How Long to Charge a 12V Car Battery at 6 Amps?

Do you have a drained battery?

Are you wondering whether to charge it at 6 amps or at another charge rate and would like to know how long it takes and how to get the best out of your charger?

In this post, I cover:

  • how long it takes to charge a 12V battery at 6 amps,
  • how to get the best performance using a 6 amp battery charger,

when to use it as well as the downsides to a 6 amp battery charger.

How Long to Charge a 12V Car Battery at 6 Amps?

A 6 amp battery charger takes about 4 – 10 hours to fully charge a 12V car battery, depending on the battery’s capacity, depth of discharge, and battery temperature.

A smaller battery like a 50Ah battery will probably charge in about 5 hours while a larger 105Ah battery is approximately 11 hours.

Overall, you can use this charger to charge your battery overnight.

Note: These are estimates and assume that the battery is only 50% discharged.

A completely drained battery will take a longer time to fully charge compared to a partially discharged battery also.

Good quality chargers also make adjustments to the way the battery is charged, for example, the charging current may be lowered or increased to keep the battery temperature within limits that is necessary for keeping it working as long as possible.

All of these factors – temperature, depth of discharge, and battery capacity affect how long the car battery will take to charge with a 6 amp charger.

How to get the Best Performance from 6 Amp Battery Charger?

#1. Select the correct mode on the charger that matches the battery type

6 Amp chargers can have various modes depending on which battery type AGM, Lithium Phosphate is being charged.

Make sure you select the correct battery type on the charger that matches your battery type so that your battery is charged as required by the battery manufacturer.

Using a battery type selection – AGM or Lithium that does not match your battery type may cause your battery to be undercharged or overcharged!

#2. Switch off car accessories

If you are charging the car battery while it is still installed in the car, make sure that all car electronics are switched off to minimize battery drain otherwise the battery will take a longer time to charge or not charge fully.

#3. Monitor the battery charging

As your battery charges, check on its charge status from time to time and also monitor the battery temperature.

It should be warm to the touch – high battery temperatures are bad and can damage the battery.

Some battery chargers may stop the charging process altogether before the battery is fully charged when they detect that the car battery is not accepting charge as an example, leaving a partially charged battery.


Why to Use a 6 Amp Charger for Your 12 v Battery?

6 amp chargers are good mid-range chargers, are generally cost-effective and useful when you have to charge and maintain batteries with capacities in excess of 40Ah!

For car battery sizes between 40 – 120 Ah, definitely consider a 6 amp 12V battery charger and maintainer.


The Downsides of Using a 6 Amp Charger

  • Slow to charge large capacity batteries

The 6 amp charger can take in excess of 12-15 hours to charge a large capacity battery that has been deeply discharged

If you have a flat battery with a capacity 130Ah or higher and need it charged fast then consider a battery charger with higher amperage.

  • Not suited to maintaining small capacity batteries

While you can use 6 amps to charge the battery, it is high for maintaining the battery in the charged state.

Only use a 6 amp charger to maintain your battery only when it has a maintain feature that supplies a low current to keep the battery in the charged state.

Consult your charger documentation to confirm whether it is suitable to use with your battery capacity.


Can You Leave a 6 Amp Charger on Your 12 v Battery?

No, do not leave a 6 amp charger connected to your 12 v battery over a long period – several weeks, or over the winter to maintain your battery charge unless it has a maintain or float function.

Doing so will wear and damage the battery.

If it has the maintain or float feature, the charger provides 6 amps at peak during the bulk charging phase of the battery and when fully charged, adjusts the charge current to a much lower and safe level to maintain the recommended battery voltage without damaging it.

Avoid dumb 6 amp chargers without the float or maintain feature. These chargers can damage your battery if left connected for a long time!

Confirm that your battery charger type is designed for float or battery maintenance applications before connecting it to your battery for a long period.

Which 12V battery capacity (Ah) for 6 amp battery charger?

50 – 110 Ah battery capacity is suitable for use with a 6 amp charger. It charges this battery size in about 4 – 10 hours assuming it is discharged to only 50% of its capacity.

Confirm that it is suited to charging your battery type (AGM or otherwise) before use.

Related questions

Can You Overcharge a 12 v Battery Using a 6 Amp Charger?

Yes, you can overcharge a 12V battery with a 6 amp charger that constantly charges a peak current of 6 amps regardless of what state of charge your battery is.

Use a good quality 6 amp smart battery charger and maintainer suited to your battery type (AGM, wet, or Lithium) that makes adjustments to the actual voltage and current to avoid overcharging and damage to the battery.

Final Thoughts

A 6 amp car battery charger charges a 50-110Ah car battery, discharged to 50% of its capacity in about 4-10 hours.

The actual time to charge depends on how deeply discharged the battery is its age, capacity, and temperature.

You can leave your battery charger connected to the battery for an extended period provided it has the float or maintainer feature that adjusts the current to a safe level that maintains it in a fully charged state.

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