New Battery
- Thread starter LordGozer
- Start date
Also, 14.2 volts will not fully charge a battery either. This was always the short coming of a standard alternator, improper regulation! The intelligent alternator can never behave as a "standard" alternator because it has no built in regulator. It is always controlled by the ECU.
It seems the Ford and Merc systems are different to T6, in the case of my Merc, by disconnecting the neg rail sensor the alternator only charges at 14.2/3 volts, the system as you say is still controlled by the cpu but in the Merc`s case as the cpu does not know the soc of the battery it defaults to a continuous safe charge of 14.2 volts in all driving situations which is a level of charge at which the battery cannot be overcharged. I read this is the same charge level as a standard alternator, you say that 14.2 will not fully charge battery but it certainly won`t over charge it and unlike a smart alternator it doesn`t wait until the soc reaches 80% before it starts to charge. My Merc after 24 hours rest reads 12.69 volts, I believe this indicates a fully charged battery, I also run a mk1 Audi TT 2005, the battery is now 8 years old, car has halogen head lights, heated seats, air con, CD/Radio, all less efficient than modern electronics, the system is charged at 14.2 volts and the battery shows no sign of giving up.
This all started for me by trying to get rid of stop/start, this led to the neg battery sensor then to whether removing sensor was safe, this then brought up hits on other motor forums asking the same question, how to get rid of stop/start that led on to flat battery's on the BMW forum whereby members were disconnecting the sensor and having no more flat battery's.
To me Stop start, smart alternators and AGM batterys are all about saving the planet (if you believe the CO2 is bad garbage), there appears to be little fuel saving in real world terms but far more expensive battery's, complex and expensive servicing especially once outside of warranty. If the manufactures have actually upgraded systems to cope with the extra wear then by not using those systems my car should last longer, advantage me.
It won`t be mechanical failures that scrap a car it will be the electronics, by disconnecting the sensor on my Merc, I can use any lead/acid battery, it`s only the stop/start that needs AGM.
AGM aftermarket falters as drivers disable start-stop function - Batteries International
This all started for me by trying to get rid of stop/start, this led to the neg battery sensor then to whether removing sensor was safe, this then brought up hits on other motor forums asking the same question, how to get rid of stop/start that led on to flat battery's on the BMW forum whereby members were disconnecting the sensor and having no more flat battery's.
To me Stop start, smart alternators and AGM batterys are all about saving the planet (if you believe the CO2 is bad garbage), there appears to be little fuel saving in real world terms but far more expensive battery's, complex and expensive servicing especially once outside of warranty. If the manufactures have actually upgraded systems to cope with the extra wear then by not using those systems my car should last longer, advantage me.
It won`t be mechanical failures that scrap a car it will be the electronics, by disconnecting the sensor on my Merc, I can use any lead/acid battery, it`s only the stop/start that needs AGM.
AGM aftermarket falters as drivers disable start-stop function - Batteries International
Whilst it is correct that a fully charged battery will read 12.7 volts it doesn't automatically follow that if a battery reads 12.7 volts then it is fully charged. There are only two ways to establish whether a battery is fully charged or not, one is by checking the SG which is increasingly impossible due to the construction of modern batteries. the other is by observing the charging process. When a battery reaches its absorption voltage (14.4 for most flooded batteries, 14.5 for AGM) and charge current falls to 5% of battery capacity then it can be considered as fully charged. If the battery never reached absorption it cannot be fully charged!
I don't think stop/start is about saving the planet, it is more about reducing localised CO and Nox in areas where there are likely to be high densities of pedestrians.
I guess it isn't popular to consider the welfare of others these days.
I don't think stop/start is about saving the planet, it is more about reducing localised CO and Nox in areas where there are likely to be high densities of pedestrians.
I guess it isn't popular to consider the welfare of others these days.
Quote, I don't think stop/start is about saving the planet, it is more about reducing localised CO and Nox in areas where there are likely to be high densities of pedestrians.
I guess it isn't popular to consider the welfare of others these days.
I don`t believe petrol engines produce much Co and Nox, diesel is the problem and it`s down to choices, if you consider the welfare of others don`t purchase diesel, I own 3 cars all are petrol.
Quote, Whilst it is correct that a fully charged battery will read 12.7 volts it doesn't automatically follow that if a battery reads 12.7 volts then it is fully charged.
Splitting hairs there arn`t you, 99% charge is still better than 80%.
Rob.
I guess it isn't popular to consider the welfare of others these days.
I don`t believe petrol engines produce much Co and Nox, diesel is the problem and it`s down to choices, if you consider the welfare of others don`t purchase diesel, I own 3 cars all are petrol.
Quote, Whilst it is correct that a fully charged battery will read 12.7 volts it doesn't automatically follow that if a battery reads 12.7 volts then it is fully charged.
Splitting hairs there arn`t you, 99% charge is still better than 80%.
