Spoiler

As my battery was dead and sulfated I got it going and fully charged. The only thing I did in the last month was change the Amundsen head unit for an Android from china. I was told that when you put on your battery terminal leads and you clearly hear and see a spark then something is draining the battery.(Is that a fair assumption?) I have disconnected the android unit from the main connection but still getting a spark on that terminal as I connect it. Reading a lot of contributions to this dead battery problem it's annoying that there are quite a few. So Hope for some info how to check what or what could be draining the battery, it's a Bosch from 2022...all the best

 

You will always get a spark when fitting the terminals. If not then the battery is dead.

Cool, thanks for that Blue. Have found earlier questions and answers about checking fuses. I understand one connects meter to positive on battery, so take fuse out and connect other meter cable to fuse connection on car..?

What meter are you referring to?

Sorry , a multimeter measuring amp?

What are you looking for a parasitic drain on the battery?

Well Blue, car was standing for 5 days, it was started to move it to cut grass then started and put back again. Next day couldn't open car changed battery in key still wouldn't open so used key and checked battery was at 4 volt. Battery charger showed sulfated battery. Started with another charged battery then set the two batteries in parallel to charge and no sulfated lamp came on so charged the battery. So why would the original battery lose power overnight? 👍

Could possibly be two things together or separately, something is draining your battery and/or your battery though showing as fully charged is not really fully charged and the charge is only as full as it can get but not fully charged.  If a plate(s) are still sulphated or  perhaps buckled then that will reduce what the battery is capable of.

 

Did you remove the plugs to each of the 6 cells to check the electrolyte "water" levels on each cell and top up as required before charging the battery, did you also check to see if each cell looked buckled or sulphated or just take what a battery charger or tester told you.  Did you take a voltage reading with your multimeter directly on the battery terminals on the battery out of the car or when fitted to the car 24-48 hours after chagrining the battery.  What were the voltage readings immediately after stopping the battery charging and again 24-48 hours later.

 

Just starting the car to move it and back again, to cut the grass, does the battery, the engine and the car no favours at all.

 

It's an AGM battery sealed. 11.9 battery was reading 10 hours later 11.9. was out driving today battery now reading 12.2  so I will wait a day and connect the android unit again...cheers Blue

Did the car have an AGM battery from the factory, if not and it was changed to an AGM was that 'coded' in to the computer?

 

Even allowing for variables 11.9v is low, that is only 30-40% of charge, AGM regularly run at 80% (around 12.v), fully charged is  about 12.7v  or 12.8-12.9v for a new battery.

 

For 12.2v if taken a good few hours after the car was run isn't too bad if also allowing the car's computers and bits and bobs using around 0.2v-0.3v.

 

Also depends on when, how and what was used to take the readings.

 

I'd be replacing the battery before anything else, you can't diagnose modern car properly with a good voltage! You will have all sorts of communication codes, you won't know where to start or start looking at the wrong stuff.

"I'd be replacing the battery before anything else, you can't diagnose modern car properly - without - a good voltage!"

 

(I often put the opposite word by mistake too)

 

The battery needs to be in a good state of charge for diagnostics, particularly for electrical and engine starting problems, but also for the computer stuff that's all over the car.  If the car battery at too lower charge to keep the computer bits happy then you can get all sorts of unexpected warning lights and messages (and unseen error codes) even if the engine starts and the driving lights seem bright enough.

 

You should not need to replace a 2 year old AGM, you might need to if it has been abused by you, the charging system (or computer control of that hence the question about coding) or there a constant drain and you repeatedly let the battery get to, and remain too long at, a state of charge that is too low.

 

Normally I would say recharge the battery (I have recharged batteries at less than 4v a few times) but in this case I think a replacement battery would be a better idea, you need to start with a battery in good state of charge and good state of health before you can probably successfully proceed with the diagnosis of your issue.  If you get a new battery do make sure it is 'coded' in, and all correctly, for this occasion.

 

On 16/07/2024 at 21:04, Blue8793841 said:

I'd be replacing the battery before anything else, you can't diagnose modern car properly with a good voltage! You will have all sorts of communication codes, you won't know where to start or start looking at the wrong stuff.

Now been driving a few days and battery is at 12.4 when I stop, seems to charge better in the car. So I will connect the car media player again. I will look for a new battery. Thanks again for your guidance.

On 16/07/2024 at 22:22, nta16 said:

"I'd be replacing the battery before anything else, you can't diagnose modern car properly - without - a good voltage!"

 

(I often put the opposite word by mistake too)

 

The battery needs to be in a good state of charge for diagnostics, particularly for electrical and engine starting problems, but also for the computer stuff that's all over the car.  If the car battery at too lower charge to keep the computer bits happy then you can get all sorts of unexpected warning lights and messages (and unseen error codes) even if the engine starts and the driving lights seem bright enough.

 

You should not need to replace a 2 year old AGM, you might need to if it has been abused by you, the charging system (or computer control of that hence the question about coding) or there a constant drain and you repeatedly let the battery get to, and remain too long at, a state of charge that is too low.

 

Normally I would say recharge the battery (I have recharged batteries at less than 4v a few times) but in this case I think a replacement battery would be a better idea, you need to start with a battery in good state of charge and good state of health before you can probably successfully proceed with the diagnosis of your issue.  If you get a new battery do make sure it is 'coded' in, and all correctly, for this occasion.

