How much power does my 3000 watt MSW inverter use when off but connected to the battery?
sdowney717
Registered Users Posts: 3 ✭
I notice, it sparks when connecting to the battery, so it must draw some small power all the time as it charges capacitors on the 12vdc side. And they dont stay charged as if I disconnect inverter from battery, they discharge by themselves after a few minutes. Reconnect and it sparks again.
So far no one seems to know about power used when off but battery connected.
What will happen if the 3000 watt msw is left connected to a battery for many months and battery is new and not being charged.
So far no one seems to know about power used when off but battery connected.
What will happen if the 3000 watt msw is left connected to a battery for many months and battery is new and not being charged.
Tagged:
Comments
-
Welcome to the forum sdowney717,
You are correct, the filter capacitors on AC Inverter DC inputs can draw a pretty big spark when initially connected.
Many inverters document their power draw when On (no load), Search Mode (power up once a second to look for AC loads), and Off... Some are "OFF" with a switch or relay, others are "electronically" off and may still draw some current:
Just a random example:
https://www.solar-electric.com/lib/wind-sun/SureSine.pdfSelf ConsumptionAnd you are correct to worry about "vampire" loads (loads that daw 24x7 but you may not know they are there).- Inverter On (no load) 450mA
- Inverter Off 25mA
- Stand-by 55mA
If you cannot find a specification for your inverter, you can use a DC Current Clamp DMM (digital multimeter) to see how much leakage current there may be:
https://www.amazon.com/gp/product/B00O1Q2HOQ (inexpensive, good enough for most uses)
https://www.amazon.com/gp/product/B019CY4FB4 (mid priced meter)
Note there are AC Current Clamp DMMs and AC+DC current clamp DMMs... The AC versions are very good units but don't work with DC current (may be confusing descriptions as they do measure AC+DC voltages, just not DC current).
Lets say you have a 200 AH @ 12 volt battery bank, and it sits for 6 months during the "off season". And you will accept a 10% discharge over that time:- 200 AH * 0.10 discharge = 20 AH
- 20 AH * 1/24 hours per day * 1/180 days = 0.0046 amps = ~5 milliamp draw "acceptable to you" vampire load
- 0.0046 amps * 12 volts = 0.055 Watts
The typical "answer" is to use a circuit breaker (or pull a fuse, when the inverter is "off") to ensure no unplanned discharging of your batter bank (inverter, other DC loads such as a radio, lights in a closet, etc. are forgotten/left on).
Other things to think about... Different batteries have self discharge... Flooded Cell Lead Acid--Need to be charged at least once a month. AGM once every 6 months. Lithium Ion--years.
Also hot batteries self discharge faster--Batteries setting at 95F in a hot RV--They will discharge 2x faster than those stored at room temperature...
If you have solar panels--They can keep up with self discharge (in general)... But some folks get bit by parking in shade/under roofs, or drifting snow in winter (solar charge controllers also have minimum current draw--And a few folks have had their cabin solar panels drifted over by snow, and the charge controller killed the bank).
-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Thanks for the info. Inverter is in my 37 foot boat, a 1970 Eggharbor sedan.
Since the inverter gets little use, as does the boat, I do worry about the power cutting off for whatever reason at the marine, and the battery then getting drained by vampire electronics, like inverter, radio, small LED volt-amp meters, etc...
-
I think maybe the radio always on memory wire could be left disconnected?
I could install a battery switch on the inverter DC wire
I have two small LED panel meters that reads volts amps off the battery, I wonder what each of these items draw in milli-amps.
Other thing, I could when leaving the boat, rotate the 2 large battery selector switches to off, that leaves only the radio and bilge pumps with power available. Bilge pumps use float switches.
I also wonder if my VHF marine radio uses some small amount of power. It is a newer one with the MMSI broadcast security button.
Categories
- All Categories
- 220 Forum & Website
- 128 Solar Forum News and Announcements
- 1.3K Solar News, Reviews, & Product Announcements
- 192 Solar Information links & sources, event announcements
- 887 Solar Product Reviews & Opinions
- 254 Solar Skeptics, Hype, & Scams Corner
- 22.4K Solar Electric Power, Wind Power & Balance of System
- 3.5K General Solar Power Topics
- 6.7K Solar Beginners Corner
- 1K PV Installers Forum - NEC, Wiring, Installation
- 2K Advanced Solar Electric Technical Forum
- 5.5K Off Grid Solar & Battery Systems
- 425 Caravan, Recreational Vehicle, and Marine Power Systems
- 1.1K Grid Tie and Grid Interactive Systems
- 651 Solar Water Pumping
- 815 Wind Power Generation
- 623 Energy Use & Conservation
- 608 Discussion Forums/Café
- 302 In the Weeds--Member's Choice
- 74 Construction
- 124 New Battery Technologies
- 108 Old Battery Tech Discussions
- 3.8K Solar News - Automatic Feed
- 3.8K Solar Energy News RSS Feed