Does charging your car battery on fast charge damage it?

Dave W should you ever get that ford POP back, I'll forward you details of how to over come those Vacuum operated wind screen wipers and to fix advance/ retard to the distributer as well. I had a 1934 Austin 7 with the same problems and with 3rd brush dynamo. I can't remember, details of the POP dynamo or charging arrangement, I should, as wife's brother had one. I remember we changed the cylinder head from another Ford engine which raised the compression ratio and it then was quite a flier. Side valve engine of course, how crude was the valve adjustment. John

Batteries do not respond well to high current on charge. But of course, we don't know how high the high setting is in practice, and we don't know the size of the battery (in Amp-Hours). My answer would be: Get yourself a modest ammeter reading up to 10 Amps, and measure the current going into the battery on High, and on Low, charge settings.

A normal car battery of about 50 Ah can be charged at 8 to 10 Amps - as long as you turn it off when the process changes to 'gassing' - with lots of bubbles and gurgling - which means that all the chargeable stuff is now fully charged. Much more than that - either more amps or more time - will tend to overheat the battery - it should never get hot enough to feel more than warm. This causes damage to the chemicals and reduces the available charge.

Hope this helps

Cheers, Tim

Chargers of more than 10 amps are not so common now, many are 4A and this is hardly high and will suit most batteries. A boost of 2 or 3 hours will allow the engine to be started and the alternator will do the rest ! If the battery is consistantly going flat there is a problem with the electrics or the battery is f dead - replace ! Modern electronic chargers will NOT charge a dead battery ! If it senses below about 8 volts - NO GO ! One way round this is an old transformer type charger and run for 15 mins or so then let the electronic unit take over once the battery voltage has come up a bit. Maypole do a very neat little 6/12v 4 A for about £28, just about to order a second one ! A lead acid battery will sulphate up in 12 months if left un used and allowed to go flat. Modern cars have many circuits that are live even when everything is OFF so will flatten a battery quite quickly if the vehicle is not used. It is a good plan to disconnect the battery if not in regular use. The alternator is a 3ph device so will give a smoother output than most chargers and will control the voltage to 14.25/14.5v, this is the running voltage of the vehicle not 12v Noel

For those of an adventuring mind, it is possible to rejuvenate a sulphated conventional wet lead acid battery that is otherwise sound with EDTA, a food addative is one of it's uses. With 100A+ batteries at over £100 it's worth a try !

Edited By noel shelley on 24/11/2021 17:14:59

Edited By noel shelley on 24/11/2021 17:31:14

I bought a Clarke AC180 at a Car Boot Sale a few years ago … It’s vintage 1999 or thereabouts, but Clarke kindly sent me a copy of the manual

This page may be of general interest :

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MichaelG.

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.

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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.

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.

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!

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

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

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

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

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

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

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

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

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.

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

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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

Noel, many thanks. Dave w