[Billfitz]

Seriously? Pick up your fob. The key is now in your hand.

[donkey]

Originally Posted by Billfitz

Seriously? Pick up your fob. The key is now in your hand.

No thats the fob

[ToniCipriani]

Originally Posted by donkey

No thats the fob

(This needs to be read with Doug DeMuro's voice.)

"Now here's the wierdest quirk of them all. Being a BMW, even this lowly 3-series it's still a BMW, so, it doesn't use a key to lock and unlock your doors. That's so plebian. So instead you TOUCH the door handle to unlock it!!! How cool is that??!!"

"So what happens if your battery runs down, you'd be locked out of the car, right? BMW thought of that so it actually

(presses button and pulls out a key, and shows key in front of camera)



has a KEY INSIDE the fob??!! Now you take that key, and insert it into this hidden keyhole and... there you are, you're in your car."

[Beek]

(This need's to be read with Pee Wee Herman's voice)

LOL ... I knew all about the key in the fob, I even knew where to put it in the steering column to make the car go Vroom. Never dawned on me there might be a place in the door to use it also ... I went and looked ... there is. You all just give me a bit more time and I'll find another way to make an ass out of myself, we all got to do what we're best at right?

[Billfitz]

Originally Posted by donkey

No thats the fob

[DrifterX]

A little while ago, I read a really informative BMW document on how BMW programs battery charging logic in our cars - can't seem to find that document now but the main message was, the alternator doesn't consistently charge the battery like traditional vehicles to help with fuel consumption. You're not going to get much charging in short trips, even though it's super cold out. You won't get much charging even on a long highway drive, mainly because the battery receives full charging only when it's heavily discharged or while engine braking. Cold temperatures don't help on the former case because even if the alternator is engaged most of the time, it will take a while to charge the battery in such cold temperatures. Engine braking is a very good way to charge the battery - but how many people really drive like that with auto? I do it quite often between red lights given I have a manual.

I got this same message for the first time a couple weeks ago when it started getting frigid. I haven't been driving the 340i much lately due to holidays and getting a second car for the longer commutes not too long ago. Even though I drove ~85 hwy kms each day for a couple days and a couple runs around town, I kept getting the message. It wasn't until I idled the car for 10-15 mins when the message finally went away - although it may have been a cumulation of all the driving I was doing.

I thought maybe it had something to do with my hardwired 2 channel dash camera but it's definitely how the vehicle, itself, is managing the charge... it just doesn't give the full charge the battery needs during such cold temperatures. It would rather disable electronics which is a bit annoying.

After reading complaints/feedback from multiple posts in this forum, other articles and that document, a battery tender/charger is a must for BMWs now a days to keep the battery in good shape; especially for cold weather and if you don't drive it everyday like I used to.

[donkey]

Originally Posted by DrifterX

A little while ago, I read a really informative BMW document on how BMW programs battery charging logic in our cars - can't seem to find that document now but the main message was, the alternator doesn't consistently charge the battery like traditional vehicles to help with fuel consumption. You're not going to get much charging in short trips, even though it's super cold out. You won't get much charging even on a long highway drive, mainly because the battery receives full charging only when it's heavily discharged or while engine braking. Cold temperatures don't help on the former case because even if the alternator is engaged most of the time, it will take a while to charge the battery in such cold temperatures. Engine braking is a very good way to charge the battery - but how many people really drive like that with auto? I do it quite often between red lights given I have a manual.

I got this same message for the first time a couple weeks ago when it started getting frigid. I haven't been driving the 340i much lately due to holidays and getting a second car for the longer commutes not too long ago. Even though I drove ~85 hwy kms each day for a couple days and a couple runs around town, I kept getting the message. It wasn't until I idled the car for 10-15 mins when the message finally went away - although it may have been a cumulation of all the driving I was doing.

I thought maybe it had something to do with my hardwired 2 channel dash camera but it's definitely how the vehicle, itself, is managing the charge... it just doesn't give the full charge the battery needs during such cold temperatures. It would rather disable electronics which is a bit annoying.

After reading complaints/feedback from multiple posts in this forum, other articles and that document, a battery tender/charger is a must for BMWs now a days to keep the battery in good shape; especially for cold weather and if you don't drive it everyday like I used to.

I've always been under the impression BMWs charge more when you hit the regular brakes. There's a gauge next to the battery icon under the speedo or tach (i forget which) that fills up when braking, not when engine braking.

