There are times when the battery discharges itself and we don't know why. The car hasn't been sitting for long, we didn't leave anything on, it's not an old battery and yet the car won't start. The problem that may be behind it are the known current leaks or parasitic or abnormal consumption battery.
Here we are not the ones who have abused electrical consumers with the engine off. Nor is it that we constantly start and stop the car, without letting the battery get charged. It is that some component of the car continues to consume energy with the car stopped and closed.
When this happens, the car battery discharges unexpectedly quickly. It is a common breakdown in vehicles that are older or in which the electrical system has been touched. For example: to place a new sound system, a Bluetooth hands-free, a universal central locking...
How to know if there are current leaks or parasitic consumption?
In the next video After 6 minutes, we explain each step in detail:
Or if you prefer, here are the steps in writing to locate current leaks:
- The first is locate the fuses. The most common is to find them in the engine compartment itself. But there may also be another fuse box on the left side of the dashboard, behind the glove box, or at the bottom of the center console.
- check that he has not stayed in the car nothing on that can alter the measurements: radio, lights, ignition on, open doors... Lock the car with the key so that it turns off completely. If we are going to look at fuses inside we will have to leave a door open, so we have to trick the car by pressing the door button to make it believe that it is closed. Even if the interior lights did not turn on, there could be a witness or on-board computer that consumes and deceives us in the measurements.
- Next, we must disconnect the negative terminal of the battery, (with the positive it is easier to cause a short circuit). For this we will need a small wrench, fixed or ratchet of the appropriate size. It is easy to have some of them at home.
- The next step is to get into the skin of an electrician. Us you will need a multimeter to detect current leakage. There are many prices but for 15 or 20 euros you already get a suitable one. In the measuring instrument we will place the black cable in the common port (COM) and the red one we will put it in the plug that allows the greatest intensity to be measured (Amps), normally identified with the inscription 10A, 20A, 30A ó 40A.
- Then we will put one of the measuring tips of the tester in contact with the cable that we have released. While the other will be placed on the battery terminal that we have left free. This is done this way, because to measure intensity it is necessary to do it in series. In other words: opening the circuit and interposing the multimeter to measure the intensity of the current that passes through it.
- At this point, the multimeter will already give us a measurement. A normal value of consumption with the car stopped, it should be around 0,05 A. If it shows a value greater than this, it means that there is some parasitic consumption draining your battery.
- The way to proceed below is simple. It's time to remove the fuses one by one to check whether the intensity value decreases. We put it and remove another. So with all until the ammeter shows a normal value or we see that the intensity drops (it could be that there were several current leaks).
- If when removing a fuse, consumption returns to a normal value (current leaks disappear), we have located the problem. It will suffice to consult which system corresponds to the fuse that we have removed, in the car manual.
Car battery consumption by alternator
What if we check all the fuses and we don't find the problem? In that case. it would be quite likely that what was eating dinner every night at the expense of our battery it was the alternator, due to a fault in the rectifier diodes. To check it, we will connect the battery terminals as they were before starting all the checks.
the best you can do first is to check if it is capable of charging the battery. This will completely rule out the possibility of it being an undercharging problem, rather than a battery discharge problem. Something that can be caused by the alternator itself or just its voltage regulator. In the article how to check the battery and the alternator you have everything.
Once this is ruled out, the steps are simple:
- configure the multimeter in Amps and DC
- The check consists of releasing the alternator terminal (which goes directly to the battery positive, red), to open the circuit and be able to put the multimeter in series. That is, a measurement point on the alternator terminal and another on the cable, so that the current passes through the multimeter.
- In this way, if we have a current leak greater than 0,5 A, it means that we will have to go through the workshop to repair or replace the alternator.
If you do not have time to follow these steps and you want an immediate solution, we will explain below how to start car with dead battery and what is its price if you finally decide to change it in case it is in poor condition.
Starting with a discharged battery due to current leakage
In case you have run out of battery and you have to start the car yes or yes, there are several options to achieve it. It will depend on the conditions you have at the moment.
Jump start a car with a dead battery
If you have some pliers and a good samaritan who will let you connect them to his car battery, you are in luck. This is the easiest and least damaging method for the different parts of the car. Just follow the steps in order:
- Park both cars with the engine compartment close without touching any part of its bodywork.
- Place the cars in such a way that the cables of the battery clamps reach the battery.
- Open both hoods. Normally your batteries will be covered with a cover, so discover both batteries.
- Once you have the cars ready, it's time to use the clamps. You should first connect the positive poles of both batteries. Take the red clips and hook them to the pole with the “+” symbol on each battery. First in the car that is loaded and then in the unloaded one.
- Put the black cable in the negative pole (“-”) of the car that has a charged battery.
