Battery woes

[Martin Butler]

Hi, , everyone, somethings gone wrong on my car, went out Wednesday to find my battery flat, so i have a fully charged spare, fitted it Friday morning, did one run, to the supermarket, and, i find this morning , its flat again, no lights ,or anything left on, so there should have been minimal drain, the first battery is only a month old, the spare is the one i took off about 3 years old, i have checked all earths and their all clean and tight, any ideas what could drain the battery so fast, Also when i fitted the other battery, normally the engine fires straight up, but this time, it spun over a couple of times before it fired,

[xsport]

Is the alternator charging martin ?

[SD1too]

For how long had your spare battery been standing since it was fully charged? As you probably know, a car battery will slowly discharge itself even when not connected to anything. Your report that the engine didn't fire immediately suggests that your spare was, in fact, partially discharged.

Regarding the first battery being only a month old, did you charge it immediately after delivery? And what use has it had since then? If it's been starting the engine frequently without being taken on a long run, that could be the explanation.

Simon

[Martin Butler]

Originally Posted by xsport

Is the alternator charging martin ?

Thats the first thing i thought, so when i swopped batteries today, i put the new battery on, fully charged up, used my tester on it, and the alternator is pumping out at a healthy rate, i made sure the terminals were tight, because i noticed they were not fully tightening down on the old battery, i had to seat the clamps down fully, and now they are fully down, and tight. i will test again tomorrow to see what voltage drain there has been,

[Martin Butler]

Originally Posted by SD1too

For how long had your spare battery been standing since it was fully charged? As you probably know, a car battery will slowly discharge itself even when not connected to anything. Your report that the engine didn't fire immediately suggests that your spare was, in fact, partially discharged.

Regarding the first battery being only a month old, did you charge it immediately after delivery? And what use has it had since then? If it's been starting the engine frequently without being taken on a long run, that could be the explanation.

Simon

Yes i put it on charge as soon as i got it, it was only about 50 per cent charged, the old one i charged up two days before it was needed, The tester shows no weak cells, but at about 3 might even be older years, it was on the car when i bought it, it might be coming towards the end of its life, batteries do start to fail at about 4 years

[bl52krz]

The battery on my car was 11 years old when it packed up overnight.

[SD1too]

Thanks for the helpful information Martin.

Originally Posted by Martin Butler

Yes i put it on charge as soon as i got it, it was only about 50 per cent charged ...

It's not good that you were sold a new battery at only 50% charged. Out of interest, how did you determine that figure given that specific gravity readings can no longer be taken?

Originally Posted by Martin Butler

... the old one i charged up two days before it was needed ...

Hmmm, the crucial question is what was its condition before you charged it? How long ago was the previous charging? Keeping a spare battery sounds fine in theory but it needs to be kept connected permanently to a smart charger to maintain a full charge. Allowing a car battery to cycle between discharge and charge will shorten its life and eventually lead to the situation you've described.

Originally Posted by Martin Butler

... it might be coming towards the end of its life, batteries do start to fail at about 4 years

There's no fixed period Martin; a battery's life depends upon how its been treated. As Dave's post above shows, ten years is possible.

What was the actual charging voltage? You should expect somewhere between 13.2 and 14.5 volts but no more.

Simon

[Martin Butler]

Used the car this morning, and tested it when i got back, with everything on, the voltage read 14.5 checked the battery with everything turned off, and it was still reading fully charged, so no noticeable drop over 24 hours, i cleaned all the contact switches, bonnet, boot rechecked in the boot, nothing has power when the key is out, i will see again tomorrow,

[Martin Butler]

tried it this morning, and yes, it's flat again, ok, so what systems are live when the car is locked, I'm assuming central locking, alarm, lights, internal and external, anything else?
clearly i have a drain, seems to not be noticeable up to 24 hours, then from 24-48 it drains the battery, i can rule out earth leads, i have checked them, external lights, including boot, go out when the plunger is pushed, i do have a boot mounted sat nav, but its shut down, and not used, does anyone have any clues, what ever it is clearly is a problem, for the time being, i'm going to have to leave the battery clamps off overnight, and reconect when i need the car, when i got this new battery, i charged it up fully, because it wasn't fully charged, left it for 2 weeks before fitting it, checking the voltage, because there had been a number of bad reviews posted on line about this company, and the battery appeared to not drop voltage , other than what might be expected,

[SD1too]

Originally Posted by Martin Butler

... clearly i have a drain ...

Morning Martin,

My feeling is that we need to do some more tests before being sure of that conclusion. Your new battery might be defective, i.e. not holding charge, since you say it was supplied partially discharged.

1. To prove that you have a fault causing continuous drain, disconnect the negative battery cable.

2. Now select the 10 amp DC current range on your multimeter and place it in series with the battery's negative connection to the car body (red probe to the disconnected cable and black probe to the negative battery post).

3. Note the readings every ten minutes over a period of forty minutes. Initially the current will be quite high (up to about 2 amps) but should fall quickly to about 0.1 amps (100 mA). When it does, change the meter range to 200 mA for easier reading.

4. After 20 to 30 minutes you should be seeing about 35 mA (official figure between 30 and 45 mA).

Simon