Does charging your car battery on fast charge damage it?

[Ex contributorParticipant @mgnbuk]

Modern electronic chargers will NOT charge a dead battery ! If it senses below about 8 volts – NO GO !

If a 12V battery has been discharged below 8V, consider it dead & due for replacement anyway.

While it may come back for a while if you do manage to recharge it, it will be damaged & it is only a matter of time before it dies permenantly – usually at a most inconvenient time. Starter batteries ar designed to be kept charged, deliver a short burst of high current to start a vehicle & then be recharged back to full again straight away. They do not take kindly to being deeply discharged or being left in a discharged state. Deeply discharged in this context is 50% of rated capacity – regularly discharging a starter battery to 50% will substantially shorten it's life expectancy. This is something that battery manufacturers document, showing the expected number of recharge cycles that can be expected at varying depths of discharge. If deep disharging is required (i.e traction batteries) the internal construction of the battery is different & these can sustain regular discharging as low as 20% of capacity without undue life shortening – downside of these is that short high current bursts (like starting an engine) can damage them.

Modern 3 stage electronic chargers do a very good job of getting batteries to fully charge & then maintain them if left connected with no danger of overcharging. The inexpensive versions that Aldi & Lidl sell (around £14) seem to work well initially, but I have had a couple fail (one in warranty & replaced, another out of warranty) & am loath to buy another. I use an Accumate on my bike batteries – well into it's second decade now. All the bikes have the Accumate quick connectors permenantly fitted, so sequential top-ups over the winter are a doodle.

EDTA is another crutch to try to extend the life of a battery that is past it. Better to bite the bullet & replace a failing battery if you need whatever it is attached to to function when you need it.

Nigel B.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by mgnbuk on 24/11/2021 20:33:42:

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If a 12V battery has been discharged below 8V, consider it dead & due for replacement anyway.

[…]

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If I may say so; I think that’s a rather sweeping generalisation

Last week, I inadvertently left one of the map-reading lights switched on in the Suzuki

Yesterday [i.e. 7 days later] , the Battery was flat as the proverbial pancake … but it’s a good brand, and only a couple of years old.

The Clarke AC180 showed it as faulty and refused to charge it … but after an hour connected to an ‘ordinary’ old charger, it was [just as noel said] happy to do so.

… I’m confident that the Battery is good for a few more years [if only we can train the owner].

MichaelG.

[noel shelleyParticipant @noelshelley55608]

Banks of traction batteries at over £1000 a set, EDTA has been known to give a couple of years of extra life, so is worth the effort. As Michael G has said, a good battery flattened by a fault that is recharged soon after will not loose much if any life expectancy, so I cannot accept if completely that it is fit only for the scrapman. IF on the other hand it has been neglected and been left flat for many months then that is different matter. Noel.

[not done it yetParticipant @notdoneityet]

If you want the best, get a proper modern charger that works on most batteries – except the really dead ones.

Mine is a CTEK MSX 5.0.

It will ‘recondition’ a lead acid battery that had lost capacity or refuses to take charge after being over-discharged (but there is a limit – I connect another battery in parallel to initiate a charge if necessary).

This post has reminded me to top up my spare battery and later today my car battery will get some attention as it has been left discharged a bit for the last few days (car fuel system is leaking air, so needs attention).

Wife’s car battery became discharged during the first lockdown (alarm, etc drained it) and would not accept a full charge from a normal ‘old fashioned charger or a lidl float charger so I borrowed one of these from a friend. That battery is still going now, but I am going to renew it shortly – as I am expecting it might fail at some inconvenient time during the winter.

They are expensive but they do work for battery charging in situ for most vehicles – one model (I think the larger, higher powered, version gave trouble for my friend when charging a Range Rover or Discovery. The vehicle electronics clashed somehow – he doesn’t know why, but that is what he found. He has both sizes as they are used to improve battery power on vehicles with very large batteries, stored in his yard.

These chargers are favoured by farmers who are introduced to them. That must be a good sign, if they use them!

