Technical Stop Start Story

[Mick F]

No doubt the system can't "see" the battery whilst it's sitting at 14odd volts whilst being charged.

Until the charging system stops, the battery won't be a "real battery".

Just a guess,
Mick.

 

[UFI]

No doubt the system can't "see" the battery whilst it's sitting at 14odd volts whilst being charged.

Until the charging system stops, the battery won't be a "real battery".

That's what the IBS is for. It's job is to monitor charge parameters over time and it "should" be able to determine whether a stop is possible based on the current state of charge.

I don't think the system uses voltage as it would be meaningless, I'd wager it monitors internal resistance, which can be used to measure SOC regardless of voltage.

 

[UFI]

UFI, have you done any experimentation with an integrating voltmeter/ammeter to look at power flows into & out of the battery over a typical daily cycle? I'm curious how this changes as the battery ages; I'm interested in finding out just how much more power is used by an older battery as opposed to a factory-fresh one.

It would be interesting to measure this but I'd really need a weak but servicable battery and a new one to compare to, and some form of data logging. The best option perhaps would be to do a test loop on an old battery and log the fuel used. Repeat with a fresh one. It could be repeated for batteries at different states of their original CCA. This way we could correlate percentage of CCA to increases in fuel use. I'm thinking someone must have already tested this before. You would think the battery manufactures would be shouting it from the roof tops: Replace your battery early! Save fuel!

Anecdotally, I don't see the benefit of S/S being lost after two weeks of battery life. S/S can save about 10% on the fuel bill, even with cars not designed for it. It seems like it would take a seriously weak battery to cost you 10%.

 

[larslarsen]

That's what the IBS is for. It's job is to monitor charge parameters over time and it "should" be able to determine whether a stop is possible based on the current state of charge.

.....

So if we observe the restart after a few seconds, the system is not operating normally, might be already out of specified operating range?

The restart after a few seconds seems to be a safety feature (used only if battery monitoring by S&S failes), to avoid deep discharge, could result in unability to restart the engine after stop.

So if the dealers are telling us, that this is normal, it might not be true?

What is surprising for me:
The LOG file of the car, the dealer showed to me, did not contain any error and the battery status in this LOG file is 100%, even if "restart phenomen" is actually observed.
Restarts are classified in LOG "due to low voltage", but nobody, including FIAT technical department was able to find the reason.

The only solution was always (3x) battery replacement, what did not cure the issue in winter period.







Sent from my iPhone using FIAT Forum

 

[Mick F]

How can they test (properly) a S/S battery and give a meaningful report?

I asked this question up thread and didn't receive any real reply.

It seams to me - with my very limited knowledge and very limited experience - that if there's an issue with S/S the only option is to replace the battery.

This is a bit against good practice, as surely the battery should be PROVED to be faulty before replacement? It's all very well saying the battery is probably past its best and replacing anyway, but the battery in itself is probably ok in other applications.

Mine is probably past it's best and I'll be fitting a new one next week, but if the car didn't have S/S, I wouldn't even be considering that the battery needs replacement.

The thing is, I have no proof that the battery is kapput. Any testing done shows the battery is good.

How do you test a S/S specific battery?

Regards to all,
Mick.

 

[jrkitching]

How do you test a S/S specific battery?

Put it in a Fiat 500 and see if it works .

 

[Mick F]

Yes, we know this!!

There must be a better, more technical, way to test it.
What are the symptoms? .......... not just saying it won't S/S properly.

Lack of sufficient voltage?
If so, what should it be?

Lack of capacity?
Should it always have to be 100% and 90% won't do?

Not holding charge?
How long should it hold max charge?

Any figures out there?

Thanks,
Mick.

 

[jrkitching]

I'm thinking someone must have already tested this before. You would think the battery manufactures would be shouting it from the roof tops: Replace your battery early! Save fuel!

Anecdotally, I don't see the benefit of S/S being lost after two weeks of battery life. S/S can save about 10% on the fuel bill, even with cars not designed for it. It seems like it would take a seriously weak battery to cost you 10%.

You've understood where I'm coming from on this one, and you're right in saying that you'd need to set up a fairly rigorous experiment to get any meaningful results.

I too find the 2 week argument hard to accept, though I also believe the effect may be significant after a year. I've long suspected there's an economic argument for replacing the battery before it actually fails outright (irrespective of S/S).

I don't buy the 10% saving argument either - you'd need to be doing some seriously urban driving to be stopped for long enough to achieve that; also none of the analyses that I've seen take account of the extra fuel used to replace what's been taken out of the battery when the engine is stopped, or the extra cost of running a larger and heavier battery. They also don't account for the fact that you can always kill the engine on any car if you know you're going to be stopped for awhile.

