| Standby losses on inverters [message #67265] |
Sat, 12 December 2009 13:09  |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
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There has been some comments on the use of power by inverters (especially sine wave inverters) when no load is being supplied.
From what I have seen, most sine wave inverters have a standby loss of in the range of .6 to .8 amps (some up to 1.5 amps) at 12 volts. The "modified square wave" inverters generally are a bit lower.
Some of the better sine wave inverters have a "sleep mode" which in effect turns them off until a significant load is applied to them. They do this by sending one cycle of power out every second or two (some let you adjust that time) to see if there is any load that has been connected. If they sense a load, they "wake up" turn on fully.
This system can work fairly well to reduce the standby losses of an inverter to an absolute minimum. However, it does have some issues that need to be understood.
1. If the connected load is not large enough the inverter will not "wake up". I had a sleep mode Trace 4000 watt inverter in a large solar system at my home. When I would turn the washing machine on, it would not start because the only load was the water fill valve, which was not large enough to wake the Trace up. I would have to turn something else on to put enough load on the inverter to keep the washer working through it's cycle.
2. If the connected load is small, like several wall wart power supplies, their total load may keep the sleep mode from working at all, that is the inverter will not go to sleep, and you will be back to the idle current load plus whatever small loads you have connected.
3. Some sensitive electronic equipment may not like a cycle pulse of 120 volt power every second or two, although I never found it to be a problem on anything I had connected to my Trace.
4. Things like TV's etc. which have remote controls will not work with the remote (and sometimes with the set on and off buttons) as they have electronic On/Off systems that always listen for a signal from the remote, and if the internal system is not on except for one cycle every second or so, they will not turn on. The inverter needs to be awakened up by some other load, then the TV will work. Many electronic controlled microwave ovens have this issue, or their clock load will keep the inverter on, and it will not go to sleep.
All in all, the sleep mode is useful to reduce standby losses of the inverters which have them, but they still can have some funny things that you could find in some situations.
So, if you are concerned about the idle current of an inverter, you might consider one with a sleep mode, as long as you understand the limitations of those circuits.
Rob Allen
former owner of '76 x-PB
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| Re: Standby losses on inverters [message #67296 is a reply to message #67265] |
Sat, 12 December 2009 19:21  |
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[quote title=idrob wrote on Sat, 12 December 2009 11:09]There has been some comments on the use of power by inverters (especially sine wave inverters) when no load is being supplied.
From what I have seen, most sine wave inverters have a standby loss of in the range of .6 to .8 amps (some up to 1.5 amps) at 12 volts. The "modified square wave" inverters generally are a bit lower.
Some of the better sine wave inverters have a "sleep mode" which in effect turns them off until a significant load is applied to them. They do this by sending one cycle of power out every second or two (some let you adjust that time) to see if there is any load that has been connected. If they sense a load, they "wake up" turn on fully.
This system can work fairly well to reduce the standby losses of an inverter to an absolute minimum. However, it does have some issues that need to be understood.
1. If the connected load is not large enough the inverter will not "wake up". I had a sleep mode Trace 4000 watt inverter in a large solar system at my home. When I would turn the washing machine on, it would not start because the only load was the water fill valve, which was not large enough to wake the Trace up. I would have to turn something else on to put enough load on the inverter to keep the washer working through it's cycle.
2. If the connected load is small, like several wall wart power supplies, their total load may keep the sleep mode from working at all, that is the inverter will not go to sleep, and you will be back to the idle current load plus whatever small loads you have connected.
3. Some sensitive electronic equipment may not like a cycle pulse of 120 volt power every second or two, although I never found it to be a problem on anything I had connected to my Trace.
4. Things like TV's etc. which have remote controls will not work with the remote (and sometimes with the set on and off buttons) as they have electronic On/Off systems that always listen for a signal from the remote,
So, if you are concerned about the idle current of an inverter, you might consider one with a sleep mode, as long as you understand the limitations of those circuits.
Thanks Rob, I'll just put a switch on the inverter and it'll turn off my 60w reefer (and idle current) when not in use. My boon docking is limited to less than a week usually. My small post on inverters has generated quite a bit of conversation, that I've found interesting.
geo groth '73 260 Sequoia
Carson City Nevada 89703
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