Charging BMW 8yr old Agm battery

Nel2014 · 10-06-2019, 02:08 PM

Hi,

I replaced my Bmw battery about 1 year ago as I was getting the battery light on my car and it was shutting down the welcome lights and heaters / rear defrosters. I replaced it with an Exide Agm battery with similar specs. Since replacing it my start stop has never worked properly. One year later the car struggles to start especially when I have not used it for a couple of days.

So I bought a smart charger and haves used that it seems to last for a good month before I need to charge it again.

I decided to try and charge my bmw battery that has been off the car for a year.When I plugged in my smart charger it showed 14.5v and had 95% charge. I have kept in charging overnight for 11 hours and now fully charge.

I am wondering whether it is worth installing back in the car and trying the original battery again?

I took some photos below

Chappers 71 · 10-06-2019, 04:03 PM

Did you register/code the battery when you changed it?

Nel2014 · 10-06-2019, 04:20 PM

Yeah I registered it using carly

rasa bmw · 10-07-2019, 01:30 AM

and was it deffo the same exact spec battery,,as it will need coding also,,also check alternator,,been a few threads lately on different forums about them not functioning properly

Nel2014 · 10-07-2019, 07:33 AM

My old battery has been on charge for 20 hrs now and still saying 95% charged ans 14.5v. I think i said it took 11 hours to fully charge - my mistake.

The charger stills says its charging and hasnt come up with any errors. Should I just carry on for another 4-5 hrs or assume the battery is no good after that if no change.

therealdb1 · 10-08-2019, 06:53 PM

What is the charge rate?

From the photo you appear to be charging a 90 Ah battery with an 8 A charger so even if the battery was completely flat it should be fully charged in 11.25 hours.

However, real world, the battery would not be completely flat and it is unlikely that your charger can supply 8 A indefinitely but you would still expect it to be fully charged after 20 hours.

Having said that, it is an old battery and you have left it standing for a year which car batteries do not appreciate so it is unlikely that it will ever now reach 100% capacity.

What you have is about as good as it will get. Whether or not that is sufficient to use on a car you can only test under load but my guess would be since you have already replaced the battery, and it sounds like you do not drive enough to keep the one on the car charged without a bit of assistance now and again, the old one will not be any better but more likely worse.

arkie6 · 10-08-2019, 09:32 PM

You likely have shorted internal plates in that battery is why the charger is never reaching 100% charged. The charger uses the charging current to determine state of charge. As the battery approaches full charged, the charging current drops off to a very low value. Apparently, your charging current is not dropping off to a very low value or your charger has a malfunction. You can take the battery to AutoZone or Wal-Mart and they will test it and tell you what the condition/capacity is.

therealdb1 · 10-09-2019, 04:55 AM

Quote:

Originally Posted by arkie6

You can take the battery to AutoZone or Wal-Mart and they will test it and tell you what the condition/capacity is.

Not in Bedfordshire, UK he can't but I agree with you the battery capacity is down and will not recover.

They do not last forever.

arkie6 · 10-09-2019, 01:20 PM

Quote:

Originally Posted by therealdb1

Not in Bedfordshire, UK he can't but I agree with you the battery capacity is down and will not recover.

Yeah, I missed that this was a UK thread. Do auto parts stores in the UK that sell batteries also test batteries for free?

arkie6 · 10-09-2019, 01:22 PM

I see that charger has the capability to display the Amps (A). What is the charging current A when the % charged is indicating 95?

therealdb1 · 10-09-2019, 06:51 PM

Quote:

Originally Posted by arkie6

Yeah, I missed that this was a UK thread. Do auto parts stores in the UK that sell batteries also test batteries for free?

Some do it depends how much they want to sell you a battery but I wouldn't say it is commonplace around where I live but they have not even discovered motorways (freeways) in my county!

Nel2014 · 10-10-2019, 12:36 PM

Thanks for all the replies. After 24hrs still showing 95% charged i gave up. I think it was showing 0.6 amps so not really much amps going to it.
Have given up on the idea of putting the old battery back in my car.
Have looked online for so 2nd hand ones from cars that are be broken up for spares but they all seem to have slightly different part numbers. Probably not a good idea anyway if they have been sitting for a while.

therealdb1 · 10-10-2019, 04:32 PM

Wouldn't even consider a second hand battery for an E9x!
A duff battery can cause all sorts of odd issues on these cars so the last thing you need is to fit a battery that you know nothing about and hope.

