Multimeter on battery help

[Maund]

So I've just bought a multimeter to measure my leisure battery for the pump.

I have no idea on which setting on the multimeter I should be using to check the level of the battery

Any help? Thanks.

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[Guest]

You could measure voltage by putting meter onto 20v. This will give you an indication of battery but does not represent amp hours which is what you're after.

good luck!

 

[Maund]

Thanks, just done that and it comes up with 12.41 now to find out if that's ok haha


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[spruce]

Your multimeter must be pointing to the 'v' with a straight line after it. That depicts DC which is direct current. The v with a wavy line is for alternating current and you don't use that.

You can only determine a battery's state of charge once you have left it to rest for about 4 hours.

A fully charged battery will record 12.7 volts or higher (12.8 to 12.9v).

75% charged = 12.5v

50% charged = 12.4v

25% charged = 12.2v

Fully discharged = 12v or lower.

 

[Maund]

Thanks for the help, going by that my battery is at 50%


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[spruce]

Thanks for the help, going by that my battery is at 50%


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At first glance that appears to be correct. But if you've had something running off of it recently then the battery might recover up a point which means it could be 12.5 and 75% charged.

When we are driving along the volt/amp meter we have across the battery terminals will show between 14.2 and 14.5v of charge (not amps - the flatter the battery the higher the inputs amps are.) Once the engine is switched off that high voltage very quickly drops, but as it gets to the lower 13v range it takes longer to drop a point.

As a guess you won't be far off if you took a reading after about 2 - 2.5 hours of complete rest. But you have a more accurate volt meter registering to 2 decimal places. The meter on the van is to 1 decimal place. I once checked the volt/amp meter for accuracy against my multimeter and tbh, it was pretty close.

 

[Maund]

Battery is reading 12.11V been charging it with this charger for 6 hours and it’s still reading 12.11V, is the charger powerful enough?

 

[spruce]

Battery is reading 12.11V been charging it with this charger for 6 hours and it’s still reading 12.11V, is the charger powerful enough?

If you put a multimeter across the terminals whilst the battery is charging you should have a reading of 13 + volts.

12.1volts means the battery is totally flat. It also means the charger hasn't done a thing. Is that fuse ok? With the charger clamps off the battery , not touching each other or a conductive surface, test the output of the charger with you multimeter. It should show a reading of 13.8/13.9 volts. If it doesn't there is something wrong with the charger.

You need a higher voltage than the battery (12.9v) to 'push' current into it. The higher the voltage the more charge the battery will receive.