My battery has been low all winter, gonna get a trickle charger and if that doesn't help replace the battery

[donkey]

Originally Posted by Billfitz

no way bro

[HighlandPete]

Originally Posted by donkey

I've always been under the impression BMWs charge more when you hit the regular brakes. There's a gauge next to the battery icon under the speedo or tach (i forget which) that fills up when braking, not when engine braking.

My battery has been low all winter, gonna get a trickle charger and if that doesn't help replace the battery

It is not braking in itself that triggers the over-run charging, (harvesting of normally wasted energy), but lifting off the accelerator to zero position.

The more 'time' we can over-run (zero throttle) with the least amount of braking, the more the battery is boosted.

We really need the habit of lifting off completely, rather than just lifting off gradually, even tapping down a gear to increase the engine revs (a bit of engine braking) for extra boost. Also try and avoid early and/or heavy braking.

[HighlandPete]

Originally Posted by DrifterX

After reading complaints/feedback from multiple posts in this forum, other articles and that document, a battery tender/charger is a must for BMWs now a days to keep the battery in good shape; especially for cold weather and if you don't drive it everyday like I used to.

I drive about 8,000 miles a year, pretty much spread out the same week by week, typically used 3 days in a week. Winter time the charge isn't enough to keep the battery topped up. I use a CTEK tender about 3 times a winter, to keep the battery in good shape. Battery now in its 7th year.

Unless we are in favourable driving conditions, where we harvest extra alternator boost, most of us will only be running our battery at ~80% SOC. Any unfavourable circumstances and SOC can easily drop off over time. Winter time that can be quite fast.

[DrifterX]

Originally Posted by HighlandPete

I drive about 8,000 miles a year, pretty much spread out the same week by week, typically used 3 days in a week. Winter time the charge isn't enough to keep the battery topped up. I use a CTEK tender about 3 times a winter, to keep the battery in good shape. Battery now in its 7th year.

Unless we are in favourable driving conditions, where we harvest extra alternator boost, most of us will only be running our battery at ~80% SOC. Any unfavourable circumstances and SOC can easily drop off over time. Winter time that can be quite fast.

That's pretty good, I would have thought it'd need it more than 3 times a winter, not sure how cold of a winter you get. I drove about 27,000km/year until we got our second car. Have yet to put a charger on my battery; I'm going to try my intelligent charger/starter that I got 3-4 years back for my old car. It's supposed to be able to charge AGM batteries but it doesn't have a specific setting - it detects the battery type by itself so I'm not sure how safe it'll be long term. It has all the reverse polarity protection, desulfation and overcharge protection though.

My dealer has their newer rebranded CTEK 4.3 trickle charger on sale... not sure if I should get it if I already have a smart charger.

[Billfitz]

Originally Posted by HighlandPete

It is not braking in itself that triggers the over-run charging, (harvesting of normally wasted energy), but lifting off the accelerator to zero position.

+1. We're not driving electric cars with regenerative motors. What happens is that when we're not using the engine for propulsion it's still turning over, so rather than waste the energy that it's still creating it engages the alternator to charge the battery. When it charges the least is under heavy acceleration. Figuring that you want to accelerate as fast as possible it doesn't divert energy from that task to charge the battery. It's very different from old systems that had the alternator running, and adding to fuel consumption, all the time. It's a very efficient system, but has its quirks, especially in cold weather.

[bimmer456]

Originally Posted by Billfitz

+1. We're not driving electric cars with regenerative motors. What happens is that when we're not using the engine for propulsion it's still turning over, so rather than waste the energy that it's still creating it engages the alternator to charge the battery. When it charges the least is under heavy acceleration. Figuring that you want to accelerate as fast as possible it doesn't divert energy from that task to charge the battery. It's very different from old systems that had the alternator running, and adding to fuel consumption, all the time. It's a very efficient system, but has its quirks, especially in cold weather.

The braking charges the battery more as it does not charge as much or at all when coasting to be more efficient. You can see this in eco pro that it charges more when applying brake force.

[SportySpice]

With the subzero night time temps we're having here, I've been using a Battery Tender from Costco all week. I don't think it has a desulfation mode like the CTEK maintainers. Does the desulfation mode add considerably more benefit to protecting / extending battery life than a more basic float charger? Which device are you folks using?

TIA. This is a great thread, btw.

[HighlandPete]

Originally Posted by bimmer456

The braking charges the battery more as it does not charge as much or at all when coasting to be more efficient. You can see this in eco pro that it charges more when applying brake force.

