2.0 HDI picasso Starts fine, but I've noticed on cold mornings, if electrical load it high, the voltage is very low on tickover. This happens for the first couple of minutes of driving (I believe the glow plugs are turned on for this time after cold start to reduce emmisions, so this may be a factor). There is a big change in the sound of the interier fan & the lights dim very noticabily, I suspect this must be at least below 11V, but will have to measure one cold morning. Just measured the voltage now, & the voltage on running is 14.2V, but if a heavy load is applied the voltage dips to around
12V for a split second then recovers back to 14.2V, no matter what the engine speed is, but the morning problem isn't there. This dip worries me more than the morning problem, as I would have thought modern alternator regulators respond to changes in load better than this? I've never noticed this on any other car I've owned. Is this normal or could the battery or alternator be on it's way out?
They might be, but have you checked the battery clamps & the earth bonds between body & battery & body & block? (Low voltage on tickover on a cold morning with glow plugs & demister on isn't unusual)
Thanks for the input. I've has a quick look over, & everything seems fine, will try to have a better look at the weekend. What's interesting is the alternator is connecting to the engine management system. I can't find much info, but it seems it uses a smart alternater where the exciter coil / regulator is controlled by the EM, could be a problem around there. This could explain the split second voltage dip when turning on loads, & I've also noticed when you rev the car within the first few minutes from a warm start, the voltage fluctuates up & down, even though it's at 14.2V on idle, no matter what the electrical load is.
Ah, some of them do that as an anti stall method, (well emissions & vibration control). If it's managing 14.2V on idle with all the electrics on then I wouldn't worry about it.
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