Hi im new to the forum i usually find the answers i need but in this case i have searched the webs for the answer to this and have come up short.

I have a 2011 cooper s equipped with IBS. i am planning a huge audio build and will be adding a lithium battery to the rear of the vehicle. my question is will the Ibs system allow this or will it give me problems... ill be running 1/0 from batt+ to rear of car for extra battery ai will not be doing big 3 as that causes issues with the ibs from what ive read.
my whole build is revolved around this battery being added.

any info would help me out extremely as im currently on the verge of tearing all of the hair out of my head...

Thanks in advanced

 

What is IBS?

 

Intelligent Battery Sensor, its in some of the r56 models i lucked up and have it in mine

 

Interesting question, should be interesting to if anyone has any real thoughts. How many amps will the sound system pull? If it's close to the capacity of the alternator, that's going to be a problem..

 

total system draw will be around 230a. 150a will be sub amp and 80a for mids highs in my full active set up.
in theory the lithium im adding should be able to handle the full load of the system independently from the cars electrical

 

OK, I'm a bit confused (doesn't take much). The Mini alternator is like around 120 amps, so if you pulling twice that much, how do the batteries stay charged?

 

That is maximum draw. When all the amps are outputting as much as they can. You might get them that loud showing off in a carpark or at a competition, but mostly you will draw less than 10a to listen at reasonable levels when you are driving around.

To answer your question, the IBS is probably equivalent to a smart alternator setup like a few newer cars have. As long as you connect you earth straps back to the main earth point on the body, and not to the negative terminal, the battery sensor will still work as normal and you shouldn't have any problems.

I am on a lot of 4WD forums with people who connect accessories direct to earth on the battery, bypassing the sensor, and flatten the batteries. Earthing back to the body point (which is usually bigger and more structural to make it easier) usually fixes the problem.

James

 

Batteries act as a reserve that is used when power draw exceeds alts limits although bigger alts help with high powered systems. the system wont be full tilt all the time but i will have a lithium charger for rejuicing the rear batt and can put the front batt on a charger if it ever comes to it but normally it would take a long time to deplete the batteries charge and 230a is max power draw. if amp is at 1 ohm it would draw 180a @12v for a 2k system however ohm rise and amp effiecincy will drop these numbers extremely so i may only draw 80-100 amps from the sub amp and 40-60 from the mids/highs.

 

Ah, gotcha. That makes sense, thx for explaining it..

 

thanks brotha you the man and yes the amps and rear batt will be grounded to chassis/sub frame so it should be mostly independent from the front

 

You'll have a charge controller for the lithium-ion batteries, so the system will look like just another electrical load to the alternator. You don't want the lithium-ion battery in parallel with the car's battery - the lithium-ion battery requires a different charging profile than a lead-acid battery. You need a battery isolator between the two batteries so the alternator can charge the lithium-ion battery and supply current to the amps, but the amps can't suck current from the car battery. I have a similar setup on the boat, there's the engine start battery and the "house" battery for the lights, radio, instruments, etc. The alternator charges both but even if the house battery goes flat the engine start battery doesn't get run down.

 

Thanks for this advice. I don't think the lithium I'm getting has said controller as it's made for car audio applications with agm Batts and alternator integration. I'll look into the battery isolation thing a bit more but I don't think that's relevenat in car audio anymore at least I haven't heard it from anyone. But if the isolator will "hide" my lithium from the cars system it may be worth doing to avoid any issues with the IBS system. It's deffinetly thought provoking thank you

 

Marine stuff tends to be more conservative since it can easily become life threatening if you can't get the engine started. Not so much an issue for car audio.

I have some experience with lithium ion batteries from work, make sure whatever you choose has the proper charge control and protection built in. Over-charging a Li battery will cause the internal cells to eventually expand, and potentially rupture and catch fire. Over-discharging a Li battery will quickly kill it and make it more likely to suffer from over-charge problems. The Li batteries in your phone, computer, etc. have internal protection circuits to prevent this but even still there are occasional problems.

The IBS sensor on the main car battery senses the current draw from that battery, so as long as your additional battery uses chassis ground you should be fine.

 

Im sure you have come and gone but how did this work out for you? I have the same issue (IBS) and I want to add in a Lifepo4 bank in the rear but all the "car audio" guys never have an answer for me on what I should do. I really wanted to do a front battery delete but Im not sure how that would par with the IBS, there is no "lithium" option when registering batteries...