Why a Trickle Charger may not be Charging the Car Battery (With Solutions)

If your car battery is drained, not able to start the engine and you have a trickle charger then you might want to hook it up to the battery to revive it.

Now the results you get may be mixed. For example, the battery charge level may not change even after several hours of charging with a trickle charger.

Does it imply that the battery is damaged and should be replaced? Is there another way to revive it??

This post explores why a trickle charger may not be able to charge the car battery and also shares some solutions that may help you get the battery working again.

Why Your Trickle Charger May Not Be Charging the Battery (6 Reasons)?

#1. Weak or improperly connected trickle charger cables. Confirm that the charger is properly connected to the car battery terminals. The charger clamps should firmly connect to the battery posts.

Remove any corrosion that may have formed and is restricting the flow of current to the battery.

Also, confirm that the charger cables are connected the right way (no reverse polarity connections).

Is the positive clamp of the charger connected to the battery positive and the negative to the battery negative terminal?

If there is a reversal of connections the battery will not charge.

#2. Confirm that the charger is properly connected to and receiving power from the outlet. Check the trickle charger power source. Is the charger plugged into the outlet?

You can confirm that the charger works by connecting to another battery. It saves you time if you confirm that the charger works as expected.

#3. Batteries exposed to extreme cold temperatures do not accept charge easily. Has the battery been exposed to extremely cold temperatures? If so, consider as a first step, move it to a heated room for about 24 hours before attempting to charge it again.

Note, there is no guarantee if the battery will be revived and if so, how long it will last.

#4. You need to allow a trickle charger sufficient time to charge a battery. Some trickle chargers are only able to supply up to 1 amp of current.

If the battery is severely depleted, considering a 50 Ah battery, you may need at least 2-3 days to get it charged again. If using a 1 amp charger, for instance, consider limiting its use to batteries of up to 30 Ah.

Use an external charger with a higher charging current to speed up the charging process.

You may also be interested in this post: Should you leave a solar trickle charger connected to the battery? How to prevent damage to the battery

#6. The battery may be dead. A dead battery will not be able to accept or hold charge. You can have the car battery tested at a reputable car repair shop.

If confirmed as damaged, replace it. If it is still under warranty, you can get a replacement.

How to Tell if A Trickle Charger Is Working

Trickle chargers may have a visual display of LEDs that show the charge status and level of the battery.

Check that the trickle charger does not have any error messages. These show that the charger is not charging properly.

Additionally, using a good quality digital meter, you can measure the battery voltage periodically.

Since the trickle charger is a slow charger, the intervals should be long enough for you to note a sizeable change in battery voltage.

For example, at a charge rate of 1 amp, after 5 hours, the battery capacity change will be about 5 Ah which works out to be only 10% of the capacity of a 50Ah battery.

What you can do if a trickle charger does not charge a battery

trickle chargers supply a small current and in fact, are designed to maintain charge of an already charged battery.

If the trickle charger does not work, consider the following:

#1. Boost the car battery using a set of jumper wires or a battery jump starter and drive the car for 30+ minutes as a temporary measure.

This is faster than waiting on a trickly charger to charge the battery. If the battery has been severely depleted, you’ll need to arrange to charge it fully.

#2. Use an external charger with a higher charging current. You can also use a good-quality car battery charger with charging currents in the range of 3-10A to charge the battery.

Make sure the charger is set to charge your car’s battery type (AGM or otherwise) otherwise the battery may not charge fully.

#3. You may need a new battery. Even when you are able to charge and start the car, in some cases, the battery may have suffered permanent damage and need to be replaced.

For example, If the battery still does not hold charge and drains quickly even after it has been fully charged, then it might be time to get a new battery.

You can confirm by arranging for the battery to be tested before you purchase another.

Related questions

Will a Trick Charger Charge a Dead Battery?

There is no guarantee that a trickle charger can and will be able to revive a dead battery.

In some cases, some car owners have reported using trickle chargers to charge the car batteries again after several days but it’s probably not the most effective solution.

Trickle chargers in general are designed to maintain the charge of fully charged batteries and can take too long to charge. use an external fast charger with a higher current of 3-10 A for faster results.

You may also be interested in this post: Can you charge a dead battery?

How Long It Takes a Trickle Charger to Charge a Battery

The charge time depends on the battery capacity and to what extent it has been discharged. The larger the battery or the more discharged it is, the longer it will take to charge.

The table below shows indicative charge times for selected batteries using a 1 amp charger. This assumes that the battery has only been discharged to 50% of its capacity.

NoBattery Capacity (Ah)Charge time (hours)
Source: Adapted from the Noco Genius 1 amp charger

Final Word

Trickle chargers are slow chargers. They are designed to maintain the charge of already charged batteries.

If a trickle charge is not charging the car battery, you can check that charger is properly connected to the battery, it is receiving power from the outlet and the battery is still in good condition.

A dead will not accept charge and needs to be replaced.

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