# How to measure the current in different brands of batteries?

#### hansarne

Joined Jan 10, 2019
9
I need to measure the current in different brands of alkaline batteries - 1.5v AA and AAA, as well as 9v (6F22) - using a multimeter, and a resistor as load. How much resistance must the resistor have in order not to "blow up" both the batteries and the multimeter?

#### Alec_t

Joined Sep 17, 2013
13,153
The current will be set by the battery voltage and the load resistance. Only the short-circuit current is an inherent property of the battery, and I can see no point in measuring that, because you will rapidly flatten the battery and probably damage it.
As for damaging the meter, that would depend on the type of multimeter and its rated maximum current.
You can find the rated safe current for different batteries by reading manufacturers' datasheets.

#### hansarne

Joined Jan 10, 2019
9
The current will be set by the battery voltage and the load resistance. Only the short-circuit current is an inherent property of the battery, and I can see no point in measuring that, because you will rapidly flatten the battery and probably damage it.
As for damaging the meter, that would depend on the type of multimeter and its rated maximum current.
You can find the rated safe current for different batteries by reading manufacturers' datasheets.
I work with pyrotechnics in theater, and need to be able to measure the power (short and "intense") for different brands of batteries in order to determine which type is best suitable and which provides the most power. There is a difference in the power of 9 volt batteries, and I have to find the battery (s) that have the most current.

#### MrChips

Joined Oct 2, 2009
27,131
That is not how you measure batteries.
If you want more current you get a bigger battery.
For example, a "D" sized battery will supply more current than a "C", which provides more than an "AA", which provides more than an "AAA".

What limits the current is the size of the battery, its battery chemistry and its internal resistance.

If you wish to compare the current capability of the battery, use a 1Ω 2W resistor and measure the voltage across the resistor. Test 1.5V batteries only. You cannot compare these to 9V batteries in the same manner.

#### dl324

Joined Mar 30, 2015
15,114
I work with pyrotechnics in theater, and need to be able to measure the power (short and "intense") for different brands of batteries in order to determine which type is best suitable and which provides the most power. There is a difference in the power of 9 volt batteries, and I have to find the battery (s) that have the most current.
You're approaching from the wrong direction.

What you should do is determine how much current you need for any pulse, how many pulses you need, and the frequency of the pulses.

You'd be better off making a test circuit to simulate the load and number of pulses you want from the batteries. Sounds like a job for a microcontroller controlling electronics to switch your load and monitor battery performance, not a multimeter.

#### hansarne

Joined Jan 10, 2019
9
That is not how you measure batteries.
If you want more current you get a bigger battery.
For example, a "D" sized battery will supply more current than a "C", which provides more than an "AA", which provides more than an "AAA".

What limits the current is the size of the battery, its battery chemistry and its internal resistance.

If you wish to compare the current capability of the battery, use a 1Ω 2W resistor and measure the voltage across the resistor. Test 1.5V batteries only. You cannot compare these to 9V batteries in the same manner.

I'm using various, wireless firing modules which can be hidden in between props and mobile set designs. The battery sizes in these modules are fixed – AA, AAA or 6F22 – so using «D» and «C» sized batteries is not an option .

#### BobaMosfet

Joined Jul 1, 2009
2,028
I work with pyrotechnics in theater, and need to be able to measure the power (short and "intense") for different brands of batteries in order to determine which type is best suitable and which provides the most power. There is a difference in the power of 9 volt batteries, and I have to find the battery (s) that have the most current.
Testing a battery by shorting it or trying to dump it's whole load to determine it's current is wrong. You can also damage the battery doing it this way. What you should be doing is gathering battery datasheets and comparing those, because they will tell you everything you need to know.

#### hansarne

Joined Jan 10, 2019
9
Testing a battery by shorting it or trying to dump it's whole load to determine it's current is wrong. You can also damage the battery doing it this way. What you should be doing is gathering battery datasheets and comparing those, because they will tell you everything you need to know.
I have to admit that I am a novice in terms of electronics, measurements and the like .. I just need a quick, approximate measurement of the batteries to be able to decide which ones can be used and which ones can not be used for the highest possible current. Instead of using a resistor to measure 9 volt batteries in this way, can I make a closed circuit where I use a miniature light bulb as a load, for example a light bulb of 12v 0.2A. Then, using Ohms law (R = U / I) to determine the resistance I find the resistance in the bulb to be 60 ohms. Will this be sufficient for an OK reading?

#### MrChips

Joined Oct 2, 2009
27,131
No. The resistance of a light bulb is not constant. The resistance changes with temperature.
When there is no current through the bulb, the resistance is low.
When a voltage is applied to the bulb, the bulb gets hot and the resistance goes up.

#### Audioguru

Joined Dec 20, 2007
11,248
Basically, a cheap Chinese "super heavy duty" battery is garbage and a local manufacturer's alkaline battery is good.

#### KMoffett

Joined Dec 19, 2007
2,918
Google is your friend. Many people have done extensive tests of batteries.
Also, Lithium generally have higher capacity than alkaline.
NiCads have a very high pulse current capacity...but lower terminal voltage.
How low a voltage will your modules tolerate?
Is cost factor?

Ken

#### LesJones

Joined Jan 8, 2017
3,813
Although the terminal voltage in Ni-Mh cells is lower than alkaline cells I think they will be capable of supplying a larger current. You have not given us any idea of the current that you require to fire your devices. Another thing to consider when drawing a large current from cells is the resistance of the contacts in the battery holders. Most battery holders use a coil spring for the negative contact, This may well have a higher resistance than the internal resistance of the cells.

Les.

#### JohnInTX

Joined Jun 26, 2012
4,694

#### dl324

Joined Mar 30, 2015
15,114
I just need a quick, approximate measurement of the batteries to be able to decide which ones can be used and which ones can not be used for the highest possible current. Instead of using a resistor to measure 9 volt batteries
You're still not approaching the problem in a methodical manner.

The first thing you need to define is what load the battery needs to drive. Then you need to determine how frequently that load will be driven. Then you need to consider how long you want the battery to last.

The first thing you should do is forget about 9V transistor radio type batteries. They're convenient to get a higher voltage than single cells, but there's a compromise. The batteries have less capacity than the wimpiest AAA battery you can find.

If battery size/weight are a concern, that needs to be included in your problem statement.

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#### KMoffett

Joined Dec 19, 2007
2,918
Are there two batteries per "wireless module"? One for the receiver and one for the "igniter?"?
Ken

#### Danko

Joined Nov 22, 2017
1,443
I need to measure the current in different brands of alkaline batteries - 1.5v AA and AAA, as well as 9v (6F22) - using a multimeter, and a resistor as load. How much resistance must the resistor have in order not to "blow up" both the batteries and the multimeter?
You can safe measure short circuit current of battery by this way:

#### Ylli

Joined Nov 13, 2015
1,058
If you are doing stage pyrotechnics, then I am going to assume you are using commercial e-matches as the ignitors. If you are not, you should be. What does the e-match list as all-fire and no-fire currents?