How to test car battery?
 

Hello all :)

Having problem starting tha car after 7-8 hours of parking. I think the battery is flat and car starts without a problem with a jump start.

Iv got a muli-meter thing but iv never used it. How do i test the battery to see if its holding its charge?
I think testing it after a drive then testing it in the morning should do the job.

the multi-meter has these settings:
10DC
50DC
250DC
1000DC
100MA DC

10AC
50AC
250AC
1000AC

some symble that looks like a horse shoe : symble x 1000
symble x 10
so how do I test battery?

You need to select 50VDC range
Good battery condition will be 12.7-12.8v
You should consider 12.50-12.59v as flat/poor condition
If you can, take the battery out of car (making sure you put alarm into valet mode before disconnecting "-" terminal and then "+"terminal, in that order) CHARGE FOR 24 HOURS MIN.
CHECK ELECTROLYTE LEVELS AGAINST MIN/MAX MARKINGS ON BATTERY - TOP UP WITH DISTILLED WATER WHERE NECESSARY (CELLS NEAREST "+" AND "-" QUITE OFTEN LOW)
Charge again until charger needle rests at 0A
Check battery cell acidity(density) level with hydrometer
Install battery back into car connecting FIRST "+" terminal, then "-”.
Put key in ignition turn one click past accessories.
Turn on main beam headlights for 30 secs.
Turn off lights and take reading!
If reading is in 12.7-12.8v fire up engine - give throttle one good blip.
Check reading with alternator charging; expect to see 14.1-14.5v.
Now switch on main beam headlights, heater blower (to max. speed) and heated rear windscreen.
Take another reading; you should hope to see no more than a 0.2-0.3v drop in your original "unloaded" value.
If value drops to 13.2v or less suspect a faulty alternator (check condition of brushes first)
*****PLEASE USE ABOVE AS GUIDE IF UNSURE GET A SECOND OPINION*****

A volt meter will only test the battery voltage, and will only show up a dead cell or a discharged battery.

Ideally you need to get it load tested. That is when a load is applied to it and the corresponding volatage drop dictates the battery condition. Any decent garage will have one (although they may like to tell you it's knackered to try and sell you one ;)

Most good car parts places will test a battery for free, they put a great big resistive test on it to give a true reading of power the battery has in it, they will tell you if it is duff, and probably try to sell you another;), thats the only snag, don't buy a crap battery, stick to a good name, exide ETC

Edited to say- Have you checked if your alternator is working OK?

Will test battery tomorrow morning. Im gonna buy the cheapest battery I can get my hands on. keeping car for anther month then upgrading to a scooby :)

When I had a suspected dodgy battery I just took it into Halfords. They did a 'drop test' free of charge.

Check that you also have a good earth between battery and chassis, and, battery and engine.
Dont overlook a faulty alarm system as well!

Job done. thanks to everybody that posted in this. You all helped me.
Got a new battery for #30. now I hope i dont need to spend any more b4 i buy a scooby.

Get yer Scooby mate, you won't get problems like this with it, i had a Rover 214sli, got through 5, yes 5 alternators in 4 years:eek: and a new battery, the electrical system was crap.

Got my Scooby, had it for nearly 3 years(MY00 classic), still got the original battery on it with no problems at all, the only cost has been the services, which can be expexted abyway.