Is it my Alternator

[robbiefurn]

Merc Citan 2015 Van (Diesel) possible alternator issues?:
Battery when off :12V, Battery when on and with load (like heater, radio, lights etc) 14V . Battery is 2.5 years old
Lights flicker and heater goes low now and then usually at junctions or start up, slight burning smell very ocasionally only lasts 20s. Somtimes engine dips like its going to conk out for a fraction of a second. Performance is rubbish (might be unralated)
What do your recon ?
Many thanks

 

[Harry Bloomfield]

Battery when off :12V, Battery when on and with load (like heater, radio, lights etc) 14V .

12v suggests battery is faulty (but), 14v suggests alternator is fine. The burning smell, suggests something is amiss, and the 'amiss', might be discharging your battery. You need to check the discharge on the battery, when everything is supposedly turned off.

The 'amiss', might also be pulling your voltage down, causing the misfires too.

 

[Mottie]

Alternator overcharging intermittently?

 

[Burnerman]

I don't like the sound of this one particularly.........there is obviously a high current discharge somewhere, indicated by the fall of engine revolutions and the slowing down of other auxiliary items.
You can expect a bit of this if the heater plugs switch themselves back on under extreme cold conditions, but not to this degree.
The battery voltages are about correct.
Personally I'd slip off the alternator drive belt and try things again - don't run the alternator disconnected in any other way.
Re the burning smell.......any whiff close to the alternator itself? I guess you could try running the engine with the bonnet up and looking closely
but there will be a risk of damage to something.
Has any work been done to the van recently that could have upset the routing of the battery cables?
John

 

[robbiefurn]

Sound advice gents, so somethings possibly causing a high current drain. Potental Arc? albeit intermittant? one of the reg plate lamps is a bit iffy

 

[Mottie]

Alternator overcharging intermittently?

I have seen that happen a couple of times years ago and that was both on Cortina’s. When the alternator cut in and overcharged, the engine slowed down on tickover and the battery bubbled and gassed heavily. Maybe that’s the 'burning' you can smell?

 

[robbiefurn]

Quite possibly, i'll pop the bonnet and have a.wiff. No visible issues with the battery, new air filter fitted recently which is very close to the battery cables and would have certainly moved them a bit. Also worth mentioning i tried to jump start my car couple of months back from the van using jump leads( failed to jump)