Parasitic Draw "Solution" - Install a 12v battery disconnect switch?

[mhw21zap]

Hello,

I recently experimented with disconnecting my 12v battery's negative terminal while out on a camping trip. I brought my Hulkman 2000A jump starter, 2 Amp battery maintainer + my portable battery pack (Ecoflow River) as a precaution. However, when getting in and out of the car repeatedly, I got worried about my battery drain and just disconnected my negative terminal under the rear seat. I did this each night of the trip and it worked well.

Side-Effects? None (thus far lol)

I was worried about my computer reset, but at least for now, I didn't notice anything different. Not that I care - but my radio presets, Bluetooth to my phone, current mpg / odometer, etc. - they all returned to normal each time.

However, I think an easier work around would be to just install a battery disconnect switch. This would free me up from having to pull out a wrench and remove the terminal post each time I need to disconnect / reconnect my battery every time.

Has anyone else done this yet? I don't plan on disconnecting the 12V (-) unless I'm out in nature, away from an outlet to keep my battery maintainer, this is only for when I have no better option and can't risk getting stranded in the middle of nowhere. What do you guys think of this? Something like a knife-blade disconnect switch like this(?)

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[GingerMan512]

I was thinking of connecting a solar battery tender to the 12v in the truck bed holding it in with some strong magnets. Are those leads always on?

 

[Rod]

What the hell am I missing here? There should be NO need for a disconnect or battery minder. The car needs to be fixed. Have you just decided to live with it?

 

[GPSMan]

Hello,

I recently experimented with disconnecting my 12v battery's negative terminal while out on a camping trip. I brought my Hulkman 2000A jump starter, 2 Amp battery maintainer + my portable battery pack (Ecoflow River) as a precaution. However, when getting in and out of the car repeatedly, I got worried about my battery drain and just disconnected my negative terminal under the rear seat. I did this each night of the trip and it worked well.

Side-Effects? None (thus far lol)

I was worried about my computer reset, but at least for now, I didn't notice anything different. Not that I care - but my radio presets, Bluetooth to my phone, current mpg / odometer, etc. - they all returned to normal each time.

However, I think an easier work around would be to just install a battery disconnect switch. This would free me up from having to pull out a wrench and remove the terminal post each time I need to disconnect / reconnect my battery every time.

Has anyone else done this yet? I don't plan on disconnecting the 12V (-) unless I'm out in nature, away from an outlet to keep my battery maintainer, this is only for when I have no better option and can't risk getting stranded in the middle of nowhere. What do you guys think of this? Something like a knife-blade disconnect switch like this(?)

There are better and safer options, I think. I use these on off highway equipment:

A little bit of security factor too.

 

[GPSMan]

FYI-

Mine is acting odd.
I left it in park, key to running for almost 4 hours. I wanted to see if the DC/DC would top off the 12v battery. It wouldn't.

Seems Ford thinks the 12v battery should stay "medium charged" all the time, just like the hybrid battery.

The hybrid battery is kept 30% to 70% (so much of the time around 50%) on purpose.... for longevity. Any logic at all to keeping a 12v lead-acid battery at medium charged all the time? In mine, I'm watching it closely... seems to be doing this intentionally.

Long trips, lots of opportunity to top off the 12v battery, it just won't do it.

Based on voltage alone, my 12v battery hovers about 60% charged.
I can't get it to go up, but it's not going down either.

But for those camping or "tinkering" leaving the doors open, lights on, or radio playing, this means 40% less capacity from an already small-ish battery.

 

[MakinDoForNow]

FYI-

Mine is acting odd.
I left it in park, key to running for almost 4 hours. I wanted to see if the DC/DC would top off the 12v battery. It wouldn't.

Seems Ford thinks the 12v battery should stay "medium charged" all the time, just like the hybrid battery.

The hybrid battery is kept 30% to 70% (so much of the time around 50%) on purpose.... for longevity. Any logic at all to keeping a 12v lead-acid battery at medium charged all the time? In mine, I'm watching it closely... seems to be doing this intentionally.

Long trips, lots of opportunity to top off the 12v battery, it just won't do it.

Based on voltage alone, my 12v battery hovers about 60% charged.
I can't get it to go up, but it's not going down either.

But for those camping or "tinkering" leaving the doors open, lights on, or radio playing, this means 40% less capacity from an already small-ish battery.

If l leave either one of mine in ready state for hour and half my battery will show 12.6 after several minutes of being off though I have not checked it an hour or two after that to see what it settled at. I think you may need to charge the 12v then run a de sulphate cycle. Could it be possible that you need to run the "up to 8 hour with the truck locked and undisturbed relearn soc of 12v" mentioned in manual? Sounds like you have the condition I am living in fear of.
Could it be possible that you did a bms reset when your battery was at 60% and the bms somehow thought that was the max soc of your 12v so that's where it's stopping the charge?

