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Inverter Draw
By mettleramiel, Section Newbies Posted on Sun Jun 24th, 2007 at 08:22:02 AM MST
How to measure

I've had my 60watt solar set-up working for a few months now, but there is one thing that I still don't know how to do. I would like to know how much power my 1000watt inverter and my charge controller (which doesn't have an off switch) is drawing from my system. I spent a couple of days measuring the power coming from the panels every hour and then using as close to that amount as I could at night and it seemed as if they had hardly used any power at all. And no, I don't have manuals for either of these devices. Thanks!

Inverter Draw | 6 comments (6 topical, 0 editorial)

Re: Inverter Draw (3.00 / 0) (#1)
by AbyssUnderground on Sun Jun 24th, 2007 at 03:09:33 AM MST
(User Info) http://www.repowered.co.uk

Use a digital multimeter to do this. Set it to the 10A setting and disconnect the inverters positive lead from the battery. Connect the positive lead of the multimeter to the battery and the multimeters negative lead to the inverters positive lead. The display of the multimeter will now show the current draw.

Charge controllers use very little power. Mine uses 10mA (0.01A). I barely reads on my meter. However to find out, use the same method as above for the inverter.

You should always turn off or disconnect the inverter when its not in use because they draw a stupid amount of idle current. Mine uses around 1A when idling and my system simply wouldn't be able to cope with that sort of draw 24/7. Remember that renewable energy is also about conserving power. If you don't have the power, don't use it, and disconnect anything with a parasitic load when you're not using it (eg the inverter).

Overnight my inverter will waste 10-12Ah of power. My solar only generates that amount per day, IF I'm lucky. That 10-12Ah of power could be used to run my desk light, or my phone charger, or even my laptop for a few hours. Inverter idle currents are very wasteful.

http://www.repowered.co.uk - My Renewable Energy site.
msn[at]m3ezw.co.uk - my msn if you want a chat.

Re: Inverter Draw (3.00 / 0) (#2)
by coldspot on Sun Jun 24th, 2007 at 06:43:54 AM MST
(User Info)

Also-
A 1,000 Watt Inverter is nice, when you need that much power that is.
(I know, as I have one, and a 400 with a 500 also,and a NIB 2,000 a used 3,000 that max's at 12,000! But I seem to always only use the 75 or 60 size ones? )
Matching the load kind of like matching the prop to genny, matching the inverter to the load so as to be using only whats needed.
$0.02
:)

Re: Inverter Draw (3.00 / 0) (#3)
by cyplesma (cyplesma@aol.com) on Mon Jun 25th, 2007 at 01:29:35 PM MST
(User Info)

If your in the States then go to wall mart or an auto supplier store and get a big black on-off switch (has a big red key)(their between 10-15 bucks), own one haven't started using it, or go to a boat/marine store and get one of their bigger battery on-off switches (don't use these myself so but I remember year 2000 prices were above 30.00 bucks)

use that switch to turn an inverter on or off.

right now I keep my system somewhat portable so I use jumper cables to clamp on a battery and use the other end to connect to the inverter. to select which inverter I'm using for a given load.

Re: Inverter Draw (3.00 / 0) (#4)
by cyplesma (cyplesma@aol.com) on Mon Jun 25th, 2007 at 01:32:18 PM MST
(User Info)

I only keep a max of two feet of the jumper cable connected to the clamps, use the rest of the jumper cable for other connections, can be a bit expensive (cost of jumper cables), but looks nice and is very quick to do.

[ Parent ]

Re: Inverter Draw (3.00 / 0) (#5)
by ghurd on Tue Jun 26th, 2007 at 08:43:36 AM MST
(User Info)

You mean like these from HF, on sale for $3 at the reatail stores.
Rated 1000A surge, 100A cont.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92688

They seem OK.
G-

[ Parent ]

Re: Inverter Draw (3.00 / 0) (#6)
by cyplesma (cyplesma@aol.com) on Wed Jun 27th, 2007 at 12:33:58 PM MST
(User Info)

that's them exactly.

and that's 10.00 less than I paid for mine. I may have to stock up on those.

of course you do need to build a box, but diy folks don't usually have a problem with that.

[ Parent ]

Inverter Draw | 6 comments (6 topical, 0 editorial)

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