paneuro

Hi Scott, I got the new pulleys and I have now fitted them and got it all up and running with new regulator, once its started I put the meter across the battery posts on idle and its showing 15.06 volts I haven't tried it when its warmed up but I will give it a good run tomorrow and check it. I would think it would come down a bit once it has brought the battery back up to where it should be. cheers Paneuro.

paneuro

Hi, If it seems to high how do I disconnect the IBS?

tstiglich

The IBS regulates your charging. Without it, you are in essence running open loop. What type of battery? 15.1V is fine for a FLA, especially if the battery is discharged and/or cold.

scottalexander

Good work installing those new parts.

When you installed the voltage regulator, did the slip rings look worn?

Were the slip rings covered with deep, black soot?

paneuro

The slip rings were fine, all that was required was a light clean with 1800 grit water paper. It is an AGM battery 95amph and is registered, I have pics on my iphone of all the bits but unfortunately I don't know how to put them on here, I'm hoping that once I have given it a good run it will settle down to where it should be. If not somebody will tell me how to disconnect the IBS. thanks paneuro.

scottalexander

Disconnecting the IBS is a 2 second job.

While you are looking at the negative side of the battery, you will see a thin wire (mine is blue) and it can be unplugged from its harness about 10 inches away.

When the IBS is unplugged, your volt meter should read a constant 14v with no variations.

You won't be able to take advantage of variable charging rates with the IBS unplugged.

paneuro

Hi Scott, what is the advantage of IBS being plugged in? the reading I had when I ran the car for a few minutes, {its still up on stands as I'm fixing on the undertray} was 15.06/05? should that not be reasonable considering I have just taken a lump of charge from the battery when starting the car? regards paneuro.

scottalexander

I was just reading the voltage article below that will give you perspective:



Since a 12 volt battery has six cells, any 12 volt lead-acid battery needs at least 13.8 volts to start to charge. This voltage will be enough to fully charge or maintain the battery on a trickle charge, but charging time will be very long at 13.8 volts.



To fully charge in reasonable times, alternator output must be 14.2v to 14.5v as measured right across the battery posts.



If the IBS is disconnected, some of the literature shows the alternator produces a constant output around 14.4v verses being able to monitor the real needs of the system and current load.



Above 14.5 volts charging voltage, batteries have a greatly increased tendency to release excessive acidic vapors, hydrogen gas, and to corrode things around the battery. The battery terminal charging voltage must be less than 14.7 volts to prevent excessive gassing. Charging voltages over 14.7 volts can prematurely dry the battery by boiling out electrolyte, and increase risk of a battery hydrogen gas explosion.



Let's say the battery charging voltage is 14.61 volts with the engine at high idle.



14.4 volts is the gassing threshold. The battery will slightly gas, but not enough to be harmful, and the battery will get a quick full charge recovery after starting.



14.8 would start to be a worry (there might be liquid or corrosion on the battery) and 15 volts would be a real concern, but 14.6 is fine. Less than 14.3 would be a "weak" alternator or regulator.



Much less than 14.2 at a fast idle is bad wiring, bad alternator or regulator, or a bad connection or fuse link. When running at a normal slow cruising engine RPM, the voltage across the battery terminals should stay over 14.3 volts even with full load, like lights, heater blower, and everything else, running. If this system was in a restored BMW, I would probably change the regulator to reduce maximum alternator voltage. This would prevent deterioration of metal around the battery from excessive charging vapors. It's OK in my daily driver as long as I watch the battery for purged acid deposits.

paneuro

My son has a 3 seres estate and has been getting recall letters from BMW concerning some wiring connection beneath the floor where the wires exit the trunk area. When I enquired with the local dealer if there were any recalls on mine they said there was but it is not a safety issue, if the car was in any dealership for anything they would check these connections and if, depending on how badly they were corroded they would either clean them up or replace the cable from back to front. I don't know if this has any relation to evaporation or gassing but the first time I'm near the dealer I will ask them to have a look. If the voltage is to high I will disconnect the IBS and see what that produces. The brushes on the regulator didn't look that worn to me and I found a company online who supply replacement brushes for £2.60. I might get a couple and fix the old regulator, wish I had found them before I bought the new regulator, you can also buy the slip ring as well. These things always come to light after I've spent the big bucks. cheers paneuro

paneuro

Hi Scott, I got it all back together today and took it for a decent run, 7 miles to supermarket and 7miles back, when I got back I kept it idling and put the meter on the battery. I got a reading of 14.5and 14 .6 volts. What do you think. Cheers Paneuro.