Please note - I am not a mechanic or expert in anything.

 

It doesn't really matter when you read this as the battery and its condition and state of charge is always important especially with modern cars with all the electrical items and systems on them, the car may start and lights seem bright enough but the battery may still be too low for the car's computers and this may cause them to throw wobblies of all sorts - just check out some of the threads here if you find this hard to believe.

 

But at time of writing the days are getting shorter and darker and colder so you will need the car battery to be in good condition and connection and in a good state of charge to get you through without what can be a lot of hassle and inconvenience if you let the battery get too low, or fail altogether.

 

Letting the battery get too low can cause all sorts of problems and some of them unexpected, many people will think that because the car starts and the lights seem bright enough that the battery must be fine and well charged but this might not be the case.

 

Now is a good time to check your battery - that both battery terminal post clamps are tightly secure (and battery securely clamped to the car), that there are no spillages of any sort or mess on the top of the battery and that the battery has a good level of charge in it.

 

You may want to consider a suitable battery charger, not a very fast or booster charger though, to keep your battery well charged and not be caught out with low charge problems and/or your use of the car's electrical items especially when the engine , so alternator, aren't running .

 

This may also perhaps save you being caught out and being one of the very many that need to call out the breakdown services because the battery is flat,  the AA number one most common cause of breakdowns - Flat or faulty battery.  The AA won't say this but I will, very rarely is it a faulty battery, a few might be charging system faults but the vast majority will be user error, ignorance or neglect.  Remember prevention is better than cure - and not have the computer hassles or become an AA statistic. 😉

 

Edited 14 September, 20223 yr by nta16
Please note - I am not a mechanic or expert in anything.

Excellent write up.

Spillage?

 

Topping up batteries or even batteries venting fluid is so last century!

Just now, J.R. said:

Spillage?

 

Topping up batteries or even batteries venting fluid is so last century!

 

Depends how archaic your car is to be fair...

Having read the phrase so many times "a long slow recharge" is now so imprinted on me that I am going to lie down and have one.

5 minutes ago, AnnoyingPentium said:

 

Depends how archaic your car is to be fair...

 

By my best estimate the last time I was able to remove a non removable piece of plastic and access filler plugs to top up a battery that everybody else would replace because it was sealed for life and would not hold a charge was 1992.

 

I did get really destructive with one some years later, the current non AGM liquid acid type and I totally destroyed it with no way of putting Humpty Dumpty back together again and I did not even come within sniffing distance of any acid.  The top plate covering the labrinth overpressure vent matrix is ultrasonically welded.

 

You could leave a battery upside down for a month and it would not spill a drop of fluid or even vent gas unless you were to charge it at double voltage. The case would become horribly distorted through the heat of overcharging like the batteries in my fire alarm panel (voltage regulator failure)  but it still would not leak acid.

Please note - I am not a mechanic or expert in anything.

 

On 28/11/2021 at 23:08, J.R. said:

Spillage?

 

Topping up batteries or even batteries venting fluid is so last century!

I wasn't specifically thinking of that sort of spillage but as Ryan has put them there old batteries, perhaps in the back of my mind I was, IIRC some old batteries for the "classic" (over-priced and over-valued old - how many times you read that) cars still have 6 screw top or am I in a flashback.

 

The spillages I was thinking of were all sorts I've seen on batteries, must have been lunches and teas for some, gunk going the width of the battery.  I've changed the wording or I might delete it later, see who else moans about it.  Being serious I do have trouble with words and spelling particularly to a screen, I often miss out words without noticing or alter a sentence and then make it difficult for others to read because I don't see it, so just shout out.

 

1992 IIRC  I had a car with two 6v batteries, I think the tops unscrewed but not sure as I can't ever remember having to do anything with them.  I've got a feeling the battery before the one I have now was 'sealed' but all that was needed was to peel the plastic label back to lift or unscrew the lids.  Or perhaps even it was one with lift off lids anyway.  I don't think those unsealed batteries go back that far, but I have been known to loose a decade.

