Battery Replacement

[Weasel]

Originally Posted by 3Series

That's good to know. When I replace my battery, I'm going to replace it with a non-AGM since that's what I probably have, 2007. My understanding is that a white case will indicate AGM and a black non-AGM. Of course, I'll look at the label to confirm.

It's 3 degrees here and my garage is probably 20 degrees warmer so I haven't been inclined to open the boot and look at the battery.

To clear it up, white case = lead acid and black case = AGM

[Weasel]

And I'm wondering about the exploding battery deal.... There's only one way I've seen batteries explode, a spark igniting the hydrogen gasses produced by the battery. But the batteries don't produce that much unless it is being overworked, (maybe the guy put a lesser battery in?) and he must not have installed the vent tube installed as the gassed should have been directed to outside the car... without the vent tube hooked up the gasses go right to the rear fuse/relay box, which at the very lease causes corrosion, and that area could have been the source of spark/ignition as well.

And no one that site seems to know the depth and complexity of the charging systems on these cars, especially with the intelligent battery sensors, power modules, efficient dynamics, etc. Long gone are the days of simple charging systems, or any simple system really. There almost aren't ANY simple switched 12v systems left on BMWs other than the lighter sockets and seat heaters... everything else is PWM signals, even the interior lighting since valvetronic...

[jigaro]

Maybe it's just me, but i just think this issue is much more simple then we all make it to be, i simply took the BMW battery out and put the other one in, i had the dealer do it, with all the propper updates and such.

The battery that i had put in, is way better then what BMW had in a first place, it's a known brand and it has won the award at the battery show in moscow 2010...the reason i'am saying this is because, when i bought my X and had it shipped from USA, i got the car history report and there was 3 different times that dealer had changed the car battery, so you would think BMW would get it right after 3 tries, but noooo, as i said before i used to get dead battery 3-4 times a month, so i guess these BMW batteries are not strong enough to withstand all the electronics that this new X has.

Weasels input would be nice about this, i'm sure he has spoken houndred times about this issue on this forum, but he could just tell us why BMW batteries can not deal with the X's electronics...

[Weasel]

I think half of the problem on the E70 battery issues is caused by the efficient dynamics charging profile. I think the engineers may have gone overboard with the cutting back of the alternator load in favor of a MPG or two... which is why they have much less problems after programming. Although there is no official charging system update programming I do believe the charging system was made a bit more robust with the newer software.

[bigx5er]

Originally Posted by motordavid

I was reading the February issue of Roundel, and in the Tech Talk section, the Tech Ed, Mike Miller, responded to a similar question. His response was remarkably frank, imo:
"Welcome to a brand new world, Alex. We can't replace our own batteries anymore, starting with the current generation of BMWs. Without the BMW service computer, it's back to the dealer at battery-replacement time...
...the entire car needs to be reprogrammed after power is cut. We're one step closer to a world where there is little to no secondary market for a BMW without a warranty."

Maybe a bit of hyperbole, but I get his point, and he is beating this drum with some regularity lately in Roundel.

Re-program something, after a batt swap; the batts on E70s for some owners, have a half-life of less than a year, and if one does a DIY or, has a parts joint do the R&R, it is a trip to Biff&Buffy's BMW Dlr for a few bucks re-load. Or...buy the dlr's ~$300 batt, and maybe or maybe not pay for the re-program. Poifect!

I'm wondering if this is part of the new "Joy" of driving new BMWs...

GL, mD

Amen! Pathetic by BMW. I read that article and was not happy. Now do I need to proactively replace my battery or risk being stuck somewhere since I can't just drop in a replacement?

[Weasel]

I just changed a battery today that had fully died, and was only 6 months old. It was a napa battery fwiw. But in my personal experience over the years I've found that when a battery is replaced and not registered (on vehicles that require it) the replacement battery goes down really fast, lasts on average 6 months. I'm actually wondering if one were to register replacement in the power module on a car with a two year old battery, (without actually replacing the battery) if the battery will last longer by being charged more robustly. I may never have the opportunity to test this theory through the shop though.

I understand why it is the way it is, what is being done and all... and it is good technology. But it isn't perfected yet.

[Penguin]

Originally Posted by Weasel

I understand why it is the way it is, what is being done and all... and it is good technology. But it isn't perfected yet.

I must admit that I really don't understand why BMW has made charging the battery so complex. While I am not an "expert," I have looked into the theory and practical aspects of battery charging quite a bit in the past, and it appears that appropriate charging can be best determined simply by the voltage-amperage curve/response -- no need at all to know if the battery is new or old. In fact, since batteries have a variance in aging, as most things do, it is much better to determine the charging program from the amperage/voltage response, rather than "knowing" how old the battery is.

I've been working with electronics for 50 years as a hobby, starting with vacuum tubes, moving to transistors, then integrated circuits, and then surface-mount components. I;ve even designed a few simple circuits.
I can see no reason that a battery would need to be "registered," other than having an unsophisticated system that could not sense the voltage/amperage response.

Perhaps some Electrical Engineer out the could enlighten this Mechanical Engineer as to why a new battery should have to be "registered."


P.S. I can understand the need if the type of battery was changed from a simple lead-acid vented battery to an AGM (since they have different maximum charging voltages), but if the battery is replaced with an identical type and the same. or similar, AH capacity, I cannot understand the need to do anything beyond switching-out the batteries.

[Weasel]

I believe it has slow learn adaptations now... meaning the charging system does adapt to the aging process of the battery. And if a fresh new battery is thrown in the system won't charge it to it's capacity. Take that and add "efficient dynamics" to the mix where the DME tries to reduce load on the engine by not running the alternator on acceleration as much as deceleration and you have the German take on a charging system. It takes some trial and error with plenty of revisions before new ideas are ironed out to work properly, and software updates are most likely making it more robust judging solely by the reports of people not getting the "increased battery discharge" messages much after programming. (although there isn't official info confirming this)

I tried to save the E70 training manual from online, but only the introduction chapter came through... the energy management section has good info on this stuff that could be beneficial to the thread but I can't get to it apparently. Maybe if I try on the windows machine it will? I'll try again later.

[AzNMpower32]

Well, BMW has had Brake Energy Regeneration for at least 3 years now, the tech came out in European models in late 2007 on most newer models like the 1er and 3er, and the X5 as well. So it's not like 2011 is the first model year they've had it on an X5.

[Weasel]

Oh I know it isn't really "new" to them, but I think they went to modest with the charging on such a power hungry model. There are too many high amperage power users on these vehicles to charge that sparingly imo.