testing a battery

MapForJ

How would you test a car battery besides using a multimemter. My car would not start so had to jump it. Battery has been acting funny lately but when checked with multimeter it has 12 volts and when engine on has around 14 so it seems to be charging. I also tested with an aldi battery tester Lit 3 leds

After two mins with lights on no engine the led were down to two. is that bad?
Also the trip odometer goes back to zero when the engine is turned off. Would it be loose connection


A friend told me go to her garage and the guys would test it but before i spend money I want to see if i can find out if it needs replacing.

I have a mechanic I can go to as well but lots to pay for so i would prefer just buy a new one instead of paying for test to be told buy a new one

bbability

How old is the battery? Have you brought the car for a drive after jump starting the car? YOu should bring it for a good run to give it a good charge.

MapForJ

bbability wrote: »

How old is the battery? Have you brought the car for a drive after jump starting the car? YOu should bring it for a good run to give it a good charge.

yes not sure how old was in car

aujopimur

Your local motor factor will load test it for you.

MapForJ

aujopimur wrote: »

Your local motor factor will load test it for you.

what does that mean exactly and will it cost?

aujopimur

They use a thingy similates a load on the battery, normaly it's FOC.

Indeed, it's basically a big resistor thing type thing, they won't charge you to test a battery

MapForJ

RoverJames wrote: »

Indeed, it's basically a big resistor thing type thing, they won't charge you to test a battery

and what does it tell? The multimeter says 12 volts and when engine running 14 volts

Leaving lights on for two mins reduces the power on the aldi tester. Is leaving lights on a 'load'?

It gives a voltage reading too, but it places a decent load on the battery with the engine running.

MapForJ

thanks guys will get a load test tomorow

sh1tstirrer

You could also try dismantlers for a battery, I got one last year for €30 and it is still going.

MapForJ

two cells F***** got a new one. thanks for the help;)
When he checked the load one of the cells started bubbling? What is that? I asked but i cannot recall the answer Am just curious and want to learn as much about battery as poss

coylemj

A car battery is a set of six lead-acid cells connected in series. Each cell is designed to deliver 2V so when connected in series the whole battery should deliver 12V. If the guy who tested your battery was able to say that two of the cells were faulty, he probably tested the cells with a hydrometer to test the specific gravity of the acid and from the reading was able to say that two of the cells were knackered.



Lead-acid cells normally bubble when the battery is being charged though most of them these days are sealed. If the acid level is low in some of the cells they can bubble when a high current is passing through them because there is less surface area exposed to the acid so what lead surface is being used is effectively overloaded.

MapForJ

coylemj wrote: »

If the guy who tested your battery was able to say that two of the cells were faulty, he probably tested the cells with a hydrometer to test the specific gravity of the acid and from the reading was able to say that two of the cells were knackered.

yes he did. And then did a load test

Lead-acid cells normally bubble when the battery is being charged though most of them these days are sealed. .

most are sealed? read that only 10 % are sealed

If the acid level is low in some of the cells they can bubble when a high current is passing through them because there is less surface area exposed to the acid so what lead surface is being used is effectively overloaded

yes i think that is what he said. By surface you mean surface of plates? Thanks for the explanation