How Long to Charge a 12V Car Battery at 50 Amps?

Is your battery drained? Are you considering charging it with a 50 amp charger and wondering if it is safe and how long it will take to charge fully?

In this post, I cover:

  • how long it takes to charge a 12V battery at 50 amps,
  • whether it is safe to use
  • which features to look for in a 50 amp charger
  • which battery sizes (Ah) to use with a 50 amp charger

How Long to Charge a 12V Car Battery at 50 Amps?

A 50 amp battery charger takes about 45 minutes to fully charge a 12V, 50 Ah car battery, assuming it has been discharged to 50% of its capacity.

The actual time to fully charge depends on the battery’s capacity, depth of discharge, and battery temperature.

Battery capacity (Ah)

A 100Ah battery will probably charge in about 1.5 hours while a 2,000Ah battery bank will take approximately 30 hours to fully charge.

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.

Depth of discharge

If the battery bank is more deeply discharged, the 50 amp charger will take a longer time (than the time estimates provided) to fully charge.

So, all the factors – temperature, depth of discharge, and battery capacity combined contribute to the actual time it takes to charge a car battery with a 50 amp charger.

Is It Safe to Use a 50 amp Battery Charger?

Yes, it is generally safe to use a good quality 50 amp battery charger with at least a 50Ah battery or larger.

Confirm that it has the auto-shutoff feature to stop or reduce the charging current when the battery is fully charged if you plan to leave it connected for a long time.

Additional Tips to Safely Charge Car Batteries

  • Connecting smaller battery sizes less than 50Ah risks damage to them from the higher than recommended bulk and float charge currents that can cause damage to the battery.
  • Minimize the likelihood of an explosion by charging the battery in a well-ventilated area.

If the charger lacks temperature compensation or the battery is likely dead, monitor its temperature periodically and be ready to switch off if the battery is too hot to the touch.

  • Only connect battery types that your charger supports
  • Do not charge damaged or frozen batteries

When to Use a 50 amp Battery Charger?

Use a 50 amp battery charger when you need to quickly charge larger battery banks at least 50Ah.

For example, a 10 amp charger will charge a 100 Ah battery (50% discharged) in about 7 hours compared to a 50 amp charger which takes only 1.5 hours ( over 4 X the speed!)

What to Look for in a 50 amp Battery Charger?

When choosing a 50 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.

4 Tips to get the Best Performance from 50 Amp Battery Charger

#1. Only connect to battery banks at least 50Ah and larger to avoid the dangers of overcharge with the smaller capacity battery banks.

#2. Only connect supported battery types and make sure that the correct mode on the charger that matches the battery type is selected

50 Amp chargers can have various modes depending on which battery type AGM, Flooded, Lithium-ion Phosphate is being charged.

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.

#3. 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.

#4. Monitor the battery during charging

During the charging process, do not leave the charger and battery unattended. Instead, monitor the battery temperature periodically.

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

Be ready to switch off the charger if the battery is hot to touch!

Can You Leave a 50 Amp Charger on Your 12 V Battery?

If you have a good quality 50 amp charger with a maintain or float function and are charging a maintenance battery at least 50Ah or larger, then you can leave it connected to your 12 v battery.

This is useful if you plan to leave the car parked for an extended period without the worry of overcharging and damaging your battery.

Avoid 50 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 50 amp battery charger?

In general, you can use the 50 amp battery charger to charge battery sizes 50 – 2,000 Ah (this is a guide – consult your charger manual to confirm).

It should be able to fully charge the battery in about 45 min – 30 hours (based on 50 – 2,000Ah) assuming it is discharged to only 50% of its capacity.

Related questions

Can You Overcharge a 12 V Battery Using a 50 Amp Charger?

Yes, you can overcharge a 12V battery with a 50 amp charger that constantly charges with a peak current of 50 amps regardless of what state of charge your battery is or you connect a smaller battery bank like 10Ah!

Use a good quality 50 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 50 amp car battery charger charges a 50 – 2,000Ah car battery, discharged to 50% of its capacity in about 45 min – 30 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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