@richard-imrie The instrument uses only around 1 amp while working, but, I found that a 2 amp regulator is needed to make sure that it starts correctly (shown is 4amp) The instrument needs at least 12.6v to keep from chirping at you. Richard, I have had issues with the Parani's at 5.6v and I am thinking that might be a bit aggressive from my testing. The instruments are fine up to at least 14.8v (full NiMh) that I have observed, but, that was on Geodimeter's and not the Trimble's
I got the impression from the Parani manual that its voltage range is 5-9V (presumably because it is RS232?), which sort of made it a bit tricky because USB power supplies are 5V while the car battery is 12V so both are outside the range, which is why I put in the step down regulator on the 12V car battery - not sure why I set it at 5.6V.
My experience with car batteries is that while they might be 13.8 on the charger or when the car is running, they drop to 12.6 ish as soon as they are taken off, so the instrument battery indicator never shows a full charge.
@richard-imrie You are right, I got it confused with the the top limit. Parani's do not like over 12.0 volts. My bad, sorry it has been a few years since I went through it
