Stop / Start batteries - warning

[Maninblack4612]

Talking with a mate last week his car battery had gone flat through not using it. He got the local garage to come out & give him a jump start. The battery is what is known as an AGM (Absorbed Glass Mat, apparently) used in most cars with Stop / Start. The mechanic told him that charging it with a convential old fashioned charger wouldn't charge it properly & could destroy it. The other day my car wouldn't start so I got out my years old Halfords charger. I couldn't find the manual &, in any event, I was pretty sure it wouldn't do the job. I then remembered that, some years ago I'd bought another charger to use with my wife's Smart car's inaccessible battery. The manual told me that this was OK for AGM batteries & it has fully charged the battery overnight last night.

For anyone interested, this is the make I used, an earlier version of this https://www.ctek.com/products/vehicle/ct5-start-stop

Hope this stops someone destroying their battery, replacements can be £200 plus.

 

[rulefan]

DO YOU HAVE A CAR WITH STOP/START TECHNOLOGY? CAN YOU USE ANY BATTERY CHARGER?​

To start off, the answer is no to the question above.
Firstly, what is Start/Stop technology? Motor manufactures have been put under pressure from respective governments to make vehicles more efficient. To achieve this a number of different methods have been adapted. There are many but this blog does not set out to list them all. Obviously the first is when stopping at a road junction or waiting in traffic the engine turns off. When the accelerator is pressed the engine starts and the car pulls away. Hence Start/Stop Technology.
The alternator takes about 10% of the engines power so when the battery is charged the ECU (engine control unit) turns off the alternator saving power and fuel. When braking, some of the power developed from that braking is used to boost the battery.
Because of the way the battery is discharged it is necessary to recharge the battery quickly to keep up with the demands of the electrical system on the vehicle for this reason a new generation of batteries have been developed for Stop/Start technology.
Lead acid starter batteries are a series of lead grids known as plates. Onto these plates is pasted a lead compound which is the active material, as pure lead is very pliant it is difficult to form a grid so the lead has been alloyed to give the grid its rigidity. When County Battery Service started in 1974, almost all the starter batteries were of lead antimony construction. There are obvious advantages but the disadvantage with antimony is that the battery gassed at a relatively low voltage so used a lot of water. Over the years this method of construction has been largely replaced with a lead calcium alloy which allows a greater rate of charge before gassing making these batteries almost maintenance free.
The AGM battery has been strong in the marketplace since the 1970’s but generally for use in emergency power and telecom systems. These batteries have now been developed using high purity lead with a calcium grid allowing a faster higher voltage and amperage charge rate but with virtually no maintenance for use in Start/Stop vehicles.
An AGM battery needs a different charging algorithm than a standard flooded battery. With traditional battery chargers, as the battery becomes more charged the battery voltage increases as that voltage increases the amperage going into the battery will fall. You may have noticed that as the battery becomes more charged the amperage needle on the charger falls, if left on the battery starts to get hot and the electrolyte in the battery starts to bubble. This would be fatal for an AGM battery if this much gassing occurred the vents in the battery would open (to prevent explosion) and the gases would escape rendering the battery unserviceable.
With a new generation of batteries has sprung a new generation of chargers. These chargers are normally electronic with lights indicating state of charge rather than a needle. These chargers have fixed charging algorithms which peg voltage and amperage to prevent overcharging.

 

[Maninblack4612]

DO YOU HAVE A CAR WITH STOP/START TECHNOLOGY? CAN YOU USE ANY BATTERY CHARGER?​

To start off, the answer is no to the question above.
Firstly, what is Start/Stop technology? Motor manufactures have been put under pressure from respective governments to make vehicles more efficient. To achieve this a number of different methods have been adapted. There are many but this blog does not set out to list them all. Obviously the first is when stopping at a road junction or waiting in traffic the engine turns off. When the accelerator is pressed the engine starts and the car pulls away. Hence Start/Stop Technology.
The alternator takes about 10% of the engines power so when the battery is charged the ECU (engine control unit) turns off the alternator saving power and fuel. When braking, some of the power developed from that braking is used to boost the battery.
Because of the way the battery is discharged it is necessary to recharge the battery quickly to keep up with the demands of the electrical system on the vehicle for this reason a new generation of batteries have been developed for Stop/Start technology.
Lead acid starter batteries are a series of lead grids known as plates. Onto these plates is pasted a lead compound which is the active material, as pure lead is very pliant it is difficult to form a grid so the lead has been alloyed to give the grid its rigidity. When County Battery Service started in 1974, almost all the starter batteries were of lead antimony construction. There are obvious advantages but the disadvantage with antimony is that the battery gassed at a relatively low voltage so used a lot of water. Over the years this method of construction has been largely replaced with a lead calcium alloy which allows a greater rate of charge before gassing making these batteries almost maintenance free.
The AGM battery has been strong in the marketplace since the 1970’s but generally for use in emergency power and telecom systems. These batteries have now been developed using high purity lead with a calcium grid allowing a faster higher voltage and amperage charge rate but with virtually no maintenance for use in Start/Stop vehicles.
An AGM battery needs a different charging algorithm than a standard flooded battery. With traditional battery chargers, as the battery becomes more charged the battery voltage increases as that voltage increases the amperage going into the battery will fall. You may have noticed that as the battery becomes more charged the amperage needle on the charger falls, if left on the battery starts to get hot and the electrolyte in the battery starts to bubble. This would be fatal for an AGM battery if this much gassing occurred the vents in the battery would open (to prevent explosion) and the gases would escape rendering the battery unserviceable.
With a new generation of batteries has sprung a new generation of chargers. These chargers are normally electronic with lights indicating state of charge rather than a needle. These chargers have fixed charging algorithms which peg voltage and amperage to prevent overcharging.

To quote Michael Caine "Not many people know that"

 

[Bunkermagnet]

I think most Ctek battery chargers are stop-start compliant being smart chargers, I know my MXS 5.0 is.
One thing I was told many moons ago is that do not try and bump start a car with stop start. I was told of someone who tried it with their Citroen and fried the control electronics. Now whether that is beause of trying to be bump started or because it is French is anyone's guess

 

[USER1999]

Mercedes are recommending starting my car every couple of weeks, and running it for 15 minutes minimum to keep the battery charged.

 

[Blue in Munich]

Mercedes are recommending starting my car every couple of weeks, and running it for 15 minutes minimum to keep the battery charged.

Not a bad idea for the air con either; apparently there's a lubricant in the refrigerant for the O-ring seals. If it sits too long unlubricated then the O-rings crack, refrigerant leaks & the air con fails.

 

[Bunkermagnet]

Not a bad idea for the air con either; apparently there's a lubricant in the refrigerant for the O-ring seals. If it sits too long unlubricated then the O-rings crack, refrigerant leaks & the air con fails.

Thats also the reason you should run your aircon regularly all year round, as I day do never turn it off