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F.C.
Original Poster
2,576 posts
78 months
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I was wondering what voltage people are seeing when driving along with air con on?
I was watching my volt meter dip to 11.6volts when the air con was in use and am wondering if my battery has started to show signs of early failure (8 months)?
Optima Yellow Top YTR27 J which is a 460 CCA battery.
Fitted to a 6.2 LSX
opinions?
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Storer
2,028 posts
85 months
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Tony
What does it read without the aircon on?
With the interior fan and the aircon condenser fan (and possibly the rad fans too) the system is working very hard.
Did you notice what it read when the battery was new. Without all the fans on you would expect mid 14 amps at the battery with the engine running.
I have no ammeter so can't give you a reading.
Paul
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F.C.
Original Poster
2,576 posts
78 months
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Running "normal" no fans etc, between 12.4 and 13.7 Volts IIRC.
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F.C.
Original Poster
2,576 posts
78 months
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Did you mean mid 14 Volts rather than Amps?
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Storer
2,028 posts
85 months
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Yes Tony
Volts not amps. Some beer and half a bottle of red wine caused a brain malfunction.
Your lower figure is just that, a bit low, but anything over 13 volts is normal.
Paul
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spatz
1,636 posts
56 months
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you should be aware of the fact that an alternator is not outputting its full rated power(amps)
unless you are reving it to 5500 rpm. At idling or cruising it is probably only 10-20 amps, so if you
have this kind of consumption your alternator power is not enough and battery will have to provide.
In fact the heavier the load the bigger the drop in voltage, but I would not be concerned at all
it is very normal.
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bluesatin
2,998 posts
142 months
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I would check you have suitable size cable from the alt to the starter motor.
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ROWDYRENAULT
718 posts
84 months
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normally run 14.2 or a little higher volts and pretty much any rpm with the A.C. on. I am using a Power Master Alt. Lee
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Steve_D
8,700 posts
128 months
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spatz said: you should be aware of the fact that an alternator is not outputting its full rated power(amps)
unless you are reving it to 5500 rpm. At idling or cruising it is probably only 10-20 amps, so if you
have this kind of consumption your alternator power is not enough and battery will have to provide.
In fact the heavier the load the bigger the drop in voltage, but I would not be concerned at all
it is very normal. Not sure I'm understanding this. My powermaster (8003) produces 70A @ 2400 alternator RPM = about 800 engine RPM and full power @ 7500 alternator RPM = about 2500 engine RPM. Steve
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Storer
2,028 posts
85 months
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I'm with Steve on this.
An alternator produces it's maximum output at no more than 33% of maximum engine revs .
The regulator prevents overloading the battery at higher revs. If this was not the case then town driving would see batteries run flat within a week.
Paul
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spatz
1,636 posts
56 months
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ok i am referring to my alternator bosch motorsport whivh has a max of 18 000 rpm on the alternator
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ROWDYRENAULT
718 posts
84 months
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Of course Volts aren't amps just because your Voltmeter says 14 volts while you are running, does not mean that your not draning the battery. If you have 60 amps of draw and a 50 amp alternator eventually the battery goes dead. That statement is subject to review by the sparkys in the crowd, of which I am not. Lee
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F.C.
Original Poster
2,576 posts
78 months
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ROWDYRENAULT said: Of course Volts aren't amps just because your Voltmeter says 14 volts while you are running, does not mean that your not draning the battery. If you have 60 amps of draw and a 50 amp alternator eventually the battery goes dead. That statement is subject to review by the sparkys in the crowd, of which I am not. Lee If you are producing 14volts then you will charge the battery. If the the draw were 60 and the amps produced were 50 then your battery would not be seeing >12v and therefore wouldn't charge. My battery is showing a charge allbeit small most of the time, the problem is when the car is in slow moving traffic with aircon and possibly rad fans etc running, the volts drop <12v. Once on the move the charge rate goes up but still not to a "comfortable" rate below 2000 engine rpm.
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spatz
1,636 posts
56 months
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very simple charging is more or less starting at 13v+, a full charged battery with no load will read something like 12.6V max. As soon there is a load the voltage is dropping. just have a look when cranking the starter motor then you see really low voltages and that is absolutely normal.
In my setup I have no charge at idling so if I am sitting in traffic too long, i will run out of juice !
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Steve_D
8,700 posts
128 months
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spatz said: ok i am referring to my alternator bosch motorsport whivh has a max of 18 000 rpm on the alternator The Powermaster is also rated at 18000 max but produces full power @ 7500 alternator RPM = about 2500 engine RPM. Steve
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spatz
1,636 posts
56 months
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davefiddes
839 posts
130 months
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Not sure how Ultima looms are wired now but back in the day there was a LOT of current put the Lucas ignition switch. I found mine was developing quite a significant voltage drop and getting quite warm. I replaced it with a 60A master relay (I think - it was a while back) driven from the switch. Main voltage display on the dash went up by over a volt, lights were brighter, etc.
If you're worried about it measure the voltage on the battery with the engine running and the A/C on and compare with the reported value on the dash.
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ROWDYRENAULT
718 posts
84 months
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Spatz, et al, I know you guys can get a little euro-centric but if you are telling me that the Bosch altenator is 2050 euros maybe I am reading that wrong, apoligies if I am but damn boys, have you lost your mind? Lee
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spatz
1,636 posts
56 months
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it came with my engine I did not buy it as you can see in Motorsport there is no limit
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UltimaCH
1,748 posts
59 months
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ROWDYRENAULT said: Spatz, et al, I know you guys can get a little euro-centric but if you are telling me that the Bosch altenator is 2050 euros maybe I am reading that wrong, apoligies if I am but damn boys, have you lost your mind? Lee Yup, the cruel reality of european living and no improvement in sight and as Spatz said just above, with the name "Motorsports" guess the sky is the limit. I too find the price quoted outrageous, but I guess the volts produced must be made in solid gold...
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