[Bianchi Dave]

Originally Posted by HighlandPete

Isn't the issue defining whether it is a manufacturing defect, or simply a customer letting it go flat and it being unrecoverable.

There is documentation on how BMW dealers need to look after batteries on stock/showroom cars, to prevent too low a state of charge. Keeping charging calendars, etc.

I get that Pete, but think its unreasonable for the customer to have to consider such issues on a new car. "Here is your car sir, oh and by the way, the MHT system requires you purchase a £300 battery charger....."

My current use (pardon the pun) is no different to my previous F31s which I had for 10 years and never missed a beat.

I had a decent 70 mile drive yesterday and chose a route with plenty of coasting and braking. The stop/start was functioning normally and I've not had the message again. A few trips planned in the coming week too, so I'm hoping it will sort itself it out (provided the battery is not too depleted).

[peelerec]

Appreciate the value on this thread even though I’ve never had a MHT issue. This thread should be stickied. It’s an absolute need to know item for those of us with the mild hybrid.

[xenon]

Originally Posted by Bianchi Dave

I get that Pete, but think its unreasonable for the customer to have to consider such issues on a new car. "Here is your car sir, oh and by the way, the MHT system requires you purchase a £300 battery charger....."

That's absolutely not what they're saying though, is it? There is a world of difference between a car in a showroom that's not started but with people pissing about with it all the time and a car in normal use.

In normal use has anyone actually had a problem with MHT and been left stranded? No.

It's a load of fuss over nothing IMO.

[HighlandPete]

Originally Posted by xenon

In normal use has anyone actually had a problem with MHT and been left stranded? No.

It's a load of fuss over nothing IMO.

So easy to panic when we get warnings...

Years back we never got warnings, if our battery was low. I often wonder how many cars would have thrown a warning, if there was the mechanism, when you'd hear the slow cranks on a first morning start. Many of us ran around on a battery with a low state of charge most winters.

There are still many cars out there today, where the first sign of the battery being low is a slow start. At least BMW are giving us warnings, and/or switching off consumers, protecting the start up and giving us the best chance of preventing total failure.

I do sense some users are very concerned about the 48 Volt battery SoC. That is going to be up and down, simply on its use and function while driving.

The other factor, some of us don't drive enough miles for the battery to keep in a good SoC. That in itself is not something new, or unique to BMW.

[xenon]

I agree - it gives a warning and does its best to shut down non-essential consumers ergo what's the problem?

[Bianchi Dave]

To be fair I have experienced 'slow starts' with previous cars, so perhaps it's as you guys say - that the facility to give an early warning is now available. Certainly hope so

[nashdm2]

Just bringing this thread back to life.

Has anything else been learnt on this since the last entry please? I have a MHT coming which will spend a lot of time in my garage between uses? Thanks...

[The_Tok'Ra]

I'm on the verge of buying a CTEK Pro25S as well. My car has never been above 2 bars in the "Energy Flow" display since I spent a lot of time in the car setting everything up.

I drive my car every day during the week, but I only have a 15 minute commute each way, in town and a short country road, it's just not enough to get a good charge in the battery.

With winter coming in, my lights and heating will be on a lot more often and obviously that will put more of a strain on the battery. I've also noticed that when the SoC drops to one bar the car will on occasions will start itself up on it's own after it's already cut the engine with stop/start, so it must be doing that to help with the SoC.

What I don't have access to however, is a nice dry garage to charge in with the bonnet up. I actually have a double garage as it happens, but this car is just a few inches to wide to fit down my driveway, it was meant for smaller cars from many years gone by.

Does anybody know how far the bonnet has to be open in order for the car to actually charge?

TIA

[sjb993]

Originally Posted by The_Tok'Ra

I'm on the verge of buying a CTEK Pro25S as well. My car has never been above 2 bars in the "Energy Flow" display since I spent a lot of time in the car setting everything up.

I drive my car every day during the week, but I only have a 15 minute commute each way, in town and a short country road, it's just not enough to get a good charge in the battery.

With winter coming in, my lights and heating will be on a lot more often and obviously that will put more of a strain on the battery. I've also noticed that when the SoC drops to one bar the car will on occasions will start itself up on it's own after it's already cut the engine with stop/start, so it must be doing that to help with the SoC.

What I don't have access to however, is a nice dry garage to charge in with the bonnet up. I actually have a double garage as it happens, but this car is just a few inches to wide to fit down my driveway, it was meant for smaller cars from many years gone by.

Does anybody know how far the bonnet has to be open in order for the car to actually charge?

TIA

The bonnet just needs to be unlatched - you’ll then get the Bonnet Open warning in the iDrive display. I trickle charge my battery with the bonnet in that position.