- Start the car that will donate energy.
- Put the black cable in the negative pole (“-”) of the car with a discharged battery.
- Start the car of the discharged battery.
- Remove the tweezers:
- First, those of the negative pole. Start with the unloaded car and then remove it from the loaded one.
- Second, those of the positive pole in the same order. That is, first the unloaded car and then the loaded one.
- Recover the two batteries with their covers and close the two hoods.
Keep in mind that if your car has a discharged battery it will have to work for a while to load it again. If even doing this it does not start again, it means that the battery is not in good condition and must be replaced.
Start the car by pushing
If you don't have clamps or there is no other car to connect your battery to, you are left with the option of start the car by pushing. It is less advisable because the catalytic converter or some part of the engine can be damaged, although we have tried it and have not had any problems. you will have to be at least two people to do it comfortably. Follow these steps:
- The person behind the wheel must leave the ignition key turned to the on position.
- You should also depress the clutch and put second. leave the clutch depressed
- The outside person or persons must push the car
- When you reach enough speed you should release the clutch and accelerate a little.
- Once turned on, do not turn it off because your battery is still discharged. It will only charge after driving for a while.
Note: You have to take into account that in diesel engines it is more difficult because they work with a higher fuel compression ratio and you have to exert more force to reach that point by pushing the car. It will be of great help to put the car downhill, but always keeping safety in mind, since with the car off the brakes will not work properly.
Starting the car downhill with a dead battery
The steps to start the car downhill are the same as pushing, but you have to take into account a couple of things so as not to take any risks. The slope will do the work of people pushing, but don't forget that If the car won't start, the brakes won't work right. (something not recommended if you go downhill). Normally, when the car is off, there is brake fluid left in the circuit that connects the pedal to the brake calipers, so you will have one or two stops before it empties, the pedal becomes hard and you can no longer brake.
For us the most important thing is road safety, so we advise against using this method except in highly controlled environments. That is to say, a private space, where no one passes and there is enough flat area after the slope. It is better to call a friend with a car and pliers or a tow truck. The most normal thing is that your insurance includes this type of assistance. We repeat the steps adapted to this method:
- Leave her ignition key turned on.
- Step on the clutch and put second. leave the clutch depressed
- Take off the parking brake for the car to go down the slope
- When you reach enough speed you should release the clutch and accelerate a little.
- Once turned on, do not turn it off because your battery is still discharged. It will only charge after driving for a while.
How to charge a dead battery
The fact that your car battery has been discharged does not mean that it has to be replaced directly. It may be the result of leaving the lights on all night or, as detailed at the beginning of this article, having abnormal electrical consumption with the car off. If your case is any of these, start the car with pliers (or one of the other methods) and circulate for a while to charge it.
To be sure, the best way is circulate at constant revolutions for a quarter of an hour. For example, take a ride on the road or highway 2.000 rpm or more would be fine. Another option to charge it without having to start the car is to use an external battery charger. You can buy one for little money.
If after doing this, the battery still has no power to start the car, it means that it is no longer in good condition and needs to be replaced. In some cases, liquids can also be refilled, but there are batteries cheap enough to avoid this method, such as the ones we show you in this buying guide to choose from best car battery charger.
price of a car battery
The price of a car battery varies a lot depending on the type we need. From the battery needed for a small car that can be from 50 euros to 250 euros or more for large displacement cars. It also affects its price, if it is intended for a car with Start / Stop system. If so, you will need a higher capacity battery, to be able to start at each traffic light where the car stops. We recommend the article What battery do I put in my car?, to choose the most suitable for your model.
The fact that the engine is diesel can also affect the price of the battery, since by requiring more force to start you need a battery with more capacity. We recommend that you call and compare prices between workshops so as not to pay more than the bill. It won't take you more than a few minutes.
How to change a battery damaged by current leaks
If your battery has had abnormal electrical consumption for a long time, the most common thing is that it ends up deteriorating. We recommend the article How to check car battery and alternator, to make sure that the time has come.
If it is indeed time to change it and you want to do it yourself, it is one of the easiest operations in most models. You just have to take into account the security measures and, if necessary, how to maintain the car's memories. Take a look at the article How to change the car battery.
More information about this model
- Plazas 5
- Power 122 - 186 hp
- Consumer goods 5 - 6,1l/100km
- Assessment 4,7
The procedure that you do to measure consumption is valid for old cars, but loosening a terminal in a modern car means that you have to reprogram the battery code in the control unit. For example, if you remove a terminal on a 6 A2009 or any European car with Start and Stop, the brown lias, if you don't reprogram
Good afternoon Daniel. I do not know the case that you mention, but of course it is not something extensible to all modern cars or with Stop & Start. I have worked in an official service and no car of the PSA Group or of other brands that has been manipulated in any way that has disconnected the battery has had to do more than adjust the clock and the radio.
