BimmerFest BMW Forum banner

WARNING!!!! Only charge the battery from...

180K views 40 replies 15 participants last post by  andrewdv777 
#1 ·
Only charge the battery from the terminals under the hood.​

Here's why.
The charge circuit in the car limits the amperage to the battery to prevent damage to it based on age and condition. Bypassing this and charging directly to the battery will make the circuit think it's weaker than it is and then limits the alternator charge amperage to the battery while driving. Over time the battery will create a memory at 70, 80 or 90%. Who knows what the value will be, but it will be less than full capacity.

Here's how I know:
Before changing my battery, I tested charging the old one from the under hood terminals. It took .10 amps. At the battery it took 4amps.
After swapping the battery: it charged at 1 amp at the battery (before install) and
1 amp under the hood(after installing). After registration it took 2 amps from under the hood.

So the car circuit upped the voltage to the battery after registering it. I would expect after some time the charge circuit will determine the actual values and bring the voltage down. This will be the charge voltage from the terminals as well as the alternator.

This car is not your average bear....
It has a dedicated charge circuit that is separate from the rest of the car. In most cars the battery goes to everything all the same. Meaning all circuits get the same supply voltage. If a circuit needs say +5v, then that circuit has a voltage divider as a part of it, old school is a resistor, new school if a transistor or MOSFET.

The 6 series, and others I suspect, sends power directly to the battery with it's charge circuit. AND I suspect there is a car buss that is supplied by the alternator and the battery. And maybe even smart with switching to maintain constant voltage to other circuits.

I could dig into this further but why. I'm done and know what I need to. Besides I have another project to work on.

All software BWM pertaining to the 6. Stay tuned.
 
See less See more
#2 ·
Charging the battery

Trying to understand what you are recommending, is it not so, that connecting the charger to the positive terminal of the battery and using the earthing point of the battery is the same as doing it from the jump start points in the engine bay. The +ve cable runs from the front through the car to the battery. The battery condition sensor monitors the battery at the battery inside of the boot and then sends the signals to the control centre.
BMW recommend and instruct the use of hard wiring to the battery +ve terminal and the -VE point in the boot with the C-TEK charger, rather than just using jumper leads to the same points. All as a matter of convenience.
 
#3 ·
Trying to understand what you are recommending, is it not so, that connecting the charger to the positive terminal of the battery and using the earthing point of the battery is the same as doing it from the jump start points in the engine bay. The +ve cable runs from the front through the car to the battery. The battery condition sensor monitors the battery at the battery inside of the boot and then sends the signals to the control centre.
The difference between charging amps on the new battery from terminals under the hood before and after registering the new battery (increased by 1 amp) shows that there is current limiting between the positive terminal under the hood and the battery. So it's not a "direct" wire.

+ve and -ve??? Is that a British thing?

Also of note (symantecs here) there is no "earthen ground" for cars. There is only difference of potential between + and a ground plane. And some countries have cars with a positive ground plane. Weird, I know.

Take a voltmeter and measure between the + terminal of the battery and the ground of an outlet...MAKE SURE YOU KNOW WHAT GROUND IS!!!! You can blow a meter if you plug into a hot blade. BTW, aren't you guys 220v?
 
#4 · (Edited)
Points

I appreciate that there is no direct to earth on a car (ground/earth one and the same), it is the terminology we use for what the negative -ve / black cable in a car and positive +ve red cable or charging terminal. Perhaps a British thing!!!! I don't think so !!!
As for the cable not going directly to the battery, as I said I believe it would or if not then there must be another connecting point within the loom. The reason the battery is in the boot is that certain types of battery cannot operate properly with the varying temperatures that exist in the engine bay, secondly it is also a matter of space, given more room in the boot and a more stable environment. Unless you fully disconnect the battery then they do not recommend that you charge directly to the battery terminals, as this will damage some of the the cars electronics
finally I don't understand why you seem to make attack comments when a person is offering information in good faith, it smacks of arrogance !!! Yes I do understand what ground means !!!
Having checked the wiring diagram and the parts manual, the cable from the +ve terminal (red) in the engine compartment runs directly to the battery point, where it connects to the battery cable(plus pole). Which I think somewhat negates your comment/ warning !!!!!!!
 
