Technical The Consequences of Low Voltage....

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Technical The Consequences of Low Voltage....

Hi.
Once upon a time you put a heavy load across the battery, most garages had them it has a voltmeter to monitor the voltage during the test. One thing they would show was a low cell as it would gas, during the test if ithe voltage drops very rapidly to below 11 volts bin the battery.
If the battery is good it should not drop below 12.4v in the car after 12 hours after being fully charged. In fact I'd be looking for 12.6v.
Even the best battery will have a hard time with stop start so I don't use it on my car.
 
Hi.
Once upon a time you put a heavy load across the battery, most garages had them it has a voltmeter to monitor the voltage during the test. One thing they would show was a low cell as it would gas, during the test if ithe voltage drops very rapidly to below 11 volts bin the battery.
If the battery is good it should not drop below 12.4v in the car after 12 hours after being fully charged. In fact I'd be looking for 12.6v.
Even the best battery will have a hard time with stop start so I don't use it on my car.

I remember those well Murphy. Two large probes with a sodding great resistance piece between them. Effectively you were performing a controlled short of the battery - large current drain involved, probably more than a starter would pull I guess? You would be looking to see what voltage was showing under this extreme load Probably around 9.5 to 10 volts for a good one? As you say a poor cell would bubble. I suppose now a days, with sealed batteries, you wouldn't see this. Very easy to get a spark at the terminal either on connection or on removal or both!

I came across this: https://www.ebay.co.uk/itm/Automoti...019266&hash=item56e1ea3e75:g:9GoAAOSw61BeMO9K So the concept still seems to be with us.

This seems to do the same job but seems to eliminate the sparking problem and incorporate a few other features like starter motor current draw testing. I rather like the look of it: https://www.sealey.co.uk/product/5637185981/battery-drop-tester-612v#

There seems to be a whole new generation of battery testers, like this one: https://www.machinemart.co.uk/p/11901-bt01-digital-battery--alternator-t/ but I don't know anything about them and I'm suspicious of the fact they have relatively thin wire connectors so obviously can't be passing much current.

I have a gut feeling that hitting a battery with a nice big current demand will quickly show up whether it's up to scratch or not, so I have a leaning towards the old types but worry just a little about doing this to a car with a lot of electronics (especially when I see a battery condition monitor on a battery post) Personally I find I get quite good results with a volt meter across the battery terminals, switch on the head lights/rear screen heater and, with ignition disabled, crank the starter motor for a few seconds whilst observing the battery voltage. That seems to pretty quickly find the bad ones - although the cunning devils now sometimes cut the supply to lights, rear screens etc when cranking!
 
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I changed the battery, filters and spark plugs - and I still get the start stop triangle - and I have the running on one cylinder problem. Any suggestions?

Hi Mads Gorm, my experience (and I repeat, my experience, with a 4x4 TA) was that my car ran on one cylinder and the stop/start triangle appeared.

I think the link to stop/start is simply that the car recognises that there is an issue (running on one cylinder) so the software withdraws the stop/start function. In my case the root cause was a failing uni-air module. I went down the (traditional) route of trying to eliminate the misfire by replacing ignition system components (plugs) swapping coil packs (to see if misfire then occurred on other cylinder etc) but this was not an evidence based process, more wishful thinking. In the end a dealer (correctly) diagnosed the uni-air module. This unit controls the valve timing of the inlet valves and is driven by hydraulic solenoids that use engine oil as the actuator fluid.

There is a very good piece on the system on the INA website (the OEM manufacturer) a read of this will make you realise that the system is going to be very sensitive to oil grade and cleanliness. My unit failed at 50k miles on a vehicle that had limited service history, I know of others that have failed on lower and higher mileages.

The uni-air module bolts to the cylinder head and is not cheap! supply and installation by FIAT was 800GBP a couple of years ago...

I hope this is not the root cause of your problem.
 
Liteboy any news? Personally think battery done,6 years is good going. Would expect it to give up when weather gets colder.


Left the battery on my ctek charger/conditioner overnight and the battery seems to be performing normally at the moment. My wife works week on week off at the local hospital about 20 miles each way so topping it up might just be enough. Will see how it goes now the overnight temps are dropping especially after a weeks little use.
 
Hi.
A 20 mile trip each way should keep the battery nicely charged.
One thing that has come to mind was current drain. My 51 plate 1.2 Doblo was its residual current drain. It was high at 300ma. Leaving it for a few days resulted in poor cranking speed and the battery dropping to below 12v on occasions.
I tried many things and could never get to the bottom of the issue. I eventually used to disconnect the battery after the weekend as I had a van to use during the working week.
I'd say anything over 50ma residual current drain is too much.
This though could be an issue on low use cars and yes it causes sulfation of the plates of the battery greatly reducing capacity.
 
Hi Mads Gorm, my experience (and I repeat, my experience, with a 4x4 TA) was that my car ran on one cylinder and the stop/start triangle appeared.

