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Lead Acid Battery

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mikeb
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Post Number: 322
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Posted on Tuesday, 13 July, 2010 - 02:22 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I thought the acid level in my car battery was ok, only to find that there was some sort of air lock - my plates were only half covered for months.

I put in a load of distilled water and recharged. The Specific Gravity now looks ok for each cell but starting is sluggish.

Should I put some acid in to help the recovery?

rgds

mb
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bruce
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Post Number: 369
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Posted on Tuesday, 13 July, 2010 - 03:02 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Mike,
Unless you've had a leak, you cant lose acid ions, so you only replace water. It's no easy matter checking the state of a car battery, although I did build myself a device to check SLAs ( not those soppy 'state of charge' things - I mean a proper tester ) It wouldnt do a car battery as it stands, but the principle is the same.
Before you blame the battery, you have to check the alternator with a proper meter. This will tell you if the battery is taking charge as well. I got a clamp meter for about 20 quid form somewhere ( I've never used it ! ). It could also be your starter, of course, so be carefull out there!
I often find, in cases like this where it is difficult to isolate the exact fault, to sell the car.

Bruce
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hackinblack
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Post Number: 504
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Posted on Tuesday, 13 July, 2010 - 04:39 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

as bruce rightly says you cant lose acid without a leak,so topping it up with distilled water is the only option
if the battery is more than 4yrs old,its probably not worth messing with,other than re-charging it slowly for as long as possible at a very low rate 1/10th of Ah capacity or less;this can sometimes help coax the cells back to life,and at least make it useable;with a reduced capacity

you should check the other components before faulting the battery and forking out for a new one

it may have been overcharged by a failing voltage regulator/alternator

if only some cells where low this points to dropped cells,so bye bye battery

check all the main leads for corrosion and firm connections;
this beleive it or not,can cause problems with ABS systems!
the electrical spikes send them screwy,at least they did on my parents skoda/VW fabia...

also make sure the battery is clamped down correctly,ive seen soooo many held down by the leads and gravity;they literally get shaken to death.wont do a new one much good either...
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mikeb
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Post Number: 323
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Posted on Tuesday, 13 July, 2010 - 07:57 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Thanks, as ever, for info gents!

I dont have a clamp meter. Thought of 'dissing the battery once engine has started and inserting an ammeter to check charge current - but would that stop the engine? (the EMC would have a power loss for a short period).

Why does life get so complicated when you start thinking 'bout things ..... note to self - try to stop thinking 'bout things.

rgds

mb
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bruce
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Post Number: 370
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Posted on Tuesday, 13 July, 2010 - 08:40 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

As I say, the clamp meter I got is only an el cheapo brand, but ( I assume ) it works and is amazingly cheap; they used to cost hundreds..
There will be 2 cables from the positive terminal: one is very thick and is for the starter; the other is circa 5mm and does the alternator. The alternator is capable of delivering 40-50Amps to a flat battery.
Now, if you attempt to disconnect the battery while the engine is running, I've been told you will trash the alternator, so best not to do that. However, you might be able to disconnect ( ONLY ) the alternator cable , AND insert your ammeter BEFORE you start up. Not easy.
Years ago, ETI had a cct. for determining the current in and out of the battery by using the resistance of the earth strap as a sensor! Clever.
If it was easy, everybody would be doing it.

Bruce
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piers
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Posted on Tuesday, 13 July, 2010 - 08:46 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi Mike,

shouldn't stop the engine, but disconnecting the battery whilist the engine is running is not recommended, will lead to alternator damage.

A better option to check alternator output without a clamp meter is to disconnect the alternator main output terminal and securely fit a suitably meaty ammeter there before starting the engine, removing the need to disconnect the battery. Check charging volts too, should be 14 to 14.5 volts max. Switch on a few electrical loads like headlights, heated rear screen etc, that give a steady loading to load the alt up, make it work a bit.

Piers

(Message edited by Piers on 13 July, 2010)
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chuckieboy
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Post Number: 143
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Posted on Tuesday, 13 July, 2010 - 09:22 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

The best way to test your alternator ouput is start the engine give a little reves for a few seconds, Then with a voltmeter measure the battery voltage while the engine is running and you should see a voltage reading 13.8V to 14.4V if this is good then the alternator is working ok well it shows you that the regulator is good.Has another test get someone to hold the revs to about 2000RPM. This should show no more than 14.5V tops if it goes to around 15Volts or more then alternator is no good. about 95% of alternators fail to give any output current before the regulators fail.(No voltage limit)
Second test still with the engine running turn on mains lights and high bean again measure the battery voltage it still should remain in between 13.8V to 14.4V again get some one to hold it about 2000RPM. This then shows that the alternator is fully functional and is good.
If your car is slugish to start first thing and it starts ok after you have had the engine running for 5minutes then I would say without a shadow or doubt it's your battery. in the modern world of car batteries today they are normally sealed and show a green dot when good. I have ever only seen one case that I can recal where the starter motor was at fault. The battery voltage dropped straight to 5V and the starter motor was red hot (big give away) And the car never started.

