Cause of sudden flat battery

[littlespark]

My eldest girl has a 10 plate Kia picanto. Bought for her by her grandparents, and she was supposed to be taking it away today, up to Aberdeen to move into her new flat.
During lockdown, it hasn’t been used all that much, but it has been used.
A few weeks ago, I swapped out the radio for a cheap Chinese thing with a screen, and Bluetooth.
Last week, I replaced both sidelight bulbs, and yesterday one of the rear wheels was jammed on by the handbrake.
Today. Two cars packed with all her stuff, first the doors wouldn’t open with central locking, then the ignition did absolutely nothing. Checked the battery.... 2.5 volts!

I don’t want to just charge it up, take it up to her and for it to drain again.
I was wondering if replacing the bulbs had caused a leak through to earth.(if there was already a problem with the switch? Can’t see it, as the lights are only powered through ignition)
I thought it might have been the radio? As it needs a perm 12v to keep the memory (I had to swap the 12v and aux 12v in the loom to get it to work properly) But that was fitted weeks ago, the problem would have appeared before now.

 

[David Prosser]

Most likely the battery is just expired. If it's not been replaced in the life of the car it may well of been on it's way out for a while and the recent reduction in use has just accelerated if final demise.

If it was me I'd try a new battery first.

 

[R-fur]

I would measure the drain by sticking an ammeter in the battery lead then disconnect things to narrow it down.

 

[static zap]

Don't know my picantos
(if its been parked anywhere different)
check for soggy carpets .before it has a chance to dry out.
(Some recent rain was a bit exceptional)
.. Is radio intuitive to use ..or has volume been wound down
and forgotten if not always auto "off"ed .
-- events like this will help finish off an aged battery-- (if no obvious drain)
..or just lighter use as others have mentioned..

 

[littlespark]

The radio is simple enough, and the installation instructions were clear enough to know what was 12v and what was aux.
The socket in the car was right shape, apart from these 2 being wrong way round, and a + on the line that was supposed to be reversing signal (flicked between radio and reversing camera screen all the time)
The Clock and tuner memory’s were forgotten when I turned ignition off, so I knew they were wired wrong way.

up until yesterday, it drove fine. Took it for a fill up, checked the tyres.... she even washed it. I checked, the battery isn’t wet.
A neighbour has a battery charger, so I’ve got it charging just now.... I’ll put it back in the car tomorrow and give it a run.

 

[DPG]

Worth checking the charging voltage from the alternator is high enough also.

 

[littlespark]

I’ll do that when I get the engine running again.


I wish I lived on a hill, then I could have bumped it....

I wish there was more space under the bonnet of that thing.... or I had smaller hands

 

[static zap]

(Just washed ..... )
Wash n waxed -fan belt !
The charge voltage /and same with blowers + headlights

 

[plugsandsparks]

mmm 2.5V , i would be first thinking drain. When its charged up again, see if there are any interia lights on. Most modern cars have PDU's which either time out or drop out if battery gets too low. My car for example has a PDU , even the radio will drop out if left on too long BUT one or two interia lights stay on all the time. These switches i can easily accidently catch when loading up to the gills.

 

[pc1966]

Most likely the new radio. Charge the battery and measure the standing current (as much doors, etc, closed to avoid interior lamps being on, etc).

While it could be the battery (if over 5-7 years old typically), a mate of mine once went on a 2 week holiday and on his return could not start his car at the long-stay car park, turned out the radio was drawing something like 200mA when off FFS! His 40Ah battery would have lasted less than 10 days off charge.

 

[Let me think]

Had similar issue with wife's car last month (also 10yrs old). Refused to start one day hadn't been run in about a week with a few cold nights thrown into the mix ~10V. Jumped started it. Checked alternator output, all looking good. After about 30mins running. Had her restart car, everything appeared fine, until she tried to start it the following day, same problem.

Jumped it again, started fine after she came back from a long run. Voltages looked good, checked to make sure no lights etc had been lift on. Later that day car won't start again. voltage ~9V.

With age of battery and voltage dropping, decided to bite the bullet and treat her to a new one. Had concerned try to recondition, but to risky as far as I was concerned.

Only place I could find that would accept my order and deliver to Scottish islands was Halford's. Only for them ~1 week (on date when battery was due to arrive) to cancel order as their courier won't deliver to the islands. Would have been good to know at the time....saved a lot of hassle.....arrggg

Turns out island filling station did have one in stock (which I though would have cost and arm and a leg, was actually cheaper than Halfords - which I couldn't believe). Car now sorted and working fine. Happy wife!!!

Hopefully you get daughter cars up and running again soon.

 

[littlespark]

Had the battery on a charger last night. Turned it off at midnight, voltage was about 13.5v (just off my multimeter) Still the same this morning.
Put the battery back on the car, checked standing current (again, just my multimeter) and it read .5A. Sounds a lot, but i wouldnt think my MM is very accurate.
Started engine fine, checked voltage, getting 15v which will be right coming from alternator.

I took it for a short run along to local garage to price a new battery (£50 ish) and brought it back. I'll leave it a couple of days and see if the voltage drops again.

Thinking it could be cheaper me driving it up to aberdeen and coming back on the train rather than my wife bringing another car, with kids and dog after ive just took her up in the big car yesterday with all her stuff

 

[DPG]

Make sure you check the quiescent current drain after everything has shut down. May take over ten minutes on a modern car.

Assuming the drain is ok, I would definitely recommend a new battery. A decent brand one.

 

[G1ZQC_David]

Other than checking all of the above, it may be the battery, (this needs proving), they can die suddenly, through Sulfation if left flat for a prolonged period.

 

[UNG]

What date is on the battery label always a good indication of the age of the battery if it is more than 5 - 6 years old get a new battery before it kills the alternator and becomes even more expensive to fix

 

[G1ZQC_David]

Your garage should test it for you, by applying
known load, and monitor the voltage drop.

 

[James]

I have found that the first time your car fails to start or is turning over slow in winter,
change the battery if it is more than 5 years old.

testing them costs more in time and money than replacing the dam thing, especialy if over 5 years because the best your likley to get is another 6 to 12 months anyway.

 

[littlespark]

I think the overall concensus is get a new one. Fair enough
I don't want to take the car up, just for her to ring in a months time to say its failed to start

 

[Jim_e_Jib]

I think the overall concensus is get a new one. Fair enough
I don't want to take the car up, just for her to ring in a months time to say its failed to start

If the battery voltage has dropped to 2.5v it will likely have been damaged as lead acid batteries don't like to be discharged too deeply.

As DPG suggested, it would be worth checking the quiescent current once everything has had time to power down and before you put the new battery in. I'm sure your multimeter is accurate enough to measure something of the order of half an amp and that is a very high drain-I'd be expecting less than a tenth of that.

If the reversing camera is new as part of the radio system, is that powering down properly?

 

[pc1966]

I'm sure your multimeter is accurate enough to measure something of the order of half an amp and that is a very high drain-I'd be expecting less than a tenth of that.

Try on high-current (e.g. 10A range) first, or only if you can, otherwise you might find it pops the fast-fuse for a lower current range with something surging on switch on (like a light bulb, or charging some electronics's input smoothing capacitors.