[CP911]

Originally Posted by Cumberlandjames

There are so many things that impact battery charging, the type of charger, battery condition. age and temperature to list a few. Looking at the CTEK charger I see it uses very small gauge leads. This in indicates that it does not produce much current and therefore will take a longer time to recover a discharged battery. It appears to be more of a "tender" that applies a trickle charge during store to keep the charge up rather than a "charger" used to actually recharge batteries such as a shop would use.
After such a long trip the battery should have been fully charged so if it was not you best have a dealer do a proper capacity test on on it. This is where you apply a specified load to it and allow it to discharge to an end point voltage and it must last a certain time or be replaced.
The other thing to consider is the car's charging system. Have a qualified technician check out the car before you get stuck somewhere.

The BMW/CTEK charger is both a charger and a tender. It uses 4.3A to charge lead-acid/wet batteries. Sure, a stronger current can probably be used to speed things up, but batteries of all types typically have a threshold for safe charging current where going above the threshold could further degrade battery performance/life over time. It is also a tender that will monitor voltage and trickle charge back up to full once the battery level drops down a certain amount. My understanding is that the CTEK charger is a high-quality unit for home use and OEM for several luxury car brands' chargers, such as BMW and Maserati, for example.

Also, I'm not so sure a long road trip would necessarily mean it should've been charged. It was stopped and started a few times (uses a lot of current/power) during the road trip, music was thumping away, and heat was most definitely on since it was 11 degrees outside. I'm thinking I was using a lot of juice and the alternator could only do so much. Could be wrong though. I'm not really concerned about having a charging system problem at this time. Will definitely keep an eye on things and take note of how long the battery takes to top off next time around in 1-2 months from now when I hook it back up to the charger.

[CP911]

Originally Posted by TajoMan

Also, the other main advantage is that it can be charged very quickly.
Since the internal resistance is so low, there is not much heat generated when the battery gets charged quickly with a lot of current.
That's why it is being used in conjunction with regenerative braking.
It cab be charged quickly during short deceleration.
Once the car starts, the battery gets charged up quickly.

Originally Posted by XutvJet

2) Our cars run higher quality (and expensive) AGM lead-acid batteries due to the heavy electricity draw. These batteries are good, but take some time to fully charge. In cold weather, they can take a long time to charge and if you're only driving 10 to 30 mile trips in really cold weather, the battery charging system likely can't keep up.

Conflicting statements here. Which is it?

[CP911]

Originally Posted by XutvJet

3) BMW makes the charging system such that the battery only charges up to 80-85%. The reason being AGM batteries can be wrecked if overcharged. Also, undercharging greatly reduces their life.

This is interesting. The BMW/CTEK charger manual states to make sure that you are in the correct mode i.e. AGM vs. li-ion because one charges to a slightly higher voltage (14.4 vs. 14.3 IIRC?) and could therefore damage the one with the slightly lower voltage. No mention or warning to avoid charging > 80%.

[CP911]

Originally Posted by XutvJet

^From everything I've read on the BMW forums and per the CTEK owner's manual, the only charging setting you should be running on a BMW AGM battery is the cold setting (snowflake symbol). Using any other setting could possibly damage the battery.

FYI - They have updated the modes setting display on the newer chargers. No more snowflake setting. Just car/motorcycle for both AGM and Li-ion battery types:

[TajoMan]

Originally Posted by CP911

Conflicting statements here. Which is it?

Not really.

AGM battery can take (or discharge) a lot of current in short period.
However, it is still lead-acid battery.
It take longer time to charge due to slower chemical reaction in cold weather.

Also, the battery capacity is pretty big for the size of car. So it does take longer to charge (compare to other cars that have smaller capacity battery).

It is faster than regular lead-acid for sure.

If our car uses regular lead-acid battery, it will have a lot shorter battery life.

[Viffermike]

Originally Posted by CP911

FYI - They have updated the modes setting display on the newer chargers. No more snowflake setting. Just car/motorcycle for both AGM and Li-ion battery types:

And no 'Recond' mode, either. Interesting.

[CP911]

Originally Posted by Viffermike

And no 'Recond' mode, either. Interesting.

