Revs Bouncing In The Morning

[nbuuifx]

I've not long had the Mondeo.

I noticed that the last couple of days when I start up in the morning and have a load of electrics on that when I get to a junction the revs bounce up and down, dropping to nearly cutting out at 500rpm ish then bouning back up to 1200rpm ish then back down again etc, it doesn't cut out. The fans go in time with the revs (dropping back then powering up again).

It carries on running but doesn't always pull away the best (probably if I pull away on the dip) - There were a lot of electric running as I had just used the voice control 'demisting on'. If I switch them off it doesn't do it.

Is it something to worry about? Anything to look into whilst it is under some kind of warranty?

[BOF]

I'd suspect that the battery is on the way out. Can you measure the battery voltage under similar conditions?

It could also be the alternator.

When you say that the fans are going up and down, is that interior (ventilation) fans, or do you have the radiator fan on for, some reason?

What kind of warranty do you have? How old is the car, or, more particularly, the battery?

[nbuuifx]

Thanks for the reply. I've had the car 2 weeks. It is a 59 plate 2.0L Titanium.

It came with 6 months AA warranty.

It was purchased from a non Ford main dealer. The battery was flat when I went to view the car. They said the workshop did a full battery test and recharge and confirmed all was OK. On my first day of ownership I got a battery warning after turning off the engine (whilst still sat in the car fiddling with all the different buttons!) Since then I haven't had any battery warnings.

The fans I was talking about were the interior fans. As I had said "demisting on" to the voice control it puts the fans on full blast in the car you can then hear/feel the fans going faster and slower with the revs.

Tried this morning with just A/C on and it was fine, but then when I manually put both heated screens on it started doing it a little - only does it for the first few mins.

[BOF]

My suspicion is that the battery voltage is being pulled down well under the normal 13 - 14 volts (charging). I think it is probable that the battery doesn't have much capacity left, but it could be that the alternator is bad and isn't giving out enough current for these big loads, or maybe even that the drive belt is slipping.

Has it had a decent journey to ensure that the battery gets fully charged? The warning message can be a bit sensitive in early cars, so that, on its own isn't necessarily definitive. I think with the converse+ display you can get a voltage reading, so that might be interesting (a DVM is probably still more accurate, though).

Beyond that, it is definitely worth watching, because maybe the garage should give you a battery or an alternator, under warranty. Have you tried telling the supplying dealer that something is wrong? Most dealers will try to give as little as possible, so you've got to be careful about what you tell them, because anything they can use an excuse, it is likely they will. OTOH, if they are a bit worried about it being an alternator, and they finally decide that it is a battery, they might be quite relieved, because it will be quite a bit cheaper for them, overall.

[nbuuifx]

I got in and turned the car on whilst holding the OK button, I then wentdown until I got battery voltage when I got there the voltage reading said 11.5v which was a bit low but then I realised that by this point the fans were on, the radio was on, the convers+ screen was on, and I think the auto lights may have been on (or do they only come on when the engine starts?)

The car started fine and the voltage quickly rose to 14.4v. I put everything on to make the revs surge and the voltage jumped between 13.6v and 14.4v (not sure if it had enough time to change before the revs rose again - but I don't think my DVM refreshes any faster)

Will check it again tomorrow with as much off as possible to start with.

[nbuuifx]

11.8v this morning with the headlights switched off, the radio off, and the climate off. Obviously the convers+ was on, the mirrors had just unfolded various lights had just been on.

If I don't put all the electrics on the revs are fine, if I wait a few mins then they seem fine.

[BOF]

I got there the voltage reading said 11.5v which was a bit low but then I realised that by this point the fans were on, the radio was on, the convers+ screen was on, and I think the auto lights may have been on (or do they only come on when the engine starts?)...The car started fine and the voltage quickly rose to 14.4v. I put everything on to make the revs surge and the voltage jumped between 13.6v and 14.4v...11.8v this morning with the headlights switched off, the radio off, and the climate off. Obviously the convers+ was on, the mirrors had just unfolded various lights had just been on. If I don't put all the electrics on the revs are fine, if I wait a few mins then they seem fine.

Sounds like a battery that is getting a bit tired. The battery will probably survive a bit longer, if you are careful with it, as it seems you are being.

There is not much capacity in the battery, and starting the car takes a fair percentage out of it. The alternator is then at its max until has had a time to put some back in.

It may get worse when it gets cold and you have to give the glow plugs a bit before it will start, and it may be a worry if it doesn't start first time. The best outcome would probably be if you could talk the supplying dealer into giving you a new battery, but that may or may not work, and it may or may not be a good tactic to wait until it does get worse to make the case for a new battery clearer. Somewhat depends on how good the dealer is and how good your relationship with them is.

You could tell them about the problems now and see how they react. Then if you do have to, for example, call the AA out, they may feel that if their expense is limited to a new battery, they haven't done too badly.

[nbuuifx]

Its a petrol so not got to worry about the glow plugs but winter will still be more of a drain on the battery.

Will mention it to the dealer as it was something I said needed to be sorted before I collected it (hence why they had tested it etc)

Seems to be fine even when left for a couple of days between uses.