# Measuring a battery's voltage and current

#### danny davis

May 9, 2012
306
well the fluke 88 meter is on autorange so i can't control the range selector because there isn't any its automatic, so i don't think that is the problem

Aug 13, 2011
1,114
88? I thought you had an 87. The 88 is a multimeter for automotive use.

In any case, that only eliminates one possibility.

#### danny davis

May 9, 2012
306
The Problem is that i'm trying to explain is that is there a such thing as a SERIES LOAD?

What does a series Load do? the voltage stays the same right? but it only changes the current? there is no voltage drop?

When do you measure voltage in series?

#### GreenGiant

Feb 9, 2012
842
The Problem is that i'm trying to explain is that is there a such thing as a SERIES LOAD?

What does a series Load do? the voltage stays the same right? but it only changes the current? there is no voltage drop?

When do you measure voltage in series?

the load will ALWAYS be in series with the battery, yes when drawn out it may look like the battery is in parallel with the load but you can always reduce the load down to one value, and make one single loop.

The voltage drop on a battery is going to differ based on the load, if you have a 3V 10Ah battery and you put a 10 ohm resistor on it the voltage will drop more than if you had a 3V 40Ah battery, but if you have a 12V 10Ah battery the voltage will drop a lot more than the 3V, and a 12V 40Ah battery will drop less than the 12V 10Ah but more than either of the 3V batteries

Batteries have a 100% SOC voltage and a 0% SOC voltage, whenever you draw current from the battery you are going to lower the voltage, whether it be by 1 microvolt or 100 volts

The higher the resistance the smaller the drop because the current through the resistor will be less

The more current draw there is, the more the battery's voltage will drop

#### davenn

Moderator
Sep 5, 2009
14,263
What does a series Load do? the voltage stays the same right? but it only changes the current? there is no voltage drop?

When do you measure voltage in series?

There is ALWAYS a voltage drop across the load, that drop will equal the value of the supplied voltage from the battery or power supply

you dont, you always measure the voltage in parallel with the load, current is measured in series. I showed you a diagram of that several pages ago

Dave

#### jayaram

Aug 6, 2012
1
Mr danny!! I advise you to try this simulator and verify your doubts by rigging up the circuits in parallel or series as you wish
http://www.docircuits.com

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,728
I can imagine that Danny's confusion results from looking at a schematic in different ways. take this image:

It is the same circuit, 1 battery, one load, drawn in two different ways.

The circuit to the left looks like the load is parallel to the battery, whereas the circuit to the right looks like the load being in series with the battery.
Anyway you look at it, however, it is a closed circuit.

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