Once you have carried out these tests and everything checks out ok on the car then take it to somewhere like halfords and get the battery tested of casue they will tell you that the battery is no good or it's weak but at least you know in your own mind that they are correct. I have a device which clamps onto the battery and tests the internal resistance of the battery this then tells you the state of charge and the state of health and the remaining CCA. Unlike SLA batteries and the deep cycle batteries a load test will not tell you anything even though some car batteies state the AH as well as the CCA(cold cranking amps). It's the CCA that is the most important part of a car battery.

Hope this helps you. I'd be willing to put a pint or two that is your battery. I would not even consider trying to disconnect anything from the battery while the engine is running, This could casue a spike and blow the ECU or alternator.

(Message edited by chuckieboy on 13 July, 2010)
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twintub
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Posted on Tuesday, 13 July, 2010 - 10:52 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I got a new battery (NOT a well known brand) from Ford RapidFit a while back, but 3 months after the 3-year battery warranty expired, the battery voltage dropped to such a low level during cranking that the engine management system was deprived of too many volts to be able to give a spark. The engine was still able to turn at a fair speed, albeit slower than normal. The starting problem only happened after leaving the car standing for a week, and behaved normally if used everyday. The electrolyte level was only marginally low but I topped it up.

There was no way that I wanted another cheapo brand battery so gave RapidFit a miss and headed for Halfords. Lo and behold, their own branded battery was identical to the RapidFit model except for the label, and they no longer stocked any well known brand. Anyway, I made sure I used the car every few days to keep the battery charged, but as the battery was on its last legs, and the car had numerous other faults (it was 12 years old!) I sold it on.

If you do indeed replace your battery, I strongly advise you to buy a reputable brand, even if it is twice the price. Incidently, the original FORD battery (whatever brand it was) must have come from a decent manufacturer because it lasted for over eight years!

Even if a car battery is described as 'sealed' they invariably have removable screwtops so you can top it up! i.e. they are not truly sealed!
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arw
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Post Number: 878
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Posted on Wednesday, 14 July, 2010 - 12:07 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I used to have a Renault 5GT Turbo which ate a 56Ah car battery every 2-3 years - a lot depends on the cycling and loading of the battery. They hate frequent discharging and having a heavy load (e.g. the car's anti-percolation fan which ran for 20 minutes after the engine had stopped) I reckon shortened the life. Various brands were tried and they were all pretty bad.

I think the capacity is a key factor - hammering a lower capacity battery will easily damage it, as they can only withstand so many charge-discharge cycles. Yet in other cars that I've owned, the battery almost outlived the car itself.

I also had two of those 'jump starter' battery packs which contained a motorcycle lead acid battery (400 amp! ROFL) and both of them failed in no time at all. Lead acids need a trickle charge periodically and should not be allowed to run flat.

BTW I also worked in the lead industry in the 1980's, and a massive amount of lead used in the UK (for roofing, leaded windows etc) all comes from recycled car batteries. Not surprised....
Alan Winstanley
www.EPEmag.net - EPE hobby electronics and more
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piers
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Posted on Wednesday, 14 July, 2010 - 12:15 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

>Yet in other cars that I've owned, the battery almost outlived the car itself.

My father has a 10 year old Nissan, still on it's original battery. It went a bit flakey back in the winter so he had it checked, garage reckoned it was fine...

Piers
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terrym
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Posted on Wednesday, 14 July, 2010 - 02:37 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I've got a BMW that eats batteries every 2-3 years. You can tell when it's time to change it, the performance drops right off.

TM
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gizo
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Posted on Wednesday, 14 July, 2010 - 04:21 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

There are some knowledgeable vehicle electrics people on here who might know something about this thing, which is probably becoming widely available now.

I impulse bought a "magic vehicle restarter" something like this, but only about half the price::

http://www.supercheapauto.com.au/online-store/products/Portajump-Emergency-Car-Jump-Starter-12V.aspx?pid=168294#details

There is 30V DC sitting at the socket.
It is about 70 mm cube, and 600 grams.

