e30 voltage regulator, where to buy?

[lightshine 0]

cant remember exactly but my battery measures about 10 volts with the key out, and about 13.5 volts at idle with aircon etc turned off. Am i right in thinking this is a little low? i Am not running any huge stereo system or anything.

I also checked the voltage regulator (Bosch alternator) when i had the air box out. One of the brushes measured 6 mm from the plastic bass to the bottom of the curve in the brush, the other brush was longer. According to the repair manual i have it says replace if brushes are short than 6 mm.

I have cleaned up several wiring connections around the engine to try and improve the situation. I am hopping my low battery voltage and charging will be improved by replacing the voltage regultor. Are there different types of voltage regulators? i faintly remember reading about someone who had low idle charging and replaced there voltage regulator with a 14.4 volt one? i would have thought they would have all been 14.4 volts

Where do you get them from / how much are they ? , thanks

[*Glenn* 854]

Even with 13.5v charge rate the battery still should hold 12v at rest. How old is the battery and have you charged it and load tested it with a pile tester ?

[lightshine 0]

Even with 13.5v charge rate the battery still should hold 12v at rest. How old is the battery and have you charged it and load tested it with a pile tester ?

the battery is brand new, like only 3 months old,

i just did some test to make sure,

key out , 10.52 volts across terminals

negative cable disconnected (to make sure there is no drain), 10.54 volts across terminals

ignition on + high beams + front and rear fog lamps 7.4 volts

idle with no lights or anything on 13.68 volts

idle with high beams +front and rear fog lamps about 12.5 volts

Edited January 13, 2011 by lightshine

[*Glenn* 854]

What brand of battery ? and where are you situated ?

[hotwire 352]

You are confusing yourself with irrelevent tests here

At 10.5v the battery is completly flat - wont be starting the car at that voltage

11.8 is technically a flat battery, 12.6 -12.8 (depending on battery composition) is fully charged (at rest)

The charging voltage is directly proportional to the state of charge of the battery - flat battery - the alt (yours) will not be charging at 14.4, mid 13's sounds about right. Voltage will increase slightly with revs

As the battery state of charge comes up so does the voltage (both at rest & charging)- the current input from the alt in turn decreases. It will be then that you will see the charging voltage up over 14v (test with holding revs - not idle.

From memory the Bosch alt for E30 has a 14.3v reg - this is the maximum voltage it allows (the alt uncontrolled can get up to 19v)

As for brushes - 6mm is still servicable & will not be causing a problem. If worn out - the brush & slip ring will show signs of arcing & the charge light will flicker.

From the sounds of it - get the car checked by an auto sparky

As to where to get a reg from (if required) - as above ^^^

[lightshine 0]

OK thanks, the battery definitely measured 10.5 volts and i started the car soon after. Maybe i need to check my voltage meter

[lightshine 0]

the battery is a top start calcium hybrid low maintenance battery, calcium battery's need a higher charge rate correct? i am wondering are calcium batteries not suited for e30's ?

[hotwire 352]

Calcium batteries are more suited to modern alternators that do run a higher voltage - late 14v's

That said - they will be ok with the E30 version alt - some battery configuations suiting older vehicles only come in Calcium now.

Sounds like your meter is crook - 10v & still starting the car

Do you actually have a problem with the car?

[lightshine 0]

Calcium batteries are more suited to modern alternators that do run a higher voltage - late 14v's

That said - they will be ok with the E30 version alt - some battery configuations suiting older vehicles only come in Calcium now.

Sounds like your meter is crook - 10v & still starting the car

Do you actually have a problem with the car?

i thought it may be my volt metre but it is not. I have tested my multimeter on various things and am pretty sure its reading correctly. Further to measuring the idle voltage i have been running a voltage gauge temporarily inside the car to make sure the charging voltage is consistent. This voltage gauge also shows about 10.5 volts with the car off. Voltage while driving is roughly 13.5 - 14 volts.

I have never had a problem starting it, but it when turning it over it seems a bit struggled compared to after i charged the battery on an external charger and it cranked alot faster. Also the radio frequently shuts off when i put my foot on the brakes if the car is off.

[hotwire 352]

Makes no sense to me if the battery is at 10.5 at rest - if it is - IT IS flat

9 - 10.5v while cranking is normal

Where are you checking the voltage?

You may have a lazy starter or a suspect battery/ lead connection in the circuit. Check them all

Regards radio - check radio wiring/earth

[lightshine 0]

Makes no sense to me if the battery is at 10.5 at rest - if it is - IT IS flat

9 - 10.5v while cranking is normal

Where are you checking the voltage?

You may have a lazy starter or a suspect battery/ lead connection in the circuit. Check them all

Regards radio - check radio wiring/earth

It certainly reads 10.5, that is using a digital multimeter directly onto the battery post, i even disconnected both battery leads and measured the voltage on the post and it was still reading 10.5 volts. The car started afterwards. The in car volt gauge reads about the same so i dont believe my multimeter is at fault.

I certainly noticed the starter motor sounded like it was cranking faster after the battery was on the charger and also the battery voltage was reading higher with the car off. But after a few days it was cranking slower and the rest voltage was back down to about 10.5 volts.

I dont think the radio cutting out when i step on the breaks is a issue created by a short or a wiring issue i think it is due to the voltage drop when the breaks lights come on.

I cleaned up a whole lot of connections a few weeks ago, starter motor, battery terminals, ground strap on sump, ignition coil contacts, i didnt clean the alternator contacts, but the in car volt gauge i put in to monitor the charging voltage while driving always shows 13.5 - 14 volts.