 

ETA: I remember now sorting a neighbour's (Halfords battery) about 5-6 years ago and I'm sure I could unscrew the sunken level caps if I wanted to add water.

 

You have to bear in mind on my car even though it's a 1970s car I have things like if I wanted to turn the heater on I have to lift the bonnet and turn the tap, not much, it's either off or full heat, previous model I had didn't have a boot light or interior light, I'm used to the older stuff on cars.

 

 

On 28/11/2021 at 23:13, J.R. said:

"a long slow recharge"

Hey!  You've missed a word out, long slow low recharge!!  Pay attention.  I did wonder if there should be commas but I think not.

 

I copied and pasted most of above from a Thread I put up in General Maintenance but it's lost there and the 'battery issues' have started (do they ever stop) and we're on the first cold snap that weakens (like c/h systems) and too late at second cold snap when they break and it's no-goes and breakdown call outs and batteries not on shelves (and waits for c/h call-outs, repairs and parts).

 

Just trying to get in prevention before it's too late and it's the misery and hassle of cure, soon get cold without the engine running.

 

Edited 14 September, 20223 yr by nta16
Please note - I am not a mechanic or expert in anything.

    I fully  agree with the need to have your car battery fully charged to avoid problems. Especially since, as someone said, there are computers that can give you grief and disable electrical gizmos. My battery is an EFB type and is sealed like many(all?) batteries are now. Until recently I was only checking the condition through the spyhole at the top and checking that the right colour is there, black in my case. However I saw a post on here recently  that really made good sense, switching off the start stop once the engine is running.

 

   The poster recommended doing it before decent journeys but I have taken it a stage further and switch it off before each journey, long or short. To me the rationale is indisputable; switch it off and your battery can be over 80%  charged, even up to 100%. Not doing it will restrict you to a max of 80% because of the remaining 20% being needed to operate the stop start. I am not mechanically gifted at all but such a simple thing can have such beneficial effects on the battery and I recommend it to all those people like me out there who are not good at fixing cars. It takes only  a fraction of a second to do and you cannot fail but improve the performance of your battery. I do realise that the stop start can be permanently disabled by removing the dongle from the battery post and I will mention  having that done to my independent when  it next goes in for service. I  also understand that there could be adverse insurance implications if that gets done  so that may not happen, depends what my mechanic says.

 

   Hope this helps with the discussion.

Please note - I am not a mechanic or expert in anything.

 

We switch off the start/stop at the button after the engine has started too but if we forget no worry we can do it mid-journey I think there are times when the engine should be off (to stop further fumes).

 

I've yet to investigate this 80% or 100% charging seems strange to me but who knows what (else) VW are up to with their over-complicated computer programming and what overrides or false switching  info are in the computer programs, bit like perhaps Merc drivers thinking they've fully turned off traction controls.

 

Just heard a report on the radio about breakdowns on EVs being mostly tyres and the 12v battery system (my words -  often misuse, abuse, neglect, ignorance). 😄

 

Edited 14 September, 20223 yr by nta16
Please note - I am not a mechanic or expert in anything.

It really is worth getting a trickle charger. As long as you park up either in your garage or close to it and a power source, it is simple to clip on a trickle charger and leave it running all the time it is parked up. They are cheap (some as little as £25) and will do a great job extending your battery's life. Slow charge is so much better than slamming in 20-40+ Amps, and once fully charged, the trickle charge continues to 'trickle' in a very low current (a few hundred milliamps) to keep it topped up and also overcome modern cars' constant use of the battery even when parked up.

I had a motorcycle until I was 70+ and was definitey a fair weather cyclist: so I used a trickle charge all the time. My batteries always lasted 10+ years.

