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Sine wave inverter/charger for small solar backup system
By cujet, Section Controls Posted on Sat May 10th, 2008 at 07:42:36 PM MST
Inverter questions.

I have (3) 24 volt/40AH lead acid aircraft sealed batteries. I get 1 or 2 of them per year from our fleet. They perform well and seem to last quite a while.
In any case, I would like to purchase a pure sine wave inverter and power it with the batteries. It is likely I would charge the batteries with solar panels (less than 200W). It would ALSO be nice to use 120V home power to charge (such as from the gen set) and for this unit to function as a UPS powering the fridge/freezer, TV and computers. I suppose it would be OK to use the inverter full time and simply charge the battery to cover the load. Not trying to run much with the inverter. My current 1500W will do the job.
What inverter do you suggest?
Inverter, Charge control and most electronics questions go under "Controls" so I put this in the proper section. If we ever get a board upgrade, I hope we add a section on product reviews.

Sine wave inverter/charger for small solar backup system | 18 comments (18 topical, 0 editorial)

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#1)
by dnix71 on Sat May 10th, 2008 at 03:54:28 PM MST
(User Info)

This place sells Xantrex and Ames. I have an Ames 300 watt sine wave inverter.

http://www.invertersrus.com/puresinewaveinverters.html

Set up your battery bank as 24v for those inverters.

The starting loads are much higher than the run loads for fridges, so you might consider getting the 3000 watt model.

But consider that those power ratings a fair amount of power is used by the inverter at idle. You'll probably need some grid based trickle charging to keep from running down the batteries on cloudy days and at night. That site also sells battery chargers.

Re: Sine wave inverter/charger (3.00 / 0) (#2)
by ghurd on Sun May 11th, 2008 at 12:39:34 AM MST
(User Info)

Maybe it's just me?
I am confused, you are confused, or we are both confused.

"I would like to purchase a pure sine wave inverter and power it with the batteries". Yup, batteries are the best choice to power an inverter.

"Not trying to run much with the inverter... fridge/freezer, TV and computers."
"(less than 200W)"?

"I suppose it would be OK to use the inverter full time and simply charge the battery to cover the load"?

And everyone would love to heat their house with a single AA alkaline battery this winter.

Most of my inverters are red, like 75%. Some of the smaller ones are blue. The really small ones are black. The larger ones are also black.

The red ones are Vector. The Blue ones are Statpower, Portawattz, or Freedom (a joint venture between a couple major players that didn't work out). The black ones are Prowatt or Tripp Lite. I certainly missed a few colors.

My truck is arguably purple or blue. The wife's car is "Champaign" but I say it is gold. SUV is black.
All the batteries in them have Exactly 6 caps and Exactly 2 terminals.
What spark plugs do I need? Oil filters?
What radio station do you suggest?

That is not even touching on the full time / gen set 120/24/120 UPS thing.

After thinking about all that, and reading a lot more,
I would suggest...
"My current 1500W will do the job"

Re: Sine wave inverter/charger (3.00 / 0) (#3)
by brkwind2 (mcool61@nspamyahoo.com) on Sun May 11th, 2008 at 07:02:28 AM MST
(User Info)

My inverter is red. My wifes hair is blonde. I plan to use her to power the whole house.
Rover, stop it.
[ Parent ]

Re: Sine wave inverter/charger (3.00 / 0) (#6)
by cujet (cujet@aol.com) on Sun May 11th, 2008 at 08:24:03 AM MST
(User Info)

Not helpful.

I must admit that my communication skills are lacking, sorry. Can you point me in the right direction on how to edit my previous post.

Please understand that my inability to verbalize my thoughts properly really has nothing to do with my level of understanding.

Understand this: I GET IT. I understand inverters, solar and electrical power in general. Again, sorry for not being clear.

I'll try to be more clear.

What "pure sine wave" inverter/charger would function as either a UPS or full time unit, provide a peak of about 3000W and a running load of 500-600W, be reliable, quiet, reasonably priced and well made? Are the Taiwan ones on Ebay any good? Or should I only consider a Xantrex?

In my case, after a hurricane, I run my DIY Lister genset during the day. At night, I generally shut it down. The inverter would carry the fridge/freezer at night.