Think at this point I would ditch the old battery and go back into the car with Carly or whatever and double check your battery settings for the one you are using.

Once this is confirmed as ok then you need to check that the car is properly charging the battery with the alternator running and then assuming that is ok check to see what the discharge from the battery is when the car is left to stand.

These vehicles have all sorts of circuits still active when you think you have shut it down and maybe one is drawing a bit too much current.

It could, of course, be that your 1 year old battery is not up to scratch and if this is the case I would return to the seller for a guarantee replacement.

Nel2014 · 10-11-2019, 10:34 AM

The seller wants to see a print out of the batterys health from kwik fit or simarlar. The thing is when i drive the car over a certain distance it charges the battery. When I do something like plug in carly and do a fault scan or have the radio on for 5 mins with the engine off the battery will stuggle to start.

therealdb1 · 10-11-2019, 04:13 PM

If it cannot run the radio for 5 minutes without being on charge the battery is knackered or is not being charged.

Take it to a decent battery supplier for a capacity check and they will be able to tell you which of the two it is.

Don't worry about driving the car there as they should test it under load and from what you are saying it will not take long to reach the conclusion it is down on capacity.

If they are an Exide dealer they may be able to arrange a guarantee replacement for you since it is over a year old now. Otherwise get them to give you some paperwork to take to the original supplier.

10-06-2019, 02:08 PM	#1
Nel2014 Banned 22 Rep 260 Posts Drives: BMW 320d Join Date: Dec 2014 Location: Bedfordshire iTrader: (0)	Charging BMW 8yr old Agm battery Hi, I replaced my Bmw battery about 1 year ago as I was getting the battery light on my car and it was shutting down the welcome lights and heaters / rear defrosters. I replaced it with an Exide Agm battery with similar specs. Since replacing it my start stop has never worked properly. One year later the car struggles to start especially when I have not used it for a couple of days. So I bought a smart charger and haves used that it seems to last for a good month before I need to charge it again. I decided to try and charge my bmw battery that has been off the car for a year.When I plugged in my smart charger it showed 14.5v and had 95% charge. I have kept in charging overnight for 11 hours and now fully charge. I am wondering whether it is worth installing back in the car and trying the original battery again? I took some photos below
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10-06-2019, 04:03 PM	#2
Chappers 71 Major General 5480 Rep 5,427 Posts Drives: Beige G31 40ix m sport Join Date: Feb 2016 Location: Kent, The Garden of England iTrader: (0) Garage List 2018 G31 xdrive 40i ... [4.00] 2006 E92 335i SE [9.50]	Did you register/code the battery when you changed it? __________________ G31 40ix M Sport E92 335i. E36 328is coupe E39 540i V8 6SP manual E34 3.6 M5. E34 525i sport. VW Jetta Mk2 GTI 16v. 1679cc 1967 resto-cal beetle
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10-06-2019, 04:20 PM	#3
Nel2014 Banned 22 Rep 260 Posts Drives: BMW 320d Join Date: Dec 2014 Location: Bedfordshire iTrader: (0)	Yeah I registered it using carly
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10-07-2019, 01:30 AM	#4
rasa bmw Colonel 243 Rep 2,026 Posts Drives: 640d sport/f31 330d x drive Join Date: Jul 2017 Location: northumberland iTrader: (0)	and was it deffo the same exact spec battery,,as it will need coding also,,also check alternator,,been a few threads lately on different forums about them not functioning properly
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10-07-2019, 07:33 AM	#5
Nel2014 Banned 22 Rep 260 Posts Drives: BMW 320d Join Date: Dec 2014 Location: Bedfordshire iTrader: (0)	My old battery has been on charge for 20 hrs now and still saying 95% charged ans 14.5v. I think i said it took 11 hours to fully charge - my mistake. The charger stills says its charging and hasnt come up with any errors. Should I just carry on for another 4-5 hrs or assume the battery is no good after that if no change.
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10-08-2019, 06:53 PM	#6
therealdb1 Lieutenant 106 Rep 576 Posts Drives: Graphite E93 335i Join Date: Aug 2017 Location: Norfolk UK iTrader: (0)	What is the charge rate? From the photo you appear to be charging a 90 Ah battery with an 8 A charger so even if the battery was completely flat it should be fully charged in 11.25 hours. However, real world, the battery would not be completely flat and it is unlikely that your charger can supply 8 A indefinitely but you would still expect it to be fully charged after 20 hours. Having said that, it is an old battery and you have left it standing for a year which car batteries do not appreciate so it is unlikely that it will ever now reach 100% capacity. What you have is about as good as it will get. Whether or not that is sufficient to use on a car you can only test under load but my guess would be since you have already replaced the battery, and it sounds like you do not drive enough to keep the one on the car charged without a bit of assistance now and again, the old one will not be any better but more likely worse.
	Appreciate 0 Quote

