Thought I would post this here as I have found this tool to be a useful asset as a multimetering tool: The Scotts Mod ORDTS.2 firing ohm meter (single 18650). Essentially an unregulated box mod, what separates this device from the USA 3D Fire Meter and the Coil Master 521 Tab is its real-time digital display of I/R/V/W values courtesy of the ModMeter chipset. Resistance readings match to the hundredths those provided by Evolve DNA 200 devices and meters from USA Ohm Meter. Where the ORDTS.2 proves its merit for builders of mechanical devices is in its ability to display current and delivered voltage readings under load. Build quality is fantastic: Custom powder coating. Wiring kept to minimal lengths. Epoxy in lieu of hot glue. 3D printed display bezel. The ORDTS.2 is not simply a firing ohm meter. It is a unique metering tool housed in a recontoured Hammond 1550P which showcases real-time I/R/V/W values which can be applied towards safer building. I ordered the following ORDTS.2 with 99.99% silver wiring...
Dual 22g 316L Ø3.75mm 7/6 wrap @ 0.12Ω on a Kennedy 24. A single LG HB6 (IR=22.3mΩ @ ~72°F) was verified at 3.97V on a DMM[*] before being installed. After firing for ~3 seconds, we see that the recorded values upon release of the firing button are:
• Rise in resistance to 0.13Ω
• Delivery of 74.4W of power to the coils
• Current draw of 23.9A from the cell
• Cell voltage drop down to 3.11V
The HB6 was removed from the ORDTS.2 and verified on said DMM at 3.95V after a brief 10-minute rest. 3.95V was reverified on the firing ohm meter upon reinstallation. Can the ORDTS.2 be improved? Absolutely. Wiring can probably be further optimized for a reduction in power loss percentage. Additional venting where the cell positive is oriented. A master lock switch. All in all, insofar as I have had the opportunity to use this meter, I have been left impressed with its potential.
[*] DMM specified accuracy = 0.5% + 2. ((3.97 x 0.5) / 100) + 0.02 = ± 0.04V. 0.04 / 3.97 = ± 1% accuracy for 3.97V reading.
Dual 22g 316L Ø3.75mm 7/6 wrap @ 0.12Ω on a Kennedy 24. A single LG HB6 (IR=22.3mΩ @ ~72°F) was verified at 3.97V on a DMM[*] before being installed. After firing for ~3 seconds, we see that the recorded values upon release of the firing button are:
• Rise in resistance to 0.13Ω
• Delivery of 74.4W of power to the coils
• Current draw of 23.9A from the cell
• Cell voltage drop down to 3.11V
The HB6 was removed from the ORDTS.2 and verified on said DMM at 3.95V after a brief 10-minute rest. 3.95V was reverified on the firing ohm meter upon reinstallation. Can the ORDTS.2 be improved? Absolutely. Wiring can probably be further optimized for a reduction in power loss percentage. Additional venting where the cell positive is oriented. A master lock switch. All in all, insofar as I have had the opportunity to use this meter, I have been left impressed with its potential.
[*] DMM specified accuracy = 0.5% + 2. ((3.97 x 0.5) / 100) + 0.02 = ± 0.04V. 0.04 / 3.97 = ± 1% accuracy for 3.97V reading.
