How Long to Charge a 12V Car Battery at 10 Amps?

Having an idea about how long it takes to fully charge a car battery with a 10 amp charger is important.

For instance, it can help you decide when to expect the battery to be fully charged.

You may be wondering if your battery will be charged overnight.

Knowing why the actual times may vary from the indicated times is also helpful as it is easy to think it is a fault with the charger when it is not.

In this post, I cover:

  • how long it takes to charge a 12V battery at 10 amps,
  • whether it is safe to use
  • which features to look for in a 10 amp charger
  • which battery sizes (Ah) to use with a 10 amp charger

How Long to Charge a 12V Car Battery at 10 Amps?

A 10 amp battery charger takes anywhere from 1.5 – 17 hours to fully charge a 12V car battery, depending on the battery’s capacity, depth of discharge, and battery temperature.

Battery capacity (Ah)

A smaller battery like a 20Ah battery will probably charge in about 1.5 hours while a larger 230Ah battery is approximately 17 hours.

Note: These are estimated charging times that assume that the battery is only 50% discharged. A flat battery will take a longer time to fully charge compared to the times above.


You can expect slight variations in the actual time depending on the battery temperature.

Good quality chargers make slight adjustments to the full charge voltage – slightly lowering it when the battery temperature is high and increasing it when it is lower to extend the life of the battery.

All of these factors – temperature, depth of discharge, and battery capacity affect how long the car battery will take to charge with a 10 amp charger.

Is It Safe to Use a 10 amp Battery Charger?

Yes, it is generally safe to use a good quality 10 amp battery charger with your battery provided that it has the auto-shutoff feature to stop or reduce the charging current when the battery is full and adjusts the charging rate depending on the battery temperature.

Also, in general, check and implement the recommended safety precautions for charging batteries.

For example, make sure that you charge the battery in a well-ventilated area and monitor the battery temperature periodically.

The 10 amp battery charger is ideally suited to battery capacities 20 – 230Ah.

What to Look for In a 10 amp Battery Charger?

When choosing a 10 amp battery charger, in addition to looking out for a well-regarded charger based on genuine user feedback, consider selecting one with the following additional features.

Ability to charge dead batteries or batteries with low voltages – batteries whose voltage is as low as 1 volt or less.

This is particularly useful when you have a dead battery. Some chargers are not able to charge batteries with a voltage that low.

Look out for a charger that is able to charge various battery types such as AGM, Gel, Lithium, or Flooded batteries, or at least the types you have.

You can take comfort in being able to charge the different battery types without buying another charger.

How to get the Best Performance from 10 Amp Battery Charger?

#1. Confirm that the correct mode on the charger is selected that matches the battery type

10 Amp chargers can have various modes depending on which battery type AGM, Flooded, 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.

#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, monitor the battery temperature especially if it does not have temperature compensation. It should be warm to the touch – high battery temperatures are bad and can damage the battery.

When to Use a 10 Amp Charger for Your 12 v Battery?

If you have battery sizes in the 20 – 230 Ah range and are looking for reasonably fast charging times then definitely consider a 10 amp 12V battery charger and maintainer.

Can You Leave a 10 Amp Charger on Your 12 v Battery?

If you have a good quality 10 amp charger with a maintain or float function, then you can leave it connected to your 12 v battery if you plan to leave the car parked for an extended period without the worry of overcharging and damaging your battery.

Avoid 10 amp chargers without the float or maintain feature. They can damage the battery if left connected for a long time!

Which 12V battery capacity (Ah) for 10 amp battery charger?

In general, you can use the 10 amp battery charger to charge battery sizes 20 – 230 Ah (this is a guide – consult your charger manual to confirm).

It should be able to fully charge the battery in about 1.5 -17 hours (based on 20 – 230Ah) assuming it is discharged to only 50% of its capacity.

Related questions

Can You Overcharge a 12 v Battery Using a 10 Amp Charger?

Yes, you can overcharge a 12V battery with a 10 amp charger that constantly charges with a peak current of 10 amps regardless of what state of charge your battery is.

Use a good quality 10 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 10 amp car battery charger charges a 20 – 230Ah car battery, discharged to 50% of its capacity in about 1.5-17 hours.

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

If the charger has a float or maintainer feature, you can leave it connected to the battery for an extended period without worrying about overcharging and damaging it.

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