I think the link to stop/start is simply that the car recognises that there is an issue (running on one cylinder) so the software withdraws the stop/start function. In my case the root cause was a failing uni-air module. I went down the (traditional) route of trying to eliminate the misfire by replacing ignition system components (plugs) swapping coil packs (to see if misfire then occurred on other cylinder etc) but this was not an evidence based process, more wishful thinking. In the end a dealer (correctly) diagnosed the uni-air module. This unit controls the valve timing of the inlet valves and is driven by hydraulic solenoids that use engine oil as the actuator fluid.

There is a very good piece on the system on the INA website (the OEM manufacturer) a read of this will make you realise that the system is going to be very sensitive to oil grade and cleanliness. My unit failed at 50k miles on a vehicle that had limited service history, I know of others that have failed on lower and higher mileages.

The uni-air module bolts to the cylinder head and is not cheap! supply and installation by FIAT was 800GBP a couple of years ago...

I hope this is not the root cause of your problem.

Thanks a lot for the reply - I will try one more thing - changing the brake switch - then its off to the mechanic.
 
...I took a bit of a plunge with the ELM327 WiFi adapter as there are quite a few on the market, but the thing arrived, is small and neat (about the size of a cigarette packet) and I can have it in the car all the time when out and about. This is the ELM unit I bought;

https://www.amazon.co.uk/gp/product/B0721DC46Y/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

Seems to work well. Only issue is that the Licence for iOS MES is another £50, so you need to be keen. But I am very please with the purchase so far. :)

Dredging up an old thread here: I have bought a wifi ELM327 adaptor - which looks identical to the one R1NGA showed in the earlier posts here (but from a different supplier as first not available anymore).

The reader is working - I can use it in my Volvo V50 (which is basically a rebadged Ford Focus) without issue, with a free app, and was able to clear a stored fault code there)

Bu it doesn't work with the iPhone MES app. I've seen the support page about a resistor, but the wifi version is a completely different circuit board, so no help. THere's mention of a 'test' setting in the MES app - but I can't see this (I've not paid yet, but it says to run the test before paying). Also, the app refers to the need to use yellow lead - do I still need to have the lead set when using the wifi OBD connection?

Thanks
Pete
 
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Hi Pete.

My take on this.:

The MES site.. right at the bottom of homepage..

Shows what the coloured cables do - they disable certain pin to pin connections..

I cannot see how a 'widget' can overcome this 'need'

Where are you based.. somebody might have a paid.up version and the cables to test your widgets function before parting with
'Fifty Europes'

Charlie
 
Badly worn plugs can cause the coil or coils to break down.
It's simple really why this can happen. Say for example a new plug has a 1mm gap and needs 10kv to fire the plug as it wears to 2mm it then requires say 20kv that extra 10kv can flash across another path, between leads and the internal insulation of the coil or coils. Manufacturers make recommendations for a reason and they know best. If you want long lived plugs then fit platinum ones, I'd not leave a standard plug in for more than 15000 miles.

I tend to agree re coils and wonder if there is some relationship between starting on very low voltage and coil failure. If everything else has been changed then it suggests the coil may well be the culprit.

Moral clearly is keep the battery charged. Its a big pain in the behind but the alternative seems to be a lot of suffering and expense.
 
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It's very unlikely that low cranking voltage will damage the coil.
Essentially modern coils work just the same as they always have, with the exception that old systems use points and a capacitor for switching, the points are the switch that when closed allow the coil to charge with magnetic flux, when they open the flux goes inducing a high voltage in the secondary, the capacitor effectively tunes the coil for maximum output. In modern systems, a transistor is the switch, there is still a capacitor in the primary circuit, either embedded in the coils or in the ECU. The difference is on old systems there was on coil and a distributor but these days either 4 or 2 in a block, even can be one or two in a wasted spark system like in the 2CV.
High volts from the battery could damage the coil but not with low voltage. Excessive plug gap is more likely to cause damage, sadly modern coils are less robust than the old oil filled ones.
 
Hi Pete.

My take on this.:

The MES site.. right at the bottom of homepage..

Shows what the coloured cables do - they disable certain pin to pin connections..

I cannot see how a 'widget' can overcome this 'need'

Where are you based.. somebody might have a paid.up version and the cables to test your widgets function before parting with
'Fifty Europes'

Charlie

Thanks Charlie. I’ll explore more. Seems reawakening the tread to ask about MES has sent it off on a debate again :)
 
Thanks Charlie. I’ll explore more. Seems reawakening the tread to ask about MES has sent it off on a debate again :)

I noticed that too :)

However, I also use MES on PC with the colour combination adapters which are needed to access some of the Service functions as opposed to the Engine and other Driveline signals. Strangely however, I seem to be able to both clear Engine codes and reset Oil change and Service flags all with the same WiFi ELM327 plug-in. So not sure where that leaves your question Pete, although I suspect not all the WiFi adapters are the same.