#5 ·
finally I don't understand why you seem to make attack comments when a person is offering information in good faith, it smacks of arrogance !!! Yes I do understand what ground means !!!
I apologize. I did not intend to offend you or anyone. I only meant for the reader (any reader) of my post to understand that it can be dangerous if they do not know what they are doing.

I can imagine it now...
"Honey, the meter blew up in my face. I read how to do it on a web site".

Sincerely, I meant nothing towards you.

Here is some of what I found from BMW WDS
"The IBS is a mechatronic component for monitoring the battery condition. The IBS is secured and connected to the negative terminal of the battery. The power supply for the IBS is fed across a separate cable. For data transmission, the IBS is connected to the DME (Digital Engine Electronics) or DDE (Digital Diesel Electronics) via the BSD (bit-serial data interface)."

Also the BSD is tied into the alternator and does several things.

And from TIS

"On vehicles with IBS, recharging the battery directly at the battery terminals could lead to a misinterpretation of the battery condition and even unwanted Check-Control messages or fault memory entries.

If the battery is recharged while installed, it must be recharged using the jump-starting points...in the engine compartment.
Only then can you be sure that the recharging is correctly recognized by the vehicle electronics on vehicles with intelligent battery sensor (IBS)"

I was only making this thread to show actual proof that there really is a reason for charging from the installed jump-starting points and not the battery.

I needed to know since I will be installing a Ctek 7002 and thought I would share what I found out.
 
#6 · (Edited)
appreciate your comments

AS I pointed out previously I have a C-tek 7000 series connected to my car, it also has a battery condition monitor within the wiring, in fact it is a traffic light system, red/ amber/ green lights.
The extra wiring that comes with the C-Tek 7000,( is a higher spec model than that sold by BMW which is C-tek re-badged). Also has extra wiring which allows you to permanently wire the car. In fact BMW will sell you a connector which is installed into the back plastic strip which forms the lip inside of the boot, which is then hard wired to the battery, so when you connect you charger you just plug it in..... perhaps they don't market these in the US but I bet if you visit the parts department they will supply you with one somehow..... it is all about convenience.
The bottom line being as Yorgi often states that one of the key weaknesses of this model is the electronics and the power supplied. I learned my lessons from having flat battery on numerous occasions until I worked out an effective regime of trickle charging my car once per week and my battery is now 6 years old and still going strong. This C-tek model allows you to do a battery recondition charge, but it is recommended not to do this too often.
Ps if anyone cocks up after the effort we have put in to assist in this area, then they well justify your comment 'I read it on the web' !!!!!
I will post a pic of my installation !!!
 
#7 · (Edited)
I agree completely about the power supply and electronics which is why I am doing this. I also plan on doing a weekly maintenance charge.
Maybe I'm hyper sensitive but I swear the throttle was smoother after installing the new battery. Before I had to feather the throttle from a standing start because it stuttered a bit. And in the short trip I took yesterday it was smooth. I'll just have to go test drive it some more today, you know in the interest of knowledge. :p

Is this the connector you are talking about that the Ctek comfort indicator panel plugs into?

Electronics Technology Electronic device
Lookie, you can see green. WoooHooo, The old one was black.

I also got one of the comfort panels.

Cable Electronic device Technology Wire Electronics accessory


It would be nice and clean to have it installed in the trunk.

Please post pics.

Thanks
 
#8 · (Edited)
Wiring battery charger pics

Here are the pictures of my battery charger connections, hopefully uploaded correctly. The lights do flash on the connector subject to the battery condition. This then connects to the wiring connector of the C-Tek charger.
 

Attachments

#9 ·
Comfort Indicator

I have only had my 645 CiC a few weeks and had no indications of battery issues, but I don't drive it a lot so I bought a CTEK 3300 and Comfort Indicator. I installed the Comfort Indicator eyelets permanently under the terminals in the engine bay to provide a convenient connection for the charger.

I left the trunk open and removed the trunk floor while charging to ventilate the battery and was happy to see I did not have to disconnect the trunk light as it turned itself off after some minutes.

