Battery gives 6 volts output, is it recoverable?

ibook

My car battery went dead so I took the battery out of the car & bought one of the LIDL chargers.

Unfortunately it doesn't seem to charge, the charger manual states that it will not charge if the detected battery voltage is less than about 7 volts. The battery shows 6 volts on a multimeter.

So is the battery recoverable at all? I have a 12 volt adapter from another device, can I use that to charge the car battery? At least to get the battery charged a bit over 7 volts so the LIDL charger can then trickle charge it.

Thanks for any advice.

alias no.9

No. Nearly half of the cells in your battery are dead. Time for a new one.

L1011

I've recovered a battery from dead flat* before by rigging it to a 12V supply from an old ham radio of my fathers and eventually finishing it off with a "proper" car battery charger

*was reading about a volt, but thats effectively dead - couldn't even get a glimmer of a light off the car with it

Should point out that it was drained slowly rather than going 'kaput' in one go (lights left on for a VERY long time), as SteveC has made a good point below.

Steve

Car batteries tend to die suddenly rather than fade away so it may not be good news.

Best bet is bring it to a garage / mechanic and they'll test it for you.

L1011

alias no.9 wrote: »

No. Nearly half of the cells in your battery are dead. Time for a new one.

This isn't a NiCad phone battery we're talking about here...

Pete67

You could always put it back in the car and jump start the car. The alternator will charge it quickly enough, especially if you go for a drive for half an hour or so.

If the battery is flat due to leaving light on or similar, then it can be recovered. If it won't hold the charge (goes flat again for no apparent reason) then you need a new one.

unkel

ibook wrote: »

I have a 12 volt adapter from another device, can I use that to charge the car battery?

You might as well give it a try. Nothing to lose!

I've revived a completely dead battery (about 6V) by trickle charging it directly from a solar panel

Edit: what Pete said - that's probably the quickest way to recharge the battery

alias no.9

MYOB wrote: »

This isn't a NiCad phone battery we're talking about here...

No but car batteries are also made up of a series of independent cells. A battery that's only registering 6 volts will be pretty knackered. It may take charge a couple more times but I'd wager that even if it does, the next time the car is left sitting for a weekend, it won't start on the monday. It'll cost the same for a new battery now as it will in a month or six weeks time and you'll save yourself a lot of hassle.

L1011

Its entirely possible for it to be registering 6 volts with every single cell uniformly discharged.

ibook

Thanks for the replies.

Is there a danger of the battery exploding or giving out hydrogen gas? I read a number of articles on the net that indicate this might happen if the charge is not properly done. Would this happen if I kept it plugged for a few minutes until I get the charge upto 7-8 volts?

I'm a bit cautious of jumpstarting as I was told theres a possibility of frying the car electronics. Besides, I dont know anyone who could help me jumpstart it.

I guess its best to visit a mechanic, but the DIY is pretty exciting :-) If it goes dead again, I'll get a new battery for sure.

L1011

Generally, have a set of jump leads and ask any random bloke passing (or girl if you don't want to be sexist...) and you'll usually find someone with a car to help. It just needs leads (20 quid max) and another 12V car.

If done right there is little risk to the electrics. Just make sure the battery isn't physically damaged on either the jumping or jumpee vehicle and connect the cables in the right order. http://autorepair.about.com/cs/doityourself/a/bljumpstart.htm gives the order, I can never remember and had to google on my phone the last time I had to do it.

Dunno about the charging battery exploding, thats the reason I charge mine in the shed though!

Steve

They don't give off hydrogen, I think it's chlorine gas or something, it's only older batteries though (the ones with the caps for topping up) and yes it it is flammable so if this is the case, do it in a ventilated area.
AFAIK, newer sealed batteries don't give off gas when charging.

L1011

SteveC wrote: »

They don't give off hydrogen, I think it's chlorine gas or something, it's only older batteries though (the ones with the caps for topping up) and yes it it is flammable so if this is the case, do it in a ventilated area.
AFAIK, newer sealed batteries don't give off gas when charging.

Its hydrogen... water starts to break down so emits hydrogen and oxygen.

ibook

Well I just gave it a shot and used a 9v adapter to boost the voltage up to 8v. The LIDL charger is now able to trickle charge the battery. :-)

I live in a 1 bed cupboard so it's in the living room with the windows wide open.

Thanks to all for your invaluable help.

Steve

MYOB wrote: »

Its hydrogen... water starts to break down so emits hydrogen and oxygen.

What creates the rancid smell then? I always thought it was hydrochloric acid breaking down (or maybe its h2so4, don't know).

Alun

SteveC wrote: »

What creates the rancid smell then? I always thought it was hydrochloric acid breaking down (or maybe its h2so4, don't know).

Probably small amounts of hydrogen sulphide (rotten egg gas) being given off during charging.