Battery issue

[dave225]

Just collected my "new" 9-5 which had been standing on the last owner's drive for some time.
Engine was a bit lazy turning over but I assumed (incorrectly) it would charge up on the long run home. It hasn't and every time it only just spins enough to start it.
I'm trying to calculate how long it should take to discharge, so I'm after the quiescent current drain of a 9-5 when its standing. Obviously the self dischage rate gets added, which I can find out from the battery maker.
Any help appreciated.

Thanks
Dave

[collywobble]

All I can find in the WIS are the following values for parasitic current draw (without accessories such as telephone fitted):

Transport mode: 5mA

Customer mode: 16mA

Hope this helps - personally I find quantum physics easier to understand!

[sgould]

Forget the transport mode, that disconnects things for the car on a transporter.

The battery will be about 70Ah.  Which means it will discharge completely in 70 hours with a 1 amp drain.

With 16 milliamps drain, a fully charged battery should last about 4375 hours or about 6 months.

[nine-fiver]

The 9-5 will try to start on a battery that is very nearly dead, often with a dud cell in it. The battery will often read 12V or more, and even accept charge to some degree. Cranking will be slow, but 9-5s are not all that quick to spin up anyway.
Only a new battery can solve the problem. But I would certainly get yours load tested by a mechanic who has a hand held battery computer to put it through its paces. Three years is all you will get on a battery these days, particularly if you short trip a lot.

[CitTone]

Three years is all you will get on a battery these days, particularly if you short trip a lot.

At the risk of tempting fate, the one I have came with the car, and I've had it over 4 years now, with the majority of my journeys 10 miles or less. I've been waiting for it to turn its toes up all year.

Received wisdom is that modern batteries give little warning anyway, and just fall off a cliff when they have had enough, rather than "getting tired". Doubtless mine will wait until I'm late for work and it's dark and sleeting.....

[Mr Linear]

or come out of Tesco on a dark wet night with a trolley load of shopping!

 

[AlanM]

The 9-5 will try to start on a battery that is very nearly dead, often with a dud cell in it. The battery will often read 12V or more, and even accept charge to some degree. Cranking will be slow, but 9-5s are not all that quick to spin up anyway.
Only a new battery can solve the problem. But I would certainly get yours load tested by a mechanic who has a hand held battery computer to put it through its paces. Three years is all you will get on a battery these days, particularly if you short trip a lot.

This happened to me last winter on a relatively low mileage V6 3.0TiD. It started normally and I went to a friends house about a mile away. When I came to start it, no joy. Needless to say my friend's house is at the bottom of a long drive but fortunately he had a charger, so the car started normally a couple of hours later.

Drove straight to Halfords for a new battery which I hope will last longer than the nine years of the original 

[Steve440]

Received wisdom is that modern batteries give little warning anyway, and just fall off a cliff when they have had enough, rather than "getting tired". Doubtless mine will wait until I'm late for work and it's dark and sleeting.....

I agree this is how my failed a few months back, I drove my car 15 miles in the day time. Stopped for 20 mins at a  friends for a cuppa and when I came to start it the battery was completely dead. No signs of poor performance or any failure beforehand. 

Steve

[Geoff1951]

My experience echoes the above. Little warning, fires the engine up fine one day, barely turns it over the next. Got around 4 years from a Bosch, replaced by a Yuasa earlier this year.

[CitTone]

According to the receipts, mine is 6 years old.

(Crosses fingers!)

[TomPaine]

According to the receipts, mine is 6 years old.

(Crosses fingers!)

I'd replace it asap personally (unless you live a life where it not starting wouldn't be that big a deal and you'd just replace then). As others have said they go entirely without warning, and having had two go on 9-5s at 5-7 yrs I replaced my last one at 5 yrs as a preventative measure.

[nine-fiver]

Something to consider. A deep cycle charge every year will prolong the life of the battery to some degree. Do it on the car but with the terminals disconnected of course. It only takes a night to do and a few minutes the next day to hook it back up. No loss of radio 'marriage', but the clock will need doing. Recycle the battery too if you can, after you change it over for the new one. I bet the cold weather is finishing off a few elderly batteries too?

[CitTone]

My battery got caned flat earlier this year when the car conked out waiting in a queue for fuel due to low tank pressure, and had to have two additional batteries piggy-backed on to restart it. That may well count as a deep discharge!

[warmrain]

Something to consider. A deep cycle charge every year will prolong the life of the battery to some degree. Do it on the car but with the terminals disconnected of course. It only takes a night to do and a few minutes the next day to hook it back up. No loss of radio 'marriage', but the clock will need doing. Recycle the battery too if you can, after you change it over for the new one. I bet the cold weather is finishing off a few elderly batteries too?

I am not sure a deep discharge and then full charge (as has been advised for some Ni-Cd computer batteries) will do it much good -- if this is what you meant by "deep cycle charge".  There are some "smart" chargers for lead-acid batteries which claim to reverse any small degree of the detrimental sulfation that occurs over time, but the lead-acid battery likes to operate in a near-to-fully-topped-up condition.  An inexpensive digital readout multimeter can give you useful information about the charge level of your battery ( it needs to have rested 6-8hr with no current draw). 

Lots of information here:
http://batteryuniversity.com/learn/article/lead_based_batteries

To the original poster: If the battery has been stood for a long period it would be useful to bring it up to full charge with a "smart" charger but it may well have suffered a degree of permanent damage and loss of capacity.  See also article above on decreased/limited life when "deep cycling" car lead acid batteries.

As a side issue I have sometimes had the impression (perhaps subjective) that the car runs smoother when the battery is near full charge rather than when near fully discharged.  My explanation is that the ignition cartridge and associated electronics probably works better with a charged battery buffer to draw on, with an overall more even working voltage, rather than the more choppy voltage you might get when drawing entirely on just what the alternator has to give (as in when the battery is almost flat).  I really need to drive it around with an oscilloscope attached to prove it!

[sgould]

Phoenix has posted recently about how the battery in modern cars is part of the electronics.  The technicalities of it are beyond my understanding....

So you could well be right.  It may also be a sign of your battery beginning the slide into oblivion.