I can do all the above on my own car without issue, as can I with a friends' 15-plate TA Trekking. However, my neighbours 13-plate TA 4x4 simply won't play ball with the WiFi doobry, it insists I use cables and a hateful Windows PC :confused:
 
Hi.
Once upon a time you put a heavy load across the battery, most garages had them it has a voltmeter to monitor the voltage during the test. One thing they would show was a low cell as it would gas, during the test if ithe voltage drops very rapidly to below 11 volts bin the battery.
If the battery is good it should not drop below 12.4v in the car after 12 hours after being fully charged. In fact I'd be looking for 12.6v.
Even the best battery will have a hard time with stop start so I don't use it on my car.
My 2018 TA 4x4 gets very little use at present and in fact has only done 7716 miles since I bought it new in June 2018.
It currently lives in the garage, and on checking the battery voltage today my multimeter read 12.18 volts. \\\this seems a bit on thelow side to me, but it does start readily.
It is now on my Optimate smart charger,and, if past experience is something to go by it will need 12/15 hours, before the charger says "OK"
Any comments anyone. Thanks in advance
 
My 2018 TA 4x4 gets very little use at present and in fact has only done 7716 miles since I bought it new in June 2018.
It currently lives in the garage, and on checking the battery voltage today my multimeter read 12.18 volts. \\\this seems a bit on thelow side to me, but it does start readily.
It is now on my Optimate smart charger,and, if past experience is something to go by it will need 12/15 hours, before the charger says "OK"
Any comments anyone. Thanks in advance

All seems entirely reasonable to me. Modern cars always seem to have a small amount of background drain, so use of an intelligent charger for extended lay-up times like this is, well, intelligent (y)
 
I'll add an anecdote to this thread, and will update it if I can get the issue resolved. Essentially, my battery ran flat (it was quite old), and needed a jump to the nearest service. Just a day before the battery issue, the rear left brake light had gone bust so I already had a warning triangle on the dash. After a battery replacement, the good folks at the dealer attempted to swap the brake bulb as a courtesy but upon exiting the garage it went out again immediately. This, of course, would require further diagnostics for which I didn't have time. Since then, the other big issue I have found is that engaging the ELD lights up the led on the button and the dash reads out "ELD Connected" but the little green ELD light in the dash doesn't illuminate. It's sort of working, as it is sending power to the rear wheels when the fronts slip on snow, but not as smoothly as it used to (jerky and abrupt), and usually engaging the differential disables ESC and traction control, but I'm getting those lights flashing up even with ELD on, and not a peep from the ELD light in either green or yellow. I have a sinking feeling this is going to come down to a new ECU or body computer, but I have yet to take the poor thing back to the dealer as I live out in the sticks and have no other transportation for the moment.
 
...the other big issue I have found is that engaging the ELD lights up the led on the button and the dash reads out "ELD Connected" but the little green ELD light in the dash doesn't illuminate. It's sort of working, as it is sending power to the rear wheels when the fronts slip on snow, but not as smoothly as it used to (jerky and abrupt), and usually engaging the differential disables ESC and traction control, but I'm getting those lights flashing up even with ELD on, and not a peep from the ELD light in either green or yellow.

My 4x4, the ELD light in the dash doesn’t illuminate if I press the button. I don’t think it’s supposed to. I do get the ‘connected’ message and the light in the button itself is on. The dash light should only illuminate if the ELD actually kicks in - and then should only show during the (usually brief) time that actually happens (see pages from the owner manual below). The ELD light is green. The light does not illuminate if 4x4 is active (with or without the button pressed) and engages but without needing the ELD as well. In other words, there is no indication on the dash that 4 wheel drive (but not the ELD) has been engaged.
 

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Our other car is a ten year old Volvo V50 - which is fundamentally a Ford Focus with a different badge.
Over recent weeks it has shown all sorts of 'worrying' message about ABS failure, headlight control system failure (the self levelling for HID lamps), traction control warnings, and the generic EODB light has been on and off. Fault reader showed the only fault as incorrect communication between lo and hi speed CAN bus.

It did similar things in the cold of last winter, but less often (the car was of course being driven more then)

All these 'issues' were in fact ghosts, caused by the fact the ten year old original (stop-start AGM) battery was not holding a full charge - with the voltage dropping to about 12.0v overnight (fully charged should hold 12.6v, 50% charged 12.4v and less than 12.2v shows need to replace). I have replaced the battery and everything is now happy. Throughout, the ABS was working (I tried), the headlights were correct and the traction control/ESC also still worked.

By the way: the Volvo battery from EuroCarParts listed at £430, but of course with 40% discount (that's still over £230). Same battery from Tayna Batteries was £97, inc vat and next day delivery. (Exide EZ700 AGM battery)
 
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