The driver will always know better than the computer how long the car is likely to remain stopped. A manually activated switch on the steering wheel would, to my mind, be a useful addition, together with a (persistent) menu option for setting S/S to Off/Manual/Auto.

Personally I'm a fan of S/S, but more because of the benefits to everyone of not having large numbers of stationary cars idling in cities than because of any supposed economic saving you might make. By the time you've taken everything into account, I doubt the cost difference over the life of the car amounts to much, either way.

You will notice it when the time comes to replace a battery, though.

 

[jrkitching]

Yes, we know this!!

There must be a better, more technical, way to test it.
What are the symptoms? .......... not just saying it won't S/S properly.

Lack of sufficient voltage?
If so, what should it be?

Lack of capacity?
Should it always have to be 100% and 90% won't do?

Not holding charge?
How long should it hold max charge?

Any figures out there?

Thanks,
Mick.

You say this, and you're right, there must be a more technical way to test -

but how long would it take, and how much would the equipment cost?

Compare that with how long it takes to swap out a battery.

How do you know when most battery powered stuff needs its batteries replacing? Do you test your torch batteries when the light goes dim, or do you just fit new ones?

Obviously the costs are different, but then again, some Fiat franchised service departments have minimum diagnostic charges not far short of the cost of a decent aftermarket battery.

If you've got a 500 that's more than a couple of years old, replacing the battery first looks to me like the cheapest way forward.

There's also a technical limit to battery lifetime in a repeated charge/discharge environment - lead/acid batteries are never going to last as long on S/S cars. But if you want my opinion, Fiat could have designed the car's S/S battery management software to do better.

 

[Mick F]

Some Fiat franchised service departments have minimum diagnostic charges not far short of the cost of a decent aftermarket battery.

If you've got a 500 that's more than a couple of years old, replacing the battery first looks to me like the cheapest way forward.

This was the very point that made me get off the fence and fork out £100.

It still sticks in the craw somewhat. The battery works! It's probably much better than many other batteries out there.

(Thinks) ........ I wonder if there's a market for ex-S/S batteries? There's no point chucking them in the recycling system when they've got years of life left in a non-S/S car.

TTFN
Mick.

 

[jrkitching]

(Thinks) ........ I wonder if there's a market for ex-S/S batteries? There's no point chucking them in the recycling system when they've got years of life left in a non-S/S car.

There's probably as many possible applications for recycled 12 car batteries as your imagination allows. Most folks now have a shedload of stuff that needs 12V DC or less - rig up a solar panel or two & who knows what you might come up with?

Or you could buy a decent LED light and rig up a standby lighting system for when you next have a power cut.

Reading some of the latest reports on the state of the UK power distribution network, that might be sooner than you think.

If this thread's anything to go by, one thing's for sure - there'll be a plentiful supply of part worn S/S batteries!

 

[UFI]

I asked this question up thread and didn't receive any real reply.4

Mine is probably past it's best and I'll be fitting a new one next week, but if the car didn't have S/S, I wouldn't even be considering that the battery needs replacement.

The thing is, I have no proof that the battery is kapput. Any testing done shows the battery is good.

How do you test a S/S specific battery?

Mick, pay attention, especially as this is your thread

I posted this S/S battery tester a couple pages ago:

http://www.matson.com.au/product/826-start-stop-battery-tester-with-printer

You could try ringing the manufacturer and see if they can direct you to a shop locally that has one. At 6x more cost than a standard CCA tester, I'm sure not many will.

 

[UFI]

So if we observe the restart after a few seconds, the system is not operating normally, might be already out of specified operating range?

The only solution was always (3x) battery replacement, what did not cure the issue in winter period.

I can't really comment since our winter is always above freezing, but the system should really not be designed to stop if it can't sustain that stop condition for a 'reasonable' length of time.

I did try to reverse engineer the S/S system a little, but since my interest is in Lithium batteries, and I don't think S/S will ever work with Lithium, I gave up. I know that it's more than voltage required to get a stop, because at one point I had more than 15V resting voltage(!!!) and still no S/S at all. This lead me to believe that the IBS monitors internal resistance. With a LiFe the IR is much lower, so the IBS sees this as a battery that's low on charge, even if the LiFe was overcharging.

 

[Mick F]

Mick, pay attention, especially as this is your thread

I posted this S/S battery tester a couple pages ago:

http://www.matson.com.au/product/826-start-stop-battery-tester-with-printer

You could try ringing the manufacturer and see if they can direct you to a shop locally that has one. At 6x more cost than a standard CCA tester, I'm sure not many will.

