Battery drain - looking for help and ideas

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Igor Sakhnov

Igor Sakhnov

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Turning auto update and wifi hotspot off in SYNC had dropped steady state draw to 0.066A that should in theory be well within normally supported draw.
On the other side, two months old battery (optima yellowtop) is not able to hold the starting charge for 12 hours anymore. I did try and it had no problems starting three times in a row after 30 minutes drive while failing to crank and requiring to jumpstart just before the trip. I would conclude that alternator is highly unlikely to be a culprit here.
I think it is about time to find a shop to figure out what is really going on here :(
 

The Car Stereo Company

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first off, are you sure the alternator is charging the truck? did you do a bms reset on the truck? check those first. otherwise go look for a car audio shop to double check your wiring. if its clear, then check the dealer for the electrical issue. you can have a car audio shop check it, but if the truck is under warranty and the electrical connections you made are good, then it should be a warranty related issue.
 

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first off, are you sure the alternator is charging the truck? did you do a bms reset on the truck? check those first. otherwise go look for a car audio shop to double check your wiring. if its clear, then check the dealer for the electrical issue. you can have a car audio shop check it, but if the truck is under warranty and the electrical connections you made are good, then it should be a warranty related issue.
I don’t think anyone asked about FORSCAN.

Any chance you’ve used FORSCAN to turn off auto stop /start, nav in motion(?) or any of the other mods that DISABLE BMS ?

Good suggestion about resetting BMS too.
 

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Factory battery draw spec is 0.050A after all systems have powered down.

Any chance you’re using a 3rd party phone app to control vehicle lock/unlock/remote start? I wasn’t aware those even existed, but there is a service message that they will cause battery drains due to keeping the vehicle awake.
 
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Igor Sakhnov

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I don’t think anyone asked about FORSCAN.

Any chance you’ve used FORSCAN to turn off auto stop /start, nav in motion(?) or any of the other mods that DISABLE BMS ?

Good suggestion about resetting BMS too.
Yes, I did use FORSCAN to turn off autostop and tweak couple of other options like mirrors. Will go and restore to original settings today.

Any guidance on how to reset BMS?
 
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Igor Sakhnov

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Factory battery draw spec is 0.050A after all systems have powered down.

Any chance you’re using a 3rd party phone app to control vehicle lock/unlock/remote start? I wasn’t aware those even existed, but there is a service message that they will cause battery drains due to keeping the vehicle awake.
Nope, no 3rd party apps. Measured this morning to be at 0.067A and I would expect this to be close enough to 0.050A to be the reason.
 
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Igor Sakhnov

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first off, are you sure the alternator is charging the truck? did you do a bms reset on the truck? check those first. otherwise go look for a car audio shop to double check your wiring. if its clear, then check the dealer for the electrical issue. you can have a car audio shop check it, but if the truck is under warranty and the electrical connections you made are good, then it should be a warranty related issue.
Voltage jumps from 12V to 14V on start and holds at 14+ while idling.

On the BMS reset, I will search for guidance but would appreciate if you have some handy. Thanks!
 
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Igor Sakhnov

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So, found and performed following
  1. Switch ignition on (engine off)
  2. Pull and release high beam 5 times.
  3. Press and release brake pedal 3 times.
  4. If successful the battery light will flash 3 times within the next 15 seconds.
  5. BMS reset completed
 

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except you disabled BMS by turning off Auto-stop/start via FORSCAN. I had to disable As/s to keep from scramming my amps on restart, but I used the expensive dongle from CJ Pony. I would disable that FORSCAN mod FIRST because you can reset a disabled feature all you want and it won’t have any effect. Use sport mode or just keep pressing the button. Heck, you can jumper the disable switch if it’s that big of a deal.

It’s been a while, but I believe the master FORSCAN spreadsheet identifies which mods suppress BMS.
 
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Igor Sakhnov

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except you disabled BMS by turning off Auto-stop/start via FORSCAN. I had to disable As/s to keep from scramming my amps on restart, but I used the expensive dongle from CJ Pony. I would disable that FORSCAN mod FIRST because you can reset a disabled feature all you want and it won’t have any effect. Use sport mode or just keep pressing the button. Heck, you can jumper the disable switch if it’s that big of a deal.

It’s been a while, but I believe the master FORSCAN spreadsheet identifies which mods suppress BMS.
thanks, will restore all to the original state shortly and try again. I guess I will have to look at CJ Pony, last time I chose an easy route of note disassembling the console.
 
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