Something strange about battery voltage

greasemonkee · Post by **greasemonkee** » Tue Mar 11, 2008 9:37 pm

In case it's been mentioned before, please point me in that direction. Been having some issues with the battery offsets using RC 750cc sat. injectors. I use an underdrive alternator pulley so naturally the voltage drops more than the norm. By unhooking the alternator and loading the battery, it's been relatively easy to correct the offsets at sub 13 volts. The only problem is that under 12.5 volts (as registered by an accurate volt meter), the logger displays severe inaccuracy. At a true battery voltage of 9.8 volts, the logger registered 11.8v. Subsequently, the battery offset columns are incorrect and any degree of accuracy is impossible at lower voltages.

Post by **calvin** » Tue Mar 11, 2008 11:20 pm

battery formula not good you say/ I'll have to double check. Even if the formula is bad you can still adjust because of the trace.. let me think.. i have to double check... but i believe trace uses raw values. so where trace is should be good

Almighty-Si · Post by **Almighty-Si** » Wed Mar 12, 2008 12:33 pm

Yea I just used the trace and turned stuff on and as the trace changed I adjusted the cells and it has been fine for me.

Post by **calvin** » Wed Mar 12, 2008 3:57 pm

i will revaluate the voltage formula

Adam Hopkins · Post by **Adam Hopkins** » Wed Mar 12, 2008 5:31 pm

Calvin, I am also having problems with idle at my car because of underdrive pulley. I can go log and verify if you need me to I could not seem to get mine right, but customers with big injectors and stock pulleys are no problem. Greasemonkee may be on to something, good find man. Maybe I can fix my personal car now. You know how it is, a painters house always needs to be painted. lol

Post by **calvin** » Wed Mar 12, 2008 6:48 pm

doesn't matter if the voltage is not showing good. It should be fixed but with trace u can see where it reads and adjust properly

Adam Hopkins · Post by **Adam Hopkins** » Wed Mar 12, 2008 6:50 pm

ok makes sense

greasemonkee · Post by **greasemonkee** » Wed Mar 12, 2008 10:12 pm

That crossed my mind, but assumed the volt scale was fixed. Should have figured Calvin to be clever enough that these were adjustable.

Post by **calvin** » Wed Mar 12, 2008 11:03 pm

i don't think the voltage scale is adjustable in the next release it will

Post by **calvin** » Fri Mar 14, 2008 11:55 pm

i have the right fourmula now. It's was way way off i'll fix

Post by **Gaskleppie** » Sat Mar 15, 2008 10:27 am

Is this going to have some kind of impact on the amount of battery compensation on the fuel maps?

Post by **calvin** » Sat Mar 15, 2008 2:59 pm

no because it would still roughly be the same. I don't know i don't think so. THe display numbers are different

JaredKaragen · Post by **JaredKaragen** » Sat Mar 15, 2008 9:44 pm

Hrm, I have noticed something odd happening the last week or so... battery offsets were dialed in with no problems; but now a few weeks later since the new .cal, when dropping to idle after a little stretch of driving, it almost acts like it is drowning out; idle will hold steady at some rediculously low RPM amount (idle is at 900rpm BTW) and if I tap the gas it easily catches up, but then drops waaaay down again... If I switch to my last tune without the battery offset done (just the default injector config from eCtune) it runs just like before without this correction. all options were the same, and I even tried copying my values/maps over to the new CAL and it still did it. I can't narrow it to this yet, but I thought I would share the info.

greasemonkee · Post by **greasemonkee** » Sat Mar 15, 2008 10:14 pm

If we want to invite more variables - if not, disregard: Mine had been doing that also on occasion, a daily basis though. Fueling was decent during the event. I noticed something, the alternator wasn't working at all when this happened. Voltage was 12.5v (actual)@ 950 rpm no loads. Turn lights and blower on and off again and it goes back to the usual 13.5~v. I turned the idle up to 1050 rpm and hasn't been a problem yet.