[noel shelleyParticipant @noelshelley55608]

For those for whom a flat battery would be a REAL problem then the fitting of a fixed float charger, sometimes called a maintaining charger, on the vehicle with a kettle type socket mounted under the bonnet or some inconspicuos point on the vehicle to allow easy connection to the mains 240v may be worth considering ! Having used a DURITE unit, it is small, gives an indication of charge state and worked well, it's one to consider !

Crankhandle or bump starting will all be a thing of the past when we all have EVs ! Would towing an EV recharge the battery ? Noel.

Edited By noel shelley on 25/11/2021 10:16:47

[CirclipParticipant @circlip]

Yes John, cylinder head from a Ford "8" on Ford "10" block, E93A engine, standard "Special" builders trick. Mine was in an AKS plastic body "Alfa" two seater look alike, fooled one or two Alfa owners.

 

Regards Ian.

Edited By Circlip on 25/11/2021 11:07:47

[Grindstone CowboyParticipant @grindstonecowboy]

Posted by noel shelley on 25/11/2021 10:15:31:

Crankhandle or bump starting will all be a thing of the past when we all have EVs ! Would towing an EV recharge the battery ? Noel.

There is a video doing the rounds showing a chap stranded in the desert with a flat battery on his EV, so he smugly opens the boot, pulls out a petrol generator but then has to walk miles to a garage with the empty petrol can as he's also out of fuel

Rob

[Anonymous]

Lead acid battery chargers are voltage sources. The ideal charge voltage is 2.45V per cell at 20C, ie, 14.7V for a 12V battery. The charge voltage should vary with temperature, but often isn't. The above figures are for fast charging when the battery is disconnected after charging. For float charging the voltage should be lower, around 13.8V. Float charging is less common these days. Many of the new charger ICs work on a cyclic basis – fast charge, disconnect, wait for the battery voltage to drop and repeat.

Current acceptance is dependent on state of charge (SOC) and temperature. The last pack I designed for a hybrid EV would accept a couple of hundred amps of regen, provided SOC was less than 60%. The 12V batteries used were only 25Ah nominal capacity.

The quickest way to kill a lead acid battery is to over-voltage it. The problem of accepting regen energy at high SOC is one of over-voltage. The battery will accept the current, but the battery voltage will rise to damaging levels. Over-voltage leads to disassociation in the battery and the production of hydrogen. When I first started working on EVs in the early 1990s our battery test room had to have hydrogen sensors fitted, as did our vehicles.

A deep discharged battery can be recovered but putting it on charge immediately. It is leaving the battery discharged that kills it. Short term low voltage excursions are not a problem. Many years ago I was involved in the design of an engine management system for US heavy duty trucks. The power supply input specification was 6V to 60V. Trucks use 24V batteries. The 60V was needed because jump starting was normally done series, not parallel. The 6V arose from cold cranking at -40C. Cranking current was 1500A and that will drag a 24V battery down towards 6V if you're in Wisconsin in the winter months.

Two additional problems with battery packs are temperature control and cell balancing. Batteries like to be warm to perform to maximum ability so ideally there needs to be a means of heating the battery. Conversely one also needs to be able to get rid of heat when ambient temperatures are high. Measuring battery temperature is tricky. Ideally the sensor would be deep in the battery. The best we managed was to put sensors directly on the terminal posts and hope that gave a reasonable approximation to battery internal temperature. However well battery manufacture is controlled individual batteries will have slightly different capacities. Over many cycles the battery SOCs will diverge resulting in a battery being under, or over, charged. The ideal is to add cell balancing. The passive method simply puts a power resistor across the most highly charged battery. The last pack I designed used active cell balancing, ie, a resistor, or a low current (1A) power supply, could be connected across any cell under software control.

In a lead acid battery terminal voltage is a good measure of SOC, provided the battery is left to "relax" after charging. On our battery packs we let the batteries sit for 5 hours before making SOC estimates.