Yeah... this newest charger is advertised to be intelligent enough to detect condition/health and charge level of the battery and perform whatever type of charging maintenance is necessary to ensure an optimal charge and battery health. It also works with other types of wet/AGM/lead-acid batteries. I used it to charge up my Volvo XC70's battery as well. It had been showing me a low battery warning on the dash randomly since I bought it used about 6 months ago. I don't drive it much and only use it for short trips like running errands or getting groceries, so that is likely why. Now, thanks to the BMW/CTEK charger, there is no more warning on the dash and all is well.

[mecodoug]

My 2006 E90 330i had a significant draw at rest, after a week on a trip once it barely started at the airport (in winter) even though the battery was fairly new. That was not the case on the 2011 335d or the M240i.

But paying the dealer $400 for a battery, even an AGM is insane. Maybe $225 including registration from a decent battery shop. Less if you are like me and have a buddy with a coder. A replacement AGM for the diesel was $192 from Autozone and that was the absolute biggest (1000 CCA) AGM available, significantly better than OEM. Coding is a 5 minute affair if you have the tool.

[wdc330i]

Originally Posted by mecodoug

My 2006 E90 330i had a significant draw at rest, after a week on a trip once it barely started at the airport (in winter) even though the battery was fairly new. That was not the case on the 2011 335d or the M240i.

But paying the dealer $400 for a battery, even an AGM is insane. Maybe $225 including registration from a decent battery shop. Less if you are like me and have a buddy with a coder. A replacement AGM for the diesel was $192 from Autozone and that was the absolute biggest (1000 CCA) AGM available, significantly better than OEM. Coding is a 5 minute affair if you have the tool.

There was a recall on my 2006 M3 for the clutch, which had a parasitic drain on the battery...

Edit: And I'll guess that batteries are more like $600 now at the dealer.

[Maynard]

When I bought my 2016 the dealership was specifically pushing the recommendation to lock the car right after use, even in home garage - this shuts e/t down faster, saves battery drain, prolongs its life (all this per the dealer, so BMW are well aware of it). That said, I probably only do it now and then, and have never seen the low battery warning. My typical winter driving is mainly work commute of about 30min each way, parking outdoors all day, and often no longer trips on weekends; this is also the mildest winter we've had up here in Upstate, so no shortage of super cold temps.

All this makes me wonder if there aren't some bad batteries that got into the supply mix, or if additional features really do make a bigger difference (I don't have heated seats, tech package, or regen-braking). This still has me thinking about a trickle charger, as the thought of a $500+ battery replacement is kind of a drag.

[Elvisfan]

Originally Posted by CP911

The BMW/CTEK charger is both a charger and a tender. It uses 4.3A to charge lead-acid/wet batteries. Sure, a stronger current can probably be used to speed things up, but batteries of all types typically have a threshold for safe charging current where going above the threshold could further degrade battery performance/life over time. It is also a tender that will monitor voltage and trickle charge back up to full once the battery level drops down a certain amount. My understanding is that the CTEK charger is a high-quality unit for home use and OEM for several luxury car brands' chargers, such as BMW and Maserati, for example.

Also, I'm not so sure a long road trip would necessarily mean it should've been charged. It was stopped and started a few times (uses a lot of current/power) during the road trip, music was thumping away, and heat was most definitely on since it was 11 degrees outside. I'm thinking I was using a lot of juice and the alternator could only do so much. Could be wrong though. I'm not really concerned about having a charging system problem at this time. Will definitely keep an eye on things and take note of how long the battery takes to top off next time around in 1-2 months from now when I hook it back up to the charger.

With all due respect,I think you’re paranoid about the battery. Unless you only drive the car rarely and when you do you only take very short trips,there is no reason to top off the battery. To think that BMW would purposely install an alternator that is not capable of keeping the car charged under normal or extreme conditions seems a little strange to me.

[Elvisfan]

Originally Posted by CP911

Yeah... this newest charger is advertised to be intelligent enough to detect condition/health and charge level of the battery and perform whatever type of charging maintenance is necessary to ensure an optimal charge and battery health. It also works with other types of wet/AGM/lead-acid batteries. I used it to charge up my Volvo XC70's battery as well. It had been showing me a low battery warning on the dash randomly since I bought it used about 6 months ago. I don't drive it much and only use it for short trips like running errands or getting groceries, so that is likely why. Now, thanks to the BMW/CTEK charger, there is no more warning on the dash and all is well.

Those short trips could certainly explain the need for a charger. But to think that a 700 mile trip wouldn’t be enough to fully charge the battery because you stopped a couple of times is still too much.