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      12-30-2020, 01:40 AM   #1
tankertoad
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Battery charger during ECU flash?

I have an AA tune and need to flash back to stock for emissions. I have the Simon cable and the file but AA specifies this requirement for the flashing procedure:

"Put a battery charger on the car (voltage above 12.5 volt Amps above 10 A) stable voltage. Do not use a trigger or battery jumpers (those aren't powerful enough to hold stable voltage for long periods)."

Has anyone done this with a consumer grade charger? Some say over 10 A charging but only 2-6 A maintain and I don't know which number to use. I don't want to fry my ECU and don't want to purchase a roll around shop level charger for a single application.
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      12-30-2020, 06:25 AM   #2
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Quote:
Originally Posted by tankertoad View Post
I have an AA tune and need to flash back to stock for emissions. I have the Simon cable and the file but AA specifies this requirement for the flashing procedure:

"Put a battery charger on the car (voltage above 12.5 volt Amps above 10 A) stable voltage. Do not use a trigger or battery jumpers (those aren't powerful enough to hold stable voltage for long periods)."

Has anyone done this with a consumer grade charger? Some say over 10 A charging but only 2-6 A maintain and I don't know which number to use. I don't want to fry my ECU and don't want to purchase a roll around shop level charger for a single application.
Did you remove hardware like headers? Should not need to flash back to stock if the AA tune is just that. Most places don't have the ability to detect a simple software tune. Check with AA

With a good battery I've flashed with no charger attached but you can't have any accessories running like your stereo or AC blowers.

In the old days, using stupid flashing tools I monitored the battery drain at 20-25 amps. So if you have some crazy slow flashing tool and you don't trust your battery, that's what you need.
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      12-30-2020, 08:56 AM   #3
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I've flashed my car 2 times (Stage 1 BPC, StageFP Tune for 3SIM) and both times I made sure that I had first driven the car for a good 30 minutes to ensure the battery was well charged up from driving and then attached a trickle charger (CTEK 4.3) and let the battery condition get up to stage 7 on the charger. Then I flashed the car, but made 100% sure everything including ac/blower, radio, lights etc were all off.

I flashed it sitting inside the car with the window open but doors closed (as you must).

First time was with an older/original battery (maybe 6 years old), second time was with a fresh battery maybe 1 year old.

Generally if you have access to a proper charger then use it, otherwise if you have a good condition battery and a trickle charger, and the flasher isn't going to take an hour you should be fine.

It's still a bit nerve wracking though lol.
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      12-30-2020, 03:21 PM   #4
tankertoad
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Quote:
Originally Posted by rjahl View Post
Quote:
Originally Posted by tankertoad View Post
I have an AA tune and need to flash back to stock for emissions. I have the Simon cable and the file but AA specifies this requirement for the flashing procedure:

"Put a battery charger on the car (voltage above 12.5 volt Amps above 10 A) stable voltage. Do not use a trigger or battery jumpers (those aren't powerful enough to hold stable voltage for long periods)."

Has anyone done this with a consumer grade charger? Some say over 10 A charging but only 2-6 A maintain and I don't know which number to use. I don't want to fry my ECU and don't want to purchase a roll around shop level charger for a single application.
Did you remove hardware like headers? Should not need to flash back to stock if the AA tune is just that. Most places don't have the ability to detect a simple software tune. Check with AA

With a good battery I've flashed with no charger attached but you can't have any accessories running like your stereo or AC blowers.

In the old days, using stupid flashing tools I monitored the battery drain at 20-25 amps. So if you have some crazy slow flashing tool and you don't trust your battery, that's what you need.
I did remove the headers but since the tune turns off the secondary O2s, my CAT isn't showing "ready" even after driving several hundred miles. Hence, my desire to flash to stock.

I found a charger that allows one to select 10A and "maintenance mode" so I think I'll be ok once I disable the DRLs.
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      01-01-2021, 09:46 AM   #5
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I used a 20A consumer grade battery charger when I flashed my car back to stock, updated modules with WinKFP, and then flashed the new Stagefp tune on the car.

Like mentioned before, make sure to charge the battery for a while before you begin and keep all accessories off. I also pulled the fuel pump fuse after the first operation because the process ended up running the fuel pump the entire time it was working, not great...
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      01-02-2021, 12:14 AM   #6
tankertoad
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The process took a little over eight minutes with no issues. I did drive it beforehand and used a 15A charger.

Just curious, what sound does the fuel pump make to indicate that it's running?
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      01-03-2021, 01:52 PM   #7
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When you unlock the car or open the door and hear the noise that comes on real quick, that is the fuel pump pressurizing the system so that it starts right up with the push button.

You can also prime the fuel pump by pushing the start button twice without starting the car.
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