A greeting.
The measurement with the multimeter in amps, disconnecting the terminal to measure the passage of these has many drawbacks! 1 you are resetting the pcm so it would sleep the open circuits and would not mark the problem. Also if you remove fuses... at each connection and disconnection you generate activation pulses that will modify the measurement. The method that you should use is a simple amperometric clamp: «without disconnecting any terminal» !! You can test it first on the terminal, then measure the cable that goes to the alternator (and make sure there are no damaged diodes) then test the donkey and the rifle. If the consumption at rest is high (more than 0,1 amps – normal would be up to 0,5 amps) with the milliampere multimeter, it tests each fuse which ones are active and thus detects the discharged circuit.
The measurement with the multimeter in amps, disconnecting the terminal to measure the passage of these has many drawbacks! 1 you are resetting the pcm so it would sleep the open circuits and would not mark the problem. Also if you remove fuses... at each connection and disconnection you generate activation pulses that will modify the measurement. The method that you should use is a simple amperometric clamp: «without disconnecting any terminal» !! You can test it first on the terminal, then measure the cable that goes to the alternator (and make sure there are no damaged diodes) then test the donkey and the rifle. If the consumption at rest is high (more than 0,1 amps – normal would be up to 0,5 amps) with the milliampere multimeter, it tests each fuse which ones are active and thus detects the discharged circuit.
Sorry for the typing errors... although there are several, the main one that I must amend is that... the maximum idle consumption is 0,05 Amps and the maximum tolerable in cars with accessories, etc... is 0,1 Amps. For example A Peugeot 308 consumes 0,02 ..and a VW with I Motion box 0,03 amps. Hug.-
Thank you Ochoa ⛄
You're welcome Frankie. I hope it has been helpful to you.
All the best
Hi Inigo. Thanks for the post.
I just wanted to make a comment: I think there is an error in the consumption that you write down as normal (0,2 A). Actually it should be "0,02 A".
If the consumption is "0,2 A", a 70 Ah battery would discharge in 350 hours (= 14 days). And that is by no means normal.
From what I have read in other similar articles, consumptions of 20-30 mA (= 0,02 – 0,03 A) are considered normal. And a consumption above 50 mA (= 0,05 A) is considered "leakage"
A greeting!
I agree with Cimanes…leakage consumption 0,05 A
Hello, I wanted to make a query, you will see I have mounted a Chinese double DIN in my car and it turns out that it discharges the battery, I have read on the internet that this can be solved by placing a non-return diode in the positive of the radio, if this is so, what value would it have to be said diode someone can help me thanks
Hello John
Were you able to solve the problem with the stereo and discharge the battery?
I have the same problem with an S 160 system in a 1.6 Ford Focus TDCI 2010
Hi, I'm going to make you a little note.
I think you have ignored the issue of control units and the time they take to "fall asleep", this issue can be misleading, since while they are operational the consumption can be 0.6amp or higher and after a while after closing the circuit (activate the battery) they disconnect themselves and the consumption drops to the real value.
The disconnection time of the control units varies according to the make and model of the vehicle.
Therefore, once the tester clamps are placed, when the circuit is closed, we must wait a reasonable time for the control units to stop consuming, only then can we check the masked consumption of the vehicle.
Raul, I agree with your point, since it is true that the car goes to "sleep" after a certain time. But you don't have to take it literally either, since during the test you're going to be disconnecting fuses that have little to do with the car's sleep mode. I've done it once and with this way you end up finding the circuit that derives from having a sudden change in consumption as soon as you remove the fuse. It would be bad milk if the exact moment of removing the fuse coincides with the switchboard going into sleep mode 🙂
Yes sir, it would be a lot of coincidence, but my note was on the other side, for example my case, a seat ibiza in which the consumption at rest was 0.8 and came from the central locking switchboard, when removing the fuse it went down to 0.01 , but it is that waiting several minutes the effect was the same, she alone stopped consuming and went down to 0.01. That "deception" I was referring to.
Finally, the problem turned out to be that the said control unit activated itself and continued to consume the battery, "solved" by Seat with a software update that prevents the control units from being activated again once the car is stopped.
