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13,8 V idling charging voltage ok ?
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13,8 V idling charging voltage ok ? -
08-24-2009
, 11:16 AM
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850 TDI automatic 1996 with 265.000 km So I decided to check the voltage at the battery terminals - according to Haynes manual it should be 13,5 - 14,8 V during engine operation. The reading was at idle rpm without anything turned on - 13,8 V, |
voltage - 14,5.
Franz47
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850 TDI automatic 1996 with 265.000 km |
mine is 850 TDI, manual, 11/1996, 373.600 km.
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So I decided to check the voltage at the battery terminals - according to Haynes manual it should be 13,5 - 14,8 V during engine operation. The reading was at idle rpm without anything turned on - 13,8 V, after turning on the headlights 13,7. When turning on all possible stuff - seat heaters, back window heater, fan, high beam light etc, even with highers rpms the reading dropped to 13,4 V. |
Radings were the following:
-battery itself -- 12,45 V
-preheating glow plugs on -- 11,25 V
-moment of ignition/starting the engine -- 9,80 V
-idling at 1100 rpm -- 14,15 V
-idling at 850 rpm -- 14,26 V
-idling with lots of stuff -- 14,03 V
Quote:
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Do I have a faulty regulator unit or does it behave as it should even at the expense of submaximal battery capacity? Any other comment on the values measured? Any other check I should do? |
bit low. Check the battery terminals and clean them, also check the main
cable if its corroded...
Good luck!
--
hal
#4
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850 TDI automatic 1996 with 265.000 km Last year in summer 2008 before a trip through countries with sparse Volvo-support possibilities I had my mechanic change the brushes-regulator-unit of the alternator at about 240.000 km kilometrage. I was a bit under time pressure so he could get hold only of one from a Volvo dealer, cost about 100 Euros more than from a "normal" shop, though probably the same product. I had bought the car with about 210.000 km kilometrage and had no idea whether the unit had been changed before. I did not want to get stuck because of worn brushes. Befor winter I changed the battery - put in a new 75 Ah unit. Now during summer I have the Eberspächer engine preheater on for about half an hour in the morning, drive to work about 1 hour 80 km, then back home without engine preheating the same distance, headlights low beam on during driving, air condition fan, too. In my opinion that driving should be enough to charge the battery after the engine preheating current loss in the morning. I was curious how "charged" my battery actually was and connected my home charging unit, 10 A max output. I was surprised that it took about 2 hours charging until the charging current dropped to zero, did not measure voltage, but supposedly 14,something Volts. So I decided to check the voltage at the battery terminals - according to Haynes manual it should be 13,5 - 14,8 V during engine operation. The reading was at idle rpm without anything turned on - 13,8 V, after turning on the headlights 13,7. When turning on all possible stuff - seat heaters, back window heater, fan, high beam light etc, even with highers rpms the reading dropped to 13,4 V. I tried to increase my wisdom on battery charging voltages: http://www.batteryuniversity.com/partone-13.htm. 13,8 V would just fit the 2,3 Volts, but still is the lower limit. Do I have a faulty regulator unit or does it behave as it should even at the expense of submaximal battery capacity? Any other comment on the values measured? Any other check I should do? Franz47 |
It is perhaps a hair low, but I would consider 13.8V to be perfectly
reasonable. If it's too high, the battery will overcharge while you
drive as it is constantly connected.
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-battery itself -- 12,45 V -preheating glow plugs on -- 11,25 V -moment of ignition/starting the engine -- 9,80 V -idling at 1100 rpm -- 14,15 V -idling at 850 rpm -- 14,26 V -idling with lots of stuff -- 14,03 V |
prematurely.
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Srry, I don't know if your regulator is OK, but 13,8 V seems a little bit low. Check the battery terminals and clean them, also check the main cable if its corroded... |
meter´s pins onto metal parts of the cable, too.
I think I will change the regulator again....
Franz47
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It is perhaps a hair low, but I would consider 13.8V to be perfectly reasonable. If it's too high, the battery will overcharge while you drive as it is constantly connected. |
quitted to produce car batteries some years ago) for many years working fine
with the higher charging voltage. I do not use theis745 during the winter, keep
the battery in the basement with a timer switch attached to a battery charger
for 15 min every day. The charging current drops at a voltage above 14 volts
with this charger.
Sulfatation is described as a consequence when the battery ist stored not
completely loaded for extended time. So that is what I am afraid of. The old
battery which I replaced was only about 3-4 years old. It had been bought by the
previous owner, he kept the car well in my opinion.
I think I will ask people at a local Volvo forum to measure the voltage on some
855s before buying a new regulator
Franz47
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"James Sweet" <jamesrsweet (AT) gmail (DOT) com> schrieb im Newsbeitrag news:h6vhgk$cpb$4 (AT) news (DOT) eternal-september.org... It is perhaps a hair low, but I would consider 13.8V to be perfectly reasonable. If it's too high, the battery will overcharge while you drive as it is constantly connected. My other Volvo, the 745 has a battery (brand Hoppecke - unfortunately they quitted to produce car batteries some years ago) for many years working fine with the higher charging voltage. I do not use theis745 during the winter, keep the battery in the basement with a timer switch attached to a battery charger for 15 min every day. The charging current drops at a voltage above 14 volts with this charger. Sulfatation is described as a consequence when the battery ist stored not completely loaded for extended time. So that is what I am afraid of. The old battery which I replaced was only about 3-4 years old. It had been bought by the previous owner, he kept the car well in my opinion. I think I will ask people at a local Volvo forum to measure the voltage on some 855s before buying a new regulator Franz47 |
Also are you checking the voltage on the output terminal of the
alternator? There may be a bad connection somewhere if it is low elsewhere.
#8
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Also are you checking the voltage on the output terminal of the alternator? There may be a bad connection somewhere if it is low elsewhere. |
the alternator terminal, everything insulated. How would I get access there to
the terminal? BTW is it necessary to remove the whole alternator to change the
regulatur-brushes unit?
Franz47
#9
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Also are you checking the voltage on the output terminal of the alternator? There may be a bad connection somewhere if it is low elsewhere. |
eye" visible through a window in the cap of one cell. Should be green when
battery fully charge - shows green also. So everything is probably ok anyway
and maybe the external battery charger overcharges.
The cheapest German made alternator available would drain my pocket by about 300
Euros. The new battery was about 100 Euros. So I will go ahead without doing
anything and just regularly check the battery voltage, bull eye and idling
charging voltage.
Franz47
#10
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Also are you checking the voltage on the output terminal of the alternator? There may be a bad connection somewhere if it is low elsewhere. |
I took the time now to have a closer look. The voltage at the alternator
terminal was 14-14,1 Volts, exactly as it should be according to the regulator
specs. There is a 0,3 V voltage drop between the alternator terminal and the
cable terminal at the battery.
Although I removed the cable from the alternator terminal, sprayed it with
electrical contact spray, cleaned it with fine sandpaper, the same with the
surface of the nut pressing the cable terminal to the alternator terminal -
nothing changed. The cable terminal on the alternator is connected with the
cable in a way I cannot do much about. Maybe there is a resistance. On the
battery side the cable turns into a terminal without much to do either. The
voltage drop is already at the battery cable terminal. There is no more voltage
drop between cable terminal and battery terminal. The cable disappears form the
alternator into the depth of the space - is there a connection at the starter
which could be the culprit?
Franz47
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