After some hours the first charge reached maintenance mode, I noticed the Comfort Indicator was still flashing orange. I started the charging cycle again - same result.

So I disconnected the charger and went off to think about it. When I came back 15 minutes later, the Indicator showed green.

I have since discovered that if I unlock the car and hence initiate some of the electronics, the Comfort Indicator will show orange or even red if I open a door. If I lock the door again, red will change to orange and after about 10 minutes when all the electronics have gone to sleep, orange turns to green.

So, I think I am okay. I thought others might be interested in my experience.

I have a parts dept. receipt that shows the previous owner replaced the battery with a BMW original (Exide) 6 months ago, but I don't think he had it registered (or drove much since it was done). So I guess I will make a trip to the dealer and see if they can find out the status. I wonder if they put in a date for the battery replacement and can back-date it, or is it just a matter of them checking that the battery specs are correctly set?
 
#10 ·
I have a parts dept. receipt that shows the previous owner replaced the battery with a BMW original (Exide) 6 months ago, but I don't think he had it registered (or drove much since it was done). So I guess I will make a trip to the dealer and see if they can find out the status. I wonder if they put in a date for the battery replacement and can back-date it, or is it just a matter of them checking that the battery specs are correctly set?
You cannot get the battery registration "back dated" unfortunately. All that registration does is tell the power module what type of charging cycle is needed. If the new battery is charged using a profile designed for an older battery then it could potentially be over charging it. I think it is worth getting it registered now anyway, everything may be OK given the time/distance driven was minimal. It is also worth asking them to check that the Ah rating & battery type (AGM or lead acid) registered corresponds to the battery currently fitted to the car.
 
#13 ·
If you are talking about touching the positive & negative battery cables together, some say it will clear any faults in memory. There is risk in doing this, especially with all of our electronic modules. If you are talking about registering the battery, it tells the DME there is a new battery installed, & to reset the batteries charging cycle.
 
#19 ·
Only charge the battery from the terminals under the hood.

Here's why.
The charge circuit in the car limits the amperage to the battery to prevent damage to it based on age and condition. Bypassing this and charging directly to the battery will make the circuit think it's weaker than it is and then limits the alternator charge amperage to the battery while driving. Over time the battery will create a memory at 70, 80 or 90%. Who knows what the value will be, but it will be less than full capacity.

Here's how I know:
Before changing my battery, I tested charging the old one from the under hood terminals. It took .10 amps. At the battery it took 4amps.
After swapping the battery: it charged at 1 amp at the battery (before install) and
1 amp under the hood(after installing). After registration it took 2 amps from under the hood.

So the car circuit upped the voltage to the battery after registering it. I would expect after some time the charge circuit will determine the actual values and bring the voltage down. This will be the charge voltage from the terminals as well as the alternator.

This car is not your average bear....
It has a dedicated charge circuit that is separate from the rest of the car. In most cars the battery goes to everything all the same. Meaning all circuits get the same supply voltage. If a circuit needs say +5v, then that circuit has a voltage divider as a part of it, old school is a resistor, new school if a transistor or MOSFET.

The 6 series, and others I suspect, sends power directly to the battery with it's charge circuit. AND I suspect there is a car buss that is supplied by the alternator and the battery. And maybe even smart with switching to maintain constant voltage to other circuits.

I could dig into this further but why. I'm done and know what I need to. Besides I have another project to work on.

All software BWM pertaining to the 6. Stay tuned.
I have a question for you in terms of a 2012 X5 - I want to store the car without the battery being dead when I try to restart the vehicle. Would you suggest I unplug the battery connectors or should I use a trickle charge or what would you suggest?
 
#20 ·
With a good battery tender and good supply, trickle charge every time, also remember the car should be turned over periodically to keep oil around engine internals, increase tyre pressures unless you can get all four wheels off the road. Otherwise you can flat spot the tyres. Sometimes a cover helps protect bodywork , not essential.
Connect trickle charger under the hood not at battery, Two terminals are marked easy enough. I have permanent wiring to connect and use Ctech charger for AGM battery.
 