Andrew

[Tim StevensParticipant @timstevens64731]

Andrew J reminds us all 'The quickest way to kill a lead acid battery is to over-voltage it.' Very true – so imagine the failures caused when vintage cars had three-brush dynamos, with no voltage control at all, and the driver was expected to turn off the dynamo when the battery was fully charged. How did he know? Well, if he was lucky there was an ammeter which would slowly creep towards the plus as the charge overshot the 'full' state. No other clue.

Once turned off, in daylight, the dynamo could stay off with most UK and Euro cars, as they had magnetos and no other drain of current*. US cars were almost all coil ignition (well, it was invented there) so the battery trade must have been a worthwhile investment.

* no brake light, no indicators, no electric wipers, etc.

Makes you think, though. Aren't we all glad that no products are so badly designed nowadays?

Cheers, Tim

[noel shelleyParticipant @noelshelley55608]

Was the ampmeter a centre zero ? if so surely the needle would return to zero as the charge in the battery became full ? Noel.

[Tim StevensParticipant @timstevens64731]

Sorry, Noel. but NO! The output of a three-brush dynamo depends directly on the battery voltage – more volts = more charge. So if you forgot for more than a mile or two, the battery was starting to destroy itself. And acid was splattering around, and the plates overheating.

The odd thing was, that proper voltage regulators were known and used, on coaches in particular. But perhaps the motorist was – er – frightened of technology … ?

Cheers, Tim

Edited By Tim Stevens on 25/11/2021 17:55:14

[SamsarandaParticipant @samsaranda]

John towards the end of my ownership of my Ford Pop I did fit a vacuum tank in the wiper plumbing which did help but not much, I would love to have my old Pop back, it was real engineering, Rod operated brakes, non of your servo assist.

Noel, I purchased a Maypole charger at the beginning of lockdown, I wanted a quality unit and I am very pleased with the quality, I only charge using the minimum charge rate so hoping that won’t damage my stop/start battery.

Dave W

[noel shelleyParticipant @noelshelley55608]

Hi Dave w Just got the second one and read the instructions, YES it states it's ok for stop/start. The set of leads with eyes on will be fitted to the bike with the plug hidden up and the set with crok clips for ordinary use ! Noel.

[Chris MateParticipant @chrismate31303]

I had a few experiences……
Lead acid at work:….Specific gravity and volts per cell(around 2.1 -2.2V) These are not car batteries.
I once had a very interesting situation with large glass lead acid cells/batteries. Over the years these huge cells were installed with the rectifiers in different rooms. Everything went well for years till we had a change in upper management(New souls), and new emphesis was placed on battery charging. The acid levels(specific gravity) were checked/recoded more accurately etc. It was then decided that all batteries being charged at a certain rate and I cannot remember exactly but some read say 1240 and others 1260 in different stations/towns. It was then decided to up the charging in those places below 1260 max by doing adjustments to the rectifiers(Huge-Permannt installs).

I then noticed excessive gassing where I was stationed. I reported it but no change in policy. My curiocity let me investigate and what I found then was interesting…..Decided to phone the manufacturers and get their specialist opinion on make and type of lead acid battery(Huge cells). The result was policy changing important.

Manufacturer X told me that their cells should not go over 1240 max, thats why you cant get it up to 1260, no matter how much you overcharge it.
Manufacturer Y told be their cells can be 1260 no probklem.
The company had many installations of both manufacturers. I passed the correspondence to management, and the rectifier setting were corrected where applicable. This whole episode took 3-4 months to reverse.

In this case installation knowledge was not passed on correctly to maintanance as well as the knowledgeables retired as well over years…..With excessive gassing you sit at work on a potential bomb. If these cells explodes and I saw it once(Guy causes a short bon one), it shoot the metal parts into the upper concrete floor.