Hello, I hope someone can help me: I have a 2002 Acura RSX Type S 6 Speed and the problem is that after I ordered it to change the timing chain, I used it for a couple of weeks and then it didn't want to turn on. This was about 7 months ago. they have not found the fault; after changing the battery, the alternator 2 times each, the cables that go from the battery to the alternator I checked the computer several times, I took it to the Acura dealer and they don't find anything, if anyone has an idea what it can be I would appreciate it
Hello, blessings, I wanted to see if someone could help me. I have a problem with saab 2006. My battery is discharged. I already checked the fuses or everything is fine, the lights are off, but if the problem?
hello I have a citroen I disconnect the battery and it discharges the same way I use it only on weekends on the way back the alternator will be repaired, the battery is 2 years old the use has been that, I want to know what could be the problem
Hello, I have a problem with the battery of my symbol 2005 (clio sedan version) the battery discharges itself and I have not been able to find the problem, I have already checked the voltage fuses and apparently, everything is fine and when I start it it does not turn on, it tries to start but it hangs, I have to start it with another battery and after a while it works normally, someone has already found the solution????
hello a question pork I start the coxe I'm with it and if I turn it off it doesn't start again I have to leave it for at least 1 hour until it returns to load in off
Hello friends !! ,My query is as follows, I have a Senda 93, don't charge me, I can't take it anymore hahahaha. When I turn on the car, the oil pressure light flashes and when I start the engine it turns off normally. Why does it blink when contact is made if it should be completely on? Thanks in advance, friends.
The oil pressure light flickers when I turn on my Senda 93 and goes off when I start the engine. I think the light should always be on when I put the contact on and not flicker. I put the oil pressure bulb terminal to ground and it keeps flashing. What can it be, friends???
Hi Inigo. Thanks for the post.
In my case, the consumption was 0,1A or what is the same, 100mA.
Alternator OK. Fuses OK.
The problem was the starter motor.
By disconnecting the thick cable from the starter motor, the consumption has dropped to 5mA or 0,005A.
The only consumption it has is the clock.
This car does not have any electronics.
Everything is mechanical and there is no switchboard.
Toyota Land Cruiser 2.4 TD from 1991.
Hello, excuse my ignorance on the subject, just a question when a fuse is removed to measure its amperage, how to put the red and black tips of the tester, thanks in advance
Hello, thanks for the first explanation, which is very clear, the details said later are due to different specific experiences, in mechanics you can never generalize there is a lot of detail involved.
In my Nissan d21 year 97 (super basic), the battery discharges only sometimes and in the morning, check consumption and it does not have, detect that the alternator charges only when accelerating, it is not the belt.
WHY IS THE BATTERY DISCHARGED IF THERE IS NO CONSUMPTION? THANK YOU
If the negative terminal of the battery is disconnected, is there still any electricity consumption even if it is minimal?
Hello! I try to measure by disconnecting the negative terminal by putting the multimeter in series (placing the tips and terminals as you indicate) but it does not indicate any consumption. However, the battery lasts me a maximum of two weeks. Could it be that the multimeter is failing to read intensity (if I measure voltage it gives correct readings). Thank you!
Hello. My truck turns on
añarma alone and the radio.
pressing the remote
I control her again. And the next day the battery appears discharged.
I must say that the battery only has. 4 months of use and this is the second time it has happened.
I don't know if it has anything to do with it. But
this happens on rainy days..
The alternator appears to be fine. Someone explain me !
Thank you .
«To make sure, the best way is to circulate at constant revolutions for a quarter of an hour. For example, going for a spin on the highway or highway at 2.000 rpm or more would be fine.
«I just wanted to leave my opinion on this part of the explanation that was given, clarifying that the battery still charges while in one place, without the need to take a turn on the highway... better to stay at home and charge it in the way that is explained , maintaining an acceleration of 3 to 5 thousand rpm.
The alternator of my car has broken down, I have taken it to a workshop and they have put a new one with its belt. The next day, I was left lying on the road without a battery. What can this be? is it a problem with the new alternator? of the strap? or battery? I have a milk rage.
I had the same problem, in the end a man told me exactly the method and talking and talking I told him that I locked the car without the remote control in the garage...we tried without remote control using the parasite method and there was 0,05A consumption...then we tried closing with command and
zero consumption…so for some cars you have to close with the remote since the system
It's looking for the key and it's on standby.
Hello, I read in your article that to start a vehicle without a battery, with the help of another vehicle, you have to first connect the black cable (-), but nevertheless in other posts they say the opposite, that first the red cable (+), Could you explain the difference and why this is so?
Thank you. Regards
The negative must be disconnected first when bridging with the clamps, since there is less risk of making a short circuit, when touching the ground. And the voltage peak that is generated when the batteries are connected and disconnected is absorbed in the negative, and not in the positive, which is what feeds the electronic modules, which can be affected by said voltage peaks.
The procedure for starting with tweezers is wrong... It says that we start connecting the batteries through the negative pole when it is totally the other way around, we start with the positive. In fact, a few lines below it is well stated how to disconnect them once the work is done.
Good Jose. Thanks for the warning. We have modified the article.