A couple battery questions...
11-12-2009, 08:45 AM
#26
I wonder if this would have helped me. I just replaced the Panosonic battery that was in the car a week or so ago. Battery wouldn't do anything but power electronics, not enough to start the car though. It sure looked like an original battery that came with the car.
11-12-2009, 05:41 PM
#27
2005 Black RX-8 GT 6M
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When did you get your 2006?
11-12-2009, 09:26 PM
#28
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They used to give amp hour ratings. Also stuff like number of plates. But some time ago they went to CCA as the only number. Amusing incident at work when we needed to run some instruments off a car battery, and a youngster calculated how long it would last - using the CCA number. Since then we only buy marine trolling batteries for that kind of thing. Besides being much more suitable, they're still rated in amp hours.
I've noticed that some of the lightweight batteries that can't meet CCA specs have made up an impressive sounding but meaningless rating to use in its place.
What works well for me is to charge the battery, then turn the car off and put the headlights on for 20 to 30 minutes. Measure the voltage after that.
Ken
I've noticed that some of the lightweight batteries that can't meet CCA specs have made up an impressive sounding but meaningless rating to use in its place.
What works well for me is to charge the battery, then turn the car off and put the headlights on for 20 to 30 minutes. Measure the voltage after that.
Ken
I guess CCA is Cold Cranking Amps???
Yeah, we have/had 6, 7 and 9 + plate batteries (12V Car/Small truck), the more the Lead Plates the Better/Longer Lasting and AMP Rating.
I like your Headlights ON Idea, are they 20 amp fuse??, anyway from "Fully Charged", you can work out your own Amp Hour Rating, how long does it take until Battery is Flat with Headlights on.
Or if you start out with say 12-13 Volts and end up with 6 Volts after 30 minutes you can work out your AMP Hour rating.
In this example a 40 AMP Hour Battery ??
11-13-2009, 04:16 AM
#29
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Right - CCA is cold cranking amps.
The idea with the headlights on isn't to measure the battery's capacity, but to drain off the surface charge and get a true reading of its full voltage. Check the voltage of a battery right after taking it off charge, and you're likely to measure 13 volts. Headlamps are about 4 amps each, so 20 to 30 minutes is only 3 or 4 amp hours...out of about 80 or so for a full sized battery. But that's enough to take off the false reading.
It's really a must if you're a traditionalist and use a hydrometer, looking for both the absolute specific gravity and the consistency from cell to cell.
I think I just showed my age in two ways. Took me until now to remember hydrometers, and I think this is the first time I've ever seen them mentioned on this site. Yet there was a time when every home mechanic had one.
Ken
The idea with the headlights on isn't to measure the battery's capacity, but to drain off the surface charge and get a true reading of its full voltage. Check the voltage of a battery right after taking it off charge, and you're likely to measure 13 volts. Headlamps are about 4 amps each, so 20 to 30 minutes is only 3 or 4 amp hours...out of about 80 or so for a full sized battery. But that's enough to take off the false reading.
It's really a must if you're a traditionalist and use a hydrometer, looking for both the absolute specific gravity and the consistency from cell to cell.
I think I just showed my age in two ways. Took me until now to remember hydrometers, and I think this is the first time I've ever seen them mentioned on this site. Yet there was a time when every home mechanic had one.
Ken
11-13-2009, 09:07 PM
#30
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But I've been using AGM batteries for about 20 years and my wife's cars have all been leases (deale-serviced) until this year. So it finally dawned on me to check her battery -- was very low but the plates were still covered, fortunately. If you've got a flooded battery, hydrometer is a good thing to have for testing, plus you don't have to borrow your wife's turkey baster to add water like I did.
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