There may be some finer tuning to models with the true 'coasting' feature. There has to be a balance to which system (vehicle coasting, or alternator charging), harvests most wasted energy. Braking wastes energy, reducing the maximum recovery possible.

Braking itself does not have anything to do with assisting energy recuperation, or with the Intelligent Alternator Control. Engine over-run above 1,000rpm does, as the alternator can run a greater output on command. BMW don't mention braking in the technical data for energy recuperation. The specific phase....

IGR-Low: The alternator voltage is increased during overrun phases and the battery is charged (energy recuperation)

My model doesn't have Eco-Pro or the coasting feature, but does have alternator energy recuperation on the over-run. As soon as the accelerator pedal is at zero input, the gauge swings across to maximum recovery. No need to touch the brakes for it to activate.

Braking would potentially reduce the amount of energy recovered to the battery, as the deceleration time would be a shorter, due to the added braking function.

[HighlandPete]

Originally Posted by SportySpice

With the subzero night time temps we're having here, I've been using a Battery Tender from Costco all week. I don't think it has a desulfation mode like the CTEK maintainers. Does the desulfation mode add considerably more benefit to protecting / extending battery life than a more basic float charger? Which device are you folks using?

TIA. This is a great thread, btw.

Does your tender have 14.4/14.7 volt options? AGM is normally charged at the 14.7 volt setting, if not specifically labelled AGM.

Reconditioning is an interesting one, as something like the CTEK uses 15.8 volts for the function. BMW battery charging data specifically says not to exceed 14.8 volts.

Charging
When charging batteries in the "stand alone" mode, the maximum charge voltage of 14.8 volts must not be exceeded. Even briefly charging an AGM battery with a charge voltage of more than 14.8 volts (voltages usually used in rapid charge programs) will damage the battery.

Now whether this is applicable to a failing battery, which we attempt to extend its life by reconditioning, is open to discussion.

[Kailec]

I don't have room to park my car in my garage and typically leave my car outside overnight. I'm looking to leave it plugged in and charging during the day. Given this what's the best charger to get?

[Soul_Glo]

...because 15.8v is excellent for sulphur removal but over time the sulphur has no where to go and the plates cannot perform properly being flooded in the not so helpful solution.

15.8v works but regular use is counterproductive and can decrease the battery lifespan - trade off.

If you have an AGM that is not sealed then it is a good idea to check levels and add battery water if required.

15.8v can also cause excess gassing so make sure your vent pipe is connected and not kinked OR at least charge it outside the vehicle if you have switched to a battery that is sealed (no vent pipe).

It is normal for the battery to become a little warm but if you hear hissing or the battery is too hot then stop immediately as it is a sign of over heating. If your AGM is not sealed then check the cells one at a time when charging. The fluid should be placid and if you see any bubbling to the surface then stop.

[Billfitz]

Originally Posted by Kailec

I don't have room to park my car in my garage and typically leave my car outside overnight. I'm looking to leave it plugged in and charging during the day. Given this what's the best charger to get?

I have a NOCO. The 1.5A is sufficient as a maintainer. I permanently wired the lugs to the charging posts under the hood, adding enough wire to have the connector come through the grille down by the fog light, so I don't need to open the hood to connect it.

[Kailec]

Originally Posted by Billfitz

I have a NOCO. The 1.5A is sufficient as a maintainer. I permanently wired the lugs to the charging posts under the hood, adding enough wire to have the connector come through the grille down by the fog light, so I don't need to open the hood to connect it.

Got links to the charger and pics of your permanent solution? I've never had to charge my car battery in my life..

[Soul_Glo]

Originally Posted by Kailec

I don't have room to park my car in my garage and typically leave my car outside overnight. I'm looking to leave it plugged in and charging during the day. Given this what's the best charger to get?

https://smartercharger.com/products/...mus-4-3-polar/

Another option. Fantastic range of accessories as well.

[Billfitz]

Originally Posted by Kailec

Got links to the charger and pics of your permanent solution? I've never had to charge my car battery in my life..

https://www.amazon.com/NOCO-G3500-Ul...EM5ED5EAK&th=1
It's the 1.1 amp version, there's no 1.5. The 3.5 amp is more than you need for maintaining a battery, though not more than you can use.
No pics. The only special tool required is a large torx bit, I forget the size, to loosen the charging posts so you can slide 'C' clips on the wire ends under them. This isn't a job for a newbie, but any decent mechanic with auto wiring experience can do it in about an hour.