External Power Source During Programming

[unk045]

Gentlemen,

I'm trying to minimize voltage fluctuation while programming the car to avoid any issues.

Would connecting my car with jumper cables to another car help with this? What should the voltage be around? Should I do it from the front or the back if that matters?

Thank you in advance.

[CH400EM]

Originally Posted by unk045

Gentlemen,

I'm trying to minimize voltage fluctuation while programming the car to avoid any issues.

Would connecting my car with jumper cables to another car help with this? What should the voltage be around? Should I do it from the front or the back if that matters?

Thank you in advance.

Use a battery tender if possible. Battery Tender brand is good, especially the 5amp model. This is preferred for numerous reasons as the vehicle's electrical systems will not experience surging.

The positive connection and ground post under the hood should be used since there are electrical control units connected to the battery in the trunk.

Best of luck with the coding!

[tracer bullet]

Agreed to both of the above!

[gjm120]

Originally Posted by unk045

Gentlemen,

I'm trying to minimize voltage fluctuation while programming the car to avoid any issues.

Would connecting my car with jumper cables to another car help with this? What should the voltage be around? Should I do it from the front or the back if that matters?

Thank you in advance.

I may be off here, but I think if you are doing real programming (as opposed to coding) you might need a power source beyond a battery charger/maintainer. Losing electrical power while programming can do so ugly things to modules.

Have a look at the coding sub-forum over on E90 post and do some more other digging into this.

[MINIz guy]

Jumper cables and the charging supply from another vehicle won't be very stable.

I just checked AA's flashing instructions and they ask for 3A minimum. So a battery charger will work, but not a trickle charger/maintainer.

[tracer bullet]

Originally Posted by gjm120

I may be off here, but I think if you are doing real programming (as opposed to coding) you might need a power source beyond a battery charger/maintainer. Losing electrical power while programming can do so ugly things to modules.

Good point.

[MightyMouseTech]

Originally Posted by CH400EM

Use a battery tender if possible. Battery Tender brand is good, especially the 5amp model. This is preferred for numerous reasons as the vehicle's electrical systems will not experience surging.

The positive connection and ground post under the hood should be used since there are electrical control units connected to the battery in the trunk.

Best of luck with the coding!

Need a lot more than 5 amps. You want the car to stay at 13.8V. Usually takes around 30-40 A to do that. The newer G cars can require 60-80 A.

[JimD]

I have not coded in over 5 years. But I did it successfully without any external power supply. I just hooked up my cable and laptop and made the changes. It should not take a long time, maybe 10 minutes.

I do not see a problem with hooking up a charger if you want to be sure you don't go too long and deplete the battery. But I don't think it is always necessary - I did not and it worked. I changed a couple settings so I can put my top down with the key fob as I walk up to my e88, enabled the digital speedometer the M cars have and too the "correction" off of it, and set the doors to unlock when I remove the key fob from the dash. Just a few little changes.