[The_Tok'Ra]

Originally Posted by sjb993

The bonnet just needs to be unlatched - you’ll then get the Bonnet Open warning in the iDrive display. I trickle charge my battery with the bonnet in that position.

Ah, OK that's good to know!! Thank you!!

FYI For anybody considering buying a CTEK Pro25s, You can get it on Amazon just now for £270, or the Pro25se for £277, which has longer charge leads (6M compared to 2M on the Pro25s)

I've just ordered a Pro25se as the longer leads will be usefull for my situation.

[bmnut]

Originally Posted by HighlandPete

So easy to panic when we get warnings...

Years back we never got warnings, if our battery was low. I often wonder how many cars would have thrown a warning, if there was the mechanism, when you'd hear the slow cranks on a first morning start. Many of us ran around on a battery with a low state of charge most winters.

There are still many cars out there today, where the first sign of the battery being low is a slow start. At least BMW are giving us warnings, and/or switching off consumers, protecting the start up and giving us the best chance of preventing total failure.

I do sense some users are very concerned about the 48 Volt battery SoC. That is going to be up and down, simply on its use and function while driving.

The other factor, some of us don't drive enough miles for the battery to keep in a good SoC. That in itself is not something new, or unique to BMW.

I rarely see more than two bars, often only one on the 'Energy Flow' screen on my car, occasionally it will increase to 3 or even 4 bars but I haven't (touch wood) experienced any problems with the battery SoC.

I remember raising this question with a senior tech at my dealership and expressed concern at the lack of blue bars on that very screen and the reply I got was.."don't worry about the number of bars showing because if it's only one or two then it just means that the 48V battery is doing what it's supposed to do, it's assisting the running operations of the car and minimising the need for the petrol engine to have to be running all the time. It will fluctuate constantly depending on vehicle usage because that's what it's designed to do".

That made perfect sense to me but I feel sure others may feel the need to comment further?

Just as an aside back in 2010 my wife and I went on a 'holiday of a lifetime' and were away from home for eight and a half weeks and at the time my wife had a 2008 120i coupe and I had a 2007 335i coupe. Both cars stood completely idle, locked away in our garage throughout the entire time. When we returned home I fully expected to find two cars with flat batteries and yet both cars started first time without any hesitation and let's be right battery technology back then wasn't anywhere near advanced as it is now.

Sometimes as the technology becomes more advanced and drivers are better informed by the vehicles' on board systems we have a tendency to become much more anxious and concerned about potential events that rarely manifest themselves.

[MisterG]

Originally Posted by The_Tok'Ra

I'm on the verge of buying a CTEK Pro25S as well. My car has never been above 2 bars in the "Energy Flow" display since I spent a lot of time in the car setting everything up.

I drive my car every day during the week, but I only have a 15 minute commute each way, in town and a short country road, it's just not enough to get a good charge in the battery.

With winter coming in, my lights and heating will be on a lot more often and obviously that will put more of a strain on the battery. I've also noticed that when the SoC drops to one bar the car will on occasions will start itself up on it's own after it's already cut the engine with stop/start, so it must be doing that to help with the SoC.

What I don't have access to however, is a nice dry garage to charge in with the bonnet up. I actually have a double garage as it happens, but this car is just a few inches to wide to fit down my driveway, it was meant for smaller cars from many years gone by.

Does anybody know how far the bonnet has to be open in order for the car to actually charge?

TIA

I wouldn’t worry about the number of bars on the in car display.. that’s just where the ecu tries to keep it during normal driving.. it’s better for the tiny battery long term to keep it mid-charge rather than being cycled full-empty..
I’ve had a “full” battery once after a several-mile downhill while in sport mode.. and despite switching back into comfort at the bottom, the battery was back down to 2 bars within a couple of miles of normal driving because the car decided to discharge the battery by assisting at very low engine loads. (Without eboost showing on the dash)
- does an lci car even have a battery display?

I think the concern over trickle chargers etc on modern cars is overblown. Yes they have higher load requirements from the tech. But they also monitor and manage the state of charge better and can react accordingly by disabling stop start limiting high consumption, or increasing the alternator output.

[The_Tok'Ra]

Originally Posted by MisterG

I wouldn’t worry about the number of bars on the in car display.. that’s just where the ecu tries to keep it during normal driving.. it’s better for the tiny battery long term to keep it mid-charge rather than being cycled full-empty..
I’ve had a “full” battery once after a several-mile downhill while in sport mode.. and despite switching back into comfort at the bottom, the battery was back down to 2 bars within a couple of miles of normal driving because the car decided to discharge the battery by assisting at very low engine loads. (Without eboost showing on the dash)
- does an lci car even have a battery display?

