Hi all

 

My diesel VRS has had the slow start issue for a while which seems to have got better/less frequent recently, but this morning it decided not to start at all.

 

Half turned over once then gave up.

 

It sounds like a dead battery to me, but once I've jumped it, is there anything specific to look out for (in the event that it wasn't only the battery)??

 

To be fair, my journey is a 7 mile each way commute to the station and I should probably have switched the car out a long time ago, but I like it! No DPF issues whatsoever, so I figured I'd just keep hold of it!

 

Cheers

Alex

How old is the car? I had a battery fail on my Fabia at about 4 years old. The cold weather had knocked it for six as one of the cells was no longer effective. 

Make sure to jump start it correctly by the way - i.e. using the metal bracket provided rather than the -ve battery post!

I would give the battery a good slow charge over the weekend or overnight & see how long it lasts before you start to see problems again.

The recent cold weather & your short journeys might just have taken a bit more than usual out of the battery.

 

Edited 5 February, 20197 yr by Gabbo

If it's not cold cranking the engine the battery will probably be toast.

Maybe with a slow trickle charge you might be able to tempt a little more lifespan from it but I fear it's been terminally wounded due to deep discharge.

 

Well...I've just given it a go at jump starting, and it's still dead.

 

It doesn't even try to turn over now, yet all the electrical systems seem to work.

 

I've read all the catastrophic posts about a seized engine and now am panicking I have a £15k lump of useless metal on my driveway.

 

I'm genuinely at a loss as to what to do about it...call Skoda? Call an independent mobile mechanic?

 

It's only 4 years old with less than 30k miles on it! Was perfectly fine last night.

I've tried to jump start cars in the past and sometimes the jump leads can be problematic. Unless they're a set of heavy duty ones, they can quite often not have the ability to allow the current needed.

 

As said above, get your battery on a charger of some descript, be it a standard trickle charger or a conditioner.

 

My car of late has been having a think about starting a few times, but that's just been the cold weather doing that. The glow plugs will certainly have been working overtime initially.

 

Also, check what battery type it is. If you've an EFB they're not as good compared to AGM. Certainly if there's been a lot of current draw from the battery of late. EFB need to be charged for longer to recover.

Edited 5 February, 20197 yr by tunedude

Get the battery tested. Remove and take to a garage for a proper load test.

 

Likely that is the issue so fingers crossed.

 

Thanks all. I have a local VW specialist coming to look at it today.

 

I don't need this!!

Good luck and keep us posted thanks 

The battery was toast.

 

I can't quite fathom how there was sufficient power left to power all the electrical bits with no warnings whatsoever but hey.

 

New battery (which was a small fortune) and it's good as gold now. Not that I've driven it yet, that's tonight's job!

Glad it's all fixed.

 

May I ask which battery (EFB or AGM) did you buy? How much did it cost you?

 

My 5 year old car is looking like may need a new battery soon. I've trickle charged it for 2 days, used it a bit. Now parked it up for 4 days so far, I'll see if it can hold a charge after 1 week parked at 5-10c ambient temperature.

No idea to be honest. I let my mechanic sort it. Like for like to whatever it already had in it I guess.

 

I can have a look for you if I know what I'm looking for!

Batteries should last 10 years and if you get a fresh factory built car they will. But if the car is from long term storage the batteries are often left to go totally flat. That is fatal for a lead acid. Thry will recover but their life is drastically reduced. Even after just one full discharge 

On 09/02/2019 at 07:36, alexbuck said:

No idea to be honest. I let my mechanic sort it. Like for like to whatever it already had in it I guess.

 

I can have a look for you if I know what I'm looking for!

 

Just somewhere on the top it'll say either EFB or AGM. I wouldn't worry about which type of battery you've got, as long as you're car is back up and running, you're laughing.

 

Don't worry about it. As long as it's all fixed for you.

 

12 hours ago, teescom09 said:

Batteries should last 10 years and if you get a fresh factory built car they will. But if the car is from long term storage the batteries are often left to go totally flat. That is fatal for a lead acid. Thry will recover but their life is drastically reduced. Even after just one full discharge 

Indeed. My previous 11 year old Mercedes was still on original battery, no sign of any problem.

 

My battery test went well. The car was parked untouched for 1 week, last Monday 5pm to this Monday morning 7am. Engine started no problem, once up to temperature after 10 odd minutes, stop/start kicked in. Looks like I don't need a new battery for next few years, just need to keep the battery topped up if I don't use the car for longer.

I dont have the current/rpm curve for the alternator in your engine.

A few things to remember:

At low rpm the output will be lower the the rated output so will charge your battery more slowly. if at all.
At very high rpm the car may consume more than the alternator can provide.

For example a 100amp rated may only provide 50amps at 1500 rpm and 30amps at idle.

Also modem modern cars are designed for efficiency rather than having a beastly alternator.

Hence, you battery is sometimes being charged while other times losing a bit of charge as you drive around. It really doesn't matter to your battery if it lurks between 70% and 100% charge.

I guess my main point is that if you did a 300 mile journey at low RPM with lots of electric load (lights, stereo, heated seats/read window/etc) you may find the battery is actually less charged than when you started :P

My advice, just drive it. The boffins will have crunched the numbers and for almost every use case, you'll be fine.
 

