Charging a car battey

[pedrobedro]

Friend of mine was boosting one round at the bike shop with the start'n'charge and forgot about it. The battery was smoking and nearly ball shaped when he came back to it so he got a stick and knocked the live terminal off and left it to cool down for an hour

 

[normspanners]

Got the charger out (one of these auto ones) Charger shows the battery as full and went into recondition mode.

If it was an auto one it might be 6v -12v and it sees your flat 12v bat as a flat 6v battery so will only try to charge it as that so the battery will switch of the charger at 7.5volts ish and that is a full 6v but still a flat 12v.

 

[postie jon]

have tried it with a battey drill & yes it certainly kicked it back into life and is still currently working , no sure if i would like to try i with a car battery tho, Euro car parts were doing cheaper batteries a while back , got 1 for the father n laws skoda.

 

[normspanners]

I have bought a couple of lidl ultimate speed battery chargers they are good for the price, they are a lowish amp 75a charge start, that does work on diesels if you leave it ten minutes to charge before cranking and does most battery types, are automatic and for the money I think are very good

http://www.hotukdeals.com/deals/ult...r-with-jump-start-function-34-99-lidl-2328172
But again because of the micro processor on a totally flat battery they struggle to 'see' it
you have to disconnect the battery from the car and let it build back up its self or just jump another to it to get it to crack on once going they carry on.

 

[Rig Pig]

Apparently ( I've never tried and don't recommend you do) hitting it with an arc welder for a few seconds puts enough current into it to dissolve some of the scale on the plates inside the battery and helps the battery hold a charge again.....

Having been in a workshop when a stray welding spark caused a battery on charge to explode I would be very cautious of that! It went off like an acid filled bomb!

 

[DAPPH]

Just for those that like figures .
IF I recall them correctly

Ideal charge rate for a battery to de sulphate it is 1/10 th of the ampere capacity IE 60 A/hr capacity , the charge rate = 6 amps.
This battery should nominally give one amp for 60 hrs but inpractice it is usualy several hour short due to internal resistance increasing & the electrolyte warming up to mention a few things . . . or any other combination that adds up to 60 . Such as 4 amps for 15 hrs , 10 amps for 6 hrs or 20 amps for 3 hrs.
If you have a starting current load on the battery of 300 amps the ability to deliver it is down to seconds ... so it's easy to see why people flatten ther batteries after threen or four attempts at starting if the battery is in poor condition or partly charged inthe first place. .


Most flat batteries used to be battery connections or dynamo / alternator centtresd but no end of folk ran out & purchased a new battery first off.
There used to be hand held heavy discharge testers . good but tended to get very hot & spark if not used correctly .
These days computer tests can detect th current drop per cylinder to show the discharge current thus they are testing the battery delivery as well as the cylinder compressions .

A fully charged in good condition lead acid battery has 6 cells @ 2.2 volts per cell + 13.2 volts .
classed as discharged if it is down to 10 volts but can be recharged
if it is down below 9.3 most modern chargers won't recharge it , some of th older ( 20 yrs plus ) will but not all

Below 6 volts you'll be lucky to do anything with it other than weigh it in as scrap & buy a new one but do get the electrics checked out .. you'll be looking for around 2 volts potential difference to shove a quick charge in to any battery so the alternator / dynamo should be able to put out 17.2 volts .


If I've accidentlly put the wrong numbers and someone recognise it , copy & paste the post & put the correction/s in red please .

What about a low voltage alarm?, first ebay hit or build you own here

They use current so are a little self defeating unless you are close to the equipment several times a day to be able to hear it . There are also some that act as not only an alarm but as battery disconnect / cut outs too .

 

[DAPPH]

Friend of mine was boosting one round at the bike shop with the start'n'charge and forgot about it. The battery was smoking and nearly ball shaped when he came back to it so he got a stick and knocked the live terminal off and left it to cool down for an hour

In 1969 My pal & I happened to be standing about 18 feet away from a 100 AH lead acid radio battery that was correctly set up on a proper buzz bar charging system by one of the guys in the Royal signals battery chop . ....... when it went bang .LOUDLY !
I had my tool box on my right shoulder so had some protection to my face . Being my supervising corporal he didn't have his tool box with him & was closest to the explosion , getting more acid on himself than me .
It's amazing how fast you can run to a fire hose point when you need to get decontaminated urgently .

When we went back to see what things looked like we couldn't find the end wall of the battery despite it all happening inside a vehicle hangar .

 

[wookie]

When we went back to see what things looked like we couldn't find the end wall of the battery despite it all happening inside a vehicle hangar .

I worked in one place where the electric forklift battery went boom overnight, so nobody heard it but we saw the aftermath in the morning, one side of the battery case was completely missing and the place stunk to high heaven of acid.

 

[dannyp]

sometimes a completly dead battery will come back othertimes a battery thats just had a big discharge won't. ive used the welder trick meany times the 80 v ocv backwards soon gets a completly dead battery wanting to take current once it's had a few short sharp cycels of reverse and correct polarity it goes outside on a trickel charger for a couple of days they ether work or they don't after that supriseing more often than not they are good enough for rollers and dumpers

 

[Robotstar5]

I've got an old metal cased one inherited from my dad that will charge anything, it even has little shorting plugs you move round to select 6/12V and low-med-high charge rates


blue hamerite with an ammeter in the middle ?

No, silver/grey hammerite, dug it out today and it's even got an input voltage selector link

 

[johnik]

No, silver/grey hammerite, dug it out today and it's even got an input voltage selector link

View attachment 115152

even more frankenstien than mine , still be going when all te new "smart" ones are landfill.