Lead-acid batteries

[Kiwi BlokeParticipant @kiwibloke62605]

Only obliquely related to model engineering, I know, but I’m pretty confident that advice will come from the extraordinary pool of knowledge of the forum’s membership…

We have a 2018 Honda Jazz (not hybrid) which incorporates several ‘driver aids’, in the name of safety. Cynically, I regard these as unwanted potential unreliability. The CTBA system is supposed to prevent one driving slowly into whatever is in front, applying the brakes after issuing a warning. We generally trust ourselves not to do this, so the system has never been activated: it just sits there, waiting to go wrong…

The CTBA ‘problem’ warning light now sometimes comes on, without obvious pattern, on start-up. The dealership (and the ‘net) says that this may happen when the battery is failing: the CTBA system is apparently sensitive to low voltage. However, the starter cranks enthusiastically, the light may not come on when the weather is cold and the car has sat for a day, unused, and the light may come on after a decent battery-charging journey. There is no other indication of a suspect battery, although it’s getting elderly. I admit that I haven’t yet measured battery voltage.

So questions. Does the dealer’s diagnosis sound plausible? What happens to ageing lead-acid battery voltage, and how temperature-dependent is it? Any other thoughts?

[Chris CrewParticipant @chriscrew66644]

Probably, I had a Volvo V90 that issued warnings that a night on the charger would cure. I am a very low mileage driver as I prefer public transport for any sort of distance so the car was stood on the drive most of the time just like its replacement. I know nothing about these new computers on wheels but understand that they never stop using power even when parked and thought to be switched off. So the battery on my old car eventually discharged to the point where it no longer supported the electronics properly until recharged. It was the dealer’s technician who told me that.

[Andrew CrowParticipant @andrewcrow91475]

I don’t think unusual is happening to the battery other than through age it probably is no longer charging to full voltage ie 13.8v approx.

Many functions in modern cars are set to stop functioning or give your a warning when the voltage in the battery consistently drops below about 12.8 volts, even though everything else seems to be OK.

My Ford Focus had a similar problem, changed the battery, problem solved.

Andy

[bernard towersParticipant @bernardtowers37738]

lead acid batteries do not like cold weather but not as badly as lithium, suggest you put volt meter across the batt and start car, at 1500 revs volts should be around 14 volts, switch on headlights and it should read approx the same, this proves the charging system. with the meter still connected turn a few electrical items on and see if voltage falls dramatically, if so batt at least on the way out. Best of luck. Most motoring centres will do a HRD test for you for free.

[SillyOldDufferModerator @sillyoldduffer]

What the dealer is saying is a reasonable guess given that the battery hasn’t been tested.

Though 21st Century Lead Acid Batteries are far more reliable than older types, they aren’t perfect.   Tiny impurities in the chemicals cause corrosion, resulting in internal shorts, or performance that comes and goes as corrosion flakes off due to vibration or rapid discharge (starting).  Car battery life is shortened by slow discharges, deep discharges, and by under or over-charging.  There’s more to testing batteries than an unrelated warning light coming on.    Voltage can be checked with a multimeter, but capacity and discharge needs a load capable of taking tens of amps. Have the battery tested by a garage – or buy a battery tester – about £80.

By the way, if the car has “City Brake” radar, switch it on.  Even the best drivers are distracted or caught out by other road users…

Dave

 

 

[halfnutParticipant @halfnut]

You can buy a digital battery load tester  on that popular auction site for a tenner. It will test and diagnose various aspects of battery health, including starting voltage under load.

Or most battery shops will load test it for free.

With these modern AGM lead acid batteries, they don’t crank the starter noticeably slower even when on the brink of failure the way the old batteries did.

I regularly see batteries failing at 3 years old so if your 2018 car has its original battery, it’s well overdue.

One quick and dirty, but not totally conclusive, test is put your multimeter across the battery terminals at least 8 hours after it was last used or charged. If it reads less than 12.6 volts, it is not long for this world.

Proper load testing is the best way though.

And , yes low battery voltage during starting will scramble electronic systems. Digital clock resetting to zero is common on older models too.

[noel shelleyParticipant @noelshelley55608]

That Your Battery lasted this long – Praise the Lord ! I’m with the dealer and the rest on here ! Electronics do not like low voltages and will play up or re set zero. A handy gadget I made was to find ( or buy ) something with a cigarette lighter plug on it and wire a small digital voltmeter to it, cost £5 (I used the Component Shop ). Plugged in it will read what’s going on as it happens, cranking may be 10V, but for most other loads with the engine running 14.2V. A long slow discharge is by far the best way to ruin a good battery. Even when all is OFF many things are still running, alarms Etc.

On many of my vehicles I wired an ampmeter into the alternator output, this would show the loads, headlights 10A+, heater 4A, and if a diesel with the heater plugs on 40 – 50A. You WILL need heavy wire to do this, one reason they stopped fitting ampmeters, cost. We were all happy with a 22A dynamo, then we wanted “toys ” 40A, 60A and now some even use 90A alternators. CAV made 180A ones !

Once upon a time, alternators controlled themselves, now they may be controlled by the ECU and can give strange readings. Some of the rapid fit garages and their poorly trained staff have been known to fit a new alternator because they gave ODD readings, appearing dead !