 

[GPSMan]

If l leave either one of mine in ready state for hour and half my battery will show 12.6 after several minutes of being off though I have not checked it an hour or two after that to see what it settled at. I think you may need to charge the 12v then run a de sulphate cycle. Could it be possible that you need to run the "up to 8 hour with the truck locked and undisturbed relearn soc of 12v" mentioned in manual? Sounds like you have the condition I am living in fear of.

Interesting... will look into this... Thanx

 

[OleFordGuy]

What the hell am I missing here? There should be NO need for a disconnect or battery minder. The car needs to be fixed. Have you just decided to live with it?

I would agree. But based on the number of post on this forum related to hybrid battery drain, batteries, jump charges, battery maintainers, cables, etc. it seems ford and dealers have a difficult time curing the problem so their forced to buy things to keep from being stranded. Luckily, many hybrid owners don't have the issue, but then some do. It's a mystery

 

[mhw21zap]

If l leave either one of mine in ready state for hour and half my battery will show 12.6 after several minutes of being off though I have not checked it an hour or two after that to see what it settled at. I think you may need to charge the 12v then run a de sulphate cycle. Could it be possible that you need to run the "up to 8 hour with the truck locked and undisturbed relearn soc of 12v" mentioned in manual? Sounds like you have the condition I am living in fear of.
Could it be possible that you did a bms reset when your battery was at 60% and the bms somehow thought that was the max soc of your 12v so that's where it's stopping the charge?

Hmmm that's an idea. So then perhaps I should do another BMS reset after a very long day of driving?

 

[MakinDoForNow]

Interesting... will look into this... Thanx

I edited my post and added to it. Plus this now.
I had a Honda civic for 11 years that would eat a 12v in 24-32 months. The fourth battery I would charge them de sulphate every 4-6 months and it lasted 64 months when I gave car to granddaughter.
If you take your battery out think about weighing it in grams. I would not be surprised that it may be boiling off electrolyte since it will charge from 11.8-to 12.6 so dam rapidly???

 

[GPSMan]

I don't know how to weigh something that heavy full of (Pb) in grams.

Would be interesting tho.

It's probably a Federal offense to carry a car battery into a Post Office, being both a chemical, and hazardous.

 

[MakinDoForNow]

Hmmm that's an idea. So then perhaps I should do another BMS reset after a very long day of driving?

Maybe, I don't know. It appears to me that gpsmans truck stops charging at 60% so the 12v may need to be separately charged to 100%. I had a 12v in a Honda CR-V that I charged and ran repair cycle on with a 5amp noco genius. It took six days to complete. The last 2% takes a long time due to waiting between the HV zaps.

 

[mhw21zap]

What the hell am I missing here? There should be NO need for a disconnect or battery minder. The car needs to be fixed. Have you just decided to live with it?

Yes, for the time being I have decided. I've been to 2 dealerships and had my truck in for service on 3 separate occasions. More than 17 days in the Ford Service department in total and I've yet to have one mechanic, service assistant or service manager even be willing to tell me what COULD be causing the problem. I've had to fight just to get paperwork documenting what they did during the 17 days they had it (*nothing more than measure the voltage, let the truck die, jump start it a few days later and then call me to say "hmm we can't figure out what's causing it")

I printed out the recent SSM 51598 and demanded they at least look into the possible 300 amp fuse being the culprit. "We don't see any codes, and therefore, we can't just go searching"

I'll start pulling fuses myself while hooked up to ammeter and hopefully address where it might be coming from. I'm completely hopeless. I've tried everything from deleting apps, removing my phone from bluetooth, driving in "Low", turning off all audio and volume, not using A/C, not locking the car vs keeping it locked, I bought signal blocking key boxes, I parked 50 yards away from my house, you name it.

I even had Ford Corporate open an investigation into my dealership.
I'm stuck in this awful situation where I have a truck that I LOVE, but I'm forced to live with this battery drain.

 

[MakinDoForNow]

I don't know how to weigh something that heavy full of (Pb) in grams.

Would be interesting tho.

It's probably a Federal offense to carry a car battery into a Post Office, being both a chemical, and hazardous.

Probably illegal. Most likely ounces would disclose what we need. My bathroom scale weighs in tenths of pounds. But what did it weigh new? I grew up in grandpas lumberyard about five blocks from a hospital about four times a year they would send someone to be weighed on our scales because theird wouldn't weigh over 350-400lbs.

 

[GPSMan]

for my 3.x hour test with truck parked and "ready" the ScanGauge showed this:

14.6 volts and 0 amps flowing.
Sure. Ok. Fine. For nearly four hours.
Actual voltage measured at the battery was even higher.

Seconds after turning the key off nets this confusing result:

And slightly higher here:

Then, turning on the headlamps nets:
(Might have been headlamps and more; I forget. But was just for a minute.)

and

Not sure what to make of this.
But does not make me feel like this is "healthy". Your take?

The following morning (you can tell ambient was 61 degrees also )

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