Rob.
If you are dispensing advice on an open forum it should be accurate otherwise you are misleading the uninformed. We are not even talking 99% charge. Lucky to get 85%. Just saying.
Quote, If you are dispensing advice on an open forum it should be accurate otherwise you are misleading the uninformed. We are not even talking 99% charge. Lucky to get 85%. Just saying.
Re: Charging AGM battery
Post by drivesafe » Mon Sep 03, 2012 2:54 pm
pelbo wrote:You can rarely fully charge and AGM using your car's alternator as a source. Most vehicle alternators are set up to charge the starter battery (which is a standard lead acid battery) to around 75%, which only takes a few minutes. So when your battery reaches about this percentage, the alternator cuts the amps back to around 2-3 amps. Where does this come from.
It certainly does not come from any of the battery, vehicle or alternator manufacturers.
For a starter, on average, you use less than 2% of a cranking batteries capacity to start a modern vehicle.
So if your battery was in a fully charged state, the battery would only be down to 98%, so where does this 75% come from.
In reality in normal everyday use, most vehicles will have cranking batteries with States of charge ( SoC ) in the 90 to 95% before the motor is started, so again where does this 75% come from.
Now as for this misinformation that a battery stops charging once the alternator lowers it’s voltage, and an alternator does this based on the time from when the motor was started and not because the vehicle has the mythical ability to know a battery has reached 75%, the reality is that a battery will continue to charge, even after the voltage drops.
Have a look at Fullriver’s site and you will find a graph that shows you can charge one of their AGMs from a low state of charge to a fully charged state in 30 hours with no more than 13.0v applied to the battery.
The higher the voltage applied to the battery's terminals, the sooner the battery will reach a fully charged state.
Next, if in a mythical situation, where a vehicle’s electronics could actually determine that a battery was at ( or above ) 75% SoC, which no vehicle can do at this time, but as posted, if in a mythical situation it could, as a battery with a loaded 75% SoC would have a terminal voltage of around 12.37v, the alternator would have to reduce it’s output voltage to 12.37v or the battery would continue to charge above this mythical 75% SoC.
So once again, where does this mythical 75% come from
The reason batteries, that have been discharged while camping or what ever, and are being charged by an alternator, do not get to 100% SoC is because you do not drive long enough and incidentally, DC/DC devices, contrary to all the misinformation posted about their mythical abilities, suffer from the exact same situation. If you don’t drive long enough, you will not fully charge your batteries, no matter what type of charging you use.
Battery System Supplier
http://caravanersforum.com/viewtopic.php?t=29876
Rob.
Re: Charging AGM battery
Post by drivesafe » Mon Sep 03, 2012 2:54 pm
pelbo wrote:You can rarely fully charge and AGM using your car's alternator as a source. Most vehicle alternators are set up to charge the starter battery (which is a standard lead acid battery) to around 75%, which only takes a few minutes. So when your battery reaches about this percentage, the alternator cuts the amps back to around 2-3 amps. Where does this come from.
It certainly does not come from any of the battery, vehicle or alternator manufacturers.
For a starter, on average, you use less than 2% of a cranking batteries capacity to start a modern vehicle.
So if your battery was in a fully charged state, the battery would only be down to 98%, so where does this 75% come from.
In reality in normal everyday use, most vehicles will have cranking batteries with States of charge ( SoC ) in the 90 to 95% before the motor is started, so again where does this 75% come from.
Now as for this misinformation that a battery stops charging once the alternator lowers it’s voltage, and an alternator does this based on the time from when the motor was started and not because the vehicle has the mythical ability to know a battery has reached 75%, the reality is that a battery will continue to charge, even after the voltage drops.
Have a look at Fullriver’s site and you will find a graph that shows you can charge one of their AGMs from a low state of charge to a fully charged state in 30 hours with no more than 13.0v applied to the battery.
The higher the voltage applied to the battery's terminals, the sooner the battery will reach a fully charged state.
Next, if in a mythical situation, where a vehicle’s electronics could actually determine that a battery was at ( or above ) 75% SoC, which no vehicle can do at this time, but as posted, if in a mythical situation it could, as a battery with a loaded 75% SoC would have a terminal voltage of around 12.37v, the alternator would have to reduce it’s output voltage to 12.37v or the battery would continue to charge above this mythical 75% SoC.
So once again, where does this mythical 75% come from
The reason batteries, that have been discharged while camping or what ever, and are being charged by an alternator, do not get to 100% SoC is because you do not drive long enough and incidentally, DC/DC devices, contrary to all the misinformation posted about their mythical abilities, suffer from the exact same situation. If you don’t drive long enough, you will not fully charge your batteries, no matter what type of charging you use.
Battery System Supplier
http://caravanersforum.com/viewtopic.php?t=29876
Rob.
Caravaners forum, really? Physics is physics and no amount of quoting or refering to other peoples opinions will change that.