Modern vehicle electrics = a minefield !  Noel

[Robert Atkinson 2Participant @robertatkinson2]

A lot of modern cars also have a sensor on the battery terminal. Thi is just a platic “lump” on one of the battery clamp with a couple of wires. These can be very sophisticated with their own microprocessor and non-volatile memory. Changing the battery on a car with one of these is more than a simple swap. You need to follow a specfic proceedure that my involve a diagnostic computer.
Note some, mostly bigger, vehicles may have a similar looking device that is actually a non-reversible automatic battery diconnect that operates in a collision.

While I’d like to see a check I agree if the battery is 7 years old there isn’t much to loose by changing it.
Also note that the warning light coming on during an MOT test will be a failure.

Robert.

[Colin BishopModerator @colinbishop34627]

One quick and dirty, but not totally conclusive, test is put your multimeter across the battery terminals at least 8 hours after it was last used or charged. If it reads less than 12.6 volts, it is not long for this world.

Quite agree, I have just changed the 7 year old battery on my Mazda 6 for this reason. I noticed the cranking was becoming a bit unenthusiastic and the stop start function was taking longer to kick in.

7 years is very good for a battery in today’s cars, you may be able to nurse it along for a while but at some point it will fail. On older cars you could continue cranking the starter until the battery went flat but on mine, and probably most modern ones, if the voltage is below a certain point it will not allow the starter to operate. My car is due to spend a week in an airport car park soon and I had no wish to come back from holiday and be faced with an unresponsive vehicle!

Colin

 

 

[halfnutParticipant @halfnut]

Yes 7 years is a very good run from a battery these days. The original batteries fitted in the factory are more likely to last close to that. But the replacement batteries you buy over the counter, even of the same brand, seem to struggle to last half that time. Coming out of different factories perhaps, and built to different specs. The carmaker pays for the highest spec battery so it does not fail in 2 years’ time and tarnish the car brand’s reputation.

[old martParticipant @oldmart]

I have one of those cheap voltmeters which plug into the cigarette lighter socket. It shows the charging volts, so keeps an eye on the alternator condition as well as the battery. Seven years is a good life for even a premium battery, your Honda may have had a YUASA from new and it has paid for itself by now. If you decide to replace it, then find a big battery supplier and choose one with the longest warranty. It would be easy to test the auto braking, just run up to a wall made from cardboard boxes or recycling bins which won’t cause any harm if you hit them. As already mentioned, it is common sense to have the sensor active always, an additional safety feature is always welcome.

[Colin BishopModerator @colinbishop34627]

he carmaker pays for the highest spec battery so it does not fail in 2 years’ time and tarnish the car brand’s reputation.

I think that applies to a lot of other components as well, lighting  and brakes for example.

Colin

 

 

 

[Kiwi BlokeParticipant @kiwibloke62605]

Thanks everyone for your info. and advice. A quick voltmeter check confirmed somewhat low voltage, so off to the shops for a new battery. In days gone by, I suppose it wouldn’t have been noticed, or mattered, until cranking suffered. Then, it would have been out with the charger, to wring out a few more months of will-it-won’t-it service. Things were simpler then, but I have to keep reminding myself that they were far less reliable…

Perhaps it would be more sensible to provide a “battery problem” warning light than to allow a supposed safety feature to fail as the first indication of battery performance declining a little?

[halfnutParticipant @halfnut]

Buy a cheap battery load tester online and use it every time you do an oil change/service every 6 to 12 months. It will tell you when the battery health is fading away. If you get your car serviced by a mechanic, they should be doing this and should sell you a new battery before the old one fails.

 

[halfnutParticipant @halfnut]

What voltage was your battery reading?

Just for future reference for others with similar issues.

[Michael GilliganParticipant @michaelgilligan61133]

https://www.dailymotion.com/video/x47p6nl

A few relevant seconds from 2001 ^^^

MichaelG.

[noel shelleyParticipant @noelshelley55608]

Hi Kiwi, It could be argued that your electronics playing up is a low voltage warning of sorts but it is not information you would find in the handbook. Likewise the manufacturer could have fitted a voltmeter, some did but it was not quick acting enough for the readings one needs in this case – then there is the issue of how many drivers would know enough to understand the readings?  Quite a few on here would find a voltmeter and Ampmeter interesting and useful I suspect, all many drivers would see is flashing red lights.

Whilst the temperature gauge has survived in some vehicles, I haven’t seen an oil pressure gauge for years. Noel.

[Kiwi BlokeParticipant @kiwibloke62605]

Michael – thank goodness, no AI in this vehicle… Things will only get worse.

halfnut – as requested, voltages. Battery connected, key switch OFF (but some background services running), 12.66V; Key sw I (few aux. services running), 12.59V; key sw II (ready to start), no other services selected, 12.36V; key sw II, heater fan on max, couple of windows lifting, 11.86V; key sw “start”, ie cranking, DMM too slow to register properly, but saw 11.6V; running, 14.3V; key sw OFF, voltage sags within approx 20 seconds to 12.8V. (Note, ‘key sw’ is really a big red button, flashing LED, etc., but harder to describe actions…). CTBA warning lamp ON throughout above. This soon after a couple of 35km journeys. First start of the day, at an ambient temp of around 10C, CTBA warning lamp OFF. Visual battery condition indicator, built into battery, shows configuration indicating ‘OK’. Bit odd, I thought…

[halfnutParticipant @halfnut]

Yes, 12.6 standing volts is a death knell. Good thing you replaced it before it left you stranded somewhere.

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