Car Battery Consumption: Measuring Amps Drawn & Charging Minutes after Engine Start

Hello
I have a fairly simple question. I've searched but can't find a specific answer. How much A car consumes when starting. It is known that the battery has, for example, 45 Ah. The question is how much of it remains after starting the car. Is it, for example, 90% or only 60%. I know that immediately after firing the alternator charges the battery, but the question is how many minutes the engine must run to recharge this energy loss. You're about to say it depends on the car and the temperature. It is known that in the winter there will be much more wear, but in fuel-injected cars, the starter motor does not turn, it is not known how much, so the difference should not be great.

I guess it depends more on the size of the car (engine) than the temperature

For a passenger car you can take an average of 300A/s

It depends on many factors. The question that springs to mind is why do you need this knowledge?

Well, I'll explain it to you. Well, for the third time I recharged my mother's battery in this "winter" as it is her car around the city (no one else drives it) and she drives it sporadically, if at all. The car is a Suzuki swift. The charging current is adequate, everything checked, but if you drive once every 4 days, max 5 km, then what is surprising. But it's hard to explain to her, so I drew her a graph of how her battery is decreasing day by day. But I can't explain to her that if she doesn't drive for 5 days, going and starting it at a stop (so that, as she says, burn it) won't help because it will use more electricity to start than it's worth.

And here you are wrong. It is better to start the car once every two days than to leave it idle for 5 days. The battery will charge, you will stimulate the electrolyte, the engine will work.
Start by checking the condition of the battery (electrolyte) and its capacity under load. That will tell you a lot.

The battery is dead or the draw is too high.
The starter will take 100A

mr-perch wrote:

And here you are wrong. It is better to start the car once every two days than to leave it idle for 5 days. The battery will charge, you will stimulate the electrolyte, the engine will work.

This is what I know from experience that it is not wrong. As three years ago it was minus 27 in January, I decided not to move the car for 6 days until the temperature returned to minus 8 and I fired without a problem. And the sister stubbornly fired and fired only once and failed the second time It is true that the cars are different, but the battery has a capacity of about 50 Ah. My theory is simple - when I start it, I drive for at least 15 minutes. And firing to burn the car was good when you had a polonaise.

Approx. you know more. Why in this arrangement are you asking us?
I'm done with this topic. Just explain to mom to start driving when the temperature is around 10 degrees. Gotta wait until April...

I join: either the battery needs to be replaced, or there is a problem with charging.
Possibly - the battery needs to be replaced as a result of charging problems.

Quote:

It is better to start the car once every two days than to leave it idle for 5 days

- people, what do you drive, Fela drives normally for 2 (or 3) weeks...

Well, I can't seem to get a specific answer. One says 300 A/s the other says 100 A to fire. I'm heading to bed but I encourage you to discuss something specific will come up.
Regards

Let's consider such a case.

Diesel engine, current consumption by the starter, in winter, after an overnight stop - let's say 250A, let the start-up last 15 seconds, plus 5 seconds of glow plug heating before and during start-up ~50A (cold ones have a large consumption, over 80A, which during heating reduces to 36-40A) that is:

250A * 15s = 3750As
50A * (5s + 15s) = 1000As
3750As + 1000As = 4750As
4750As / 3600s(number of seconds in an hour) = 1.32Ah

However, there are two factors that should be kept in mind - firstly, the rated capacity of the battery after buying a new one in the store and installing it in the vehicle, it decreases significantly during operation (e.g. to 70% or less). The second thing is that the battery discharged with a high current of 200-300A has a capacity much lower than the rated one (e.g. 30%). In our case, it would look like this:

60Ah(diesel battery) * 0.7(used to 70% of initial capacity, i.e. "still fresh") * 0.3 (discharged with high current) = 12.6Ah

and this capacity should be taken into account during start-up

Let's substitute it into the previous calculations - 1.32Ah for starting:

12.6Ah / 1.32Ah = 9.5

which gives us the number of winter starts that we can squeeze out of our battery. Translating this into the nominal capacity of the battery, one such start "eats" about 10% of this capacity.

