Flat Battery - best course of action?
Discussion
E38Ross said:
*Al* said:
Jump starting and driving it to charge is pointless and a waste of fuel, a battery charger overnight is a better option.I've had a battery left for months and totally flat, a good overnight charge and it was fine so it depends on the condition of the battery before total discharge. Wet cell batteries operate best if they are kept fully charged at all times.
this 100%chongwong said:
Jump starting the car and leaving it running for an hour or so,even in neutral should work fine, discharging the battery shouldn't have done any damage. If you have anybody nearby that you can rely on for a push, just push start it, shove it back in your drive and leave it running for a while, or depending on the length of your commute, just drive it to work or wherever you're going, and that should be sufficient
this will charge the battery up enough to let the car start the next day. but it wouldn't fully charge it, not by a long way. if you want the battery to last a long time taking it out to properly charge it is a much, much better way. it can take several hours of driving to fully charge a battery, if not more.
Cheers all - I'm out in the sticks a bit so can't get a jumpstart. Will call the breakdown service and depending on what they say about the battery condition (I'm hoping they have some way or a type of meter for measuring battery life) I'll either buy a charger or a new battery.
Probably could do with a charger anyway - never thought I'd leave the lights on all night.
Probably could do with a charger anyway - never thought I'd leave the lights on all night.
martinalex said:
Cheers all - I'm out in the sticks a bit so can't get a jumpstart. Will call the breakdown service and depending on what they say about the battery condition (I'm hoping they have some way or a type of meter for measuring battery life) I'll either buy a charger or a new battery.
Probably could do with a charger anyway - never thought I'd leave the lights on all night.
What make is the battery?Probably could do with a charger anyway - never thought I'd leave the lights on all night.
2 years will be in warranty period if it is fubar so you will have no expense. That's the beauty of buying a Bosch 5 years warranty quality product.
Some right b
ks being spouted on here. I'll tell you my thoughts from 35 years of motoring and plenty of flat batteries.
1. The battery is very unlikely to be knackered so you won't need a new one.
2. Get the car started (by whatever means) and go for a good drive. An alternator will provide a far greater charging current than any domestic battery charger. You're not driving a car with a bloody C40L dynamo!
Been there, done it, carry the jump leads.
ks being spouted on here. I'll tell you my thoughts from 35 years of motoring and plenty of flat batteries.1. The battery is very unlikely to be knackered so you won't need a new one.
2. Get the car started (by whatever means) and go for a good drive. An alternator will provide a far greater charging current than any domestic battery charger. You're not driving a car with a bloody C40L dynamo!
Been there, done it, carry the jump leads.
I'm no expert so I stand to be corrected but I think you will find a modern car probably pulls 40-50 amps when running (fuel injectors, computers and other electronics) , but the alternator will probably be knocking out 100+ amps. So letting the car sit idling will charge it much more quickly that any mains charger (mine is 8amps).
I have a lot of experience with flat batteries having a little used TVR, Current battery is 2 years old and has been run down to flat at least 5 times. I usually just stick the charger on for 10 minutes which gives enough juice to start the engine, then go for about an hours drive.
the trick though is how you define flat. Most batteries when they go flat still have a charge in them but its below 12v so nothing works. Sticking a charger on for a few minutes will give it enough juice to crank and start. If its actually truly totally flat (and yours may be if you left the lights on) it may be bit more difficult. On the 1 occasion my battery has been totally flat the charge wouldnt work as it looks for 12v before it powers up. In that case I just attached jump leads to another car then left it ticking over which means the battery gets charged by the other car. Then I stuck the charger on and it was fine.
This doesnt mean that your battery wont have suffered, it may have reduced Ah or stamina. Get it jump started , run it for an hour or so you'll probably be ok.
FWIW my wife has a VW golf which spends most of its life doing <2 miles per journey. Battery is now 6 years old and has never needed to be charged - I can only assume that the alternator chucks out big current so even those short journeys are enough to keep it topped off.
