azurite300e

My car uses a Bosch 0-123-510-040 115Amp alternator, and the regulator being used now is a 14.1V unit, Bosch part number 1-197-311-242. Since 14.1V is not nearly enough to fully charge the battery (14.4~14.5V is more like it), it is my intention to raise the output voltage of the alternator to 14.5V with the installation of a WAI IB387-1 voltage regulator, or equivalent. Will 0.3~0.4 volts more make a difference? You bet! and will cure a chronic undercharged battery condition.

I have not been able to locate a dealer that sells this regulator in single quantities or even over the internet. Anyone have any tips of where to order it? It doesn't have to be that exact same model, which I located on a WAI distributor website some time ago and is supposed to be the correct one for my application. Any other brand of regulator would also be fine, as long as it properly fits my alternator, and has a set output voltage between 14.4 and 14.5V.

BTW. already tried the diode trick mentioned elsewhere, but it didn't work. Besides its not the best solution anyway, in my opinion.

Thanks.
-Alex

hineywineries

I don't see any reason to modify the regulator. A fully charged battery with surface charge removed registers 12.6 volts on a DVM. 14.1 volts charging rate is just fine. I'm guessing you problem is coming from trying to keep that battery charged while drving around town with 10,000 watts of Hi Fi in the trunk. Am I right? It all comes down to P=IE. Power in amps is determind by current times voltage.

azurite300e

Hey no offense taken, just in case

But do I really appear to you as that kind of airhead?

My stereo is a no nonsense stock Becker BE1490, stock 6-CD changer, and four JBL 3.5" coax speakers. For jazz thats more then enough, besides that's the biggest speaker size a 1986 300E will let you fit anywhere without going into cutting sheet metal, which I will definitively not do.

Getting back to the battery, please read my earlier post at the mercedesshop.com forum.

http://www.mercedesshop.com/shopforu....php?p=1624544

Basically anything bellow 14.4V will NOT FULLY charge a Lead-Acid battery. I gave a pretty lengthly explanation why, and there is plenty of online literature and guides to back me up. I'd hate it would go to waste if you didn't read it, because it took me quite some time to do the write up hoping it will benefit others that also don't fully understand the Lead-Acid battery chemistry.

Thanks for the comments, though.

-Alex

hineywineries

Elex,
Didn't intend to offend you. I only suggested you had a massive sound system, because I've run into that before. People trying to supply a 200 watt sound system with a 115 amp alt and only making short trips. It's like writing checks and not making deposits. I read most of the MB shop thread. I had over 2000 posts there, but got into a pissing contest with one of the mentally challenged moderators. I got tired of spending my time giving free technical advice to people who never ever even said thanks. Anyway that's another story.

One of the posters gave you the same advice I will. You have another problem that needs to be corrected. The charging system that came with your car should be quite adequite. I don't normally do this, but to help you understand I'm not just a newbie trying to give some helpful advice, I'll list some of my qualifications. For starters I spent one solid year eight hours a day in electronics school. I was an electronics tech for about 8 years. Then I served my apprenticeship with Mercedes Benz. Eventually I opened my own MB shop with mechanics, apprentices, helpers, etc. I ran that for about 20 years. After 30 years as an MB mechanic, I'm semi retired. I've owned hundreds of Mercedes, and in fact, I own 8 right now. I've never had a need to change to any kind of higher voltage regulator. Since you don't have any heavy tunes in your car, I'm now suspecting the battery or a key off current drain. You can check the current drain with a DVM and a 1 ohm 10 watt resister.
Peter

MediumKahuna

http://www.woodauto.net VRG46401
has the stock regulator which does make 14.5 volts.
However, if you measure the voltage at your battery you'll find that it is less than the 14.5 Volts at the alternator and if it was 14 volts at the battery it would charge fine and any more will fry your battery. There are several ways to fix this: bump up the regulator voltage even more, thicker Battery+ wire to alternator, thicker ground to alternator, fix bad connections, add a "sense" wire and diode from Battery+ to regulator.
First make some measurements to find out where the voltage drop is: measure Alternator out (B+) terminal to Battery +, Alternator Case to Battery -, Excite terminal (D) on alternator to Alternator out (B+).

The regulator actually only regulates the voltage between its case and its excite terminal (D terminal) which should be 14.5 volts. If its not then your alternator is not up to snuff or you're regulator has been replaced with the wrong one. If it is 14.5 then track down where the voltage drop is and fix that. If there's much of a drop between the B+ and D terminals on the alternator then your rectifier (in the alternator) is blown.

Also the "diode in the regulator trick" does work if you you do it right but your alternator should put out 14.5 Volts already.

RBYCC

Alex

I tend to diasgree with you.
Anything above 2.15 volts per cell ( 6 x 2.15 =12.9 volts ) will fully charge a lead acid battery.
Higher voltage per cell of 2.45 ( 2,45 x 6 = 14.7 volts ) is used for deep discharge batteries.
Higher voltage will charge quicker.

Not sure what you are trying to achieve or what problem you are having.

Consider that a battery tender regulated trickle charger rated at 1.2 or 2.1 volts is enough to maintain a 12 volt battery in a fully charged state.