5 hours ago, hetty1 said:

. To me the rationale is indisputable; switch it off and your battery can be over 80%  charged, even up to 100%. Not doing it will restrict you to a max of 80% because of the remaining 20% being needed to operate the stop start

 

You misunderstand micro hybrid charging strategy. Switching off stop/start does not mean the battery will get charged over 80% or more.

 

The ~80% SOC is an average target that the battery management will try to maintain over the medium term. The 20% up to 100% is "headroom" to allow energy to be harvested when the engine is on the overrun, slowing the car as a supplement to the brakes. Energy recovery using the alernator as an electrical brake, this is when the SOC is allowed to climb towards 100%

 

Energy recovery is restricted by the charge acceptance of the battery. AGM has higher charge acceptance (quicker/higher current) than EFB, new batteries better than old, temperature dependent.

 

A SOC of 80% or more means sufficient capacity remains for smooth stop/start operation to run auxillary electrical loads during engine stop as well as the engine restart. In practice the target will vary quite a bit, if you have lots of electical demand, headlights, fans, radio,wipers, heated seats perhaps the battery management will maintain a slightly higher level to ensure stop/start is possible, or it may decide to disable stop/start because the electrical load is too high, or SOC is too low or the battery is tired (HOC).

 

Then there is the scenario that you put your foot down and accelerate, the alternator will turn off and allow the battery to take the electrical load, saving a bit of fuel in the anticipation that it can recover it later during an overrun/brake phase. If SOC trends too low or very high electrical loads are present the alternator output will be turned up to compensate.

 

In practice micro hybrid is a complex mix of calcs, voltage/current/temperature/time measurements, estimates, a bit of guesswork and propriety algorithms.

 

In short, switching off Stop/start will not alter the ~80% target, but it will stop the battery cycling to lower SOC by prevent the engine stopping.

 

 

As the car can't anticipate when you will turn off the engine (maybe it could if you navigate using the on board sat nav to a destination, but I doubt it does that) then SOC when the car is parked could be different to the 80% but on average it probably will be close(ish)

 

Edited 29 November, 20214 yr by xman

Please note - I am not a mechanic or expert in anything.

 

I understand the fiddling and farting about VW computer programs try to achieve to save an nth degree of mpg which is laughable given how heavy they make the cars but they do rather specialise in making output figures look good.

 

The bit I can never get around is the 80% and 20% harvested* from engine overrun, I know all about engine braking I've been driving 1960s and 70s cars for the last 30 years, and 1960s cars in the late 70s, until I inflated the Fabia tyres to the Eco setting I wasn't conscious of much engine overrun as you have to overcome the too-wide wheels and tyres on all these modern fuel saving cars so you foot is on the accelerator most times if it's not on the brake.  Does one of the computer programs take the throttle setting metering the fuel and have that as overrun?

 

Some vRS drivers are going to be upset to find they've been coasting so much.  😄

 

 

On 29/11/2021 at 17:42, xman said:

In practice micro hybrid is a complex mix of calcs, voltage/current/temperature/time measurements, estimates, a bit of guesswork and propriety algorithms.

Car manufactures have been known to make mistakes (many never admitted) so do we know with real life use how accurate the VW programs are and whether this is the best system if the start/stop button is never pressed?

 

* Harvested, that sounds like a word a defence lawyer would use to describe the action of his mugger client.  😄

 

Edited 14 September, 20223 yr by nta16
Please note - I am not a mechanic or expert in anything.

1 hour ago, nta16 said:

Does one of the computer programs take the throttle setting metering the fuel and have that as overrun?

 

The car stops all fuel going to the engine when, in gear but with no throttle applied and the engine speed is above about 1400 RPM.

I can see this in action on my car by setting the MFD to instant fuel consumption reading.

On one road to work I can use this method for over 1/2 mile with no throttle.

The road goes downhill and at the top it is a national speed limit 60MPH and has a 30MPH limit at the bottom.

For most of this road the instant fuel consumption reading is ZERO fuel being used.

 

Filled the car with petrol on 10th Nov and did 58 MPG since the previous fill up.