I think the concern over trickle chargers etc on modern cars is overblown. Yes they have higher load requirements from the tech. But they also monitor and manage the state of charge better and can react accordingly by disabling stop start limiting high consumption, or increasing the alternator output.

Thanks! I probably am being overly concerned about the SoC of the battery, but I do have other uses for another trickle charger, all be it nothing that requires up to 25A, and it might be quite handy when the future idrive updates are released as there is little to no chance of me seeing a fully charged battery during my normal use, and that seems to be one of the requirements to be able to install the update.

[The_Tok'Ra]

Originally Posted by MisterG

I wouldn’t worry about the number of bars on the in car display.. that’s just where the ecu tries to keep it during normal driving.. it’s better for the tiny battery long term to keep it mid-charge rather than being cycled full-empty..
I’ve had a “full” battery once after a several-mile downhill while in sport mode.. and despite switching back into comfort at the bottom, the battery was back down to 2 bars within a couple of miles of normal driving because the car decided to discharge the battery by assisting at very low engine loads. (Without eboost showing on the dash)
- does an lci car even have a battery display?

I think the concern over trickle chargers etc on modern cars is overblown. Yes they have higher load requirements from the tech. But they also monitor and manage the state of charge better and can react accordingly by disabling stop start limiting high consumption, or increasing the alternator output.

I've noticed a few people mention that in sport mode the regen braking charges the battery seemingly more aggressively than in other modes. Is that a "thing"? I've rarely been in sport mode thus far. It's not much use in town or very short country roads. Ha!

[MisterG]

Originally Posted by The_Tok'Ra

I've noticed a few people mention that in sport mode the regen braking charges the battery seemingly more aggressively than in other modes. Is that a "thing"? I've rarely been in sport mode thus far. It's not much use in town or very short country roads. Ha!

I think it’s more a side effect of keeping the engine running, higher overall rpm and downshifting giving more opportunity to regen.
rather than in comfort where it’ll coast and use stop/start wherever it can..
I’m still getting used to my car - but the last tank, circa 10% the total distance was coasting!. Even in urban driving, if your near the speed limit for the road, and it’s flat/downhill and there isn’t a car in front and your not on the throttle it’ll turn the engine off and coast.

Edit: another example - todays journey in adaptive mode (6.6mi urban roads into manchester city centre in the dark and rain) took 50 minutes in crap traffic, total engine off time was 15 minutes, and coasting was 0.8mi.. 22MPG.. the MHT battery display was flicking between 1-2 bars.

[xenon]

I'm still struggling to understand why secondary charging is necessary. The whole point of the MHT technology is that it recovers energy which would otherwise be wasted as heat and uses that recovered energy to boost efficiency. Then people completely negate that by hooking up a 1/2kW charger to the domestic supply.
<shrugs>

[sjb993]

Originally Posted by xenon

I'm still struggling to understand why secondary charging is necessary. The whole point of the MHT technology is that it recovers energy which would otherwise be wasted as heat and uses that recovered energy to boost efficiency. Then people completely negate that by hooking up a 1/2kW charger to the domestic supply.
<shrugs>

Here's an extract from the BMW SIB regarding potential battery problems when cars, like mine, aren't used regularly or are incorrectly charged. Given the cost of a replacement 48v battery, rather than risk unwittingly damaging it, I'd prefer to maintain mine as per the recommendation in the SIB.

Vehicles equipped with option code:
01CE Recuperation system
SITUATION
48 V battery may become totally discharged, and possible replacement needed if:
a) The vehicle has been charged using a 12 V charger with the hood closed during a long stationary period,
the. For example, the showroom or storage.
b) Vehicles stored for an extended period connected to a low output solar or trickle charger.
c) Vehicles stored for an extended period with no charger connected and not properly maintained 12 V
battery.
Fault memory:
803419 - Batt48: Total discharge
803408 - Batt48: Emergency announcement: Cell voltage too low
803437 - Batt48: Cell defect - total discharge
Important: Trickle chargers (< 20-amp output) or solar chargers will not be able to charge the 48 V battery,
but could prevent further discharge to the 48 V battery when the 12 V battery is properly maintained to
optimal SOC.

[xenon]

Fair enough if it's in storage for a while.

[The_Tok'Ra]

Originally Posted by sjb993

Because I use my car relatively infrequently I was keen to periodically charge the battery. After discovering that my existing CTEK 3.8A charger wasn't charging my battery (even though the status LEDs indicated a full charge), I tried to find out why. Cutting a very, very long story short I found out that BMW have stated a charger with an output >20A is required. The only reports of successful MHT charging I could find were from 2 American guys on the General Discussions section of this forum, and they had both used CTEK 25A chargers. As there seems to be no alternative, I went ahead and bought a CTEK Pro25s.