 

Thanks for your assistance Nta16...👍

2 hours ago, Bigdin said:

seems to charge better in the car.

That shouldn't be so as there are competing elements when you are driving but it may well charge faster.  12.4v is fine for an AGM battery but again it depends on when, how and where you took the reading.

 

Also depends on how reliable and accurate your battery charger is in telling you the battery was sulphated.

 

I think I would take a reading with a multimeter on the battery posts immediately before fitting media player and soon after fitting with the media player off and then take readings off relevant, or better still all, fuses.

 

Good luck, let us know how you get on.

 

On 18/07/2024 at 10:05, nta16 said:

That shouldn't be so as there are competing elements when you are driving but it may well charge faster.  12.4v is fine for an AGM battery but again it depends on when, how and where you took the reading.

 

Also depends on how reliable and accurate your battery charger is in telling you the battery was sulphated.

 

I think I would take a reading with a multimeter on the battery posts immediately before fitting media player and soon after fitting with the media player off and then take readings off relevant, or better still all, fuses.

 

Good luck, let us know how you get on.

 

Thanks Nta,  how would you precisely read fuses with a multimeter? 

As an aside, I think one of these might help a little, if you regularly leave your car undriven.

I've had one for a whole and I've just bought a second one for the wife's car, so I don't have to keep swapping it over.

It doesn't charge much, but it does mitigate the little parasitic drain of the various little gizmos on the car, such as alarm, clock, sensor for remote opening, etc. (Not to mention the parking camera on my car.)

Some people have not been satisfied with their "charger", but I expect they over-estimated how much current it puts out. (Not very much at all.)

I think it's a useful product if you leave your car standing unused for long periods. I think my AGM battery is a bit feeble, so I'm happy to give it a helping nudge.

5 hours ago, Bigdin said:

Thanks Nta,  how would you precisely read fuses with a multimeter? 

I take it you mean test the fuses with a multimeter for parasitic drain rather than testing the fuses for any fails.  There will be lots of videos showing you how to do this, and testing for fails, the video below is just the first example I found, it is in American English, I do not know if it will offer you subtitles in your language.

 

If you are disconnecting the car battery to test read the battery then do first read the Owner's Manual for your car to see what might be needed to be reset after reconnection of the battery, often it is not all that is listed but that depends on model and year of car, I find fully closing (not locking) all doors, windows, and sliding roof if fitted, and turning off all electrics that you can reduces the need for some resets but the resets and quick and easy to do (including synchronising the remote key fobs) that I do the them anyway.  Again read the Owner's Manual for how to reset items and synchronise the remote fobs (so easy to do). 

 

Please note I am not an auto-electrician, mechanic or expert in anything, there are other posters much better at such than me and I am more used to cars made in the 1960s and 1970s which are much simpler electrics (and no electronics at all as standard) but the basic principles remain the same.

 

HTH.  If not I know a straightforward video of testing for fuse fails. 

 

 

 

Sorry, I have just noticed a typo I can not edit now

 

AGM batteries when 'coded' correctly on the VW cars regularly run at 80% charge which is around 12.4 v - (not 12.v as in previous post).

 

So NTA16, car standing for 5 days and battery reads 12.2v which is a good sign. No starting problem. Thanks for you link and assistance appreciated. Yes I have a Austin A35 from 56...not much goes wrong there.

Thanks Enter name for your input. I will now connect my Android player unit.... 👍👍

1 hour ago, Bigdin said:

So NTA16, car standing for 5 days and battery reads 12.2v which is a good sign. No starting problem.

12.2v might be better but not necessarily good, depends how high the battery was before the 5 days [ just seen it was 12.2v so that might mean it's holding charge, depends if the car was driven and/or battery charged after the 12.v reading but 12.2 isn't a great reading. ]  When I suggest fully charged for the battery I mean 100% not the 80% (which may or may not be OK for your car's driving cycles).  You can have the engine start easily and the battery still be in too lower state of charge for the car's computer systems.

 

The A35 is the opposite with the battery causing starting issues and lights dimmer when the battery is low.  Until two years ago for 16 years my everyday, one and only, car was a 1973 MG Midget with 1275cc A-series and only just young enough for an alternator instead of dynamo (lift bonnet to turn heater on, tap on cylinder head, no remote cable controls at all),  Same front wheel bearings set up as A30/35 too, because of problems of getting those correct bearing sets now I built up a little library of Austin of the period Technical Bulletin Sheets or whatever they were called and old Lucas catalogues.  Lucas parts were generally so well made that some are still working 50, 60, 70 years later.

 

Back to your battery I would fully charge it or replace it at 12.2 after 5 days.  Yesterday as I was checking a neighbour's car I checked the 3 year old AGM battery on my wife's car, not driven since the afternoon before, unlocked windows down all morning, 12.56v and the weather has been hot (battery discharges itself twice as much at 30c as 40c, and twice as much at 40c to 30c) so air-con has been used and my wife's car does lots of short journeys (2 miles), I can't remember if I've used an appropriate battery charger to fully recharge that battery once twice since Xmas 2023.

 

You also need to check for parasitic draw(s).

 

I don't know if you have seen this but if not you might enjoy it, funny to see the carefree overtaking, be different on that road now. - In Colour! - THE AUSTIN A35 - MAKING THE MOST OF IT - PATHE NEWS 1956 - https://www.youtube.com/watch?v=peF3kwFL_Qw

 

Edited 22 July, 20241 yr by nta16
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