Yes, I saw that, but it doesn't really address my question. Maybe in the Big City someone may have something, but here out in the sticks, we don't have anyone who would have one of those!

My question was rather how are they tested?
What is looked for?
Just internal resistance?

Regards,
Mick,

 

[UFI]

I don't buy the 10% saving argument either - you'd need to be doing some seriously urban driving to be stopped for long enough to achieve that; also none of the analyses that I've seen take account of the extra fuel used to replace what's been taken out of the battery when the engine is stopped, or the extra cost of running a larger and heavier battery.

You must have seen this by now:

https://www.fiatforum.com/500/342685-some-interesting-data-collected.html?p=3407737

Actual data from my commute showing 4.52litres out of a total 55.65litres being burned whilst stationary. It's not quite 10% but an 'average' driver who races from light to light would be stationary longer than I. This is a 18-24km commute with approx 24 sets of lights. I can see where someone who lived in a 'real' city could easily see a 10% gain from S/S.

It's true that this doesn't account for recharging the battery, but a hot engine doesn't take all that much energy to turn over. The starter on a S/S 500 is quite typical of many cars and draws ~80A (which I've measured using the 'peak' function on my DMM) for about 1 second. Over my 24 S/S cycles it's drawn (let's round up to 30 seconds) 0.66Ah out of the battery. Even if you double or quadruple that figure it's clearly a miniscule amount, about the same as running the radio.

They also don't account for the fact that you can always kill the engine on any car if you know you're going to be stopped for awhile.

But how many do? Moreover that's a bit like saying car's don't need ABS because you can cadence brake.

The driver will always know better than the computer how long the car is likely to remain stopped. A manually activated switch on the steering wheel would, to my mind, be a useful addition, together with a (persistent) menu option for setting S/S to Off/Manual/Auto.

If you have a MT the clutch is your manual override. If you don't want a stop, just keep your foot down. If you're only stationary a few seconds, there's no problem. I would agree that Autos shouldn't have S/S without hybrid.

Also this is not true, Audi have a system that connects to the traffic lights network and know exactly how long they'll be red/green. Last I heard they were seeking approval from the German government to connect to the traffic light network in this manner.

 

[UFI]

My question was rather how are they tested?
What is looked for?
Just internal resistance?

There are only three things you can test on a battery: voltage, CCA, and IR.

Bottom line is if charging a S/S battery makes S/S work for a short time, chances are you need a new battery or simply don't drive enough to keep it charged. Smart alt's don't actually charge a battery beyond 80% so that they have some headroom in their ramp up phase which doesn't help things.

 

[Mick F]

Hi UFI, and good morning.
Thanks, that's what I'd guessed.

Even a rubbish battery can manage good voltage - not for long maybe, but good nonetheless.

The more current through a resistor, the bigger the voltage drop, so if the battery has higher internal resistance than it should, the useful voltage will suffer during high current starting.

Is it possible to measure IR using normal domestic equipment?
.... or do you have to calculate it knowing the open circuit voltage versus the voltage at a known current drain?

Purely academic really.

Regards,
Mick.

 

[jrkitching]

Hi UFI, and good morning.
Thanks, that's what I'd guessed.

Even a rubbish battery can manage good voltage - not for long maybe, but good nonetheless.

The more current through a resistor, the bigger the voltage drop, so if the battery has higher internal resistance than it should, the useful voltage will suffer during high current starting.

Is it possible to measure IR using normal domestic equipment?
.... or do you have to calculate it knowing the open circuit voltage versus the voltage at a known current drain?

Purely academic really.

Regards,
Mick.

It's rather a complex subject.

There are a number of ways to measure the internal resistance of a battery (and other electrical parameters; IR on its own won't tell you all you need to know); there's a simple DC load test; a more sophisticated AC inductance test; and there's also electrochemical impedance spectroscopy, which can measure all the key battery parameters individually.

Here is a summarised version of the different methods.

If you really want to go down the rabbit hole, I've also found you a detailed article on Electrochemical Impedance Spectroscopy -you'll likely need at least an engineeering degree to fully understand the math, but it's still worth reading even if you can't follow all the theory behind the method.

 

[Mick F]

Ta!

It seems the folk around here who test batteries aren't using a multi-model electrochemical impedance spectroscopy device, but the inferior (and suspect) carbon pile system or the more modern AC conductance type.

No doubt Fiat have one.

Regards, and thanks
Mick.

 

[306maxi]

Jaysus, I like endlessly discussing tyres, but this takes the cake Anyway I rather suspect a better charger would have revived the battery....