cranking issues so i now decided to have enough battery charged. This is a brand new battery and if it works fine with charger connected, it would be fine for me.

 

And yes now i understand why it draw so much amp since so many components are running at same time.  

Thanks to all of you.

 

You will not catch me saying that buying a CTEK 5Amp charger is a waste of time, glad you have joined the club!

I've noticed my EFB battery never gets above a 70% charge when checking in the MaxiDot display. 

During the lockdown I've seen it drop as low as 50% but the car still started perfectly fine. 

 

After a short run it brought the SOC back to 70% with no issues. 

 

Using a cigarette light charger with a voltage display also shows that the alternator delivers 14.2 or so volts until after a long drive when I guess the battery is charged enough. Then this drops to 12.2 during driving unless you start to brake. 

Then the alternator starts to deliver 14 Volta again. 

I presume this is the eco alternator at work. 

 

 

This morning, a retired exwork acquaintance managed to reach the point where his C3 did nothing much when he turned the key!  A bit unfortunate for him as he has a garage without power, so I suggested getting a basic boost pack from Halfords as he lives near them and it was in stock, so after a visit from a mutual friend with a battery and leads, he got going and stopped off at Halfords, so is sort of sorted for now!

 

Lots of people must be heading for that situation with not many options open to them if they can't get their car close to their front door/path.