Battery struggles to charge on journeys

MrRockliffe · 7 Mar 2020 at 08:33

Hi all

I don’t do too much driving at the moment, and it’s generally shorter journeys to and from shops, however I try to take my car for a good run every 2 weeks to keep the battery charged.

I’ve noticed that for the past few months, even after doing a 2 hour journey, the battery isn’t charging all that much. Stop start will re engage, but only for a handful of times before it doesn’t work again.

I have a low profile aftermarket sub installed, due to rattling door speakers (took some of the load off of them), but it shouldn’t use that much juice. All LED bulbs.

If I charge the battery using a CTEK the charge lasts a lot longer than doing a journey in it.

Car is a 63 plate and original battery I think.

Any ideas? Battery or alternator issue?

vanpeebles · 7 Mar 2020 at 08:37

New battery time.

Finglonga · 7 Mar 2020 at 08:42

New battery time as said, but also turn start/stop off as that is not helping the problem due ti the current draw every time it starts.

Another thing is don't wait too long to get a new one, as modern batteries fail without warning and it could leave you stranded.

Diagro · 7 Mar 2020 at 08:43

An alternator isn't a battery charger.

You need to plug it in to charge now and again

MrRockliffe · 7 Mar 2020 at 10:37

Diagro said:
An alternator isn't a battery charger.

You need to plug it in to charge now and again

My bad! Had it in my head that it was for some reason.... What does charge the battery?

phil-k · 7 Mar 2020 at 10:44

I have read several articles in the past where they say that cars with start/stop technology the battery isn't charged constantly to save on fuel and to make it charge all the time while you are driving you have to put your lights on

andicole0 · 7 Mar 2020 at 10:57

MrRockliffe said:
My bad! Had it in my head that it was for some reason.... What does charge the battery?

The alternator charges the battery, but that isn't it's sole purpose, you shouldn't need to charge a battery externally unless you aren't using the car enough or the battery is dying or the alternator is failing.
Pop onto a battery dealer they will be able to tell you if the battery is close to death as well as analyse the alternator output.
Andi.

bobuk · 7 Mar 2020 at 11:21

I had the same problem, replaced battery and alternator, but after a couple of months another flat battery, just lack of use. A £20.00 battery charger solves the problem, give it a charge every couple of months and all's good.

Nasher · 7 Mar 2020 at 11:24

As above, disable start/stop. It kills batteries are they are much more expensive than normal ones. False economy :/

muon · 7 Mar 2020 at 12:02

phil-k said:
I have read several articles in the past where they say that cars with start/stop technology the battery isn't charged constantly to save on fuel and to make it charge all the time while you are driving you have to put your lights on

Which makes no sense. You can't keep charging a battery. So doesn't really matter when you do it. You might as well keep it topped up at a high %.

Orionaut · 7 Mar 2020 at 13:32

Stop/start sucks!

You are lucky it has lasted this long really.

In most cases it wont even save enough on fuel over the batteries life to pay for the stupidly expensive replacement battery that most people usually need every 3 or 4 years or so.

Like most green concepts, It is bowlocks!

Dandle · 7 Mar 2020 at 16:22

The alternator isn't a very good battery charger, its there to support the electrical loads demanding power at the time rather than charging the battery. It will charge it but not as well as what a dynamo of old would. Get a proper charger and charge the battery up once a year with the that, a good battery will last years then.

MissChief · 7 Mar 2020 at 16:27

2012 Focus, 69k miles, still on original battery. To say stop start kills a battery is materially incorrect. You are right that the saving is pennies over a tank of fuel compared to the cost of a new battery though.

MrRockliffe · 7 Mar 2020 at 16:36

Perhaps I’ll take a look at some new batteries.

Are they easy to replace yourself?

MissChief · 7 Mar 2020 at 16:57

MrRockliffe said:
Perhaps I’ll take a look at some new batteries.

Are they easy to replace yourself?

You can get the battery tested. And also get the output from the alternator checked too.

snapdragon69 · 7 Mar 2020 at 16:57

Most if not all cars with Stop/Start have a battery energy management unit which should have it's parameters reset when a new battery is installed. It has programmed in and learned values such as Ah, capacity-aging, SOC, dynamic charge acceptance and if a new battery is fitted it will work, but will still be operating with outdated values.

jpaul · 7 Mar 2020 at 17:53

MissChief said:
To say stop start kills a battery is materially incorrect.

why do you say that ?
Even if the battery is only used to start a hot engine, some of the heat/chemical degradation cranking current puts on the battery, every time, will diminish its life.
- on a manual car I push the clutch in to minimise the load.
(Were starter motors beefed up , too, when stop/start came in ? ...mild hybrid aren't the starter/hybrid one, so, a new can of worms)

If he's running a significant amp too, that's will drain it, there are some calculations in earlier thread, btdtgp

brendy · 7 Mar 2020 at 17:55

It could also be the colder weather, see if it improves over the next month or two.

MrRockliffe · 7 Mar 2020 at 18:56

brendy said:
It could also be the colder weather, see if it improves over the next month or two.

Been like it since sep at least. I think part of it is that I barely do decent journeys in it though.

MichaelAwkward · 7 Mar 2020 at 19:59

jpaul said:
why do you say that ?

Cars with stop start should have an AGM battery, which work quite differently to normal wet/gel ones.

https://batteryuniversity.com/learn/article/absorbent_glass_mat_agm

That's why they're more expensive. They should last as long as a battery in a non stop start car. Some of the first cars with stop start probably had normal batteries to begin with which has led to this widespread belief that the technology kills batteries but it just isn't the case.