Alternator charging voltage regaulators from 14 - 14,5 Volts? Why?

Hallo, I have been strucling with same problem on my 855 TDI with 367.000 km. Battery never fully charged resulting in starting problems in very cold weather as the startmotor doesn't wind fast enough. You should measure the real charging voltage with a voltmeter directly on the battery terminals. At 3000 rpm it should read 14.2 - 14.4 volt at 20 degree celcuis - mine only read 13.3 Volt. Check also the connection cables and hoses they should be clean and not corroded e.q you could try to connect a start cable from the generator to the engine chassis to see if that changes the voltage to a higher read out - if so the ground wire need to be changed or connections cleaned.

I changed the voltage regulator 14 Volt type as the coals were finished (should be a least 7 mm long), and now the generator deliver 14.2 - 14.4 volt at 0 degree celcius at 3000 rpm.

Mfg Per

Where is the voltage regulator located? It is not in same thermal environment as the battery than it will be a crapshoot whether it is charging the battery correctly.

They have negative temperature coefficient so at 0°C it should be charged at higher voltage than at 20°C

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

void _-void-_ in the obvious place

"Per Groth Ludvigsen" schrieb im Newsbeitrag news:4d4fe1a6$0$36572$ snipped-for-privacy@dtext01.news.tele.dk...

Exactly the same problem here!!! In addition apparently too early sulfating of the battery because of low charging state most of the time! Luckily I do not rely on driving the car during the winter. In the summer I need it every day to drive to work but then there is no problem because starting works also with an only partially charged battery.

I did that already and that lead me to the source of the problem. Mine had 13,7 and then also 13,9 at the battery, depending on charging state, rpm and equipment turned on or off.

Wouldn´t that indicate a bad connection between alternator and chassis? To check the ground connection from battery to chassis I would connect a cable between battery minus to chassis.

Can you remember which spare part you used? When did you change? If this has worked for months it means that I will also switch to 14,4 V. Actually this means that changing the regulator to one which delivers 14,4 Volts does not do any harm and I will do the same as soon the weather gets warm enough or I will have it done.

I had mine changed by my mechanic some years ago before a trip through the Baltic countries when I would not like to get stranded because of a failing alternator. He used a "Volvo" part, rip-off expensive. It results in exactly 14 V at the alternator plus connector as indicated on the alternator.

Regards Franz47

"Boris Mohar" schrieb im Newsbeitrag news: snipped-for-privacy@4ax.com...

It is attached to the alternator on one side under a plastic protection cup covering this end of the alternator.

Probably its temperature is ambient temperature after standing a night but during driving I would expect it to have about the same temperature around the year.

Still the question remains - why do some regulators regulate 14V, some 14,4 V etc when the physics of the battery is the same in every car?

Regards Franz47

I have heard about modifying the regulator with a diode in the internal cirquit that will raise the output voltage by 0.5 Volt, but I have never needed to try it. By a quick Google search I just found such a thing that may be of help, but as I said, I have not tried this:

Looking more closely at this link I think there should be used a metal cased diode that can handle more current....

"Asbjørn" schrieb im Newsbeitrag news:iipqc9$u86$ snipped-for-privacy@news.eternal-september.org...

A very interesting solution indeed! The diode seems to be ok, if it really can handle 300V 3 A which would mean 900 W, that should be more than sufficient. The current to the rotor is quite small compared to the maximum charging current since it is only used to create a static magnetic field. The main current of 115 A 12 V runs in the stator and rectifier. This construction is one of the advantages of the AC alternator compared to the old generation DC generators where it was exactly the other way round. There the rotor collector had to carry the whole charging current, which limited rpm and required bigger brushes.

Franz

My concern was more on the operating temperature and poor cooling in this environment inside the alternator housing. There are power diodes with metal housing that can be screwed into the bracket. (But pay attention to the polarity)

Asbjørn

"Asbjørn" schrieb im Newsbeitrag news:ij115a$pe5$ snipped-for-privacy@news.eternal-september.org...

I think I will resort to the solution to buy a whole new regulator unit with a regulating voltage of 14,4 or 14,5 Volts. Franz

In most instances the diode is in the SENSE line and only sees a maximum of 15 volts, so even a 50 volt diode is overkill, and also sees very little current.

In the scenarios I am aware of where diodes have been used to raise the charging rate there is virtually no power dissipation or heat involved. a tiny little 1n1003 or whatever is overkill

to the same type again, 14V (with the 68 ohms resistor mounted). I bought it in Sweden for 40 EUR. (google "FREJ BILDELAR" and then search for product no. 311529). After driving 3 weeks in very cold weather my charging problems has gone, startmotor rewind fast and the engine starts without any problems BUT I am getting other problems now because of the higher voltage output from the alternator - have changed the coolant water temp. sensor and the fuel temp. sensor both burned off, and I think the reason for this is a combination of voltage increase output from 13,3 V to 14,2 Volt and the age of the sensors. Also noticed that the engine warm up much faster and the head lamp bulbs are much brighter. Therefore would not suggest to you to change the voltage regulator to the

The difference in voltage from 13 to even 15 would NOT cause the temperature sensors or fuel senders to burn out.

I think you have a few other problems, mostly related to high mileage, age, and maintenance issues.

"Per Groth Ludvigsen" schrieb im Newsbeitrag news:4d617aad$0$36564$ snipped-for-privacy@dtext01.news.tele.dk...

I looked at this part on the webshop. There is actually no indication that the regulated voltage is anythink else than 14 V. Franz47

I installed an Optima battery for the reasons you gave as well as an IPD adjustable regulator . My battery was always marginal now it is very good and suits my driving style as I drive less often now days . My 740 1990 had little reserve before but now it is not an issue .My standard regulator was cronicly under charging at 13.2 now at 14.8 as an Optima can take such a charge .