Dead battery

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les
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Dead battery

Post by les »

I’m looking for some help for a friend, he has told me a new and expensive 12v battery, fitted to a car he is finalising, has completely drained after a couple of weeks. There must be a parasitic drain I should think but forgetting that for the moment, the drained battery will not take a charge now, when this is attempted. Any ideas or suggestions as to getting it to accept a charge? I can’t think how to advise him with this issue.

SteveClem
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Re: Dead battery

Post by SteveClem »

I would think that the battery is under warranty. Our local ‘battery shop’ will test for free and replace if faulty.
les
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Re: Dead battery

Post by les »

Yes it probably is, but came from Southend so travel I awkward now, plus if there is a fault on the car that damaged the battery, I don’t know how that would effect the warranty. He was mystified as to what would cause it to not take a charge now, so am I.

pgp001
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Re: Dead battery

Post by pgp001 »

I find that if I let my motorcycle battery go "Dead" flat over winter, the Accumate trickle charger I have will not start charging it.
However if I hitch it up to my good old fashioned basic transformer type charger from the 1970's, it will get it going again.

Once it accepts some charge from that I swap it back onto the trickle charger and it is OK. There must be something in the electronics of the modern charger that does not like the starting voltage of a totally dead battery.

Might be worth trying to jump lead it to another charged battery and see if it will accept anything from that prior to charging it.

Phil
les
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Re: Dead battery

Post by les »

That’s a thought Phil, thanks, I’ll be in touch with my friend in a few days I’ll forward your suggestion. I didn’t think to ask what charger he was using.

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Re: Dead battery

Post by alawrence10360 »

Providing it’s connected up correctly (re neg/pos earth)I don’t believe the car could have caused a fault of this nature that you wouldn’t immediately know about ie a massive short circuit
I would jump start it with the battery in circuit and see if it takes charge
The dynamo /alternator has much more capacity to charge the battery than the average charger
If that doesn’t charge it contact the place where you bought it
I recently had a problem with a battery and they replaced it without any problem and sent it FOC without sending the old one back
simmitc
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Re: Dead battery

Post by simmitc »

It depends on what state the car is in - leaving the courtesy light on (door adjar) or sidelights on, or even ignition on will easily flatten the battery. Does it have a modern radio or alarm system? Any modern accessory draws power when in "standby" as they don't have a proper "off". Try removing the battery from the car and connecting a good old fashioned charger for a few hours.
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Re: Dead battery

Post by oliver90owner »

Do not attempt to charge a completely discharged battery at the one hour rate - it is likely to damage it, particularly if a valve regulated type or gel - well any type really. C/10 or C/20 is a far better rate (once it will take a charge).
les
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Re: Dead battery

Post by les »

Thanks for the recent replies, I’m keen to have a look but can’t get to the car because of restrictions, so I can only relay these thoughts to him, which of course I will. The car is a 70s escort, so no fancy stuff, and I’ve been assured there are no electrical components on. The jump start is a thought. I didn’t mention that my friend bought another battery and that is also showing signs of discharging. He’s less interested at the moment in reviving the first battery as he is in finding where the drain is occurring, I can’t blame him, it’s me who is interested in trying to save the dead battery for him. Going back to the discharging problem, he wondered if it could occur when the car is running, although the alternator is putting voltage in, so I was doubting that possibility. Will also mention the charging rate.

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Re: Dead battery

Post by pgp001 »

Les

Does your friend have a multimeter ?

Phil
les
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Re: Dead battery

Post by les »

Yes and I’ve given him instructions to test for a drain, —— disconnect earth terminal and put meter in series, he said he had no reading on the meter, set to mA. However without being there I couldn’t double check the settings, I’m sure there should have been a reading of some sort. Again the trouble with trying to remedy from a distance.

pgp001
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Re: Dead battery

Post by pgp001 »

It would be interesting to see what voltage is across the battery terminals both with and without the engine running.

Phil
les
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Re: Dead battery

Post by les »

Well apparently it was about 11.5v rising to 13.6 when running on tickover.

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geoberni
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Re: Dead battery

Post by geoberni »

So 2 issues here, the actual reason for the battery drain and what to do with the battery.

Finding the drain should be easy enough on a 70s Escort (for someone who knows what they are doing with auto-electrics), depending on what extras have been fitted.

But as to the 'completely drained' battery aspect....
Many new batteries will not be accepted for warranty action if they have been discharged below 10.6v.
Here's some data I lifted from a Battery retailer's website. Note the difference between 10% and 0% charge in terms of voltage.

Convention battery state of charge
Level - Volts
100% - 12.73V
90% - 12.62V
80% - 12.50V
70% - 12.37V
60% - 12.24V
50% - 12.10V
40% - 11.96V
30% - 11.81V
20% - 11.66V
10% - 11.51V
0% - 10.5V

So really depends on how drained it is....

I had to replace my caravan leisure battery last year because it was boiling when charging. I'm assuming some plates had been damaged/shorted when charging it from too low a discharge after being left over the winter without any attention. As with modern cars, there is a low discharge all the time.
As I'm lucky enough to be able to store the 'van at home, I now put power onto it every month for a day, just to maintain the charge state.
Basil the 1955 series II

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les
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Re: Dead battery

Post by les »

Thanks for your post and the figures, I’m inclined to think my friend will enlist the assistance of an auto electrician with the drain issue, I’m more inclined to fiddle with these things first but as mentioned I’m not really at liberty to travel 40 miles to take a look, not that I’d necessarily solve it. I’ll suggest previous advice regarding the first ‘dead’ battery. Hopefully I’ll be able to relay the answer at some point.

oliver90owner
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Re: Dead battery

Post by oliver90owner »

As I recall Ford plumbed the alternator straight to the battery. Do check there is no leakage through the alternator, not just the earth lead, if that is the case. I have found this on a couple of alternators in the past.

The alternator should charge at over 14V (typically 14.4V, max 14.6V) once off idle (with a well charged battery). It could be down on one phase. Rectifier packs are a cheap and easy fix if it is.
les
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Re: Dead battery

Post by les »

I’m not familiar with the Ford circuitry but nonetheless thanks for the alternator suggestion, it’s certainly worth consideration. I’m hoping for an update soon, and will pass that possibility on to him.

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