This is working to out, not using the car's read out, which is fairly accurate.

 

Thanks, AG Falco

Please note - I am not a mechanic or expert in anything.

 

Thank you for your reply, whatever the exact figures your mpg is impressive but I think some figures do need to be a little less absolute in some respects, if the engine is going at 1400 revs it must be using some fuel otherwise surely it'd stall and I'm not sure how much you can rely on the car's computer for accurately, especially a VW, for consumption readings, if you said it used next to no fuel, but ZERO?

 

And the 58 figure is impressive would be impressive at 50 but have done mpg figures on old 1960s and 70s cars I don't see how you can have such accuracy when filling new cars, accuracy on distance could be good but figures for mpg would still be approximate - unless you worked it out to about 60mpg and decided to call it 58 for margin of variances.  I've no idea what my wife gets on a good run as she never uses the display other than MPH and I forget tank fill mpg despite having to remind her every time how litres to a (UK) gallon why she could stop at the one decimal place that she can remember but she keeps going for three and misremembering, like I do for just about anything else.

 

Edited 14 September, 20223 yr by nta16
Please note - I am not a mechanic or expert in anything.

The momentum of the car keeps the engine rotating, because it's still connected by being in gear.

 

Accurate mpg figures are easy to produce for each tankful when refilled to (say) the first click. Simply note down miles covered since previous refill, then zero the trip meter each time you fill; convert number of litres of refill into gallons (divide by 4.55) and divide previous trip meter reading by number of gallons just used to refill. That's how many miles your car did per gallon on average, during the previous tankful.

Doesn't everyone have a spreadsheet of these records? 

Alternative is to use a website such as fuelly.com or spritmonitor.de where you just feed in your data and it does the sums for you; watch your unit selections though.

Please note - I am not a mechanic or expert in anything.

 

Yeah engine keeps going but even at idle it uses some fuel and if the engine is off the start system would have to kick in and I don't think even VW would have the engine off for downhills, or perhaps they might. 😉

 

The method you give is reasonable for the idea of mpg but not that accurate, first click of pump could vary how much is in the tank from previous fill for a few reasons and you'd have to be returning to the same pump, I'm not sure how accurate the trip/odometers are on theses cars good enough I'd guess but I've never checked.

 

Out of habit and just to see if my wife will ever remember the sequence we divide to 4.546 (and it's 0 next anyway).

 

My wife is the queen of spreadsheets (her brother is literally an expert in them, MS Excel at least and probably others) but she doesn't keep any on cars, she does how ever have records on 'food type' shopping going back decades IIRC on spread sheets going back to something like 1993.  I think it started when I said it wasn't worth the effort of saving shopping coupons many decades back and I said if she kept a list of the savings from them to the end of the year she ought to have half that value to treat herself to something, I created a monster and was proved very wrong.

 

The older ones don't need a website as they're used to using manual rotary calculators and keeping records from the days of black & white tellies. 😄

 

Edited 14 September, 20223 yr by nta16
Please note - I am not a mechanic or expert in anything.

The engine's not idling though it's being driven by the wheels, no fuel is going in. Research it please.

 

If you think about the brim-to-brim calculations for a while you'll probably realise that all your objections are invalid.

.

 

 

The money for Petrol / Diesel / LPG comes from my pocket and i have known the MPG of every vehicle i have ever owned since the 1970's uses as i drive the same places week / month / year after year.

All are 2 pedal cars, so Auto / CVT / DSG, Automated Manual, Servo Clutch etc.  Over the years they have become much more efficient.

By the first or second time i fill a vehicle i know how much fuel it uses on different routes and different ways of driving.

 

These days that will be using Coasting function or not.   Also it is how many miles per litre it goes.

That i started using when driving LPG vehicles.

I never minded they required twice as many litres to go the same distance because at the time LPG was half the price of petrol. 

