Will a Bad Battery Manifest into Trans Issues
 

Continuation of my original thread

https://xoutpost.com/bmw-sav-forums/...-failsafe.html

For sure, I have a Bad Battery. After 3-4 stops/starts and about 10 mile drive, I think the alt MAY be okay and it's my battery

What is weird is when I test drove the car with a good donor/test battery, it was still showing trans issues. This test drive with donor battery was very very limited. I just drove around the block.

Anyhow, original battery charged and rested overnight.
Resting voltage showed 12.7 in the morning.

Had both alt and battery load tested at autozone. Maybe 3/4 mile drive from Autozone. Their tester says *replace battery-whatever how that is interpreted*. It was at 12.4 when they load tested the battery after the 3/4 mile run.

The entire drive showed alternator hovering mid 13's , with only dips down to 12.3-12.7 when decel/throttle off.

Extended test driving, buying a new battery, etc. Probably put like 10 miles in total watching alt voltage.

For the most part, alt hovers at mid to high 13's. I do see it dip as low as 12.3 when decel.

The transmission still feels like it's in limp, and when accelerating from stop or just 1-2, it is jerky. Even jerky when decel.

WILL the bad battery literally cause all this I am feeling in the tranny ?

Got new battery on float charger. Will swap when I get home tonight to do another round 2 of testing.

YES

at least for me. My alternator gave up and came home from the gas station and left maybe 10 minutes later and driving out of the neighborhood i got trans fail safe then ac cut out etc eventually I stopped turned it off and waited and tried to start it started but was not happy. at the time i had extended warranty. Dealer flat bedded to have it serviced and said the alternator was not charging properly and therefore battery was under performing and was near is end of life so they replaced both.

The battery to me is starting juice and supplemental once on...
So assuming/presuming the alt voltage is looking fairly good, I'm not correlating right now the limp mode with good mid-high 13's V, with a ~known bad battery~.

New battery is@home charging, so I guess I will see if it was just the battery and nothing more ?

This doesn't seem right - I NEVER see mine dip below 13.8 - at any point.

If your BC voltage reading is showing low 12s your alternator is not doing anything - that just the battery voltage.

Others can (and will) chime in here - the more info. the better - but I think your alternator is suspect. :(

You are right in that the alternator should do its job after but ive seen where power draw will spike and thats were the battery comes in and help provide the juice. In my case i have currently 200K with a rebuilt transmission that needs to have the sonnex sleeves installed in the valve body any way in 200K alternator was replaced 1 time and im on my 3rd battery first 2 the dealer paid for. but only time i had trans fail safe was when the alternator was not able to provide the juice...

my cousin has a ford f550 and he had issues with limp mode i went and tested batteries etc and they were sitting with the truck off at 12.7 and 12.5 not bad but doing the alternator test i noticed times it was charging 14v and times it was sitting at 12.9 and spike to 13.5. Told him to take it to the dealer and have then verify my findings and i was right alternator was going out and was putting the truck in limp mode which would go away at times but in got to the point where it was happening and at that time it wouldnt go away.

so in your case it might just be the alternator thats going out.....you can try buying a regulator for the alternator idk the cost on the reman but ive always kept my alternators on my other cars and just replaced the regulator on the back which is where the brushes are and the part that actually wears away *so does the shaft but not as fast as the brushes.

I've never driven watching the V on cluster to date so I have no delta on what is normal or not. Mid to highs 13's. With the momentary dips to 12.3 then watch it go to 12.7 and the bounce back to the 13's

Ah. Gimme a mechanical gremlin anyday. I hate electrical gremlins

How did you measure your resting voltage?

With a multimeter?

Still connected to the vehicle?


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Charged, floated and checked back 12 hrs later. Granted I think technically from what I understand, Surface Voltage can be a couple days if I take a deep dive in my former battery troubleshooting. ---- Battery off car

My battery light on the dash came on as I pulled into my driveway January 2017. Checked voltage with vehicle off measured 12v. Started the 2002 x5 4.4 and measured voltage was 10.5v. That was my clue as to the status of the alternator. After replacement running voltage was measured at 14.4v. I never had any errors leading up to the battery light.


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wpoll -

I really should measure at the batt. terminals to see what .X V difference it might be on the BC.

Do you know what it should measure whiile on the car but everything off?


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yes, the only reason I took it off the car was I put in a known good battery for the alternate test drive

And since the good one was in, the *bad* one was going to be as planned . Charged, rested and to see what it looks like post rest. Granted, I only let it rest and checked it after 12 hrs....when I know in the battery world, surface charges can take ~a few days~

I just checked mine via the cluster on the car without starting the car and it was reading 11.6v but not getting any trans fail safe.


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My BC reading is something like 0.2-0.5v lower than what I measure at the jump terminals with a Fluke DVM. It varies a bit, depending on the load (lighting etc.)