10-08-2019, 09:32 PM	#7
arkie6 Lieutenant 397 Rep 433 Posts Drives: 2008 BMW 335i sedan Join Date: Aug 2014 Location: Russellville, AR iTrader: (0) Garage List 2008 BMW 335i [0.00]	You likely have shorted internal plates in that battery is why the charger is never reaching 100% charged. The charger uses the charging current to determine state of charge. As the battery approaches full charged, the charging current drops off to a very low value. Apparently, your charging current is not dropping off to a very low value or your charger has a malfunction. You can take the battery to AutoZone or Wal-Mart and they will test it and tell you what the condition/capacity is.
	Appreciate 0 Quote

10-09-2019, 01:22 PM	#10
arkie6 Lieutenant 397 Rep 433 Posts Drives: 2008 BMW 335i sedan Join Date: Aug 2014 Location: Russellville, AR iTrader: (0) Garage List 2008 BMW 335i [0.00]	I see that charger has the capability to display the Amps (A). What is the charging current A when the % charged is indicating 95?
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10-10-2019, 12:36 PM	#12
Nel2014 Banned 22 Rep 260 Posts Drives: BMW 320d Join Date: Dec 2014 Location: Bedfordshire iTrader: (0)	Thanks for all the replies. After 24hrs still showing 95% charged i gave up. I think it was showing 0.6 amps so not really much amps going to it. Have given up on the idea of putting the old battery back in my car. Have looked online for so 2nd hand ones from cars that are be broken up for spares but they all seem to have slightly different part numbers. Probably not a good idea anyway if they have been sitting for a while.
	Appreciate 0 Quote

10-10-2019, 04:32 PM	#13
therealdb1 Lieutenant 106 Rep 576 Posts Drives: Graphite E93 335i Join Date: Aug 2017 Location: Norfolk UK iTrader: (0)	Wouldn't even consider a second hand battery for an E9x! A duff battery can cause all sorts of odd issues on these cars so the last thing you need is to fit a battery that you know nothing about and hope. Think at this point I would ditch the old battery and go back into the car with Carly or whatever and double check your battery settings for the one you are using. Once this is confirmed as ok then you need to check that the car is properly charging the battery with the alternator running and then assuming that is ok check to see what the discharge from the battery is when the car is left to stand. These vehicles have all sorts of circuits still active when you think you have shut it down and maybe one is drawing a bit too much current. It could, of course, be that your 1 year old battery is not up to scratch and if this is the case I would return to the seller for a guarantee replacement.
	Appreciate 0 Quote

10-11-2019, 10:34 AM	#14
Nel2014 Banned 22 Rep 260 Posts Drives: BMW 320d Join Date: Dec 2014 Location: Bedfordshire iTrader: (0)	The seller wants to see a print out of the batterys health from kwik fit or simarlar. The thing is when i drive the car over a certain distance it charges the battery. When I do something like plug in carly and do a fault scan or have the radio on for 5 mins with the engine off the battery will stuggle to start.
	Appreciate 0 Quote

10-11-2019, 04:13 PM	#15
therealdb1 Lieutenant 106 Rep 576 Posts Drives: Graphite E93 335i Join Date: Aug 2017 Location: Norfolk UK iTrader: (0)	If it cannot run the radio for 5 minutes without being on charge the battery is knackered or is not being charged. Take it to a decent battery supplier for a capacity check and they will be able to tell you which of the two it is. Don't worry about driving the car there as they should test it under load and from what you are saying it will not take long to reach the conclusion it is down on capacity. If they are an Exide dealer they may be able to arrange a guarantee replacement for you since it is over a year old now. Otherwise get them to give you some paperwork to take to the original supplier.
	Appreciate 0 Quote