How long does it take to charge a 150 AH inverter battery?

Most of us use a 12 Volt and 150 AH inverter battery in the home to continue electricity supply even if there is an outage for some time. This single battery configuration is used by masses universally, that is why I’m covering the specific one.

So, have you ever thought about how long it takes to charge a 150 AH inverter battery?

In this article, I’ll explain the same and show you the formula to calculate it.

TLDR; it takes around 13~14 hours to charge a 12 Volt, 150 AH battery.

How? Here is the explanation, read it carefully as there are calculations involved…

First, understand the C rating of a battery.

The battery C rating is the measurement of the current at which a battery can be charged and discharged. Usually we see C5, C10, and C20 ratings.

In the inverter, most of us use 12 Volts — 150 AH and that come with C10 battery.

Time = AH ÷ I

Battery’s AH rating is 150 AH. Now we just need current for further calculations.

Also check out — How to calculate battery charging current and time?

The Current (denoted by I) needed to charge the battery is AH ÷ C# (in hours).

I = 150AH ÷ 10H = 15A.

So, applying the time formula:

Time = Ah ÷ I
     = 150AH ÷ 15A
     = 10 Hours (theoretical, without battery's efficiency).

A battery requires a little more current, like 1+ or 2+ Amps more, to charge the battery; otherwise the battery won’t be able to charge itself completely.

So I added 1 more Ampere to the rated value.

Time = Ah rating / I
     = 150 Ah / 16 A
     = 9.375 Hours (without battery's efficiency).

If you want to calculate exact hours, just add more than 40% loss because lead-acid batteries are only 60% efficient.

So here I am adding 40% more time to the formula:

= 9.375 Hours + (9.375 Hours * 40%)
= 9.375 Hours + 3.75 Hours
= 13.125 Hours ~ 13.5 Hours.

So, to charge a 12V 150 Ah battery, it will take around 13.5 hours of charging. If you have a different configuration of battery, do calculate the values using the above formula.

Frequently Asked Questions.

Q: What if I am of using 2 batteries of 150 AH in series or parallel.

A: If batteries are connected in parallel, the Amps will double. If connected in series, then AH and Volts will double. Similarly, additional charging current may improve.

Q: I am using a solar setup, but I only get 6–7 hours or less of clear sun. Still, the charging time will be the same. Or there are other things that I should consider.

A: Yes, just make sure the whole time it is generating enough charging current. The above formula is using DC current, not the AC current. So make sure the solar system generates more than 15–16 Amps of DC current all the time. PWM charger may need more current as it will straightaway cut the 30% of the current to match the solar with battery.

Do you have any other queries? Do let me know in the comment section below. I’ll try my best to answer all of them or you can read related contents to same topic.