Lead acid personal:
I have 3 vehicles driven regularly, not stored.
My experience is:
1-The battery from new always lasts the longest.(Longest one last 8 years)
2-Usually when I starts to get the feeling I must change a battery, its the beginning of the end, usually after 3 years. They usually lasted 4 years +/-.
3-If I accidently went to a meeting in thick mist, then forget to switch off the lights(Older vehicle) with alternator, battery drains dead completely you cannot running start it's if dead, you need a jump start(Alternator), and then within few weeks that battery will become weaker and just suddenly drop me dead in town somewhere…New one.
4-With modern vehicles with electronics I start thinking of new ones after 4 years.

Some other experience many years ago:
— I also experienced that not all new batteries are 100% "new". Example=I build 5HP petrol engine/charging 12V unit for my uncle on farm. I used 2 of my batteries to calibrate the unit switch off voltage, ok fine it works.
I then went an bought 2x new batteries for it, and suddenly the unit switch off alright, but just before the engine stops it restarts again…Problem. Ok after a week of scratching heads, I took the new batteries for a load test and both failed=They replaced both at no cost vand my problem was solved.
-Both the failing new batteries started my vehicle ok, but their voltage drop very fast, too fast if charge is removed and thast was the problem.

Edited By Chris Mate on 25/11/2021 19:41:05

Edited By Chris Mate on 25/11/2021 19:44:41

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Chris Mate on 25/11/2021 19:39:40:

[…]

Lead acid personal:
I have 3 vehicles driven regularly, not stored.
My experience is:
1-The battery from new always lasts the longest.(Longest one last 8 years)
[…]

.

For what it’s worth [not much on a sample of one] … The original battery in my BMW lasted from 2003 to 2017 before showing any sign of failure, and I replaced it in early 2018.

Bosch/Varta batteries seem to last very well.

MichaelG.

Edited By Michael Gilligan on 25/11/2021 20:08:45

[SamsarandaParticipant @samsaranda]

Noel, many thanks. Dave w

[Anonymous]

Posted by Chris Mate on 25/11/2021 19:39:40:

Lead acid at work:….Specific gravity and volts per cell(around 2.1 -2.2V) These are not car batteries.

Post Office? Telephone exchanges used to have racks of lead acid batteries to provide the DC voltage down the phone lines that drove the telephone handset in case of mains failure and hence loss of the normal supply.

Old Post Office joke: Each telephone exchange was manned overnight by a man and a dog. The man was there to fix the equipment if it went wrong. The dog was there to bite the man if he attempted to fiddle with the equipment.

Andrew

[Roger BestParticipant @rogerbest89007]

Good thread – good question.

My 35 year old Halfords charger produces a lower voltage than the alternator, measured in the car and at the battery; so I figure its fine to leave it on "high". The current drops to less than 1A when the battery is charged, so the battery is not cooked.

My car is an SMAX with a 2.0 diesel and a huge battery. It can still randomly flatten the battery, its a Ford thing apparently. Anyhow numerous recharges doesn't seem to have done any damage .

[peak4Participant @peak4]

I have an Odyssey battery in my Disco; they come with a warning about low drain on the battery irreparably sulphating the plates.
This is particularly the case with modern cars, full of electronics, where turning off the ignitions doesn't kill everything.
Remote door opening, alarms clocks, ECUs etc all play their part.

Without a drain, the batteries can be stored for a couple of years, without issue.

"Prolonged storage of vehicles with fuel injection computers, alarms, GPS and other
electrical devices that require continuous battery power to support active memories;
this power drain must be offset with a maintenance-float charger, periodic charging
or disconnecting the battery to prevent the establishment of irreversible crystallized
sulphation in the battery plate oxide. Failure to address this destroys battery capacity
and voids the warranty, as this is not a warranted defect in materials or workmanship."

Bill

[Peter G. ShawParticipant @peterg-shaw75338]

Andrew,

Your quote re man & dog in telephone exchanges is slightly wrong. The man was there to feed the dog, not look after the equipment! Otherwise, as you say, the dog was there to keep the man away from the equipment.