It does seem to do the job. Before I hooked it up my battery had an estimated SoC of 55%. It then took roughly 11 eleven hours charging to raise the estimated Soc to 100%.

sjb993,

I plan to give ther new CTEK 25A charger a go over the weekend, so I'm hoping you can verify a few things, just so I'm clear.

You are simply hooking up your charger to the 12v Lead Acid battery under the bonnet and leaving the bonnet unlatched while charging?

You are NOT going anywhere near that Mains/signal connector G14*1B that's plugged into the 48v MHT battery?

It seems that, going from the bulletin, unpluging that connector must only be done when the 12v battery is fully charged, and it will throw a code that can only be cleared with ISTA. So that seems like not best idea to me. Ha Ha!

I don't have the other CTek device you have that connects to your phone and allows you to monitor the battery status.

Silly me assumed before doing my reseearch, that a £300 charger would have that functionality built in, but no... LOL!! I don't think I'll bother with that at another £45, and it's seeminly been discontinued as well.

Do you find it a usefull tool to have, or maybe more helpfull to you in you situation perhaps?

TIA!!

[sjb993]

Originally Posted by The_Tok'Ra

sjb993,

I plan to give ther new CTEK 25A charger a go over the weekend, so I'm hoping you can verify a few things, just so I'm clear.

You are simply hooking up your charger to the 12v Lead Acid battery under the bonnet and leaving the bonnet unlatched while charging?

You are NOT going anywhere near that Mains/signal connector G14*1B that's plugged into the 48v MHT battery?

It seems that, going from the bulletin, unpluging that connector must only be done when the 12v battery is fully charged, and it will throw a code that can only be cleared with ISTA. So that seems like not best idea to me. Ha Ha!

I don't have the other CTek device you have that connects to your phone and allows you to monitor the battery status.

Silly me assumed before doing my reseearch, that a £300 charger would have that functionality built in, but no... LOL!! I don't think I'll bother with that at another £45, and it's seeminly been discontinued as well.

Do you find it a usefull tool to have, or maybe more helpfull to you in you situation perhaps?

TIA!!

The 12V AGM battery is in the boot, and the 48V Lithium battery is under a cover in the back right corner of the engine compartment (see attached photos).

The charger leads do not connect directly to a battery. You connect the charger's red crocodile clip to the positive jump-start terminal under a clip-on red cover on the left side of the engine compartment, and the black crocodile clip to the negative jump-start terminal near the blue windscreen washer reservoir cap (see attached photo).

Just in case you forget to unplug the charger when connecting/disconnecting the leads, as a safety measure, always connect the red lead first, then the black one. When finished, disconnect the black lead first, then the red one.

Set the charger to NORMAL mode.

As it turned out, I've hardly used the battery monitor - I wouldn't bother buying one if I were you.

BTW - disconnecting the mains/signal connector is really only intended for use in dealership showrooms - it allows them to charge the battery with the bonnet closed (the charger leads are fed up into the engine compartment from below).

[The_Tok'Ra]

Originally Posted by sjb993

The 12V AGM battery is in the boot, and the 48V Lithium battery is under a cover in the back right corner of the engine compartment (see attached photos).

The charger leads do not connect directly to a battery. You connect the charger's red crocodile clip to the positive jump-start terminal under a clip-on red cover on the left side of the engine compartment, and the black crocodile clip to the negative jump-start terminal near the blue windscreen washer reservoir cap (see attached photo).

Just in case you forget to unplug the charger when connecting/disconnecting the leads, as a safety measure, always connect the red lead first, then the black one. When finished, disconnect the black lead first, then the red one.

Set the charger to NORMAL mode.

As it turned out, I've hardly used the battery monitor - I wouldn't bother buying one if I were you.

BTW - disconnecting the mains/signal connector is really only intended for use in dealership showrooms - it allows them to charge the battery with the bonnet closed (the charger leads are fed up into the engine compartment from below).

Thanks sjb993,

Sorry, I should have stated the ground terminal and jump start terminal under the bonnet, rather than directly to the 12v battery, that's what I meant really, though TBH I thought the 12v battery was under the plastic cover on the other side of the engine bay, from where the 48v battery is.

I'll not bother with the battery monitor then.

I'm going to try updating my maps while the car is on charge, just to see if that will work on not.

Thanks again!

[sjb993]

Originally Posted by The_Tok'Ra

Thanks sjb993,

Sorry, I should have stated the ground terminal and jump start terminal under the bonnet, rather than directly to the 12v battery, that's what I meant really, though TBH I thought the 12v battery was under the plastic cover on the other side of the engine bay, from where the 48v battery is.

I'll not bother with the battery monitor then.

I'm going to try updating my maps while the car is on charge, just to see if that will work on not.

Thanks again!

You're welcome. Let us know how you get on.