Dead Battery

Strider590

TrickyWicky wrote: »

If it's been left flat for a long time then that may well be the cause as flat batterys and cold outside weather to not mix

^^ This

If you take a brand new battery, drain it flat and leave it for a week, it's basically ruined. Even draining it flat for a few hours is enough to reduce it's Ah capacity and it's service life.


Also.....

Jump starting is a mugs game, it's so unbelievably dangerous, your actually safer rewiring a mains socket with the power turned on, because one slip and you've got a car battery kicking out over 400 Amps without a fuse to stop it, hydrogen gas is then inevitable, sparking is also inevitable and if that gas ignites, then hot battery acid will quite happily eat through anything it touches.

Instances are quite rare, but my philosophy is that for the sake of £50 for a new battery, it's simply never worth the risk.

Ebe_Scrooge

TrickyWicky wrote: »

IT shouldn't be as long as you keep your car running. Your car only needs enough power to crank the engine and start it and once it's running your own alternator should provide enough power to keep it going and recharge it's own battery.

It sounds to me like you may have another duff battery if you ask me. If it's been left flat for a long time then that may well be the cause as flat batterys and cold outside weather to not mix. I speak from experience. It doesn't matter how new it is, if you let it discharge and leave it out in the cold it will be dead within a month.

Totally agree with your comment.

However - if the car died as soon as the donor car was disconnected, that suggests to me a problem with the alternator. *Theoretically* you could remove the battery once the engine is running, the battery is not needed to keep it running. The alternator should be generating all the juice required to power the electricals ( unless, maybe at tickover, it's not generating quite enough ? )

OP, have you got a light showing on the dash to indicate a fault with the charging system at all ?

Mankysteve

Strider590 wrote: »

^^ This

If you take a brand new battery, drain it flat and leave it for a week, it's basically ruined. Even draining it flat for a few hours is enough to reduce it's Ah capacity and it's service life.


Also.....

Jump starting is a mugs game, it's so unbelievably dangerous, your actually safer rewiring a mains socket with the power turned on, because one slip and you've got a car battery kicking out over 400 Amps without a fuse to stop it, hydrogen gas is then inevitable, sparking is also inevitable and if that gas ignites, then hot battery acid will quite happily eat through anything.

Never such be in my life.
1. Modern batteries are sealed units so no hydrogen gas
2. Any hydrogenergy gas is quickly dispersed before it even gets a chance to ignite
3. If you undo The negative first you don't get sparks and if renders the positive cable safe.

Stoke

EdGasket wrote: »

Jump starting a modern car is not recommended. You can blow one or both cars up in the process (well the electronics that is). Get a charger and either remove the battery from the car or if you are leaving it in the car, disconnect one terminal while it is charging and only reconnect when the charger is disconnected so you don't blow anything up (chargers can also blow electronics).

How modern are we talking here? I've jump started plenty of older cars and I've NEVER had one die on me. ECU's are only 12v devices after all. Admittedly, I wouldn't jump start newer cars (some even have covers over the battery that instruct you not to jump start) but that is more to do with protecting electrical components than anything else. I do have a fast charger as well which is ideal for when there's no rush.

Strider590 wrote: »

Also.....

Jump starting is a mugs game, it's so unbelievably dangerous, your actually safer rewiring a mains socket with the power turned on, because one slip and you've got a car battery kicking out over 400 Amps without a fuse to stop it, hydrogen gas is then inevitable, sparking is also inevitable and if that gas ignites, then hot battery acid will quite happily eat through anything it touches.

Instances are quite rare, but my philosophy is that for the sake of £50 for a new battery, it's simply never worth the risk.

In my experience, jump starting is only dangerous if you don't know how to do it or are careless/distracted. The one time I made a mistake jump starting (was rushing and placed the negative lead on the donor car first) I blew an 80amp main fuse to the engine (yet didn't kill the ECU), caused a rather large spark, no explosion, but most importantly learnt a valuable lesson. Never had a problem since. I'd still recommend a fast charger over jumping but only when time isn't an issue.

alastairq

For the OP....buy a new battery..they're cheap enough from the likes of Eurocarparts, etc. [£30-40 for one to fit something like an elderly Fiesta]....car batteries aren't made to be as resilient as they once were.

With modern vehicles stuffed with electronics & computers, there is a surprisingly high minimum voltage below which they won't start. [a recent non-starting modern MAN wouldn't turn over the engine if the battery voltage dropped below 23.8 volts! [taken from its computer]!!!!!! is that about then?]

It really is surprising how low a battery voltage would start an old technology car [points & stuff?],,but I think those days are gone for most of us?

kaya

You lot are hopeless, the first thing is to find out what is destroying or draining the battery that is fitted, I could fit a new battery to my car and leave it for 3 or 4 months and it would still start , you have either a short in your electrics or maybe the boot or glovebox courtesy light isn't turning off as it should , you need an auto electrician and some common sense before spending out on yet another battery

alastairq

kaya wrote: »

You lot are hopeless, the first thing is to find out what is destroying or draining the battery that is fitted, I could fit a new battery to my car and leave it for 3 or 4 months and it would still start , you have either a short in your electrics or maybe the boot or glovebox courtesy light isn't turning off as it should , you need an auto electrician and some common sense before spending out on yet another battery

good point, I should read more accurately first......

Stoke

kaya wrote: »

You lot are hopeless, the first thing is to find out what is destroying or draining the battery that is fitted, I could fit a new battery to my car and leave it for 3 or 4 months and it would still start , you have either a short in your electrics or maybe the boot or glovebox courtesy light isn't turning off as it should , you need an auto electrician and some common sense before spending out on yet another battery

Uhuh... I've left my car for months on end and I've never had a problem.

However...

Internal clocks are often running permanently, odometers are digital nowadays are many remain illuminated permanently, some cars have radios with anti-theft devices that flash, my own car has a flashing LED in the door which indicates the car is locked and alarmed (if I fitted the OEM alarm :P which I haven't), remote central locking, proximity alarms?

All this stuff takes juice from your battery. Some cars can eat a battery in a few weeks, nothing to do with a bad earth I'm afraid.

getmore4less

Get a decent battery charger

Ctek or the Aldi Lidl copies.

http://www.amazon.co.uk/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=Ctek

check on camelcamelcamel for the low price

Uniscots97

Put it this way there's so little in the battery that the key fob didn't work, I had to use the key to open the door.