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High Voltage Battery Heating - NOT Possible cause of 12v battery drain
- Thread starter MaveRichard
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- #32
So how does one liquid cool (or warm) a battery?
One doesn't. Not directly.
But you can heat or cool the metal case and use the case as a heat sink.
Image with cover off, texture I will guess adds surface area for heat transfer. Red arrow is mine to depict water flow.
Image with cover installed.
P.S. the numbers are the order in which you are supposed to tighten the bolts.
One doesn't. Not directly.
But you can heat or cool the metal case and use the case as a heat sink.
Image with cover off, texture I will guess adds surface area for heat transfer. Red arrow is mine to depict water flow.
Image with cover installed.
P.S. the numbers are the order in which you are supposed to tighten the bolts.
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- Thread starter
- #33
I completely agree here. I appreciate you input and insight. You have more experience with battery temperature monitoring than I do.
With that being said, I am trying to keep this content fairly focused. The point of this thread was to discuss cold weather battery heating as it relates to parasitic battery drain.
There's a coolant temp sensor on the inlet to the HVB and an additional 6 thermistors in the pack.
FWIW the service manual makes no mention of any coolant heater existing for the HVB which might be sort of a critical flaw in your whole theory that it's contributing to 12V drain.
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- Thread starter
- #35
Thanks for your input. I have not seen the service manual so it sounds like you are likely correct. Interesting to note that it is specifically on the inlet side of the HVB.
I am trying to find a way the explain the behavior that I am seeing as it relates to problems with this platform. Open to being wrong here, just learning and sharing what I learn along the way.
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I believe that it warms the engine coolant on its way to the engine coolant battery coolant heat exchanger and possibly enters a mixing valve at the entrance to said exchanger. Resulting in the warmer loop or cooler loop whichever is needed being used first.
I have noticed that if I place truck in ready state but do not do anything else (when I just want to charge the 12v battery for 30 minutes or more) depending on temp or ? That occasionally you can hear what I believe to be the rather quiet running of presumably the battery heating/cooling fluid pump. When ice is running it cannot be heard due to ice sound but will turn off when it's no longer needed. I have watched my 12v soc with a dash power port monitor and when ambient temp is over 70°F 12v soc will drop 0.1v in 1-3 days and when ambient is below 60°F the drop is 0.2v in 1-2 days. So something is more frequent at lower ambient temps but nowhere near enough to significantly deplete 12v. Maybe running pump for few seconds to circulate ice coolant enough to equalize battery coolant to that of ice coolant (doubtful but has been posted that battery and engine coolant can be equal temps). It would be interesting to record 12v current overnight to see how much, when, and how often something is using power.
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- Thread starter
- #37
Feel free to PM this if you have a PDF copy…
- Banned
- #38
Keep in mind there is the engine coolant system and the "everything else" coolant system.
The HV battery, the motors, the transmission, the DC/DC converter, are all sharing the same "liquid".
But, just like arteries and veins, you can have cold hands and hot feet at the same time.
There is a complex of hoses and "zone valves".
The HV battery cooler and warmer are the same "pad" using the same liquid.
Which is why I think most of the time the liquid is stagnant.
I think it is very unlikely there is heating (or cooling for that matter) while the truck is parked, not running.
The HV battery, the motors, the transmission, the DC/DC converter, are all sharing the same "liquid".
But, just like arteries and veins, you can have cold hands and hot feet at the same time.
There is a complex of hoses and "zone valves".
The HV battery cooler and warmer are the same "pad" using the same liquid.
Which is why I think most of the time the liquid is stagnant.
I think it is very unlikely there is heating (or cooling for that matter) while the truck is parked, not running.
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- Thread starter
- #39
I wonder if we are just seeing the residual heat left in the system from a not-long-enough key off cycle. Thanks for the diagram @GPSMan - looks like you are looking at a copy of the service manual. Did you get this directly from Ford?
48* ambient this morning.
I am just going to monitor this as local temps continue to drop out of curiosity. It is pretty clear at this point that the truck is not actively heating the battery coolant at rest. I changed the title of the thread to reflect this.
48* ambient this morning.
I am just going to monitor this as local temps continue to drop out of curiosity. It is pretty clear at this point that the truck is not actively heating the battery coolant at rest. I changed the title of the thread to reflect this.
While powered off the BECM (Battery Energy Control Module) does carry out charge balancing of the HVB cells, but the manual suggests it only initiates that after 24 hours unused. Also that the battery back should reach approaching ambient temperature after 2 hours.
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- #41
Thanks to investigations sparked by this thread, I am convinced:
A) The HV battery coolant temperature displayed on a ScanGaugeIII is displayed 20°F above actual.
The 20 degree offset has been consistent day after day in a variety of operating conditions.
B) There is no active cooling of the HV battery at 95°F and below. At 96°F to 105°F internal battery temperature, passive cooling begins. Liquid is circulated at ambient, provided ambient is cooler than internal battery temperature.
C) At 106°F and above is the only time I have seen evidence of A/C refrigerant used to cool the battery coolant. This is rare for me and difficult to study as I live in relatively cool San Francisco.
The service manual states ideal temperature for the HV battery is 75°F to 95°F, and furthermore says up to 122°F is acceptable.
A) The HV battery coolant temperature displayed on a ScanGaugeIII is displayed 20°F above actual.
The 20 degree offset has been consistent day after day in a variety of operating conditions.
B) There is no active cooling of the HV battery at 95°F and below. At 96°F to 105°F internal battery temperature, passive cooling begins. Liquid is circulated at ambient, provided ambient is cooler than internal battery temperature.
C) At 106°F and above is the only time I have seen evidence of A/C refrigerant used to cool the battery coolant. This is rare for me and difficult to study as I live in relatively cool San Francisco.
The service manual states ideal temperature for the HV battery is 75°F to 95°F, and furthermore says up to 122°F is acceptable.
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- Thread starter
- #42
Thanks for sharing about the BECM. I am seeing the Battery pack temps approach ambient in around that 2 hour timeframe. Battery Coolant seems to take much longer.
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- Thread starter
- #43
A) I am still not convinced this is the case, simply due to them trending towards the same number over longer drives. It is possible of course. My theory is that battery coolant is simply not circulated unless the delta between coolant and battery temp becomes too great (~20*).
B) Agree.
C) I have never seen anything over 103 battery temp since monitoring.
We're learning! And even better - this is all publicly searchable and available as these truck age and begin to have more complex problems.
- Banned
- #44
I'm not sure what you mean here.
My battery is at ambient after sitting overnight.
My battery went from 59°F (same as ambient outdoor air) to 97°F in 27 minutes driving 11.3 miles to work over level terrain with 10 or 12 stoplights. Ambient air at the end was 61°F.
- Banned
- #45
If there is 20 degree offset in the battery coolant line, does this chart still make sense if the blue line was 20 degrees lower? Aka chilled water hovering about 80°F vs the 100°F?
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