#26 ·
Herb was making a 'inside baseball' comment.

You are fine on a trickle charger, no worries.
 
#27 ·
Only charge the battery from the terminals under the hood.

Here's why.
The charge circuit in the car limits the amperage to the battery to prevent damage to it based on age and condition. Bypassing this and charging directly to the battery will make the circuit think it's weaker than it is and then limits the alternator charge amperage to the battery while driving. Over time the battery will create a memory at 70, 80 or 90%. Who knows what the value will be, but it will be less than full capacity.

Here's how I know:
Before changing my battery, I tested charging the old one from the under hood terminals. It took .10 amps. At the battery it took 4amps.
After swapping the battery: it charged at 1 amp at the battery (before install) and
1 amp under the hood(after installing). After registration it took 2 amps from under the hood.

So the car circuit upped the voltage to the battery after registering it. I would expect after some time the charge circuit will determine the actual values and bring the voltage down. This will be the charge voltage from the terminals as well as the alternator.

This car is not your average bear....
It has a dedicated charge circuit that is separate from the rest of the car. In most cars the battery goes to everything all the same. Meaning all circuits get the same supply voltage. If a circuit needs say +5v, then that circuit has a voltage divider as a part of it, old school is a resistor, new school if a transistor or MOSFET.

The 6 series, and others I suspect, sends power directly to the battery with it's charge circuit. AND I suspect there is a car buss that is supplied by the alternator and the battery. And maybe even smart with switching to maintain constant voltage to other circuits.

I could dig into this further but why. I'm done and know what I need to. Besides I have another project to work on.

All software BWM pertaining to the 6. Stay tuned.
Sure wish I would have seen this sooner!! Charged at the battery and now, nothing but problems to the point it won't even start, no lights, bells or whistles......but the battery is fully charged!! On top that, now it won't charge from the point under the hood which kind of makes your point since it basically isn't communicating from the front and back.....which can only mean.....the computer!
 
#29 ·
Not sure that is your issue, from memory if you can get a copy of the WDS, this is the wiring diagram for BMW cars, easy to get on a DVD etc or ISTA etc. But the wiring diagram shows the cable for the battery going from the front to the back of the car no separate runs. So long as when you charged at the battery you did not do it across the battery itself, but used the body for the negative and the positive terminal should have no issues, but the battery condition monitor IBS ?? maybe faulty, or you have fused a cct??? I would start looking here first. Did you start the car with the charger connected ??? I think it is rare that any module has blown due to charging.
 
#30 ·
You can charge the battery from the trunk, it is just not recommended. I suspect that you possibly damaged the negative cable, & damaged the IBS "fuse link" that will blow if you are in a crash. Use the schematic below to see how it works. Measure the positive to ground in the trunk & the jump terminal to ground to measure the voltage. You can also measure the resistance across the negative cable to see if the IBS has been damaged. You can jump across the IBS & see what happens also. The body & the engine to ground should read less than 1 ohm, this will tell you if the grounds have a problem. If you put a jump charger on the jump terminal, the inside lights should come on, & power up part of the car.
 

Attachments

#32 ·
H


Herb,
I looked up the IBS and stomach pain, bloating and diarrhea, are the main symptoms, and that's not happening...hehehe. It does say if I just take it off and out of the circuit, it should start but you will have no monitoring, which who cares if that will tell me the problem and I can replace it. Sound good?
Thank you!
Tony
 
#31 ·
Ok, all 3 of your replies gave me a better idea of what I'm dealing with and here is what is happening, I will then try to go out and test some of the info you all provided.....but it is a wee bit cold here today, so might not be out there long.

