Ford Fusion battery drain

1 Jun 2017
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United Kingdom
Hi guys I've got a 2008 Ford Fusion I've had it for about a year and the battery is died twice.
I had a new battery fitted when I bought it.

Now that only thing I think it could be is the kids play with the interior light at the back and leave it on it does turn off with the engine but the switch is still on could that still drain the battery?
The other thing is I do only use it probably once every two weeks but when I do use it it's normally for an hour or two at a time
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If the interior light puts itself out, then that should be the end of the battery drain. Of course there are several systems within the car that remain live and do use battery power and this will have an effect.
If the car hasn't been used for a fortnight and the weather is exceptionally cold then the battery may not have enough oomph to start the engine. My diesel Yeti failed after exactly the same length of time (exactly when I needed the 4x4 :() so I wasn't too pleased with that! Once I got the thing going it has recovered fine. The engine just refused to crank over - and still took the huff when I tried to jump start it.
Items that can cause battery drain are the obvious lights left on, a battery that is below par and possible alternator diode issues....its reasonably easy to check all of these.
John :)
Yeah it won't even unlock the battery is that flat it was the same last time to literally nothing when you try and turn the engine over and it wouldn't jump start last time either
I charged the battery for about 3 hours and it was good to go and hasn't been a problem until today
Last time it went was at the beginning of the really cold weather so I put it down to that but this time it's been fairly mild
If the car won't even unlock then the battery is very well down - so there is something wrong.
I'd start by having the battery checked out....a motor factor will put a heavy discharge test on it and check the results. They'll be even more delighted to sell you a new one :whistle::whistle:
After that then its time to measure current draw when the car is parked up - simple enough with a multi meter. Another way is to have the battery fully charged up, and then disconnect a terminal to see if the charge is may indeed see a small spark as the terminal is disconnected. Unfortunately this upsets the clock and radio and whatever so its a bit of a PITA.
John :)
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I noticed just now that the display light for the miles etc on the dash is staying on, so thats whats causing most probably.

Any idea why thats not going off?


Its ok it goes off after a while haha
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The display should go out after a while.....this could be anywhere between 5 minutes and an hour, believe it or not! During this time the ECU is still powered up, and if the display continues to be illuminated it will flatten the battery.
Check any switches in the boot area that could be failing, and check the doors are actually locked when you expect them to be.
Also, manually turn the radio off before you park the car up.
John :)
Three hours will not recharge a battery, looking at more like 8 hours, and if it was that flat for any time then a lot more, batteries will only accept so much power when charging, using a smart charger is best as it tells you when finished, I use a cheap Lidi charger, it has four bars when all are lit then charge is nearly complete, I will wait for voltage to be over 13 volt before removing charger, as even after it goes to final stage, it is still charging the battery a little.

Years ago we would put batteries on an equalising charge once every two months for 24 hours, however both the cars charging system and the batteries have improved since then. Today my wife's Jaguar XE auto disconnects items should the battery fall below a set level to ensure the battery does not discharge enough to stop charging, don't fully understand why it failed to start with us, the agents said faulty battery, but changed rear battery and I thought front one was for starting, so even with all the computer control still had problems starting.

However again putting the battery on charge can also upset the on board computer it seems, it monitors the volt drop to work out battery condition, however if you use a smart charger their output is so low they are unlikely to permanent damage anything, so I would aim to charge for at least 24 hours if not whole week.

Not sure what level of control the 2008 Ford Fusion has, Jaguar was owned by Ford for a time so Ford may have same system, however back in 2008 there was so much less in the car, so likely a boot not closed fully could cause boot light to stay on, and in my old car you can leave interior lights on, and at 12W = 1A then with a 60 Ah battery after 60 hours battery completely discharged.

When my father-in-law let his battery go flat, could not open bonnet as slightly under work bench in garage, could not release hand brake it was electric, so it was trolley jack under back axle and drag it out of garage with my car before we could even lift bonnet to charge battery, lucky not a 4 wheel drive car. At least with car parked outside I can see if a lights left on in my car, unlike my wife's XE I can't check car with smart phone, I have to go outside and switch on ignition to see how much fuel is left, or to warm up engine before driving off. But her phone did not help her start engine when battery was flat! Sorry should say discharged, shape of battery does not change be it charged or discharged.

But 3 hours is not enough to recharge a lead acid battery, most need at least 8 hours, the VRLA as used in Jag may be a little faster, they are also more expensive over £200 and seems we were not charged for labour?
Was on charge for 3hrs again yesterday and started straight away after

Started ok this morning too
Sorry I should have explained, when a lead acid battery discharges it forms sulphur on the plates, and when it charges it returns to the acid, while on the plates it slowly gets harder, and it can reach a stage where it will not return to the acid very easy. So unless the battery is fully charged once a month or so it will lose capacity.

The longer it is left part charged the longer it will take to fully charge. I had some small 7 Ah batteries that were left discharged for a few months, and when put on charge they sat there taking no charge for nearly two weeks, then as if a switch had been flicked they took the charge, I only know this as using an energy meter on the charger so I saw the charge rate change.

So I would keep putting it on charge until it has been on charge for at least a week, then you are sure fully charged. With a smart charger of course or they also could be over charged.
I guess you don't have a 2/ 3/ 5 year warranty on the battery?

Unfortunately i didnt buy the battery, the previous owner did just before i bought the car.
Its not marked on the battery either.

Euro car parts had 37% off at the weekend so i bought a new batt
Yeah sorry i ment it!

They said it had a new bat fitted and the radio needed the code so no reason not to believe them but i guess it could be a old batt
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