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Had problems with my EFB battery again - I’m trying it on a recondition charge but not holding out much hope - so I’m looking at a new battery as my EFB one is over four years old. I’m considering an AGM battery.

 

Does anyone have any recommendations, prices etc and do I need to have the car coded after fitting it?

 

I’m considering a Bosch one but even with discount, at ECP they’re about £270.

 

 

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On 17/05/2020 at 20:47, camelsac2002 said:

 

Had problems with my EFB battery again - I’m trying it on a recondition charge but not holding out much hope - so I’m looking at a new battery as my EFB one is over four years old. I’m considering an AGM battery.

 

Does anyone have any recommendations, prices etc and do I need to have the car coded after fitting it?

 

I’m considering a Bosch one but even with discount, at ECP they’re about £270.

 

TL;DR  Do a proper load test before replacing a battery.  If it is dead, buy a Bosch or Varta AGM battery (they are the same), and code the BCM for the new battery.  Keep an eye on your resting battery voltage, and use a charger to keep it topped up if it is too low.

 

 

I've decided the BCM (Battery Control Module) on these cars is designed to minimise the electrical load on the alternator in an effort to save every last drop of fuel.  IIRC they tend to often only charge the battery when decelerating or something. 

 

I've been regularly checking on my resting battery voltage on my 2017 R wagon, and it is mostly around 12.2 to 12.4V, which is only 50-75% charged (should be closer to 12.6 - 12.7V for a fully charged flooded or EFB battery).  This could explain why batteries in these cars don't last as long as you'd expect.  Fully charged batteries last longer than partially charged batteries, and much longer than flat batteries.  I am now using a CTEK charger every week or so to keep my R battery fully charged.

 

The reason this voltage stuff is relevant when choosing a new battery is that AGM batteries require a higher voltage to charge them fully (but not too high or they will "cook" ).  From my research a fully charged AGM battery at rest should be 12.8+V, and at 12.3V it is only 50% charged.

 

So if you are replacing an EFB battery with an AGM one it is important to tell the BCM so that it can (hopefully) increase the battery voltage to properly charge the new AGM battery.

 

AGM batteries are supposed to be better performing and longer lasting batteries in cars, so probably worth the extra expense if you are going to keep the car for more than 2 years or if you subject it to "harsh" usage (lots of short trips, using lots of electronics, charging phone batteries, running dash cams when parked etc etc)

 

Even if you are replacing the battery with one the same it is a good idea to tell the BCM (eg by changing the serial number) so that it can apply the optimum charging regime for a new battery (which is slightly different to what suits an older battery).  This will help  make the new battery last as long as possible, with less chance of being stranded with a flat battery.

 

Before buying a new battery it is always worth doing a load check to make sure the problem is actually the battery, and not a faulty alternator etc causing the battery to not be fully charged.

 

I hope that helps you (and anyone else considering a new battery)

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The post above is all you need 👍

 

I can recommend Tayna too having bought from them. Do a quick google as there's a 5% discount code out there too.

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3 hours ago, phazer said:

The post above is all you need 👍

 

I can recommend Tayna too having bought from them. Do a quick google as there's a 5% discount code out there too.

Apologies @phazer, I think I May have got the recommendation from one of your posts.  I did not take proper note of the source when Filing away for future reference. Sorry. 

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11 hours ago, NRW said:

Apologies @phazer, I think I May have got the recommendation from one of your posts.  I did not take proper note of the source when Filing away for future reference. Sorry. 

 

No worries dude :) Decent info out there is all any of us want/need.

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Its worth checking ebay too.

Tayna batteries sell on there are keenly priced and give free shipping too.

 

When I upgraded to a Bosch AGM battery a few months ago it was the best price from Tayna's ebay shop. 

 

Coding is simple with vcds or OBDELEVEN. 

 

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Hi, i just had mine replaced, i spoke to 3x independent VW tuners and they all said to use VW Genuine, i did mention about people say Bosch etc etc, they all said good battery's, but issues later down the line - unsure how this is, coz as comments above and on other posts, people say no issues. I just went with an EFB genuine. car's sat now for week n half (starting it today) and sitting on 12.6v 

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1 hour ago, r600_clubsport said:

Hi, i just had mine replaced, i spoke to 3x independent VW tuners and they all said to use VW Genuine, i did mention about people say Bosch etc etc, they all said good battery's, but issues later down the line - unsure how this is, coz as comments above and on other posts, people say no issues. I just went with an EFB genuine. car's sat now for week n half (starting it today) and sitting on 12.6v 


When mine was replaced under warranty back in early 2018 and they put another genuine EFB battery in.  No issues at all with it in last two years and even in lockdown with car sitting idle for long periods at a time, it’s started fine each time.  

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1 hour ago, r600_clubsport said:

Hi, i just had mine replaced, i spoke to 3x independent VW tuners and they all said to use VW Genuine, i did mention about people say Bosch etc etc, they all said good battery's, but issues later down the line - unsure how this is, coz as comments above and on other posts, people say no issues. I just went with an EFB genuine. car's sat now for week n half (starting it today) and sitting on 12.6v 

 

12.6V is good for an EFB that's been sitting for that long  (100% charge for an EFB is 12.6 - 12.7V)

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9 minutes ago, gregozedobe said:

 

12.6V is good for an EFB that's been sitting for that long  (100% charge for an EFB is 12.6 - 12.7V)


yeah it's been sat since last monday (11th), was originally saying 12.8v/12.7v, then since i'd say....Sunday or Saturday it's been sat on 12.6v. I'm just happy now not having to keep charging it every 2 days like i was. I run aftermarket security system as well so it draws abit of power there. When they were coding the battery it was going mental in the workshop haha 

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