- Tue May 12, 2020 8:53 am
#42797
Thanks David.
I can see now I left out an important part of this.
The Battery will get with in 2/10 but takes a while. and the battery is dropping volts with each ancillary turned on but will get back to near charging voltage but over time. With the alt connection the recovery is minimal time.
The battery is like a big capacitor, it takes time to discharge and takes time to charge.
Any knowledge on this latest craze of large supper capacitor banks for main battery?
Looks promising and they charge/recover much quicker. Yes there are faults with the cap main battery idea.
Also the problem is much less with higher RPM.
I tried large jumper cables as a temp bypass, tried a known good battery, hooked up my good 25 amp charger and two different alts.
Yes voltage drop will create issues with voltage correction and temporarily with tune a little.
Now that it is hooked up to the alt out put the issue is gone from the ECU. Probably a compromise work around, but it worked.
This is a very minor issue but I enjoy finding these little things that make over all tuning better.
Tuning is now hitting target AFR just with auto tune with road tune and MLV agrees with the data.
I can now see timing and afr faults with the O2 and EGT and I just change the timing and or the target AFR until it all looks good.
I think perhaps what I am working on and what you just posted can help others here to first look to see if the ecu voltage is good and help them fix it as it will make a difference with your tune.
It was only a minor issue but they all matter.
Thanks David.
Always good to get your input.
Black Knight
PSIG wrote: ↑Tue May 12, 2020 6:45 am I would say your voltage drop is far too high and may be causing some corrections issues. There are many references online, but for high-amp connections we aim for 0.1V drop, with 0.2V maximum in the race cars and trucks. We have exception for high-amp starter circuits (drop through the relay) of 0.3V while cranking. Typical generic automotive standard for alternator-to-battery drop is 0.4V maximum under running load (lights, fan, etc) at cruise-range rpm, but we like to see much less. I would look for connection or cable issues (positive and ground), and test the battery for condition or damage. Your battery should be acting as a large stabilizing capacitor (a good thing), with little voltage difference from the alternator.
To carry it a step further, we use a separate voltage-sense wire from the main power junction to the voltage regulator. It is minimum 18AWG even though it carries no current, for minimal effect on voltage. This allows the regulator to respond quicker to system loads and to adjust regulated voltage to compensate for any increased voltage drop. If the drop increases 0.1V, then the regulator outputs 0.1V more so the system is maintained at full voltage.
Look at it this way - with a 1.2V drop, your alternator isn't even charging the battery until it is nearly 14V output. You might want to look into adding something similar in your system after fixing any issues you find. Good luck!
Thanks David.
I can see now I left out an important part of this.
The Battery will get with in 2/10 but takes a while. and the battery is dropping volts with each ancillary turned on but will get back to near charging voltage but over time. With the alt connection the recovery is minimal time.
The battery is like a big capacitor, it takes time to discharge and takes time to charge.
Any knowledge on this latest craze of large supper capacitor banks for main battery?
Looks promising and they charge/recover much quicker. Yes there are faults with the cap main battery idea.
Also the problem is much less with higher RPM.
I tried large jumper cables as a temp bypass, tried a known good battery, hooked up my good 25 amp charger and two different alts.
Yes voltage drop will create issues with voltage correction and temporarily with tune a little.
Now that it is hooked up to the alt out put the issue is gone from the ECU. Probably a compromise work around, but it worked.
This is a very minor issue but I enjoy finding these little things that make over all tuning better.
Tuning is now hitting target AFR just with auto tune with road tune and MLV agrees with the data.
I can now see timing and afr faults with the O2 and EGT and I just change the timing and or the target AFR until it all looks good.
I think perhaps what I am working on and what you just posted can help others here to first look to see if the ecu voltage is good and help them fix it as it will make a difference with your tune.
It was only a minor issue but they all matter.
Thanks David.
Always good to get your input.
Black Knight