Alternator, voltage and charging of battery

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einar
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Alternator, voltage and charging of battery

Post by einar » Thu 21 Jun, 2018 4:52 am

The battery empties “now and then”. Even though the battery is just 3-4 years old I do suspect the battery being in bad condition. However, before changing the battery I would just ask for some input whether it could be the alternator not supporting sufficient charging/voltage to the battery. The car starts easy, and the charge light in the dash goes out immediately – as it should, and it does not light when engine runs or idles. So far, so good. When the battery is fully charged and engine is not running, it reads 13.10 V between the battery poles – still good. When the car is idling or running at higher speeds/revs the reading is 13.58 V between the battery poles. Then the question: is this sufficient? I’ve read some place that it should read 14.4 V…. or is 13.58 V enough to charge a battery in good condition? Can I by this rather simple measurement/method conclude that it is the battery that has failed – or is it most likely to be the alternator that is not working properly?
Einar
Fintail - w111, 220 SE, limousine, 1964
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Ivanerrol
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Re: Alternator, voltage and charging of battery

Post by Ivanerrol » Thu 21 Jun, 2018 9:29 pm

Voltage across the battery when the engine alternator is charging the battery should be around 14.4v.

If your battery is reading 13.1 after charge I'm suspect the battery is on it's way out. even though only up to 4 years old.
The condition of the battery itself maybe drawing the charging voltage down.

Is your battery a "name" battery or generic?
What size battery are you using?

You can take your car to a battery service station and have it checked - e.g. Every batteries. They have a hand held tester to check the battery condition. I have an ebay battery checker it was all of $30.00
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Bartman4800
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Re: Alternator, voltage and charging of battery

Post by Bartman4800 » Fri 22 Jun, 2018 10:02 am

Einar,

Unless you replaced it, your finnie has a generator - not an alternator.

Check the contacts inside the voltage regulator on the firewall. Run some wet n dry sandpaper between them.
Some extra resistance here might drop the voltage to lower than desired.
Check the wires and contacts between generator and regulator and to the battery too...


Regards, Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
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einar
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Re: Alternator, voltage and charging of battery

Post by einar » Sat 23 Jun, 2018 4:10 am

Thanks for the replies.
I checked the voltage between the battery poles with a brand new battery that I replaced in another car just a week ago. The reading is still the same 13.5 V, not 14.4 V as desired/expected.
Bart: I’m not sure whether the generator has been replaced, but according to the attached picture it seems to me to be an alternator. Correct? Or not…..

I also measured 13.5 V from two of the contacts on the alternator (or generator?). Car electricity is not my favourite, so I’m not sure whether that was a relevant measurement. Can this tell anything of the condition to the alternator/generator? Can I conclude by this measurement together with the voltage between the poles that the alternator/generator is in bad condition and should be replaced?

I may be wrong, but I doubt the battery as it is not that old and there is a small window in it that tells the condition: If it is green, it is in good condition. And, yes – it is green/bright green. Not sure how reliable this is, though ….

Any further advice(s) to put me in the right direction?
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Einar
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chopper0813
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Re: Alternator, voltage and charging of battery

Post by chopper0813 » Sat 23 Jun, 2018 7:26 am

It does look very alternator-like. Generators are normally brushed and have a third connection for the field. IMHO the quiescent state of a 12V lead acid battery should be 13.6V and, undercharge, depending on the load and the charging device, about 14.0V or just below.
The battery capacity would be useful to know. Perhaps you could also remove the battery from the vehicle and charge it independently on a mains powered charger. This would allow you to monitor the charging voltage and charging current away from the vehicle system.

rens1976
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Re: Alternator, voltage and charging of battery

Post by rens1976 » Sat 23 Jun, 2018 8:03 pm

My wife had a battery go in her car. 2 years and 2 months old. She had the RACQ guy come out and change it. He said that was about the expected life of a battery these days (2-3 years). So it may be that it has had it.

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einar
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Re: Alternator, voltage and charging of battery

Post by einar » Sun 24 Jun, 2018 3:46 pm

I went to a battery service station, and they concluded it to be in relatively bad condition. Voltage ok, but current at start moment too low …. I think is what they said, not sure, though 😊 I just bought a new one – fingers crossed.

Another question: Is the attached picture the “voltage regulator”? It may work properly, but seems to be rather old/original and could preferably be exchanged. Anyway, the connection is stuck, so is it just to pull the connection – see blue arrow – from the “house” or is it any “clip” that prevent it by getting off? As always, when “things” are stuck, I do not want to use too much force to loosen it.
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Einar
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merc-304
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Re: Alternator, voltage and charging of battery

Post by merc-304 » Sun 24 Jun, 2018 5:14 pm

Yes its Voltage reg..Unscrew it from the Firewall if you can and it may make it easier to pull the elec plug...one screw may be behind the plug though so removing one screw may enable you to gently turn the Reg box to a better angle.
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Tony From West Oz
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Re: Alternator, voltage and charging of battery

Post by Tony From West Oz » Sun 24 Jun, 2018 9:15 pm

If you have an alternator fitted to your engine (as per previous photos) then the voltage regulator should be inside the alternator. That may have been the regulator for the generator which was originally fitted to the car.
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einar
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Re: Alternator, voltage and charging of battery

Post by einar » Tue 26 Jun, 2018 4:17 am

Aha, thanks – always something to learn. This is probably not connected then …. and I don’t bother :-)
Einar
Fintail - w111, 220 SE, limousine, 1964
NORWAY

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Bartman4800
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Re: Alternator, voltage and charging of battery

Post by Bartman4800 » Tue 26 Jun, 2018 1:10 pm

Not 100% sure, but that box on the firewall might be a solenoid for your windscreen wipers.

The original regulator for the GENERATOR is a larger box with shiny black finish.


Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

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