Take a look at my website, I trust that will clear things up a bit. I do have a home machine shop, I am skilled in welding and fabrication. I generally can engineer and construct anything I put my mind to.

http://www.cujet.com/html/other_projects.html

Feel free to look around my website at my work. And yes, I built the header, the bicycle, the turbo miata, the Listeroid. All DIY.

[ Parent ]

Re: Sine wave inverter/charger (3.00 / 0) (#11)
by ghurd on Sun May 11th, 2008 at 06:43:23 PM MST
(User Info)

The 120 AH isn't going to run much stuff very long.
That's about the same watt hours as a pair of golf cart batteries.

With a 600W load, that's about 25A. That's about an hour and a half.
SLAs won't last long with that kind of abuse.
I am not sure they will supply 3000W (125A) without the inverter going LVD.

A 3000W pure sine inverter waiting for a load might drain the batteries before morning.
Some units have a "sleep" function. They wait for a load before turning on. Not sure how that fits with the fridge.

I don't get the "function as either a UPS or full time unit".
The plan is to run it 24/7, even when the grid is on?
That's a lot of wasted power, like noticably jump the bill kind of wasted power.

The 24V and pure sine limits the choices.
G-

[ Parent ]

Re: Sine wave inverter/charger (3.00 / 0) (#12)
by kurt on Sun May 11th, 2008 at 06:52:47 PM MST
(User Info)

most inverter/chargers will act as a pass through UPS and charge the batteries when connected to grid power..... i think that is what he wants.....

http://www.reresource.org/

IRC
[ Parent ]

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#4)
by TomW on Sun May 11th, 2008 at 07:34:27 AM MST
(User Info)

Sirs Hurd and Wind;

I like your style.

If we could only get folks to at least try understanding before posting.

My personal vehicle has 4 flotation tires, long travel suspension, a winch and never sees pavement. Which manufacturers gasoline will run it all year on a tank of gas?

Ok, thats my rant.

Don't forget, guys. Today is Mothers Day.

And to any Moms reading I salute you and wish you a fine day.

OK I am off to my Mom in laws for a visit.

Tom

Contact: IRC

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#5)
by brkwind2 (mcool61@nspamyahoo.com) on Sun May 11th, 2008 at 08:17:03 AM MST
(User Info)

I was gonna hang a twinkie on a stick out in front of her while she pedaled that bike with the generator on it that I strapped to the treadmill but now that you mention it, it is mothers day. Maybe I'll give her the day off.
Happy Mothers day!
Rover, stop it.
[ Parent ]

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#14)
by wiredwrong on Sun May 11th, 2008 at 09:25:03 PM MST
(User Info)

If you give her a day off this year, she'll want on next year. Just add an extra twinkie.

sorry couldn't resit
Randy OKC,OK
[ Parent ]

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#7)
by luv2weld (luv2weld at hughes dot net) on Sun May 11th, 2008 at 10:00:20 AM MST
(User Info)

Any of the major manufacturers inverters would do for you.
Just remember the starting load could be triple (or higher)
than the running load.

The problem would seem to be with the battery bank. I would
not attempt to run a Fridge/freezer on 3 batteries. OK, maybe
3 forktruck batteries!!

You say that you have a 1500 watt inverter already and it will
run the entire load. But you are looking for recommendations for
an inverter?????

The only large inverters I have experience with is Xantrex. They
are great. My neighbor also has a Xantrex. I have heard many good
things about Outback. I'm sure others on here can recommend
several more brands. (As soon as the fever allows them to return
to normal. Was there a full moon that I missed???)

Here are a few sites to help you.
http://www.roadtripamerica.com/dashboarding/Power-Inverters.htm
http://www.crutchfieldadvisor.com/S-HqXVeUyLzvt/learningcenter/car/inverter.html
http://www.donrowe.com/inverters/inverter_faq.html
http://www.gsl.com.au/howto/howto_powerinverter.pdf
http://www.dcacpowerinverters.com/inverterguide.htm

They are not product recommendations, just an explanation of whether
you should get a modified or true sine wave. However they may have
links to try to sell you an inverter.

Ralph

"The best way to kill time is to work it to death!!"

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#8)
by dnix71 on Sun May 11th, 2008 at 01:12:06 PM MST
(User Info)

You should make sure the inverter you buy can actually run the fridge.