I have a lot of experience with flat batteries having a little used TVR, Current battery is 2 years old and has been run down to flat at least 5 times. I usually just stick the charger on for 10 minutes which gives enough juice to start the engine, then go for about an hours drive.
the trick though is how you define flat. Most batteries when they go flat still have a charge in them but its below 12v so nothing works. Sticking a charger on for a few minutes will give it enough juice to crank and start. If its actually truly totally flat (and yours may be if you left the lights on) it may be bit more difficult. On the 1 occasion my battery has been totally flat the charge wouldnt work as it looks for 12v before it powers up. In that case I just attached jump leads to another car then left it ticking over which means the battery gets charged by the other car. Then I stuck the charger on and it was fine.
This doesnt mean that your battery wont have suffered, it may have reduced Ah or stamina. Get it jump started , run it for an hour or so you'll probably be ok.
FWIW my wife has a VW golf which spends most of its life doing <2 miles per journey. Battery is now 6 years old and has never needed to be charged - I can only assume that the alternator chucks out big current so even those short journeys are enough to keep it topped off.
Pobolycwm said:
E38Ross said:
*Al* said:
Jump starting and driving it to charge is pointless and a waste of fuel, a battery charger overnight is a better option.I've had a battery left for months and totally flat, a good overnight charge and it was fine so it depends on the condition of the battery before total discharge. Wet cell batteries operate best if they are kept fully charged at all times.
this 100%Getting a lead acid battery to a completely dead state does them no good at all either. Provided it's not been left in that state for any significant length of time they can be recharged and will likely work ok, but they are never quite the same in terms of CCA and capacity.
E38Ross said:
chongwong said:
Jump starting the car and leaving it running for an hour or so,even in neutral should work fine, discharging the battery shouldn't have done any damage. If you have anybody nearby that you can rely on for a push, just push start it, shove it back in your drive and leave it running for a while, or depending on the length of your commute, just drive it to work or wherever you're going, and that should be sufficient
this will charge the battery up enough to let the car start the next day. but it wouldn't fully charge it, not by a long way. if you want the battery to last a long time taking it out to properly charge it is a much, much better way. it can take several hours of driving to fully charge a battery, if not more.
just my shiny little 2 pencechongwong said:
Sorry,but I think in this case you're wrong, leaving the car at idle for an hour, maybe 2 should have the battery fully charged, I work at a long stay car park , and we do have battery chargers, but because of the comparative speed of jump starting the vehicles and leaving them at idle we don't bother using them:-) I agree with the rest of your points though, also OP if leaving it at idle, try leaving the headlamps on whiles it's running as that 'seems' to speed up the process a little bit just my shiny little 2 pence
I guess this depends on the car, alternator and battery. 2 hours idle would most likely not fully charge my 110Ah battery. If in Neutral and at 3k rpm then maybe so, but not when doing 700rpm or so. just my shiny little 2 pencematchmaker said:
Some right bks being spouted on here. I'll tell you my thoughts from 35 years of motoring and plenty of flat batteries.
1. The battery is very unlikely to be knackered so you won't need a new one.
2. Get the car started (by whatever means) and go for a good drive. An alternator will provide a far greater charging current than any domestic battery charger. You're not driving a car with a bloody C40L dynamo!
Been there, done it, carry the jump leads.
And still being spouted after your postks being spouted on here. I'll tell you my thoughts from 35 years of motoring and plenty of flat batteries.1. The battery is very unlikely to be knackered so you won't need a new one.
2. Get the car started (by whatever means) and go for a good drive. An alternator will provide a far greater charging current than any domestic battery charger. You're not driving a car with a bloody C40L dynamo!
Been there, done it, carry the jump leads.
GC8 said:
OP, if the battery hasnt sulficated then itll be alright. Leaving it discharged will destroy it though, with the sulficated plates touching each other.
Yes, sulfation takes time but the the battery capacity is decreased each time it is flattened ... It has been suggested that there is a way to break the sulfate crystals down but you need a pulser to do it and as that puts a big voltage across the battery you had better disconnect it from everything...No commercial interest:
http://www.roperld.com/science/batterysulfation.ht...
Cheers
E38Ross said:
I guess this depends on the car, alternator and battery. 2 hours idle would most likely not fully charge my 110Ah battery. If in Neutral and at 3k rpm then maybe so, but not when doing 700rpm or so.
Are you sure you've got an alternator and not a dynamo? And have you seen the power output of these new-fangled alternators?20 minutes idle, driving, hooning or dogging will be long enough to get the car back on an even keel. You don't need a fully charged battery in mid summer unless there's something else wrong with the car.
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