Hi All,

My Mk IV Mondeo (2L Diesel 2007) has a completely flat battery - no idea why it has drained, but it seemed to happen over the course of a couple of days. So I tried to charge the battery in situ.

I connected the +ve end of the charger to the +ve terminal of the battery. I then connected the -ve end of the charger to the the stud on the body work where the earth strap connects. I then turned the side lights of the car to the on position, to hopefully prevent any spike in power and then I plugged the charger into the mains!

On connection the sidelights started to pulse, so I turned them off. The hazards also began to pulsed and a relay could be heard clicking on and off. I operated the hazard light button, but could not get them to stop pulsing. So I left if for about 20 seconds and the hazards continued to pulse and the relay continued to click. So I gave up trying to charge it.

Any thoughts on what the issue may be?

Advice appreciated.

Ta

P

My Mk IV Mondeo (2L Diesel 2007) has a completely flat battery - no idea why it has drained, but it seemed to happen over the course of a couple of days.

Unfortunately that does happen. There are some 'conspiracy theories' but probably the best thing to say is that, electrically. the Mondeo is a fairly complex car (as are most these days) and there can be a number of causes.

One thing to keep in mind is that, if that is an original battery, it could be quite down on capacity by now. Or, to put it another way, with the winter coming, it might not have great prospects of surviving through the winter period.

On connection the sidelights started to pulse, so I turned them off. The hazards also began to pulsed and a relay could be heard clicking on and off. I operated the hazard light button, but could not get them to stop pulsing. So I left if for about 20 seconds and the hazards continued to pulse and the relay continued to click. So I gave up trying to charge it.

I can only think that the battery voltage has become so low that various modules are not working correctly, even with the charger connected. How about disconnecting one terminal of the battery, and putting the battery on charge that way, for a long period, and see if the battery recovers?

Edited September 12, 201510 yr by BOF

Agreed - sounds like too low battery voltage / amperage to me too

As above - try a long slow trickle charge with the battery disconnected

Edited September 12, 201510 yr by MONDEO TXS 2.2

I should have also added that, at this age, there is a possibility that the alternator (or cheaper, the wiring) isn't giving the battery a full charge.

Even if this is the case, the first thing to do is to get the battery charged, the car started, and see what happens. If you have a DVM, then the voltage with the engine running will be interesting, but first you have to get the car started, and for that you need a bit of charge in the battery...

As already said, there is only one simple way ahead here - Disconnect the battery and charge it, that way you remove the risk of damaging the cars electronics or playing havoc with them.

Thanks for the replies. In the end I bough a new battery as the one in the car is a Ford Battery and possibly the original. I will et the car sit for a few days now as don't need to use it for a week and will see if the battery stays charged. If not I may have to read in to some of the "conspiracy" theories!

If it is an original battery (and most people don't buy Ford batteries, if they can get something else cheaper, irrespective of how long they will last, so if it says Ford on it, the chances are that it is original) then, whether the battery is the fault, or not, it wasn't going to last long, and was probably making things worse, by being down on capacity - as batteries are used the capacity gradually goes down, and eventually becomes inadequate).

You should get the voltage up to at least 12.5 volts before you use it, whether that means charging it, or not.

The other possibilities are that the battery wasn't being fully charged, or that something is discharging it, but there is a good chance that the replacement battery just cures it, once it is fully charged.

Well after letter the car sit for over 5 days, the new battery seems fine and the car starts powerfully. So fairly comfortable now that the issue was just that the old battery was the original and it suddenly died.

Thanks for the advice all.