Hi all,
Hoping the electrical Jedis here can shed a little light on my recent issues.
I have a pretty stock late model A4, but the charging system uses a Blue Sea SI-ACR (auto charging relay) with a Blue Sea Dual Circuit plus battery switch.
When all my instruments stopped working, I realized my house battery has discharged down to ~9V.
On further investigation, the ACR is not combining the batteries, and since the alternator is connected to the start battery, no charge is delivered to the house battery when the engine is running.
So the next step is to figure out why the ACR has not been combining the batteries. I installed the LED indicator, and it is Off, indeed indicating the batteries are not combined.
This was a bit of a surprise, I expected the LED to flash, indicating that the start battery was being charged, but the house battery was locked out, due to the under voltage condition. The ACR was never trying to combine the batteries.
A little reading later, and the threshold for the ACR to combine is >13.5V on the start battery (from the alternator) for 2 minutes.
With the engine running at moderate revs, voltage at the start battery is about 13.3V, with only 13.0 on the other side of the fuse that connects to the ACR. At least I think that big square thing is a fuse....
So, now chasing the alternator voltage:
Output terminal of alternator with engine at moderate revs = 13.5V
Stopped the engine, disconnected the load from the alternator, started up again, and can see up to 15V at the alt output.
Stopped, reconnected load, restarted, 13.5V again.
Chasing the alt voltage around the boat:
alt output 13.5
Positive terminal of ammeter 13.5
Negative terminal of ammeter 13.5 (after tightening the nuts...)
Positive terminal of solenoid 13.3 (other side of fuse)
Both sides of battery switch, and battery post 13.3
Lead to ACR 13.0
Is my alternator simply pooched, and should be putting out >13.5 with the load connected?
Could it be anything else?
I'm surprised I'm losing 0.2 on the connection to the solenoid through the fuse.
Side note, if the fuse to the solenoid ever blows, is that not the same as suddenly disconnecting the alternator load, and risking the diodes?
I think my next step is a trip to an alternator shop, but I'm wondering if the wisdom of the board can point me in any different directions.
Thanks in advance for the help. This place is awesome. I've learnt so much already but this one is outside my knowledge.
Thanks
Simon
Hoping the electrical Jedis here can shed a little light on my recent issues.
I have a pretty stock late model A4, but the charging system uses a Blue Sea SI-ACR (auto charging relay) with a Blue Sea Dual Circuit plus battery switch.
When all my instruments stopped working, I realized my house battery has discharged down to ~9V.
On further investigation, the ACR is not combining the batteries, and since the alternator is connected to the start battery, no charge is delivered to the house battery when the engine is running.
So the next step is to figure out why the ACR has not been combining the batteries. I installed the LED indicator, and it is Off, indeed indicating the batteries are not combined.
This was a bit of a surprise, I expected the LED to flash, indicating that the start battery was being charged, but the house battery was locked out, due to the under voltage condition. The ACR was never trying to combine the batteries.
A little reading later, and the threshold for the ACR to combine is >13.5V on the start battery (from the alternator) for 2 minutes.
With the engine running at moderate revs, voltage at the start battery is about 13.3V, with only 13.0 on the other side of the fuse that connects to the ACR. At least I think that big square thing is a fuse....
So, now chasing the alternator voltage:
Output terminal of alternator with engine at moderate revs = 13.5V
Stopped the engine, disconnected the load from the alternator, started up again, and can see up to 15V at the alt output.
Stopped, reconnected load, restarted, 13.5V again.
Chasing the alt voltage around the boat:
alt output 13.5
Positive terminal of ammeter 13.5
Negative terminal of ammeter 13.5 (after tightening the nuts...)
Positive terminal of solenoid 13.3 (other side of fuse)
Both sides of battery switch, and battery post 13.3
Lead to ACR 13.0
Is my alternator simply pooched, and should be putting out >13.5 with the load connected?
Could it be anything else?
I'm surprised I'm losing 0.2 on the connection to the solenoid through the fuse.
Side note, if the fuse to the solenoid ever blows, is that not the same as suddenly disconnecting the alternator load, and risking the diodes?
I think my next step is a trip to an alternator shop, but I'm wondering if the wisdom of the board can point me in any different directions.
Thanks in advance for the help. This place is awesome. I've learnt so much already but this one is outside my knowledge.
Thanks
Simon
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