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[Webby the Bear]

evening folks. Taking my omega to school on Wednesday to do a hydrometer test on the anti freeze. Want to also check the battery to see how good it is. I have use of a multi meter. So what do i do? Simply put the red probe on the positive and black probe on the negative terminal? If so what should the reading be? Cheers :-)

[Andy B]

http://www.omegaowners.com/forum/index.php?topic=90619.0

 

[symes]

Set multi to 20v and yes red to + black to -  or reading will have - in front of numbers eg -13v 
normal voltage about 12.5 if 12v bit flat mate Hope that helps you out

[Webby the Bear]

oops. Sorry didnt think to look for something like this. Cheers Andy :-)

[Webby the Bear]

cheers symes :-)

[Broomies Mate]

Worth checking your Multi-Meter alongside another one also.  They CAN be way out.

About 5 weeks ago, there were some electrical gremlins on my Mothers Renault.  I checked the Battery Voltage with the Multi-Meter I keep in my boot and it was showing 15.6v on idle.  Straight away an indication something is not quite right.  For some reason, I questioned the result and tested my own car.  This time it showed 15.4v at idle.

I don't have that multi-meter anymore.

[Webby the Bear]

I cant get to the link at the moment as on my phone but i presumed i should be checking voltage with car off. If i then turn car on should i see a drop in voltage?

[Entwood]

I cant get to the link at the moment as on my phone but i presumed i should be checking voltage with car off. If i then turn car on should i see a drop in voltage?

The voltage should RISE when the engine is running as the alternator is now working.

Have a good read of Kevin's guide to battety and alternator checking .. once you can get to the link.

[Kevin Wood]

See if they've got a drop tester at college. This checks the voltage under heavy load, so gives a better indication than a multimeter.

[Webby the Bear]

thanks for all the pointers guys. Tested a couple of batteries. One on an avensis. 12.5 then started. It quickly dropped to just above 10. Then went to 14. 4. Teachers said that was good :-)

[I_want_an_Omega]

thanks for all the pointers guys. Tested a couple of batteries. One on an avensis. 12.5 then started. It quickly dropped to just above 10. Then went to 14. 4. Teachers said that was good :-)

The lower it drops when cranking the better really.

[Kevin Wood]

thanks for all the pointers guys. Tested a couple of batteries. One on an avensis. 12.5 then started. It quickly dropped to just above 10. Then went to 14. 4. Teachers said that was good :-)

The lower it drops when cranking the better really.

It's a measure of the battery's internal resistance, so less drop means less resistance = better.

[Broomies Mate]

I feel I need to clarify Roberts post above! 

If standing voltage is 12.5 and the voltage drops to 10.0 when cranking, that will be better than 12.5 at standing and 9.2 at cranking.

So, if a healthy battery of 12.5volts (standing) has a reading of 11.3volts at cranking, it's a sign the battery is doing a very good job.

Not the LOWER the drop (even though that grammatically makes sense in a way) but the LESSER the drop, the better.

[symes]

I feel I need to clarify Roberts post above! 

If standing voltage is 12.5 and the voltage drops to 10.0 when cranking, that will be better than 12.5 at standing and 9.2 at cranking.

So, if a healthy battery of 12.5volts (standing) has a reading of 11.3volts at cranking, it's a sign the battery is doing a very good job.

Not the LOWER the drop (even though that grammatically makes sense in a way) but the LESSER the drop, the better.

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