Vivitar 2800 Energy Study, (energy consumption data) Options

[dkirk]

Here are actual energy consumption numbers for the Vivitar 2800 that I measured today (previously posted Vivitar 2000 (DF500 board) energy consumption numbers).

The Vivitar 2800 slave flash unit under measurement was modified to operate with just the 2800A board (2800B and 2800C boards removed). The 470K ohm resistor was added to disable the auto off feature, and the Neon light was still in the circuit to enable the capacitor voltage limiter circuit.

Energy required to charge a Vivitar 2800
0 to 283 volt charge = 37.2 Joules (typical of charging totally discharged unit, total time to charge to 283 volts = 12.0 seconds)
55 to 283 volt charge = 30.3 Joules (typical of charging slave after firing it, takes approximately 10.9 seconds)
212-283 volt charge = 10.9 Joules (takes approximately 8.1 seconds)
230-283 volt charge = 8.7 Joules
245-283 volt charge = 6.4 Joules (takes approximately 7.0 seconds)

Idle current (supply current when capacitor charging limiter circuit automatically shuts down charging) = 11uA. This happens when the capacitor voltage reaches approximately 283 Vdc.

Notes:
1) A 0.1 ohm series "shunt" resistor was used with my energy montioring hardware.
2) The above tests were done using energizer AA 2100 mAh batteries, and the open circuit voltage was 5.3 Vdc.
3) The energy numbers shown above are total system energy, so they include the amount wasted in the 0.1 ohm series "shunt" resistor, plus the energy wasted due to the internal series battery resistance.
4) The above data is just from one unit, so it's just a sampling to show approximate energy consumption.

Interesting facts
The Vivitar 2800 consumes much less energy (46%) compared to the Vivitar 2000 (DF500 board version). This is mostly due to the fact that the Vivitar 2000 uses an 800 ufd capacitor compared to the 330ufd capacitor used in the Vivitar 2800. They both have similar guide numbers, and it's hard to understand how their guide numbers can be so similar when so much more energy is being discharged with the Vivitar 2000 (DF500 board version). Typical charging efficiency of both the Vivitar 2000 and Vivitar 2800 is between 35% to 37%.

I will soon follow up with battery life estimations based on the energy consumpiton number measurements that I have posted.

Don

[boman49]

Would you recommend the 2000 or 2800 flash when going IR, taking into consideration unit cost vs. energy savings?

[headnurse69]

Dang, I have to sit up straight and comb my hair again... Good work, dkirk! We need more like you around here. Sharing knowledge for others without looking at the bottom line. That's what it's all about.

[tree sight]

I am lost when some of these electrical terms are used like joules and uA. Could you tell me which would be the greater on the power supply ( energy consumption )? One hour of idle current at 11uA without considering the needed refreshing of the capacitor, or one flash using 30.3 joules typical of charging slave after firing it, and what the percentage to each other would be? Thank you so much for your work with these flash guns.

tree sight

[willraygreen]

Tree sight,

A joule is a Watt-Second, with is the same as Volts-Amps-Seconds. The 11 micro-amp current draw is from the 5.3 Volt power supply, and one hour is 3600 seconds.

The idle energy consumption would be: 0.000011 Amps x 5.3 Volts x 3600 seconds, or about 0.21 Joules per hour. This is quite a bit lower than the energy consumed to recharge the flash after firing, 30.3 Joules.

Hope this helps. . . and that I did not make any mistakes.

[tree sight]

So if we were to cut the idle current in half, this would not amount to much to our total power supply in a three weeks run time. Maybe two flashes, not really a factor then. I thought it should be lower but not by that much. So this leaves the number of flashes and refreshes as our main draws on the power supply. Thanks Will.
tree sight