Hello, hope this isn`t a duplicated topic, there are a few threads on unexplained battery discharge but this is a slightly different question.

Assuming there isn`t a problem with anything on the car, if you park up a Ford Focus (mine is a 56 plate 1.6 petrol Ghia estate) how long is it till the battery goes flat ? The reason I ask is mine was parked up for a few weeks and when I came back the engine wasn`t turning over as quickly as it usually does, though it did start. When I questioned my local garage they said it was normal for modern cars to have a residual current drain on the battery of around 0.5amps *. That shocked me, that`s over 6 watts ! So if you left your car at the airport (or wherever) and went to Australia on holiday for a month when you got back the bleedin` thing might not even start ! Is that really normal ? My car has just been left again for 2 or 3 weeks and when I came back to it the voltage on the battery (headlights and heater fan on full) was only 11.5V, it should be over 12 on a fully charged battery. When I drop tested it under real load it was down to 11.3 after 10 seconds, it should be nearly 12. After recharging all voltages were back to normal.

My previous car (a 1997 Escort Diesel) never had this problem, is this another case of progress actually being regressive ? ! ?

* this is possibly a bit high, discussed below......

i used to have this problem on mine .if i did'nt use it for 3 weeks or more it would'nt start ( even with alarm not set) , battery was new and correct type - i kept a booster back on chrage for colder mornings now i've changed to a heavy duty battery and i'ts no longer a problem

I was right that my petrol Focus will start with far less charge in the battery than my old diesel Escort. When the previous battery was on its way out I was amazed the Focus still started with a battery charge that would hardly spin the engine in my old 1.8 diesel Escort, so I bought a mid price Halfords battery, an HCB063 of 46 amp hours. If I`d have know the car had such a high residual current drain when it`s just parked I`d have bought an even bigger one. Are we saying that a 46AH battery is too small for a Focus 1.6 petrol ? If so Halfords certainly shouldn`t be marketing them as a mid heavy duty battery.

the ecu and settings require a continual power source ie the battery and will always draw current so a few weeks without turning it over and letting it idle for a bit will just drain the battery ebay will sell brancded bosch batteries at a better price than those halfords batteries which are junk by the way and halfords will sell you a lead acid non silver calcium battery for youre car despite the fact the ford wont work long with it

I would say any more than a week, you should have the car connected to a trickle charger.

A week ! ! ! Are you joking, the problem with Forums is it`s difficult to tell ! There must be loads of people who leave their cars for a week or more undriven, particularly those with more than one car. My wife`s got a Toyota Yaris and we use that most of the time, it`s easier to park* and, most significantly, does about 20 to 25% higher mpg. My Focus Estate is left at work, technically it`s a 50% company vehicle (though it sometimes isn`t needed for long periods) and we only generally use it family wise when we go on holiday, our 16 month old lad has so much stuff you wouldn`t believe it..... At work it`s on the road so you can`t easily charge it.

I`ve been thinking about this over the weekend, the figure of a 0.5 amp residual current drain can`t actually be right, over a sustained period at any rate. If it`s a 46 amp hour battery and it still starts the car after three weeks (albeit stressfully slowly) then simple maths calculates that even if you disregard the charge still in the battery - to spin over the engine - the average current drain would be about 0.1 amps. have I got that right ? It`s 9.00 on a Monday morning !

* I like my Focus, particularly its refinement and its cruise control is very handy on the motorway, but I tell you my Escort Estate was much easier to park than my Focus Estate. It had a better steering lock, it was marginally narrower, and the visibility from the drivers seat was much better, i.e. the windows were bigger and extended lower.

0.5A does seem rather high. I'd have thought the alarm/immobiliser and radio keep-alive would only have needed a few milliamps. I wonder if the garage got the decimal point in the wrong place. 0.05A seems a more realistic figure.

The drain is 50ma on a ford focus battery after a max of 45 minutes the problem is youde nerd to leave the bonnet up then lock the car leave it for 45 minutes till all the stuff has switched off ecu etc then check the draw otherwise all the systems activate

To be fair to my local garage that`s exactly what they did when they tested it.

The bleedin` thing`s gone flat again ! I used it about 15 days ago and did quite a few miles so the battery would defn have been fully charged. I`d suspect the battery was faulty but I keep reading on this forum and other sources that some cars residual current drain really will flatten the battery in 2 to 3 weeks. I have to say that`s appalling design if that`s the case. At work the car is parked on the road so I can`t easily recharge it or trickle charge it, though as I`ve already stated having to charge your battery if the car is just parked for 2 or 3 weeks is ridiculous. If that`s "modern technology", stick it up your **** !

I wouldn't agree that the battery going flat in 2 weeks is the norm - all depends how much current the car draws when it's been left long enough for everything to shut down.

I think the Focus has a relay that cuts in after a certain amount of time to cut everything off - you'd be able to see how much residual current is drawn if you can use a clamp meter to measure current through the battery positive cable. Saves disturbing everything by disconnecting the battery terminal and putting a meter in the circuit. Then it depends if the power saving relay cuts everything off, and is working as intended.

Modern technology has moved on from power saving relays, to intelligent charging and module management meaning the electrical modules are programmed to shut themselves down after certain amount of time. The electrical architecture of the mk2 Focus is over 10 years old now. But even with the modern technologies involved it's not eliminated the human factor involved in writing the software and carrying out testing etc. And they keep adding more and more electrical goodies, auxilliary batteries, stop start systems and so on.

