How to test d batteries with a multimeter

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gfmucci

2 years ago

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I have three different multimeters with 3 different dedicated battery load tests. Their spec sheets read as follows:

---Tacklife DM10:
1.5V 1.8K ohm load
6.0V 150 ohm load
9.0V 910 ohm load
12.0V 62 ohm load
---Another Tacklife DM01
1.5V 30 ohm load
9.0V 300 ohm load
---Bside ZT-M1 - All volt batteries with 10mA load current
1.5V 150 ohm load*
9.0V 900 ohm load*
12.0V 1,200 ohm load*
* The ohm load for Bside is based on 10mA load current for all batteries.

Why does each meter choose a different load and manner of designating load? Which loads are preferred? I would think that the higher the voltage of the battery the higher the ohm load should be, like in the Bside; not like the Tacklife DM10.

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peter155

2 years ago

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Use a voltage reading instead of a current reading. You can put your load (resistors) across the battery in parallel (instead of on one end in serial) and then take your voltage reading across the battery as well. If you get 1.5 or near to 1.5 then the battery is holding up under load and is good. If the voltage drops significantly lower than that then the battery is dead.

An advantage to this method is that you won't have to worry about blowing fuses on your meter.

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WolfmanLuke

2 years ago

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This is a great instructable. I only had one side comment about resistor values. Many resistors have an advertised tolerance of +/-20%, so you may want to double check the resistances of your specific resistors using the multimeter and do the specific calculation for the current you should expect.

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Phil BWolfmanLuke

Reply 2 years ago

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Thank you. You make a good point. I do usually check. My nominal 370 Ohm resistance came in at 367 Ohms.

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Polymorph

7 years ago on Introduction

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There is nothing magic about 4mA for 1.5V and 25mA for 9V. It is only saying that is what it draws.

In fact, a 1.5V cell should actually be tested with -more- current than a 9V battery. I'd flip those numbers around.

They are just being cheap and putting one range on there to measure both. It'd be better if you were to add separate inputs to your adapter, maybe load the 9V cell to 10mA and the 1.5V cell (for AAA and up) to about 30mA.

Don't test 1.5V buttons cells at that current, though.

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tsuresh

7 years ago on Introduction

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I have a Lead Acid rechargeable battery which is used in emergency lamp.

The voltage range mentioned in the battery is about 6-7.5v

Max charging current mentioned in the battery is about 1.5A

When I measure the voltage during charging it shows 6.5V

When I measure the voltage using multimeter (without charging) it shows only 4.4V

I assume that the battery life is over and not working.

To test this can I use the same method which you explained in this article ?

If I take lets say voltage is 6.5V and use 360 ohm resistance to measure current.

V=IR. Hence the current should be 18mA.

Note : The emergency lamp is not working and I suspect the battery.

Not sure if I can replace this battery with four 1.5V battery in series to check if the lamp works.Please comment on this as well.

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Phil Btsuresh

Reply 7 years ago on Introduction

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You can use this same method to test the battery. However, when a battery will not reach a full charge, the battery is defective. You should be able to test the lamp with four 1.5 volt batteries in series.

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bilal.ahmad.9279807

7 years ago on Introduction

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How we can check the 48 V Lead Acid battery load with the help of load tester.

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Phil Bbilal.ahmad.9279807

Reply 7 years ago on Introduction

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What does the 48 volt battery power? Can you measure the current flow in the circuit when its normal load is connected? Then you would use Ohm's Law to compare what the battery produces with what it should produce.

Otherwise, a standard battery test uses a carbon pile to handles.l of the current. Carbon pile testers are very expensive. Most you would find are likely to be for 12 volts. A tester for a 48 volt battery would be even heavier duty. I do not know where you would find one.

This is the best answer I know. I see you posted this question eleven times various places. Perhaps you could delete the other ten. Thank you.

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tsureshPhil B

Reply 7 years ago on Introduction

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Hi Phil,

Thanks for this tutorial.It helps me understand the concept very easily.