On a slightly more serious note, back in 1969 I took over the maintenance of a small Strowger exchange. My predecessor had been having trouble with the charging panel and hence started adding a bit more charge via the ampere-hour meter every time he visited. I carried this on. One Friday am, I made my customary visit, all ok, so advanced the A-H meter a bit and went away. Went on holiday for three days, came back, and as far as I knew all still ok. The next Friday I made my customary early morning visit only to find that instead of the customary load sharp clatter of the exchange, all was muffled, as if wrapped up in a blanket. Checked the voltmeter – "Oh bxxxxy hxxx" – it's down at 46V. Now this was a suppessed zero thing so I removed the cover and moved the arms down. The needle followed it. My guess is that the battery voltage was below 40V (it should have been 46v & 52V) and the rectifier had failed to switch on. Manually switched on the rectifier, a loud bang as the contactors operated, and a deep, loud buzz followed, but it worked. Rang the boss to let him know – end result was a temporary charger arrived pdq, followed by a new control panel and an extra rectifier a few days later. And the battery? That poor old hardworking, much abused device? Well the specific gravity was off the scale – downwards. 1/2 inch later (we had to record the specific gravity monthly) it appeared back on the scale and over the next 18 months slowly climbed back towards where it should have been.

I suspect I was within a few hours of having an exchange isolation on my hands. Which, in those days, was almost a candidate for a question to the P.M.

FWIW, the exchange was left for a week without a visit. In theory, exchanges of that type were designed to more or less look after themselves so a week without a visit should have been totally satisfactory.

Peter G. Shaw

[noel shelleyParticipant @noelshelley55608]

My experience of lead acid batteries Bill is not so as regards storage ! The only way to store them is dry ! On one notable occasion a new battery was fitted to a classic tractor started once and left for a year or so, the battery was scrapped after numerous attempts to recover it proved fruitless- there was nothing connected to the battery ! It might have been a good candidate for EDTA treatment ? But modern vehicles yes all those milliamp drains will over time kill a battery DEAD ! Noel

[Don CoxParticipant @doncox80133]

Andrew’s recent post about telephone exchange maintainers and their dogs, and later Peter Shaw’s account of his dalliance with what I suspect was a UAX13 type exchange remind me of my own experiences. I joined PO telephones in 1963 and left B.T. in 1996, I spent the majority of my time with them maintaining exchanges, with a a significant period of that time looking after some smaller, rural ones, UAX 13, 14s and later TXE2s on my own (although I did take our black Labrador to work on occasions).

Whilst we were very well trained to be able to locate and repair faults in the switching equipment, most of us had only a sketchy idea about the power plant and relied on the expertise of the “power group’ to deal with any significant problems.

The power system in place in the exchanges when I first started work in them was to have two batteries, one charging and the other “floating” the exchange with, if I recall correctly, a nominal 24 hour turnabout. The problem with this system was that the battery just about to be switched in to run the exchange was significantly, often two or three volts, over the nominal 50 volts that the exchange required. To deal with this a battery of “counter emf” cells were wired in series with the main battery, these were alkaline cells with a nominal voltage of 1.1 volts, connected in reverse polarity and they were short circuited by the switch gear only being brought into use by removing the short when the battery voltage was too high. As you might imagine, these batteries objected quite violently to this treatment and used to “boil” when in use, so much so that a layer of oil was sitting on top of the electrolyte to prevent frothing. As exchanges grew bigger the power demand increased and bigger main batteries were installed, although the counter emf cells remained unchanged. This resulted in even more violent boiling and the oil layer was replaced by plastic “pebbles” to try and collapse the froth that built up. The switchgear to achieve the control of this system usually consisted of some chunky copper “shoes” moved into and out of position by a worm drive.

Much to the relief of everyone involved, improved power plant design did away with all of this and a system known as “end cell switching was installed in all of the exchanges I looked after. This had a battery kept fully charged by a rectifier which followed the load demanded by the exchange and regulated the voltage to close limits of the required 50 volts. If a mains power failure occurred, then the “end cell” which was isolated from the main battery and separately charged by another rectifier, was switched in to replace the high level of charge initially existing as the main battery moved away from the highest point of the discharge curve. After that, if there was an engine driven generator installed that should take over, if not then a “phone call to the “power group” would get you a portable generator to connect to.

