help needed testing a car battery/alternator with a volt met
Discussion
hi missus went to pick the kids up in the car today and it wouldnt start, one of the mums gave her a jump start. i have a multimeter at home but not sure how to use it!!!! (think it was my dads) I put the dial on v- (it looks like ) but the meer shows 17.00 rather than 12, tried it on my MG and the same ting so i guess i'm doing it wrong. The car is 2.0 honda FRV, also on the bttery it has a little window with a symbol that shows that it needs charging.... just took it fora 30min drive and no change on the icon on the battery...
this is the multimeter i have...
this is the multimeter i have...
Hi
The pic shows the meter set correctly for checking the charge rate. Red probe from the meter to the battery positive, and black probe to the battery negative, with the engine running. Blip the throttle if nec (some cars need this to excite the alternator to charge - ooer missus....)Reading should be 13.6-14.2 volts for most cars if the alternator is charging correctly. If not, there could be many reasons from a knackered alternator to poor connections, eg battery terminals, engine earth, and on some cars there may even be an alternator earth lead not making good contact. This time of year will show up all sorts of maladies with car electrics.
HTH
Pete
The pic shows the meter set correctly for checking the charge rate. Red probe from the meter to the battery positive, and black probe to the battery negative, with the engine running. Blip the throttle if nec (some cars need this to excite the alternator to charge - ooer missus....)Reading should be 13.6-14.2 volts for most cars if the alternator is charging correctly. If not, there could be many reasons from a knackered alternator to poor connections, eg battery terminals, engine earth, and on some cars there may even be an alternator earth lead not making good contact. This time of year will show up all sorts of maladies with car electrics.
HTH
Pete
hi, just replaced the battery (never changed from new and probably had it for 10years!!) and my D battery is reading correct now.....
ok car battery is reading over 12volts, started car and now reading 14.36 volts.... missus said she didnt have the heated seats on or anything with the engine off!!
just to top it all off, went to take a pic of the reader, and just dropped my phone on the tarmac!!! a massve dent on the side of my new blackberry!!! dont think its my week....
ok car battery is reading over 12volts, started car and now reading 14.36 volts.... missus said she didnt have the heated seats on or anything with the engine off!!
just to top it all off, went to take a pic of the reader, and just dropped my phone on the tarmac!!! a massve dent on the side of my new blackberry!!! dont think its my week....
Edited by essexrobb on Thursday 6th January 22:37
Glad you got the tester sorted. Now - about the car, the charge rate you have given seems about right - maybe something left on? Eg - an interior light doesn't take long to run a battery down. Last year when I still had the R**ver 45, the battery was just past its best and the alarm kept coming on - turned out it was the battery dropping voltage and it was Ok once I replaced the original battery - then I went and traded it in for the Saab!!
Edited by Petemate on Thursday 6th January 22:42
essexrobb said:
hi, just replaced the battery (never changed from new and probably had it for 10years!!) ok battery is reading over 12volts, started car and now reading 14.36 volts.... missus said she didnt have the heated seats on or anything with the engine off!!
Well done..BTW if you are not going to be using the MM for any length of time take out the battery.
You car battery could have a duff cell.. cold weather normally kills off any battery with under lying health problems.
Check the levels on it if it's not a sealed type.. top up with distilled water and take it on a 15 mile run at least.
14.36v says there's nothing wrong with your chrging system so almost certainly your battery is goosed.
Only way to test a battery properly is a high current drain test by a battery specialist depot.
A viable DIY test is to remove the battery from car, take it indoors and charge it. Then leave it to stand for a few hours at room temperature, preferably overnight. Then test the voltage at the battery terminals with your meter. Anything under 12.4 volts and it's time for a new battery.
Personally I reckon that if a battery is over 2 years old and you get a "fail to start" you might as well just go straight out and buy a new battery. Saves a lot of fooling around...
Only way to test a battery properly is a high current drain test by a battery specialist depot.
A viable DIY test is to remove the battery from car, take it indoors and charge it. Then leave it to stand for a few hours at room temperature, preferably overnight. Then test the voltage at the battery terminals with your meter. Anything under 12.4 volts and it's time for a new battery.
Personally I reckon that if a battery is over 2 years old and you get a "fail to start" you might as well just go straight out and buy a new battery. Saves a lot of fooling around...
yeah i'm going to have a quick check just thought the 30min drive tonight would have had the indicator on the battery showing its charged.... will check the car now make sure nothings left on, although since the drive ri've started the car about 5 times and it still starts fine! once left the heated seats on for 20mins and that run the battery down without the engine running. will check now.
Ozzie Osmond said:
14.36v says there's nothing wrong with your chrging system so almost certainly your battery is goosed.
Only way to test a battery properly is a high current drain test by a battery specialist depot.
A viable DIY test is to remove the battery from car, take it indoors and charge it. Then leave it to stand for a few hours at room temperature, preferably overnight. Then test the voltage at the battery terminals with your meter. Anything under 12.4 volts and it's time for a new battery.
Personally I reckon that if a battery is over 2 years old and you get a "fail to start" you might as well just go straight out and buy a new battery. Saves a lot of fooling around...
When starting up the engine the voltage drops under 10,5 V, then the battery is over. If You don't have the proper tester, this will work with 90% accuracy.Only way to test a battery properly is a high current drain test by a battery specialist depot.
A viable DIY test is to remove the battery from car, take it indoors and charge it. Then leave it to stand for a few hours at room temperature, preferably overnight. Then test the voltage at the battery terminals with your meter. Anything under 12.4 volts and it's time for a new battery.
Personally I reckon that if a battery is over 2 years old and you get a "fail to start" you might as well just go straight out and buy a new battery. Saves a lot of fooling around...
essexrobb said:
yeah i'm going to have a quick check just thought the 30min drive tonight would have had the indicator on the battery showing its charged.... will check the car now make sure nothings left on, although since the drive ri've started the car about 5 times and it still starts fine! once left the heated seats on for 20mins and that run the battery down without the engine running. will check now.
Bloody 'ell - heated seats on without the engine running? - recipe for disaster!!Best of luck mate
cheers, thanks for your help and everyone that offered suggestions...
yeah that was last year and she swears blind they werent on today, more peed of about my phone...
dont think the battery can be topped up with water well owners manual doesnt suggest you can, battery 45 AH/20 HR, going to have a look now and see if i can find that model online...
thanks
yeah that was last year and she swears blind they werent on today, more peed of about my phone...
dont think the battery can be topped up with water well owners manual doesnt suggest you can, battery 45 AH/20 HR, going to have a look now and see if i can find that model online...
thanks
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