Regards

PS: With greater frosts, there is one more factor - reducing the capacity of the cold battery.

mr-perch wrote:

And here you are wrong. It is better to start the car once every two days than to leave it idle for 5 days. The battery will charge, you will stimulate the electrolyte, the engine will work.
Start by checking the condition of the battery (electrolyte) and its capacity under load. That will tell you a lot.

But it's not good for the engine, because it will only absorb moisture, so when you start it, it will heat up.

The classic symptom of a battery drain:
- the car does not start, no electricity,
- we load, it loads quickly,
- the car starts, we drive normally,
- we leave the car in the evening,
- she didn't start in the morning.

The important thing is whether it is a natural descent, or caused by chronic undercharging or deep discharge (this exhausts the battery extremely effectively).

But to find out what the cause is, at least you need to measure the voltage in the system while driving, and after it.

Well done "kybernetes" that's what I meant. This gives some idea of what the battery life cycle looks like. Thanks alot.
To be precise, I will say that my mother's battery does not rain after two days or a week, but after 3-4 weeks. In my opinion, the energy balance is negative and it gradually discharges because it runs too short.
greetings

Added after 1 [minutes]:

ociz wrote:

mr-perch wrote:

And here you are wrong. It is better to start the car once every two days than to leave it idle for 5 days. The battery will charge, you will stimulate the electrolyte, the engine will work.
Start by checking the condition of the battery (electrolyte) and its capacity under load. That will tell you a lot.

But it's not good for the engine, because it will only absorb moisture, so when you start it, it will heat up.

Exactly

Listen, the starter in this car takes max around 130A, do you need something more?

mlac wrote:

it doesn't rain after two days or a week, but after 3-4 weeks

4x 7 days x 24 hours = 672 hours, all you need is some piece of shit in the car that takes 100mA and you have an empty battery.

If there is still a problem, connect the buffer power supply, DC power supply set to 13.5 -13.8 V, you can even get ready-made power supplies.

Ps. I am browsing the topic, because I would also like to know after how much time after lighting the car we make up for the loss in the battery? I heard after 4km or 4 min

Have you checked the power consumption while parked?
Maybe, for example, the trunk lamp does not always go out.

Everything is explained well by colleagues, except that it should be remembered that the battery capacity is for a certain current that is drawn from it. Not every current will be 45Ah.

A friend once had a Ford scorpio with a 2.5TD engine (Italian VM), the glow plugs were still hot for about 10 minutes after firing, at that time there was practically no battery charging because the alternator was not working. The problem was that this lady drove about 2 km to work every day, the battery had to be recharged in the autumn and winter period once a week, and replaced with a new one 2-3 times a year, because it could not withstand such exploitation

carrot wrote:

A friend once had a Ford scorpio with a 2.5TD engine (Italian VM),

it was also like that in Isuzu, but there was and is a quick solution for it. The car after resting must give more than 14V on the battery, otherwise it will be linden.

My comments:
- check the current leakage when stationary; it happened that the immobilizer or alarm consumed a lot of electricity.
- for short city driving, it is best to buy a smaller battery than the nominal one (one model smaller, if you need 50, then take 44) - it is easier, so you can charge it faster.
- starting the engine to start it is electrically negative for a minimum of 20 minutes of driving.
- natural charging of the engine (in one drive, with the car running, with a large battery reaching 12V+ an hour after turning off the engine) requires several hours of driving.
- the energy needed to start the vehicle is only 1-2Ah.
- capacitor batteries are already appearing. That's why.
- I have a new battery, it should last like this for 2 years.

I once read somewhere a very average calculation that for one start of the car it takes about 15 minutes of driving to "send" electricity to the battery. I have accepted this calculation as quite true for many years because it more or less works, and that's it