[Peter G. ShawParticipant @peterg-shaw75338]

Don,

Quite right, it was indeed a UAX13, in my view possibly the most reliable of all the Strowger type exchanges. And yes, power plant knowledge was indeed limited to topping up the cells and recording the specific gravity of the pilot cell so as long as the power plant worked, it was left severely alone. I suppose, even removing the cover and adjusting the arms of the suppressed zero voltmeter was a no-no. Still, until today, no-one knew about that!

Although I also had a UAX7 to look after, I never got to work on a UAX14.

Black Labrador. We had one – big, greedy, lazy, ugly (for a Lab.), stinky breath, but absolutely 100% Labrador temperament. Lovely dog.

Peter G. Shaw

[Ex contributorParticipant @mgnbuk]

Yesterday [i.e. 7 days later] , the Battery was flat as the proverbial pancake … but it’s a good brand, and only a couple of years old.

You may be lucky Michael, but my experience with a battery that had been totally exhausted followed the manufacturer line that this causes premature demise. In my case it was the habitation battery on a new motorhome that, unknown to me, had a split charging fault. While the fault was rectifed reasonably quickly after the dead battery episode, the battery never recovered & was replaced under warranty in under a year due to lack of capacity. As the motorhome was built to my order & delivered less than a fortnight after it left the production line, the battery would have been a fresh one from the manufacturer.

Bosch/Varta batteries seem to last very well.

Indeed – my usual "go to" brands. Both are Johnson Controls brands & likely the same batteries with different badging, though Bosch usually sell for less than Varta equivalents. Yuasa can also be good, but there are Yuasa and Yuasa – "OEM" Yuasa motorcycle batteries can carry different codes to "replacement" Yuasa batteries recommended for the same application. Had this with my wife's Honda VTR 1000, where only an OEM battery bought from a Honda dealer performed as expected. Strangely the OEM battery was cheaper than the "replacement" alternative that didn't perform as well.

EDTA has been known to give a couple of years of extra life, so is worth the effort.

IIRC EDTA dissolves the lead sulphate & this can clear plate shorts where the shed deposits have built up at the bottom of the cells. But the lost material is still lost & capacity is reduced. From my POV, it would not be worthwhile to spend time & money on either the reach truck or the ride-on sweeper at work trying to extract a bit more "life" using EDTA – we are aware that the batteries are well past their best, that they have a high rate of self-discharge & much lower than new capacity. But they can currently perform to the low usage requirement expected of them. Should the usage change to be required to run a full shift on a charge, then EDTA will not restore that level of performance & the MD will have to reach deep into his pocket to get them re-celled.

Nigel B.

[Chris MateParticipant @chrismate31303]

Dry new cells installation: I got a scare

So once in my working life I had to deal with the replacement of a battery(Huge cells). I was a safety officer OHASA as well. So here come the contruction team and start rigging the rest of the battery room to take the new batch of dry cells.
Brand new cells were installed and then the fun started. One constrcuction worker start pouring the battery acid-liquid into the new dry delivered cells. A huge mist filled the room and these cells temperatures rised as it reacts with the plates. I could not believe my eyes, and immediately evacuate the personel from other rooms as well as the construction guy. On the phone to the boss, on his phone to more bosses. It then came back the the construction guy must continue carefully, this happennes apparently if there is a big difference between dry charged new cells and the liquid filling them again. I am not an expert here, that was the reply back. The battery room did have two large extractor fans no sparks insulated types. Too much for them.

It took the cells to stop misting lets say since 10:00 in the morning to around 18:00 that evening, then they started to cool down slowly……In the end everything settled and worked till the place were scrapped for new equipment and smaller battery/rectifier units. As far as I am concerned this was not a normal situation, no smoking.

Edited By Chris Mate on 26/11/2021 16:31:28

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