Automotive Death of a car battery and related issues

[CWatters]

Indeed. My car turns off the engine automatically at stops. So on the school run it restarts about a dozen times in 30 mins.

 

[mic*]

Indeed. My car turns off the engine automatically at stops. So on the school run it restarts about a dozen times in 30 mins.

New generation stop-start features are engineered somewhat differently to older lead-acid systems. For example, they may contain a supercapacitor (very low impedance = very fast charging) to support a sealed gel-electrolye battery.

Although 30min minimum charge for one start is very conservative even for lead-acid, I would not try starting an unsupported lead-acid battery once every 30sec with only idling between. It WILL die faster.

 

[OmCheeto]

New generation stop-start features are engineered somewhat differently to older lead-acid systems. For example, they may contain a supercapacitor (very low impedance = very fast charging) to support a sealed gel-electrolye battery.

Although 30min minimum charge for one start is very conservative even for lead-acid, I would not try starting an unsupported lead-acid battery once every 30sec with only idling between. It WILL die faster.

Not to mention your starter. I did the experiment on my last vehicle, and my starter failed within a week.

 

[Wrichik Basu]

Indeed. My car turns off the engine automatically at stops. So on the school run it restarts about a dozen times in 30 mins.

Even if I keep the issue of the battery aside based on what @mic* said, doesn't that consume more fuel? I generally had the idea that an engine in good condition, if kept in idling state at traffic signals, consumes less fuel than what it would have consumed when switched off and turned on again and again (I assume that air conditioners, heaters and defoggers are all switched off).

 

[mic*]

Even if I keep the issue of the battery aside based on what @mic* said, doesn't that consume more fuel? I generally had the idea that an engine in good condition, if kept in idling state at traffic signals, consumes less fuel than what it would have consumed when switched off and turned on again and again (I assume that air conditioners, heaters and defoggers are all switched off).

In short, no.

Maybe in the past it could not have worked so well, but electronic fuelling and engine sensing is relatively precise these days. The engine will be warm, so there will be no "cold start" enrichment. And the engine knows exactly where it is so you generally find they fire immediately, rather than needing that extra turn of the crank before running. They fire up so quick that by the time your foot has moved from the brake to the accelerator, your engine is already running again.

 

[CWatters]

My understanding is that auto start stop does or can discharge the battery deeper than otherwise but they have a BMS system that turns off the auto start stop mode if it gets discharged too much. They may also use a slightly larger battery than on comparable cars without auto start stop. Don't think the battery is supported with a super cap, at least not on my car.

 

[mic*]

My understanding is that auto start stop does or can discharge the battery deeper than otherwise but they have a BMS system that turns off the auto start stop mode if it gets discharged too much. They may also use a slightly larger battery than on comparable cars without auto start stop. Don't think the battery is supported with a super cap, at least not on my car.

Larger bttery units seem to be another approach. SC's are rated at >500,000 cycles so they are not considered a servicable part. They will outlast your steering wheel.

 

[mic*]

@CWatters, I just had a bit of a dig around and I must admit it is hard to find proprietary info on SC use in fuelled vehicles, especially without being used in connection to some form of kinetic energy recovery system. Ie, an SC integrated ONLY for stop-start battery support.

 

[gmax137]

We have a Toyota Etios Liva, four years old, petrol variant. ... Our car is not used much. Usually on an average, it is driven for around 14km per month.

Is this number (14km per month) correct? The four-year old car has 670 km (~400 miles)? At the advertised mileage (about 20 km per liter) you have burned around 34 liters (9 gallons, US) in the past four years?

I have had vehicles with low use like this (not cars, but motorcycles and scooters) and I would expect all kinds of problems: gasoline turned to sludge, clogged carburetor, dead battery, flat spots on the tires, mice eating the wiring, etc. If the use is really this low I would advise either drive it more, or sell it and use taxis to get around.

 

[Wrichik Basu]

Is this number (14km per month) correct? The four-year old car has 670 km (~400 miles)? At the advertised mileage (about 20 km per liter) you have burned around 34 liters (9 gallons, US) in the past four years

Well, I didn't think of such detailed calculations. The average value was of 2018. In the previous years, it has traveled quite a distance. The odometer reading currently is a little greater than 5000km.