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Testing car battery

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Testing a car battery. Good idea.May I suggest one method.

Read the car's manual to get the ratings of the battery

Hire a low range clamp ampere meter and a good volt meter from an electrical contractor.

Open the bonnet and clamp the clamp meter it around the +ve terminal wire, and connect volt meter across battery terminals in correct polarity

Keep the bonnet open and hold the meter in your own hand, and place voltmeter some where so that you can see the meter reading .

Tell your friend or any one to start the car ( keep sure gear is on neutral or else..(joke))

Note initial readings of both the meters

Note the maximum ampere reading and also the corresponding voltage reading,when the engine is turned on.

note down both the readings

turn off the engine and wait for say 2 minutes and again turn on, take the readings and compare with the previous reading and

note the date.

Then after using the car, say, 6 months or so, again do the same testing and compare the reading with previous testing data

Compare the values and see, when the car starts, the voltage and current is same as that of the previous date. If the voltage drops and current is showing almost same, that means the battery needs servicing. And if voltage drops and current taken is much higher, check if head lights or other electrical systems are on, if all electrical systems are off, check up with service center.

Make sure that the meters are all well calibrated.

Seems that this is tough job to me too. But this test can be done simply, if we have these meters. If you try this, please post the results. Bye

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Great write up, harikuttan! Traditional clamp meter works only on AC system. Tried my ride's battery with the battery tester, reading came slightly below "OK". As per my previous experience the lead acid battery last atleast 5 years provided distill water is topped up whenever required and no dust or mud to enter the cells.


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harikuttan, regrets! For the delay in replying. This is actually a battery tester. During testing the battery actually drains via the resistance provided and during that process if the reading remains in OK slot that means all fine.

I have heard about the DC clamp meter but never seen one.

The principle is if the rating of a battery reads 72Ahr that means it can supply 72A of current, to a load, for 1hour. So incase you want to test a battery than you need a heavy duty resistance, similar to nichrome heater coil, a DC clamp meter, switch and a timer.

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hi vikky

Battery tester is ok. it is simple. For analyzing the performance of battery; life and consistency in Ah. you will need to check differently. And battery tester may drain your battery. For occasional testing battery tester is fine


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