jtbgonesailing

OP, What is the mileage on your car and what was the ambient temperature when you recorded 15.67 volts? Also was your battery charged prior to the installation in your car? Batteries can sit on a shelf for a period of time before being sold and loose a bit of their charge. BMW's have a intelligent charging circuite that among other factors is temperature compensated. Is your new battery a FLA or AGM unit?

paneuro

Hi, the car was stone cold when I checked how much charge was going in, it was the first time I had started it after fitting new battery and earth strap, should i put some miles on it to let the system settle down and if the battery has been sitting around it will then be fully charged and may give me a more accurate reading? If I need to replace the voltage regulator, is it possible to do this without removing the alternator? Its an E61 530D 2008. thanks Paneuro.

FormerE30Owner

If your battery is a FLA type, then what "Gonesailing said" is correct - 15+ volts is possible for charging a cold undercharged FLA. Once fully charged, you should see between 14.3 - 14.6 v at idle or cruising.

paneuro

Sorry I forgot to say the battery is an AGM and the milage is 112,000 miles. thanks Paneuro

FormerE30Owner

Then, either the registration is wrong (need to register as an AGM) or your regulator is bad. I would change the alternator at the same time, IF that is the problem.

scottalexander

Since you have 112,000 miles on the car, it would be judicious to replace the voltage regular.

You'll get new lead brushes attached to the regulator with good contacts.

If it were me, at 100,000 miles I would have proactively changed the regulator for $30 and had piece of mind it was operating well and charging the battery correctly.

There's plenty of people who have original alternators going at 200,000 miles. You never know.

jtbgonesailing

A AGM battery should never be charged above 14.7 volts under any condition, serious damage will occur to the battery. As stated above have registration checked to insure AGM setting applied. At 112k miles, I would not expect the brushes in the regulator to have worn out, but something is wrong. Have the alternator/regulator checked and replaced as required. With the charging system functioning properly, the system will only charge the battery to 80% of its Ah rating, to protect from overcharging.

paneuro

I just priced a regulator with my local BMW dealer, converting to dollars its $146 , you guys over there have all the luck. I have contacted CARLY regarding the AGM battery registration and am waiting for their reply. I will keep you up to date with the result. thanks Paneuro

scottalexander

You say the local BMW dealer cost is $146.

Here's where I buy my voltage regulators inexpensively.WagnerAlt.com 800-345-5927 for $22

Adam Nations, Nations Starter & Alternator , Office- 573-334-2632 ext. 1001, adam@nationsstarteralternator.com", Nations Starter & Alternator, Office- 573-334-2632 ext. 1001, We have them for 49.95. adam@nationsstarteralternator.com

paneuro

Hi Scott, yes thats a good deal on a Voltage regulator. the one I priced was a genuine Bmw regulator. The ones you are talking about are in the America and I'm in the UK. I've imported parts for motorcycles before and it is not cheap by the time you add on import tax + 20%value added tax its not far off dealer price here. anyway if it needs one then I'll put one on it.
thanks Paneuro