I have a small upright freezer that uses about 200 watts running, BUT pulls 700 to start. I measured both with the Kill-A-Watt meter. Neither of my inverters will start that freezer. The pure sine inverter is rated 300run/600start and the mod sine inverter is rated 600run/1000start. So I don't believe the 'ratings' anymore.

The really nasty part is the Ames inverter doesn't trip out when trying to start the freezer. The output voltage drops to 60volts under load, but the freezer doesn't start and neither the inverters' overload breaker nor fuses trip. If that was left unattended something bad would happen.

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#9)
by cujet (cujet@aol.com) on Sun May 11th, 2008 at 01:55:17 PM MST
(User Info)

Thanks for the info on the small inverters. I had not considered using a small inverter, as my surge loads may be fairly high. I suppose I will just bite the bullet and purchase a Xantrex 2000 or 3000 watt pure sine wave unit.

Remember that I get batteries every year, so the number of batteries will grow over time. Probably faster than they go bad.

The desire for Solar is simply for a backup to my backup.

[ Parent ]

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#10)
by DanG on Sun May 11th, 2008 at 06:13:55 PM MST
(User Info)

Xantrex makes a Quasi-Sine Inverter - uses little steps to approximate the sine wave and varies steps from 18 to 36 depending on loading though the Quasi-MSW may not play nicely with some electronics or appliances with electronic heat or speed control, or clocks off AC signal... The thing is they are up to 95% efficient with minimal idle waste where the Prosine unit has some serious losses.

There should be some decent 6-8-10-year-old Xantrex SW2524 or SW4024 (or plus models) popping up on eBay for a good price. And buying used they have low depreciation, the core value will stay nearly the same or even increase as copper, man'f and shipping costs increase with the current economy...

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#17)
by BigBreaker on Tue May 13th, 2008 at 08:19:05 AM MST
(User Info)

That quasi sine inverter sounds interesting. It might be better to go with something like that and put an individual filter on the appliances that need a cleaner waveform.

[ Parent ]

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#13)
by tomtmook on Sun May 11th, 2008 at 07:28:30 PM MST
(User Info)

Sounds like you're assuming a much lighter load for the inverter than the Listeroid. In your initial post what is 1500W? I'm confused as to whether you have a 1500W inverter or you're saying your genset it 1500W. On your web page you say it's 15000W. Did you lose a zero?

I'd suggest an inverter/charger like Xantrex's DR1500. I'm told Xantrex is discontinuing that line of inverters, but there are others out there like the DR series. It is modified sine but mine runs my water pump without a problem.

Since the DR is an inverter charger, use it to charge and use a much smaller pure sine inverter to run your TV, computer and anything else that needs the pure sine. You'd have to manually transfer loads to the pure sine, but the DR would switch automatically. Makes for a good UPS.

A note to the guys who would power their houses with a pedaling wife, have you ever calculated how many watthours of power you get from pedaling? Just curious.

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#15)
by brkwind2 (mcool61@nspamyahoo.com) on Mon May 12th, 2008 at 08:15:32 AM MST
(User Info)

I can tell without measuring anything that is would be cheaper to buy fossil fuels because the number of twinkies it takes to motivate her goes up the longer she is on it. I think if I could figure out how to extract the power from flapping jaws I'd be good to go. To top that off I can get her to work up a good head of steam pretty quick so there is a lot of power to be extracted from that also. Maybe a small boiler strapped to the flat spot on top of her head. If she ever sees this I'm dead.
Rover, stop it.
[ Parent ]

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#16)
by luv2weld (luv2weld at hughes dot net) on Mon May 12th, 2008 at 08:16:04 AM MST
(User Info)

The watthours from pedaling isn't as important as the number
of days without dinner and the number of nights sleeping in
the doghouse!!!!!
"The best way to kill time is to work it to death!!"
[ Parent ]

Re: Sine wave inverter/charger for small solar bac (3.00 / 0) (#18)
by richhagen (richhagen (a t) Juno.com) on Mon Jun 2nd, 2008 at 07:58:26 AM MST
(User Info)

Based on your added comment that you are looking for about 3000 Watts, I would give the Outback and Xantrex line a look, the Outback VFX3524, or the Xantrex XW4024 or SW series inverter might work for you. They are a bit pricey, but you get what you pay for. Rich
'A Joule saved is a Joule made'

Sine wave inverter/charger for small solar backup system | 18 comments (18 topical, 0 editorial)

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