“For now, you might consider just measuring the resting battery voltage”, I do measure (see my previous post), I know the voltage very well. Now I need to know the parasitic current draw at a nominal steady state condition.
“Just to be clear, a battery should never get anywhere near 10.5V/0% SOC”
Yes but that’s the danger of letting the vehicle sit without sufficient driving for long enough (a few minutes of driving is no where near good enough) especially if the battery is say around 60% SOC with insufficient drive time so the battery is going to drain.
That’s why I want to know the parasitic current draw.
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From the Amazon page:I keep one of these plugged in (below the 8” Display. It’s going to have a small voltage drop because it’s not measuring at the battery so is more of a “quick and dirty” test. When I know the battery is low I will video the device as I start the vehicle to see how low the voltage goes while starting.
https://a.co/d/glj6YK9
Was $13.59 during Amazon sale days last summer
"Bright LED display monitor the voltage of the vehicle's battery with high accuracy (+-0.2Volt)."
Needless to say, it is not reasonable to expect (say) +/-0.01V accuracy from a $17 device, but +/-0.2V is quite a spread. If the actual voltage is 12.4V, the meter might read anywhere from 12.2 to 12.6V -- or 60% SOC to 100%.
Still, if the readings are consistent and repeatable it could be helpful (even if it is not particularly accurate).
Measuring the minimum voltage while starting might be difficult. In fact, it's hard even with many expensive Fluke meters. For example, my meter has a "min/max" function, but in addition to that, what's needed is a fast sampling rate. IOW, the minimum voltage displayed probably will not be the actual minimum -- unless you get lucky -- and there's no way to know.
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No harm in that. It sounds like the current varies. If so, getting an average for you calculations might be difficult.
Ideally, a data logger would be used to keep track of the current continuously over time. I'm not suggesting anyone do that -- just that whenever a factor varies, measuring it over a period of time is best.
It may be that once the BS calms down, the parasitic draw is fairly constant.
With older cars it was easy because the amp draw was steady.
So the battery voltage will drop to 10.5V (0% SOC) if the BS sits long enough? IDK, I'm asking. I thought the BMS would intervene before it got that low. Although, the Ford info you posted mentioned both 9.5V(!) and 40% as lower limits, so who knows?
Yep I agree with all that and it’s the quick and dirty ballpark measurement that I use for
trends not for knowing 12.6 vs 12.5
My Electrical Engineering degree comes in handy occasionally ?
Yes, once the BS settles down, parasitic current draw is fairly constant (it will spike during a long period of time whenever it performs its housekeeping tasks like scanning for WiFi, software updates and so on)
We really do not know how the BMS behaves, there are various clues like the two Ford articles posted in an earlier thread, some info in the owners manual, some from master techs that have posted videos and some from conversations I’ve had with the Ford service department mechanics who work on the electrical system.
It is evident that the BMS does not behave all that well just based incidentally on owners reporting their Bronco Sport died dead while they were driving (read through this thread for example: https://www.broncosportforum.com/forum/threads/2021-ford-bronco-sport-issue-spurs-nhtsa-investigation-battery-failures.10562/)
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I've done it again! Unknowingly giving advice to someone with an EE degree.
This has happened at least twice before over the years.
It’s all ok … am always learning new things from interactions!!I've done it again! Unknowingly giving advice to someone with an EE degree.
This has happened at least twice before over the years.
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Sometimes I wish forums would have people put their experience and/or credentials below their avatar.
It's sometimes hard to tell. For example, I just got a new Denon receiver (nothing fancy) and it's having an intermittent problem processing 2 channel (stereo) PCM signals. Denon was no help (although they tried). I've read the relevant sections of the manual (no help), so I started a thread on the AVS forum (after searching the forum). I've been interested in pro and consumer audio since the 1970s, and I'm a technician, but the guys responding to my post don't know that. So their replies are sort of simplistic.
In any case, it's a common problem on forums. A member asks a question, and others might assume their knowledge level is lower than it is.
I took the car into the dealer yesterday. They did a check , load tested the battery, and checked for vampire drain. They came up empty, and said the battery is fine.
Last Friday, I had an appointment for an overnight stay. The car battery was fully charged according to my battery maintainer. Yet, when I left the facility 26 hours later, my Torque Pro app indicated the battery was at 44%. That's disturbing. If I could, I'd disable Ford Pass. I disabled the auto update when I got delivery of the car.
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Assuming your battery did indeed pass a load test, this:
does not fit with this:
IF your battery is good there is clearly some kind of vampire drain occurring. I would have your battery tested by another shop.
@RushMan It would be very informative if your service department could tell you how many milliamperes of parasitic current drain (vampire drain) they measured in nominal condition after the vehicle has settled down. It probably is fairly high for you to experience the problems you are having given they stated your battery is fine assuming the charging system is also fine. Any chance you could ask your dealership for that parasitic current drain information?
Torque Pro App .. not familiar with that but will look it up
@RushMan which OBD2 Device do you have installed and working with your Torque Pro App?
Reason I ask is you may want to check the user manual or specs for your OBD2 Device for current draw while plugged into the vehicle. I have seen several products (e.g.Veepeak OBDCheck BLE+ Bluetooth 4.0 OBD II Scanner for iOS & Android) with enough current draw that the instructions say to not leave plugged in the vehicle for more than one week.
In your case the battery dropped from ~100% to 44% in 26 hours which is pretty fast but it’s possible your OBD2 Device (which probably is using Bluetooth) might be draining the battery.
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