Should be almost impossible to run a good battery down at any speed and electrical load. Modern alternators are very powerful 600 - 1000 watts. They are geared to provide high output at very low revs, especially on diesels, far more than your electrics can consume. Batteries will only take a certain amount of charging current at a set voltage and discharge state, probably not much more than  20 amps even if run down regardless of the size and output of the alternator, which they rarely would be unless you had difficulty starting it or had a lot of stuff on before starting for a long while. 

 

If your battery is flat and you have been using the car normally, ie driving it more than a couple of miles after every start up, and the alternator is good, the battery is almost certainly knackered.

 

7 hours ago, abaxas said:

I guess my main point is that if you did a 300 mile journey at low RPM with lots of electric load (lights, stereo, heated seats/read window/etc) you may find the battery is actually less charged than when you started :P

 

If this were true there would be a lot of people stuck at the side of the road.

 

You take any car, bang as many consumers on as you can at idle and I bet you never see the voltage drop to anything near as low as would be needed to draw current from the battery itself. The alternator for each car is designed to run all consumers. What good would a car be that went flat after driving it.

 

 

9 hours ago, teescom09 said:

Should be almost impossible to run a good battery down at any speed and electrical load. Modern alternators are very powerful 600 - 1000 watts. They are geared to provide high output at very low revs, especially on diesels, far more than your electrics can consume. Batteries will only take a certain amount of charging current at a set voltage and discharge state, probably not much more than  20 amps even if run down regardless of the size and output of the alternator, which they rarely would be unless you had difficulty starting it or had a lot of stuff on before starting for a long while. 

 

If your battery is flat and you have been using the car normally, ie driving it more than a couple of miles after every start up, and the alternator is good, the battery is almost certainly knackered.

Sorry, I don't buy that. I think it is possible to drain the battery through normal usage (which could be short journey or long period parked).

 

My car gets parked up days at a time, sometimes 2-3 weeks due to driving EV on most days. But when it does get driven, it goes at least 30 miles, 25 of which is on motorway at constant 2000+rpm, twice in one day (commute). When I first got the car, stop-start would work most of the time. But this winter, stop-start would rarely work. After sitting for 4 weeks, even flashed up "low battery" warning. The battery charge in the battery is clearly getting drained slowly.

 

A 40 hour battery float charge made sure the 12v is fully topped up. About 2 weeks now, 1 week of which car was parked up. Stop-start still works great and no hint of knackered battery. Alternator is clearly also in good shape, otherwise stop-start would drain the battery quickly.

11 hours ago, SuperbTWM said:

 

If this were true there would be a lot of people stuck at the side of the road.

 

You take any car, bang as many consumers on as you can at idle and I bet you never see the voltage drop to anything near as low as would be needed to draw current from the battery itself. The alternator for each car is designed to run all consumers. What good would a car be that went flat after driving it.

 

 

I think you miss the point here. Alternators are not designed to keep the battery at 100% charge 100% of the time.

They have may been in the past but why on earth should a car have something 'larger' than is needed in almost every situation?



 

Google "micro hybrid" and read to understand todays charging and energy recovery schemes used in virtually all of Skodas current cars.

 

Batteries are rarely fully charged but work to a target state of charge, allowing enough capacity to be available for energy recovery during braking.

Normal use is NOT short journeys or being parked up for long periods of time....

 

And batteries ARE kept at a high state of charge and have a longer life if so.

 

regenerative braking ? All that is, is the regulator allowing a higher charging voltage while slowing and lower voltsge while accelerating. Only when  the battery is in a good state of charge. If the battery is low the regulator will allow nominal alternator voltage constantly of around 14.4 to 14.8 volts. Batteries are kept fully charged

 

 

 

   

 

 

 

 

Edited 13 February, 20197 yr by teescom09

12 hours ago, abaxas said:

I think you miss the point here. Alternators are not designed to keep the battery at 100% charge 100% of the time.

They have may been in the past but why on earth should a car have something 'larger' than is needed in almost every situation?



 

I never said they were 100% all the time, but unless you have the latest hybrid technology the battery will be charging all the time to varying degrees when the engine is running as the alternator maintains 14v+ (or a bit less if the BMS decides so)

 

So you saying you could drive 300 miles and end up with a battery that has a lesser state of charge just because you are doing low rpms is pure rubbish (unless of course the battery management decides otherwise)

8 hours ago, SuperbTWM said:

I never said they were 100% all the time, but unless you have the latest hybrid technology the battery will be charging all the time to varying degrees when the engine is running as the alternator maintains 14v+ (or a bit less if the BMS decides so)

 

So you saying you could drive 300 miles and end up with a battery that has a lesser state of charge just because you are doing low rpms is pure rubbish (unless of course the battery management decides otherwise)

Firstly, the load your car can usually larger than the max the alternator can supply. Noting that the rating of the alternator is peak not all the time or average. Also noting that any car with an aux heater will be able to draw significantly more than the alternator can ever supply but only for a short period.

Depending on pully size most alternators provide ~50% of rated output at idle. So if you have a 140A alternator you can 'charge' at a peak rate of 70A. If it's morning and you have just got into the car, stuck the blower on, read demister etc, you'll be drawing more than 70A.  You'll probably ask, why not use a higher ratio, the answer is efficiency. Do you really think the boffins at VW is saying 'oh yes lets lower the mpg a little bit so the battery can be permanently charged at 100%'.  If you do, seek medical help :P

The issue is any sort of battery management it irrelevant against the basics of electrics. You can't take out more than you put in, that's what the battery is for.