Battery empty? How to bridge your car properly

Sooner or later every driver gets caught, the car will not start! In most cases, an empty battery is the culprit here. Either you forgot to turn off the lights or the radio when you leave the car, or it's just too cold for your battery. Did you know that a car battery at minus 10 ° C only  can provide about 65% of their actual power?

Bridging a Vehicle correctly

Does this happen in the morning when you have to drive to work, there is no way around to bridge your car. When bridging you connect two vehicles using a jumper cable. When bridging a vehicle safely, however, some points, not least the connection order of the cables, must be observed. To prevent damage to the vehicle electronics, even worse an electric shock, it is important to keep the correct order when connecting the cables.

To bridge a vehicle, you need another vehicle with a charged battery in addition to the jumper cable. The vehicle with the charged battery is used as the energy source.

Before you start the actual process of bridging, make sure that both the vehicle with the dead battery and the energy-giving vehicle work with the same battery voltage. Vehicles with a voltage of 12 volts may only be bridged by vehicles with the same voltage. The same applies, of course, for cars with 14 or 24 volt battery voltage. Mixing different voltages can destroy the electronics of both vehicles!

Now the cars get positioned so that the length of the jump cable reaches from one battery to the other. Depending on where you are, it is recommended, at least for the car with the full battery, to switch on the hazard lights.

When connecting the jumper cable, it is important to note both the colors and the order of the cables. As a rule of thumb: red cable to the positive pole and the black cable to the ground, that is the black pole of the battery. When attaching the cables, it is important to first connect the red cable to the positive pole of the vehicle with the empty battery and then to the energy-giving car. The positive pole can be recognized by the red cover over the pole and the red cable, which leads from the battery into the engine compartment.

Only then the black cable is connected to the negative pole of the car with the full battery and then to the black pole of the vehicle with the empty battery.

If all consumers, such as the air conditioning or the light, are switched off, both vehicles can be started and run for a few minutes. In this way any potential spikes can be better absorbed.

The cables are removed in reverse order. First the black cable is removed on the car with the formerly empty battery and then on the vehicle with the full battery. The same applies to the red cable.

The broken down vehicle should now continue to run and be moved in the best case a few kilometers. So everything comes up to temperature and the alternator can continue to charge the car battery.

Self-help with the Jump-Start Power Bank

But what to do if there is no second car nearby? If you're the last car in the parking lot or live in a remote place, you're on your own in such a situation. Good that you have your power bank with you. Wait, Power Bank? You heard right, a jump-start - powerbank not only lets you charge your phone or laptop. The small powerhouses are the ideal travelling companion and even offer enough power to bridge your empty car battery with the powerful lithium-polymer battery - even several times if necessary. The LED light on the Jump Starter ensures the right illumination of the engine compartment.

The included jumper cables can be connected in the similar way as described above: first connect the red pliers to the red positive pole of the car battery and then the black pliers to the negative pole. Tip: in this case, connect the cable directly to the negative terminal, because there is no spark due to electronic protection when connecting and disconnecting.

After the car has been restarted and the alternator has fully recharged the battery, the power bank can then be recharged via the cigarette lighter or (even faster) at home via the charging power supply.

Charge the Car Battery with the Battery Charger

If you already notice in the evening before that the battery of your car is empty, then it is possible to charge the battery overnight on the mains. Of course not directly, but via a battery charger.

Modern battery chargers have a microprocessor control that automatically recognizes the type of battery and the state of charge. Many models such as the Einhell CE-BC 4 M can therefore be used for gel batteries, AGM, as well as maintenance-free and low-maintenance lead acid batteries and also for both 6 V and 12 V vehicle batteries.

The battery charger is connected in the same way than the Jump-Start Power Bank: the charger is connected to the empty car battery via the insulated pole tongs: the red tongs with the positive pole, the black tongs with the negative pole. In the case of newer devices, the display and the warning light would also alert you immediately if the tongs were connected incorrectly.

Thanks to the microprocessor, the charging process does not have to be constantly monitored, because the control electronics monitor the charging cycle and set the appropriate charging mode as required. In addition, protection against automatic overcharge, short-circuit and reverse polarity protects both the battery and the charger. When the battery is full again, the charger switches off automatically. Of course, even with a safe charger, you should occasionally keep an eye on what is going on when charging.

A battery charger is especially suitable for seasonal vehicles. If you leave your convertible in the garage during the winter, you should leave a battery charger with battery maintenance mode connected. In this mode the battery is charged and discharged permanently. This prevents a deep discharge and thus a defect of the battery. Accordingly, the intelligent charging technology protects the battery and extends battery life.

In a nutshell, the battery charger ensures that Cabriolets as well as motor bikes and scooters start immediately in spring.

In this sense: Safe Journey!

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Picture of the author Hauke Leweling.
Written by Hauke Leweling
Published on 23.10.2019

Whether it's the garden or the workshop, Hauke Leweling is a true all-rounder and a freelance blogger. For Einhell, Hauke is armed not only with pen and paper but also with various gardening tools and equipment that he thoroughly tests. He shares his experiences, as well as tips and tricks, in his blog posts.