 

Now i know ASAP how many miles per kWH EV's do and how much kWh of electric might be needed even when a EV is just sitting not being used.

 

 

Edited 30 November, 20214 yr by roottoot

Switching off injecting fuel has been standard practise for many years at least for electronic fuel injection as it is easy to design in, my 1991 VX Cav GSI had that as did my wife's 1994 Ford Fiesta with the 1.6 Zetec engine, certain parameters have to be met, engine temperature , engine running above a certain RPM for it to be enabled and disabled just before normal idle speed so as to avoid the engine stopping when the clutch is dipped.

 

I think that cars with Bosch K Jetronic mechanical fuel injection also had that built in, if so that would move it back to round about 1984 in the case of my Ford Orion Ghia Injection, always easy to check when these cars had fuel computers which mine had.

Please note - I am not a mechanic or expert in anything.

 

On 30/11/2021 at 12:13, Wino said:

The engine's not idling though it's being driven by the wheels, no fuel is going in. Research it please.

I am researching it, I'm asking you and others. 😉

 

 

On 30/11/2021 at 12:13, Wino said:

If you think about the brim-to-brim calculations for a while you'll probably realise that all your objections are invalid.

That's my point, it's not brim to brim.  I can fill my old car up to brim, literally to the back of the petrol cap (not a good idea) and I know this takes time and several attempts to let the filling petrol settle, the hose tip can only be at the very start of the filler aperture (do we count the lost vapours from this) again not a good idea.

 

Doing the fill to first click and mileage is fine and reasonably accurate, good enough, but no point going to too many decimal places and a rounded up or down whole figure for mpg is fine is but it not that accurate, more accurate than VW figures no doubt and more real world.

 

Edited 14 September, 20223 yr by nta16
Please note - I am not a mechanic or expert in anything.

My brim to brim with Mk2 Fabia vRS was 'Venting', them when going on runs.  (Charcoal canister stuff never worried me or gave problems.)

So the Mk2 vRS's took 7 litres more from filling up and then 'Venting them'.  

On some trips where there was not going to be Super Unleaded available venting plus carrying a couple of fuel cans was all that was needed. 

(That used to be the likes pf going north of Inverness.)

 

If a modern car Euro 6 plus can not do 450 miles from 45 litres with people in the car at UK NSL.s then VW Group really should be discontinuing that vehicle.

 

 

 

Edited 30 November, 20214 yr by roottoot

5 hours ago, Wino said:

Doesn't everyone have a spreadsheet of these records? 

 

Nope. I just drive the car and add petrol as and when required.

First click to first click then if you won't allow the common shorthand of brim to brim.

I always push the nozzle in as far as I can, ooh er missus...

 

It's simply the most accurate easily achievable method.

Do it or don't, up to you!

Please note - I am not a mechanic or expert in anything.

 

On 30/11/2021 at 12:26, rum4mo said:

certain parameters have to be met, engine temperature , engine running above a certain RPM for it to be enabled and disabled just before normal idle speed so as to avoid the engine stopping when the clutch is dipped.

This is the bit I was looking for.

 

MPG means very little to me otherwise I wouldn't have had the cars I had and have now, A to B driving I prefer to be a passenger preferably in someone else's vehicle, I've never been in a better vehicle than someone else's where they have the hassle and expenses, mpg being just one which I'll happily contribute to.

 

Edited 14 September, 20223 yr by nta16
Please note - I am not a mechanic or expert in anything.

Please note - I am not a mechanic or expert in anything.

 

On 30/11/2021 at 12:40, Wino said:

It's simply the most accurate easily achievable method.

Yeap totally agree with that.

 

But doesn't the car already do that with it's readouts, if you reset all that needs resetting if required,  I don't know as I'm not allowed to touch any settings as it's not my car and I don't often drive it (I did plumb in oil temperature and got away with it as it never leaves digital MPH).

 

Edited 14 September, 20223 yr by nta16
Please note - I am not a mechanic or expert in anything.