If your battery has gone flat a few times you'll get sulphation between the plates and this gradually reduces the battery's capacity, getting a current reading would at least give you an indication if something is drawing current when it shouldn't.

by the sound of it youre using the car to go from a to b then its parked up and left for say 2 weeks if thats the case its not that surprising the battery is flat as on a good battery it can take 4 hours of driving to get a dsecent charge back into it it sounds like the cars just not getting used enough to replace the charge in the battery

My 03 focus estate 1.8 tdci ghia has been in me garage for 3-4 unstarted and it won't start. Battery dead as a doo-doo. I used a multimeter today to test and the reading was 6.31 volts. The car was stood up on a dealers yard for a month or soo before me buying it in early July and I've not driven it since then.

the battery is a quilty 1, a banner starting bull and only 25 months old. When it comes time to driving it full time I'm going to put the battery on trickle charge for 24 hours

The battery was fully charged the last time I used it because I`d done quite a bit of driving over the weekend, yet the battery still went flat in about 15 days.

My local garage did a residual current check (after waiting for the system to stabilise) and said the residual current was within normal limits. They added that it was relatively common for modern cars to flatten the battery after a 2 or 3 weeks of being stood.

I just phoned an auto electrician who I`ve used before and who seemed to know his stuff and he said it wasn`t unusual for a modern car to flatten the battery if it`s stood for only two or three weeks. He said something about my 06 Focus having a Gem module or something like that, which should keep the settings ? Not sure what he meant. He said a normal residual current drain would be up to 0.2 amps.

Apparently it`s not unknown for people to take the earth strap off their car if they know it`s going to be left for a few weeks, which I think sums what a ridiculous state of affairs we`ve reached.

sadly thats the way modern cars are now to be fair most people dont leave cars sitting for that long so its not an issue perhaps a small solar charger may help

A small solar charger, now that`s a good idea. Do you just place them under the windscreen ? I take it it`s not the kind of item which will get nicked ? After all it`ll be permanently on display !

There isn`t any problem with them working with the Focus electronics or anything is there ?

Also make sure you are not near any radio transmitters or mobile phone masts. I live near Heathrow airport and all the cars go flat quick here as the Radars stop the onboard systems from shutting down fully, they think someone is sending a transmitter key press every 20 seconds. Very common for cars to flattern in a week in airport car parks, for the same reason thats why they have a battery jump start car always available

Also the modern foci dont filly charge the battery, they aim for something line 85-95% charge and are actully quite small batteries at 75a/h (My last car run dual 130ah batteries! one a starter and one a deep cycle)

Plus if you run a lead acid battery below about 40% charge then sulphation HAS taken place and it will never be as good as before, They are not deep cycle batteries designed to take low charge states. You will need to put the battery on a specialist battery charger with rejuvenation profiles to counter this and even then its likely it wont fully recover

A small solar charger, now that`s a good idea. Do you just place them under the windscreen ? I take it it`s not the kind of item which will get nicked ? After all it`ll be permanently on display !

There isn`t any problem with them working with the Focus electronics or anything is there ?

Fun will be wiring it into a permantly live circuit. The ciggy lighters do shut off eventually. Best to connect directly to battery.

My Landrover has 48Watts of solar panel on the roof rack, feeding into a solar charge controller and the twin 150amp batteries. 4 Amps of charge on a sunny day!. great when I work aborad for 2 weeks and leave the car at the airport

Would be very sensible for all cars to have a large flexible solar cell covering the roof to keep the battery topped up and minimise fuel use for battery charging. Seems daft they miss this free trick, but are happy to report to knackering the starter motor and batteries so they can stop the engine for 3 seconds at the traffic lights (mmm manybe cos they sell more batteries and starters that way!)

Are you saying the solar charger wouldn`t work properly if I just connected it to (what was) the cigarette lighter ?

In your experience do you think having a solar charger on display would make your car more likely to get broken into ?

Incidentally, on the auto stop engines thing, I think a nearly as much fuel and pollution could be saved by putting countdown timers on traffic lights. Mind you, that`s assuming drivers actually use their eyes, we`ve all seen the wazzocks who tear off from lights when anyone who bother to look can see the next light up the road is just changing to red.....

Certainly on my Mk3 the ciggy lighter would only work for about an hour before the BCU cut it off the stop any loads. I would cut the cig plug off the end of the solar panel. Blue-tack/sticky pad it down on the dash or the rear parcel shelf and run the wire down to either the rear fuse panel or the passenger footwell panel and wire it directy into a permanent live

Theft wont be a problem for a £12 solar cell. Heck, My 2 large £100 each 1 meter by 50cm cells have been on the landies roof for many years in full view and just cable tied on and are still there despite the permanant ladder on the back door so its easy to get up there

The problem with wiring it straight in is it would make it more difficult if you wanted to quickly put the charger in the boot or whatever.

On the theft thing I`d be more bothered if any potential scumbag thief though the solar charger was charging something worth pinching that he couldn`t see but broke in anyway just to check.

Just stick a tamiya connector near the cell

http://www.ebay.co.uk/itm/TAMIYA-12V-12-VOLT-BATTERY-CONNECTOR-DC-PLUG-SOCKET-CAR-MODEL-BOAT-PLANE-SPEAKER-/190996010640?pt=UK_ToysGames_RadioControlled_JN&hash=item2c783fd690

Then you can upplug and remove

Seems daft they miss this free trick, but are happy to report to knackering the starter motor and batteries so they can stop the engine for 3 seconds at the traffic lights (mmm manybe cos they sell more batteries and starters that way!)

Cars I know of running a Stop/Start system have uprated starter motors plus run AGM (absorbent glass mat) type batteries, in addition to battery monitoring systems. The AGM batteries are more resiliant to discharge and recharge cycles and can provide more cranking amps but cost more. Then there's twin battery systems where an auxilliary battery will be used to power the car while stopped saving the main battery for cranking the vehicle back into life.

It's a bit of a race between the technology to help manage all the stop/start cycles, and at the same time still power up the ever increasing amount of electrical toys.

£40 for a halfords battery charger. A must for any car owner