atis-sedlenieks:
Battery is off car, sitting in my art installation.
so no need to worry about spikes unless your art-installation is using servos and/or relays, but either way nothing serious.
atis-sedlenieks:
Yes, i'm waiting for battery to go below 12v to know when to replace it with charged one- nevar heard of low-voltage chip..
I have heard of it, seen it somewhere but i have to admit i can't find a link to it atm. you could make your own using an Op-Amp as a voltage comparator. the system is actually similar to what you are doing now, albeit doing the measurement for you and simply indicating a 'yes' or 'no' to the Arduino.
atis-sedlenieks:
And voltage divider system did work and do work when I supply 12v to arduino. When supplying 5v it doesn't
So supply 12v to the Arduino ! the stepdown is not a common-GND module probably consists of 2 coils with different amounts of windings. if you have a difference in measurement check out the voltage between the 2 v- pins of it and see if that's where it's gone..
Oh yeah what kind of battery are you using, a VMF(starting) battery ? you know these don't take well to slowly being discharged over a long period of time, due to their thin plates, these tend to warp as a result of that. Deep-cycle (or hobby) batteries can provide less peak power, but are better for that purpose.
Deva_Rishi:
Oh yeah what kind of battery are you using, a VMF(starting) battery ?
Im using DYNAC AGM ST105 I think it's deep-cycle, cant find info in english, in Latvian it's something like that. edit: ok i just found this i guess it's not deep cycle.. it's AGM series
atis-sedlenieks:
Wouldn't that consume more power from battery?
It might yes (a bit not so much, you could measure the difference), actually probably just connecting the v-'s on the Stepdown and creating "common-GND" will fix your issue (which you anyway do when you power the Arduino directly from the battery, that is why you are getting the proper reading)
You might want to increase the 'low-battery' level just a little, how long they last only time will tell they are VMF, not really meant for the purpose you use them for but probably work quite ok for a while. What's in your Art installation. ? (pics ?)
Deva_Rishi:
It might yes (a bit not so much, you could measure the difference), actually probably just connecting the v-'s on the Stepdown and creating "common-GND" will fix your issue (which you anyway do when you power the Arduino directly from the battery, that is why you are getting the proper reading)
When you connect the vIn of the Arduino directly to the battery, and you connect GND of the Arduino to the TLC5940's and connect their GND to v-OUT of the stepdown converter, then haven't you already done this ?
Deva_Rishi:
the stepdown is not a common-GND module probably consists of 2 coils with different amounts of windings. if you have a difference in measurement check out the voltage between the 2 v- pins of it and see if that's where it's gone.
You do not know much about "buck" converters then?
It should be clear from simple inspection of the module that the negative of the input is the same as the negative of the output. Or test with the multimeter to prove it.
Nevertheless is is important to have the two leads from the power source running together to the converter and the two leads on from the converter running together to the load(s).