Could you please explain why do you ask the battery power ? From where I can get to know this ? Without knowing the power if I blindly connect 360ohm what would be the consequence ? And lastly, why you chose 360 ohm ?why not lets say 10 ohm or 1ohm ?

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Phil Btsuresh

Reply 7 years ago on Introduction

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The ideal would be to connect the meter to a resistance that is the exact resistance of the load in the device the battery will power. 360 Ohms probably represents an average approximate load for many battery devices. Sometimes the voltage of a battery not under load appears to be good, but the battery is too far depleted to provide the current needed to power the device. Adding a load of about 360 Ohms to the battery gives a better indication of whether the battery is still good. Even then, one application or device may be able to work on a very low current draw with a weak battery while another device needs a fresher battery because that device draws more current.

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tsureshPhil B

Reply 7 years ago on Introduction

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Hi Phil,

Thanks for your reply.Could you answer this question as well please ?

"Could you please explain why do you ask the battery power ? From where I can get to know this ? Without knowing the power if I blindly connect 360ohm what would be the consequence ?"

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Phil Btsuresh

Reply 7 years ago on Introduction

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I suspect you mean current. Power usually means Watts. Do you know Ohm's Law? Voltage equals amperes (current) multiplied by resistance (Ohms). Watts equal volts multiplied by current in amperes. You are simply employing Ohm's Law to test a battery by adding a resistance. If a 1.5 volt battery is fresh, a load of 360 Ohms should show a current draw of 4 milliamperes. Anything significantly less than 4 milliamperes indicates the battery is somewhat depleted.

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tsureshPhil B

Reply 7 years ago on Introduction

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Hi Phil,

This was totally clear for me.What I wanted to ask was about power rating.Like how much heat the resistor dissipate and will it withstand the heat if we connect 360 ohm to a 48V battery.

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Phil Btsuresh

Reply 7 years ago on Introduction

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Divide 48 volts by 360 Ohms. The answer is 133 milliamperes. 48 volts multiplied by 133 milliamperes equals 6.4 Watts. Here you can order 7 Watt resistors.

http://www.ohmite.com/cat/res_rw.pdf

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steve.criss

7 years ago on Introduction

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Thank you for this useful tool. I've been using it mostly to test button cells. Those batteries are really pesky. I have some that were testing at 3v with no load. That's exactly what they are supposed to be, but they still wouldn't power my equipment. Replacing them with new ones (also testing at 3v) solved the problem. That was somewhat of a mystery to me. Using your method, I've now discovered that my 3v button cells, which should be testing at 8.3 milliamps with a 360 Ohm load, are somewhere between 1 and 5 milliamps. Finally, an explanation as to why they didn't work.

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Phil Bsteve.criss

Reply 7 years ago on Introduction

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I am glad this is helpful to you. Button batteries are a challenge. They are small and convenient, but do not last nearly long enough. Often the voltage output seems sufficient, but the ability of the battery to produce sufficient current is exhausted. If the application allows it, some people add a battery holder for AAA or AA batteries.

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bilal.ahmad.9279807

7 years ago on Introduction

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How we can check the 48 V Lead Acid battery load with the help of load tester.

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pilm89

8 years ago on Step 2

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It wasn't mentioned but it's just as easy IMO to measure the voltage of the battery when loaded with a resistor, a dying AA battery might measure almost 1.5V with no load, but when loaded with a 150 ohm resistor for 10mA draw, the voltage may begin to collapse if the battery is weak. I prefer voltage simply because we already know what the nominal voltage for a 1.5V AA battery should be. Additionally one can choose the right resistor based on application, for example my digital camera that requires two AA batteries is labeled 0.6A at 3V, so I know each battery needs to be able to supply 0.3A, so a 5 ohm resistor loaded on the battery will quickly tell me if the battery can support this camera.

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Phil Bpilm89

Reply 8 years ago on Introduction

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Thank you for your comment and additional information. A voltage reading often tells all I need to know and works quite well.

How do you know if D batteries are good?

What voltage should a new D battery read?

How do I know if my battery is bad with a multimeter?