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The Battery Tender on my 997 went bad and stopped charging the battery over a 3 week period when I wasn't driving the car, and it went completely dead, like dead...dead... no window drop, no interior lights, no nothing.
Anyway, I used the fuse pull out, popped the frunk, disconnected the battery, and hooked up my large Smart Optima AGM charger.
Seems to have charged the Optima yellow top just fine, so maybe the battery isn't toast, but I had this Battery Sense BT voltage monitor lying around from our old BMW X5 that had lots of electrical issues I was monitoring to resolve.
Anyway, I put this on my battery when reconnecting everything just to see how much voltage drop I get over 24, 48, 72 hours etc and it doesn't seem to be too significant - maybe 3% per 24 hour period. The car is back on a different Battery Tender and I occasionally look at the status monitor....
So, here's the reason for the post - the car is not locked so subsystems are still active. About once every day, something fires up and causes a voltage dip.
I'm just curious if anyone knows what causes that. Out of curiosity, I may lock the car just to see if that prevents the event from occuring.
Hope that you won't feel offended by my comment since I always have the upmost respect for your knowledge and insights, just curious as to why you haven't incorporated this alternative.
Pete just a mention that I had issue on one of my past 997's with Voltage drop due to faulty wiring/grounding in the front trunk light.
Wouldn't hurt to check it out.
Hope that you won't feel offended by my comment since I always have the upmost respect for your knowledge and insights, just curious as to why you haven't incorporated this alternative.
I've had to open the frunk probably 5x this way. Since it always works for me, I've not done the release cable - have one in the back for the engine lid.
Personally, I think that for the people the pull out doesn't work, they're actually not doing it right.
Pete just a mention that I had issue on one of my past 997's with Voltage drop due to faulty wiring/grounding in the front trunk light.
Wouldn't hurt to check it out.
You know, I have an LED light up there. Wonder if the car is pinging it occasionally since the resistance is lower.
I'm just curious if anyone knows what causes that...
Here's a typical 24 hour period of voltage drop while NOT "tended" and LOCKed. I have an Optima Yellow. Seemingly, no voltage dip.
I just visited the garage to unlock the car (and I opened a door to hopefully keep it from auto-locking). I'll grab a new 24-hour period tomorrow.
Here's a typical 24 hour period of voltage drop while NOT "tended" and LOCKed. I have an Optima Yellow. Seemingly, no voltage dip.
I just visited the garage to unlock the car (and I opened a door to hopefully keep it from auto-locking). I'll grab a new 24-hour period tomorrow.
Thanks for the input and great comparison since we both have the same battery! No voltage spike (what do you call a reverse spike for 2 seconds) on yours, but lots of little activity events there. That slow decrease is what mine looked like to when I was monitoring it untended but think it was decreasing faster than yours. I wonder if the Sprint Booster plugged into my OBD port has any draw (the display is not on).
Anyway, it's interesting.
Will probably drive the car to my son's track meet tonight, which will also let me run the Cranking Test in the app. When I get back, think I'll leave it unplugged and lock it to see what that chart looks like.over the next 2 days since it's going to rain this weekend and I won't be using it.
That is really odd. So I guess you know the drill, first disconnect anything added on... run the test, then I guess pull half the non-switched fuses, then the other half of non-switched fuses, and start narrowing it down. Or one fuse per night.
That is really odd. So I guess you know the drill, first disconnect anything added on... run the test, then I guess pull half the non-switched fuses, then the other half of non-switched fuses, and start narrowing it down. Or one fuse per night.
Interesting...
Peace
Bruce in Philly (now Atlanta)
I'm not really too concerned about resolving the low draw - I just found it interesting and thought it would make for a good discussion. This car never sits anywhere for more than 3 days and rarely even does an overnight where it's not in the garage and on the Tender. I just decided to monitor the battery because I was concerned it wouldn't fully charge or hold a charge after deeply discharging it so completely, but maybe these Hybrid Starting/Deep Cycle Yellow tops can take some discharging abuse and recover, unlike a normal starting battery. In the Optimas, Red Tops are starting batteries, blue tops are deep cycle, and these yellow tops are a new hybrid design between the two.
I've had to open the frunk, probably 5x this way. Since it always works for me, I've not done the release cable - have one in the back for the engine lid.
Personally, I think that for the people the pull out doesn't work, they're actually not doing it right.
When in doubt, heading to a track meet, parking in a lot where you don't have a DC power supply ... That's when the cable is nice. You might still need a jump, but at least you have the frunk open.
I agree, people who have trouble with the pull out tab aren't doing it right. But even with that tab, you're still counting on the front computer (which can get damaged by externally induced static) and the solenoid working to get the frunk open. I've seen both of those things fail in one way or another on various cars.
I used Optima on some of the portable lift equipment we designed. They were always great. I read about some problems when they moved their plant. That was years ago. The hybrid design of the yellow top is most likely fine. Fingers crossed.
As far as the drain based on potential polling going on, it's hard to read the minds of software engineers and what they might be looking at based on alarm systems, motion sensors, determining sleep mode, determining system setting values, and who knows what else.
Good points Wayne. I took a pair of jumper cables with me just in case i need to pop the frunk and jump the car using another vehicle.
Starting event shows borderline voltage even though the starter is still spinning super fast since I replaced it and made that custom starter to alternator cable. I like to see at least 9.6v but this was close.
First drive since the dead battery so had the normal PSM error, less than smooth idle, and had to retrain the window limits, but the idle smoothed out once the DME readjusted and the car drove fine.
Voltage was anywhere from 13.65 to 13.8 while driving and I've seen lower voltages like this when the battery is fully charged before a drive. I'll see what the cranking test and voltage show after it sits at the track meet for a few hours and I use all the lights on the way home.
So, here's the reason for the post - the car is not locked so subsystems are still active. About once every day, something fires up and causes a voltage dip.
I'm just curious if anyone knows what causes that. Out of curiosity, I may lock the car just to see if that prevents the event from occuring
There are Battery chargers that stop charging at certain intervals in order to measure the battery voltage, That causes a expected dip in the battery voltage.
There are Battery chargers that stop charging at certain intervals in order to measure the battery voltage, That causes a expected dip in the battery voltage.
Regards
Hans
You know, that's probably it as these are smart Battery Tenders. It is probably going to float mode and taking a measurement to determine if it should monitor or charge at low amperage again.
02-29-2024, 12:13 PM
Voltage Drop Event ?