1. How can something this small contain enough energy to start a SUV or small truck as they state.
The ancients used to believe a sick battery can turn over a motor, but the terminal volts sag too much to get a good spark.
Does this fix that?

2. What sort of rechargeable watch batteries can do this? Can't believe a computer type Li Ion could even do it, and would cost much more, and charging complications.
Dremel with "cutopen disk" is standing by to investigate.

3. How does it recharge? Maybe there is a stepup converter in the cig lighter part.

4. If I happen on a distressed Lexus, not only would I have to wait 15 mins (instructions say to leave it charging via the lighter for 15 mins) to get the thing back, but..
They do caution to turn everything off, but if the problem was just a high R battery connection then this might toast the EMS, Air bag sensor, DVD, navigator, anti lock, plasma TV in the back seat, drink warmer etc etc.

The owner would give me the burnt out shell, and demand a new LS300.
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terrym
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Posted on Wednesday, 14 July, 2010 - 07:41 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

$60AU for ~20 AAA batteries - what a rip off.
Google 'porta-jump' for all the info and bad reviews.

TM
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violin
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Posted on Wednesday, 14 July, 2010 - 10:38 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

The quick method I used to use to check to see is the battery was OK or not was to remove all the caps/tops to the batteries cells and then turn over the engine and observe to see if any of the 6 cells bubbles. If any did that was an indication that the cell was on its way out and time for a change of battery.

BTW I do miss the crank handle method of starting a vehicle. This was an extremely useful method of starting my old 1952 Landrover every time the battery had become flat.
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ant
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Posted on Wednesday, 14 July, 2010 - 03:54 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hello Chuckieboy,

Where's the green dot? What's it measuring?

Regards Ant
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piers
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Posted on Wednesday, 14 July, 2010 - 05:11 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Ant,

the green dot is on the top of the battery, rather it's viewable through a window in the top of the battery. It's basically a built in hydrometer. Have a look here, about 3/4 down the page.

Battery page

Piers
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chuckieboy
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Posted on Wednesday, 14 July, 2010 - 06:43 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

You beat me to it, We have loads at work and when the green dot fades then the battery fails shortly after.

Capacity does help with a battery but higher the cold cranking amps the better quality the battery is. Has most current is drawn from the battery is at starting in a short period of time.
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ant
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Posted on Wednesday, 14 July, 2010 - 09:48 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hello Piers and Chuckieboy, I like to stay a bit informed! My batteries have always been "normal" with caps so if necessary I use a hydrometer. By and large life is easier now except that this automatic car and its predecessor are ok until I run the battery down. We lived in a rural area so I bought a 100Ah tractor battery, remarkably cheaply, and it does a grand job! It ran the computer for a long time too, when I recorded three days of Radio 3 Bach during a power cut...

Regards Ant
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alanr
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Posted on Thursday, 15 July, 2010 - 11:04 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Bruce and Hackinblack.
Lead acid batteries have a phenomenon known as "sulphating", from discharging too low or leaving discharged too long, where some of the lead in the plates is converted to lead sulphate. This effectively removes some of the acid from the electrolyte leaving it at low s.g. Sulphuric acid is therefore needed to bring the s.g. up to a working level. The hope is that a long low charge will reverse the sulphating. It usually does not and the battery has low capacity.
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atferrari
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Posted on Friday, 16 July, 2010 - 01:59 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

On January this year I bought a new car. My former one, a Ford Fiesta 1.4 Diesel with 157.000 Km had the original battery in working condition.

I bought it on April 2003.

Never even checked the battery.
Agustín Tomás - Buenos Aires - Argentina
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armadillo
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Posted on Friday, 16 July, 2010 - 03:18 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

My wife's Fiesta is the 1989 model and is only on it's second battery. The first one lasted 12 yrs.

Armadillo
There's no such thing as gravity..........
The earth sucks!
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bruce
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Posted on Friday, 16 July, 2010 - 03:49 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Well...my car battery was designed and built by Allesandro Volta and it can still make a frog's leg twitch.

Ant, I'm glad to hear that theres another R3 listener out there. It's gone downhill a bit lately since they got that dipstick Katie Derham in; nice tits, but a c**p announcer.

Bruce
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bruce
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Posted on Friday, 16 July, 2010 - 03:53 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

One more thing while I remember:

I spoke about a clamp meter to measure the current without having to break the circuit. Well, I've just discovered that EPE had an article in 2006 in which somebody made one: actually, it's an attachment to fit a standard digital multimeter.

Bruce

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