Battery fault logged
Discussion
Recently I've been getting a battery fault log, I clear it but it soon comes back. The battery voltage is 12.6 and goes up to 13.6 when the engines running, so it looks ok to me. I checked the big fuse and that's ok as well.
So can anyone give me some pointers on what to check next or know what could be causing the fault.
So can anyone give me some pointers on what to check next or know what could be causing the fault.
Except they don't all do that. If you are only charging at 13.6v while running and the ECU is logging a fault then there is a problem because the minimum charging voltage is 13.8v If it has only just started logging a fault then something has changed!
My car with the alternator and wiring in good condition charges at 14.2v at idle. I would be looking first at wiring and connectors then if that didn't improve things, the voltage regulator on the alternator.
My car with the alternator and wiring in good condition charges at 14.2v at idle. I would be looking first at wiring and connectors then if that didn't improve things, the voltage regulator on the alternator.
Well I've got some time today so I'll check the voltage output from the alternator more accurately. It was running the other day with no load and the software said 13.6v.
The software manual indicates that the voltage would need to drop below 11v or exceed 17v to log a battery fault at engine rpm above 1500rpm. So I'll take it for a run with the laptop connected and do some data logging.
The software manual indicates that the voltage would need to drop below 11v or exceed 17v to log a battery fault at engine rpm above 1500rpm. So I'll take it for a run with the laptop connected and do some data logging.
Been out and had a quick look again and I have found that the ecu reads 0.4 volts less than testing with a meter. The battery was 12.4 volt before starting the engine and the ecu was at 12v. So I started the engine, put the data logging on and went out for a 10min drive.
Looking at the data when I got back the voltage reaches a maximum of 13.8v and then drops to as low as 12v, it keeps doing this all the time. So should the voltage regulator on the alternator keep the voltage even or is it working as it should.
Looking at the data when I got back the voltage reaches a maximum of 13.8v and then drops to as low as 12v, it keeps doing this all the time. So should the voltage regulator on the alternator keep the voltage even or is it working as it should.
Part of the problem is that the alternator is from a LandRover that does not rev to 7K+.
To get round this TVR geared the alternator so as not to over rev at high RPM but the converse side of this is that they typically do not start charging till 1200RPM as a minimum.
From what I can remember the ECU stores a fault at over 15v and under 12v, it is very common for the battery voltage to dip below 12v thus logging a fault.
The voltage regulators normally fail in a state that allows high voltages and they tend you pulse for a long time before they fail high when they fail a second ECU warning is triggered and the MIL light is illuminated but an earlier check is to see if the instrument lights pulse dim and bright when driving or just with the engine reving at say 2K+.
If they pulse or the MIL light is on then you have a failing voltage regulator.
To get round this TVR geared the alternator so as not to over rev at high RPM but the converse side of this is that they typically do not start charging till 1200RPM as a minimum.
From what I can remember the ECU stores a fault at over 15v and under 12v, it is very common for the battery voltage to dip below 12v thus logging a fault.
The voltage regulators normally fail in a state that allows high voltages and they tend you pulse for a long time before they fail high when they fail a second ECU warning is triggered and the MIL light is illuminated but an earlier check is to see if the instrument lights pulse dim and bright when driving or just with the engine reving at say 2K+.
If they pulse or the MIL light is on then you have a failing voltage regulator.
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