When the car is idling, everything off (A/C, lights etc.) the BC reads 13.9 while the jump terminals measure as 14.3v.

And re. surface charge - turning the lights on for 15-20 seconds will remove any "surface charge". :thumbup:

BC voltage readings are really only relevant when the car is running. Reading it when the cars is not running is basically measuring the battery voltage with a 20-30Amp load on it!

And in that case, 11.6v is pretty decent! :thumbup:

Checking the voltage with it off is only for the battery not alternator....also low volts dont mean it wont start the car its about the amps needed to. I use odb reader while car is running and test under load especially like accelerating on ramps etc wiht lights, ac, radio, etc all on to make sure alternator can handle it.

my sisters c230 sport had 11.6 volts which is not to low should start the car but wouldnt even try lights worked etc had to jump to charge it above 12 and let it sit for a like 20 mins and was able to start it to bring it home.

oh also when i spoke with the shop manager about why i got the trans-fail safe he said bc the cars ecu is designed to cut power to things and conserve when in that situation not sure about this but i can say my power windows stopped working, my radio cut out, my ac stopped but car remained on just in limp mode. so yes you can see if alternator is not providing proper power computers will shut down or not operate correctly.

Jsoto you have a v8 or straight 6? If you have a 4.4 or 4.8 alternator should really be >14v anytime the truck is running. Mine, prior to impending alternator failure recently, would peg at 14.4v and stay there. If you are dipping into the 12's while running it could have contributed to your batteries death. If you have a 3.0 I'm not sure of target voltage but certainly never in the 12's.

Off topic. For the wiki, if I had a AGM battery, the problem might have been spotted earlier. Wet cells can take flucutuations a bit better. AGM’s are much more sensitive ...battery would probably be shorted by now.

CW - pre 4.4

methinks I'm going to have to get some codes pulled. I can correlate a cluster error and limp, hard downshift to rolling stop, trans failsafe when upshifting - not good signs. Right now, the trans issues seem to also exhibit itself before a trans fs comes up. I'm hoping it's not the latter.

Remind me. Does Limp Mode always = cluster warnings while in limp.
Or are there instances where it's in limp with no cluster indication.

When my alternator went. The very first symptom was a trans failsafe error indicated on cluster. Apparently the TCM wants to see 14+ all the time and dip even into the mid 13's could set it off. I never got a limp that wasn't indicated in the cluster. At least in my experience. YMMV

Oh boi. I was hoping not to see a response like this.

Granted, many posts seem to infer my running V is out of wack. But I'm seeing stuff that doesn't seem to be correlating on the error free cluster and I'm hoping it's not super uber coincidental --------ontop of my Ferrai esque disc change already.

I would also suggest that the hard and odd shifting occurrences you are experiencing do not relate to a low voltage issue causing the trans failsafe message. My guess would be you might need some transmission work.

:flame: Don't jinx it OB....

I don't wanna see it in words what the underlying symptoms are showing....
I was already browsing last night at my usual ZF spot to see what the remans were at these current day and age. And OCD me also went to cobra site. The longer shaft has dropped in price. Even jumped on RealOEM to pull up PN like the RMS, etc. Aside from the longer shaft, a rebuild/rms, etc was done already I think 5 years back.


Not sure if you saw my other thread on my ferrai-esque brake job. Not having a very green holiday year

I could be wrong jsoto, I hope so. I just see so many of the members here with ZF boxes needing valve body rebuilds. Snik from Texas found a decent rebuilder using Sonax and ZF parts with lifetime warranty and was very happy with the service. I believe they were World Valve Bodies out of Oklahoma.

https://xoutpost.com/1147132-post9877.html

All the symptoms are there......minus no lights on the dash. I thought it was 12V issues since the battery was very low upon initial diag. But the more test driving I gave it, the more the boat steered the other way. sigh. Kinda one of those where I know it, but I'll let the codes be the bearer of bad news. I looked it up. The same R&R was done 5 Years and 2 months ago

If one was to just do a #'s game, the cost might be the same or even cheaper than than ferrari-esque brake job.

I did find your post on the BBK brake job. Better than the actual Ferrari 458 carbon ceramic brake rotors at $15K for the fronts...

I have never found a need to upgrade the braking on my E46 or E53, I just don't drive fast in my own street cars anymore. My "need for speed" gets fulfilled by my job and I don't even have to pay for it... :D

New reman being delivered on Monday.

Be curious to see what normal volt readings look like on BC after pickup, but alt checks out clean. The 12.1 on the battery threw me off.


Aside from the Battery........I kinda knew it might be tranny as the final say before the trans failsafe fiasco. Rear Dif dropped this summer to reseal rear cover as well as output. I felt a small slip in reverse but I attributed to the rear axle just settling itself back in...