  • I have a GENIUS "smart" charge and when connected to the positive point under the hood and using the negaitive on the suspension right next to it, nothing comes on, no lights, bells or whistles (always worked before). Push the "jump" process and once the charge builds up, the key will engage, the head lights will flicker and the dash will act crazy, running through multiple system errors. Then once the charge runs out, back to blank completely and key will not engage.
  • Using the "smart" charger analyzer on these post and it says "battery failure, charge aborted". I pulled the battery completely out of the trunk, connected to the "smart" charger and it says, "battery at 100%" and it shuts off. I have a second "smart" charger and both the failure at the motor and the full charge on the battery were the same. I also have a battery tester and it says full load, and this battery is relatively new, so I know it's not the battery.
  • This car is actually a friend of mine who is a very unique guy. It was his idea to put a battery charger in the trunk and just leave it there as this car can sit for a week here and there, which usually will drain the system....even the new one. Then he figured since there was 2 places to charge why not hook the other up, hence the second "smart" charger. He may have more money than the Catholic church and will buy second chargers and stuff but taking it to a mechanic...nay nay, as he trust none in this town.
  • Now the one thing I have learned is that there are so many bells and whistles on this 07 figuring out why it drains, would be a undertaking of huge proportions. So when I pulled the battery, I tried to drain every bit of juice from the car, hoping to basically clear everything. Yeah, that didn't work either.
  • When the new battery was installed, everything was fine, and all of the cables and connections also look brand new.

So if the charge point under the hood is directly wired to the battery, and the chargers are unable to acknowledge that there is a battery connected, and all my connections are secure and look new, where could the "break" be?

Gentlemen, I'm just a grunt with a little bit of common sense trying to figure this out. If after I give it the Ole college try, and can't figure it out, I will find a pro to look at it, but for now my goal is just to start it, as i think that if i get it started and the operating system does somehow control how the battery is charged, I may be able to clear the errors. I just don't want to do further damage. I'm thinking the "smart" charge jump mode isn't enough juice to pop this system and Triple A and their professional jumper might do it.

Thank you guys, I seriously do appreciate your responses.
Tony
 
#33 ·
Do you have a multi meter to check the voltage on the current battery?
If it has gone bad, open or short circuit the smart chargers may be detecting this and not charging. And with a short circuit battery in the vehicle, a jumper pack will have a hard / impossible job to jump start the vehicle.
 
#34 ·
If you are getting the lights to come on for a short time, & they go away again, I suspect your battery is shot. A bad battery with a properly charged jump box, will not be enough juice to start the car. The voltage must be stay above 12 volts, or it is not going to crank. If you have a voltmeter, simply measure the battery under the hood & the battery in the trunk. The turn the ignition on, with the headlights, then measure it again. If your voltage starts going below 11.8 volts, the engine will probably suck the life out of the battery. If the battery is fairly new, simply take it back & get another battery. The car will most likely start & run properly. You will have a bunch of hard codes & soft codes that will need to be deleted to finish things up. Even if your battery charges out of the car, it might only be a surface charge, that will just not last long. If your friend has tons of money, go buy a new battery, & the car should run properly. Please tell your friend to not put to chargers on the car, because you are going to damage some components.

Most new cars are almost like rolling computers, as they depend on the voltage they need to keep things working properly. The 07 has 40 modules that must stay at either 12 volts, or 5 volts. Anything less than what they need, they shut the module down to protect themselves.
 
#36 ·
Ok gentlemen, first let me say thank you all for your help through your responses! I removed the battery once again and charged it directly to 100%....so says the "smart" charger...then took my meter and wham-bam...9.5 volts! Took the battery back and paid $60 for what was a $280 battery since it was less than a year old. Installed it and first crank bada-bing started right up! Problem solved! Now my question is, this car just seems to suck the life out of a battery without anything obvious being wrong. I read that others have set up "trickle" chargers to maintain the battery but I also read continuous charging is not good for a battery. I am making a point of starting the car every day, but I won't always be around. Any suggestions for a maintenance program? Once again thank you for sharing your knowledge as now I know the internet actually more helpful than just porn!! Lol!
 
#37 ·
I charge my X5 AGM battery from the underhood points weekly with a CTEK 4.3 MUS for two to five hours summer and winter respectively, that’s about 4 AH to 10 AH.

The BMW charges the battery ONLY on overrun - trailing throttle or spin down of the alternator on its sprag clutch. ALL other times the BMW alternator is ONLY maintaining accessory loads, maintaining battery current through the IBS at ZERO.

Starting the car every day drains the battery far more than could be charged by running the car 24/7.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top