How do I know how "full" in % my battery is?

[Alexander]

Hello guys,

So if I have a lead acid battery 12v and 60Ah, how can I know when it is 50% full? Which would mean I have to stop using it and let it charge again. On the charge controller you can see the volts but not the %, is it a device I can use to see in %, if yes, how does it work, how can I fix it to the battery? If not, how can I know using the volts?

 

[GMB]

You can use duckduckgo.com and type in 12 volt lead acid state of charge and look at the images for a general chart. Your battery manufacturer may have a state of charge chart on their website for your particular battery.

If you want a device, Victron makes a battery monitor (I use a BMV-712) that uses a shunt that will give you the state of charge in a percentage amount. Other less expensive options are also available, however I am only familiar with the Victron unit. I know Will did a video on a cheaper option about 6+ months ago or so.

Edit - here is Will's video on the cheaper option:

 

[Steve_S]

This guide will explain most of what you want to know and what will ask in the future.
Lead-Acid Battery Care - Solacity Inc.

With Lead Acid batteries the only accurate way to know SOC is by testing the Acid with a Hygrometer. Using voltage to gauge DOD is normally how it's done but with caveats. Surface charge on Lead Batteries can throw off the actual State and result in issues. If water levels are low, this will also affect the charge capacity and rates.

Terms such as SOC (State of Charge) and DOD (depth of discharge) are interpreted slightly differently with the battery chemistries. It IS a PITA ! I run with both Heavy Lead deep cycles & LFP and I have to flip thinking between the two... screw-ups can result in unpleasantries.

 

[Alexander]

You can use duckduckgo.com and type in 12 volt lead acid state of charge and look at the images for a general chart. Your battery manufacturer may have a state of charge chart on their website for your particular battery.

If you want a device, Victron makes a battery monitor (I use a BMV-712) that uses a shunt that will give you the state of charge in a percentage amount. Other less expensive options are also available, however I am only familiar with the Victron unit. I know Will did a video on a cheaper option about 6+ months ago or so.

Edit - here is Will's video on the cheaper option:

Okay thank you very much.
Let's say I have this thing:

How would I connect it with the battery? Do I first have to connect it with charge controller? And where on it? Because I saw the video but I didn't understood how he connected the device with the battery.