Car battery failure in a year

rodders · 24 Nov 2017 at 18:48

When I bought a second hand Cmax, Ford replaced the battery as the previous one was faulty.
When I arrived home, I checked it and the voltage stabilised around 12.65, not too bad, but I thought it would be higher, perhaps around 12.8 for a brand new battery?

One year on, the missus said it struggled to start, checked the voltage, 12.25v and today 12.17v

Just charged it, charger said fully charged, checked voltage and it was 12.45v and I sat there for about 1 minute whilst it dropped to 12.31v. I'll see what its like in the morning.

Can I really have killed a battery in 1 year? Missus does use it for short school runs etc... but it normally get a decent drive over the weekend. Or did Ford just fit any old battery they had....

Heisenberg · 24 Nov 2017 at 18:56

12.6v is about right for a fully charged battery. The car shouldn't struggle to start at 12.2 though. Newer cars feature smart charging alternators which only top up the battery when required so a fluctuating measured voltage is normal.

rodders · 24 Nov 2017 at 19:07

OK, I'll keep an eye on it. Don't want to splash out 200quid on a battery for no reason.

Do you think it's odd it was dropping from 12.45 to 12.3 straight off the charger?

adolf hamster · 24 Nov 2017 at 19:15

rodders said:
OK, I'll keep an eye on it. Don't want to splash out 200quid on a battery for no reason.

Do you think it's odd it was dropping from 12.45 to 12.3 straight off the charger?

you spend 200 quid on batteries!? :eek:

andicole0 · 24 Nov 2017 at 19:18

What's the voltage with engine running, might be a dodgy alternator.
Also take a look at the date code on the battery, you may have been given one from another car. New battery usually has at least 3 year warranty.
Andi.

joey1211 · 24 Nov 2017 at 19:19

Just had a new battery fitted, Focus 1.6 for £70. That included the garage coming out to jump start me. I'd shop around if they're asking £200

Orionaut · 24 Nov 2017 at 19:23

Its the voltage under cranking that you reallyneed to know. If you have voltmeter with a Max/Min hold function you can hook it up, start the engine and check to see what the minimum voltage is.

It should not really drop below 10.5 volts under cranking.

If it drops below 10.0 it has definitely had its day.

adolf hamster said:
you spend 200 quid on batteries!?

That isn't too far off the mark If the car has stop/start, but just think of the Jerry cans worth of fuel that you are saving each year for the trifling penalty of having to replace the special, double the standard price, battery every couple of years

Armageus · 24 Nov 2017 at 19:23

joey1211 said:
I'd shop around if they're asking £200

Depends what size engine and what technology battery is needed. The EFB and AGM batteries needed for start/stop systems are more expensive for example.

joey1211 · 24 Nov 2017 at 19:33

Armageus said:
Depends what size engine and what technology battery is needed. The EFB and AGM batteries needed for start/stop systems are more expensive for example.

My dad says that his mate has a bought a stop/start car and the batteries are stupid expensive.

rodders · 24 Nov 2017 at 19:58

Yes, it's start stop, but I never use it. First thing I do is turn it off.
I'll carry out some start voltage tests at work tomorrow.
Didn't know they cost that much when it first went faulty two weeks after buying the car. That's why i was straight back down ford.

adolf hamster · 24 Nov 2017 at 20:03

Orionaut said:
That isn't too far off the mark If the car has stop/start, but just think of the Jerry cans worth of fuel that you are saving each year for the trifling penalty of having to replace the special, double the standard price, battery every couple of years

jesus, if i get less than 4 years out of an £80 battery i feel short changed :eek:

swinnie · 24 Nov 2017 at 20:04

Take a voltage reading as you're cranking the car. If you've got a graphing multi meter even better as it'll be really easy. Wouldn't pay much attention to battery voltage when sitting there but when cranking, and then also when running to see if it is being charged.

rodders · 25 Nov 2017 at 06:52

0 degree C this morning. 12.1v prior to crank 10.44v min on crank.
14.85v whilst running.
Seemed to crank ok

Orionaut · 25 Nov 2017 at 09:10

rodders said:
0 degree C this morning. 12.1v prior to crank 10.44v min on crank.
14.85v whilst running.
Seemed to crank ok

especially Given that it is a chilly morning I would say that was fine.

Of course, the other cause of slow cranking is a dying starter, this is a bit harder to diagnose because you need a high current (500A+) DC clamp ammeter to measure the current reliably and this is a bit specialist.

Bad starting due to starter motor can also be intermittent.

As a rough guide, if it is cranking slowly, and the starter cables are getting warm then it is evidence that you have a starter issue (The warm cables show the battery is delivering lots of power, the slow cranking show that the starter is not making good use of it. Either that, or the engine is siezed

)

rodders · 25 Nov 2017 at 09:45

OK, I'll leave it for now. It's been fine since that one episode the other day.
Once, and if it breaks, I'll know what to fix, lol

Thanks.