Quick question regarding voltages

Tools used for ECU reading and writing

Quick question regarding voltages

Postby Wod » Sat Feb 20, 2016 5:21 pm

Hello all, before I write my file back to my ecu. I was taking the precautions of battery charge.

Right now am charging my car battery with a charger and the charger currently reads 13.2v
However the onboard dash reads 12.5-12.6volts.

Battery is at the rear of the car, does this mean my battery has some kind of current stabilisation?
Charger is 14.4v output max so am worried as don't want to go above 14V

Should the dash voltage be more accurate?
Thanks

Wod
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Re: Quick question regarding voltages

Postby Mark » Tue Feb 23, 2016 12:46 pm

The only 100% accurate way is to measure voltage over the battery terminals. However depending on what charger you are using your battery voltage when connected will be different. I use a CTEK MXS25 and that in supply mode floats the battery voltage around 13.8v depending on temperature, sometimes slightly less, sometimes slightly more.

What car are you working on? I do a lot of BMWs that have the battery in the boot, but I connect to the jump start points under the bonnet and have no voltage issues.

Make sure you turn the power consumers off in the car too. Turn off the blower, and definitely don't sit there with the heated seats on! :lol:

Mark
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Re: Quick question regarding voltages

Postby Wod » Wed Feb 24, 2016 3:34 am

Thanks for your reply but I went ahead and did the flash.
I kept everything turned off and the charger on (voltage stayed between 12.7-13.8) however it seems to have caused a problem,

Sometimes now, my starter crank position on the key does nothing at all. It's very wierd I have thought maybee I need to reset the ews synchronisation?
Most of the time the car still works so I guess it can't be the modified file, otherwise car would not start ever would it?

It's a mini cooper s 2004 not a proper bmw just a baby lol
Cheers
Warwick

Wod
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