I completely ignored the instructions as a ‘guide’ for wiring the shut and display. The shut was on the positive side and I also connected the display power to the same power supply. This resulted in SNAP and A LOT of smoke escaping from the ground wire. The unit appeared dead. After ordering a replacement and connecting it up, I realised that the old unit was still functioning and it was simply the ground wire that had completely burnt out. Tough little sucker! So it would seem everything appears to be ok with the exception that the display appears to be out by a factor of 10. The display shows never seems to show above 0.9 and I’m pretty sure its drawing somewhere between 1 amp and 9 amps. Thinking that I HAD fried the main chip I put the NEW unit in only to find exactly the same results 0.1 to 0.9 displaying. The circuit load is 1X Jenson nano (via DFR0205 DC-DC Power Module 25W) and 1X roboclaw connected with DC motors. Supply rail is a 14.8V Li-ion battery. Is there a configuration or calibration I have missed? My experience with ammeters like this is that when the ammeter reading is out, the shut is the incorrect value (by a rough factor of 10 in this instance). Thoughts?
You have not made it clear if you have now wired this up as per instructions or at what stage in this experiment this took place. If you have damaged the device and wired a new one in the same way it would be possible that the new one suffered the same fate.
A couple of diagrams would help. The before and after scenario.
“Please note that the shunt negative wire and power supply wires must be isolated. Refer to the attached diagram.”
would suggest the meter requires a separate power supply. Especially if the 2 black wires are internally connected. If they are it is anybody’s guess what happened when you connected the first time. You might have got the black wires straight across the main supply, hence the smoke.
There is a bit of a saying which may apply here. “When in doubt ??? Read the book” (instructions).
Sorry, you’re right. I didn’t mention that I DID infact then reread the wiring instructuons per the core electronics site. My wiring diagram is verbatim the diagram per instructions. For the power supply to power the display I have used a new 9V battery making the two circuits completely isolated.
To be clear, before reeconnecting ANY displays I have corrected the circuit with the new dispalys wire harness and the old shunt. The circuits are isolated with the shunt between the negative lead of the battery and the neagative lead of the load. To answer my question, is there a pot or other mechanism to adjust the displays output that I have missed in the instructions? Also, is it possible to damage the shunt if it was originally placed incorrectly between the positive rail and the +ive of the load?
Try the new shunt with the new meter. I suppose it is possible hat the shunt could be damaged. The resistance of these things is so low that they are a bit hard to measure accurately with a DMM or any other hobby meter for that matter.
The mV per A should be marked on it somewhere so if you check that with some substantial current through it should give you some idea. A clamp meter or some other non invasive way to measure the actual current through it would be handy.