Don't buy a cheap power inverter
 

Was looking for a new power inverter with some guts to it, something that could kick start an induction motor in my refrigerator but not cost an arm and a leg. I think I found it.

First, let me tell you that those light weight modified square wave units sold on ebay are junk unless you only need to run resistive loads, small drills and box fans, other than that just forget buying one, it will disappoint you.

Come to find out, those cheap MSW inverters are plain old lying about "surge" current output. Most are rated at 500 millisecond surge - that's only half of a second ! You won't be able to start a cheap blender let alone have an off grid refrigerator.

And yes, those off grid DC refrigerators are damn expensive too. And no, I don't want to run my propane fridge forever, I like making my own power ...

And forget about those true sine wave inverters, way too expensive, buy a Trace, a Prosine or a Xantrex and I wouldn't have room for the batteries in my budget.

So here's the deal. I found out a MSW inverter will run my fridge if it isn't a cheap transistorized paper weight.

There is a middle ground in off grid inverters, its the Tripp-Lite PV series units.

Those cheap capacitors in the cheap MSW inverters are replaced with a big hunk of cooper and steel transformer. Weights about 23 lbs VS, about 6 lbs for the cheapies that look like power amplifiers instead of what a real inverter looks like.

This is the best deal in 12 or 24 volt inverters with or without the built in chargers.

My latest score was $252 (shipping included) for this rig rated at 150% surge output for an hour.

Tripp-Lite PV1250FC

It has a "sense load" feature that leaves the unit off until a load is present, cycles on and off with refrigerator compressor.

http://media.digikey.com/photos/Trip...e_PV1250FC.jpg


Details

Features Include
o Allows users to run large, motorized AC appliances from any 12V battery or automotive DC system
o Converts 12V DC battery power to 120V AC power
o 1,250 watts continuous output power
o 2,500 watts peak output power to startup heavy motorized / inductive loads
o 2 outlets; DC input terminals for 12V battery connection
o Frequency control for operating stability
o High-efficiency operation conserves batteries to prolong run time
o Diagnostic LEDs indicate load level (high, medium, and low) and battery charge (high, medium, and low)
o DC fusing protects inverter against overload
o RJ45 port allows connection of APS/PowerVerter Remote Switch (manuf# APSRM4)

Re: Don't buy a cheap power inverter
 

Tripp-Lite

That company has been around longer than most of us have been alive..

Old and well established .

I have some test gear in my radio shack that my grandfather used when he repaired the old tube type tv's and radios,, and the equipment still works, 50 + years later...

Good company..

Re: Don't buy a cheap power inverter
 

I have a bead on 2 used triplite 5000 va UPS units that are being replaced because the batteries are dead. I will be getting those for free.

These output 220v pure sine wave.

I plan to hook one up to a large battery bank, and use the second as a spare.

We will see how it does with surge loads. I plan to try to run my 220 well pump with it (my well pump has a starter cap, so it isn't too bad)

Re: Don't buy a cheap power inverter
 

Have you tried converting a chest freezer into a refrig?

Re: Don't buy a cheap power inverter
 

Excellent score, Techguy !

Even with the MSRP of $400 the Tripp-Lite beats the Trace by about $600.

Modified Sine Wave will run a heavy induction load IF its built to take it !

That means we need one of these -

http://www.buckboosttransformer.net/acmebuckboost2.jpg

Not a bunch of these in its design -

http://theelectrostore.com/shopsite_...ors-400v-o.jpg

The start cap circuit on your well pump is needed because of wire run length.

Re: Don't buy a cheap power inverter
 

i have been running the whole house for almost 12 months with cheap
harbor freight inverters 2000 watt continuous 4000 watt peak

they will not/normally start the swamp cooler motor or the saw bench but most everything else in the house including the fridge is fine
the only exception is the girls hair straightener.
the well pump is 220 so that is out of the question for those cheap
harbor freight inverters

tech guy i want a 12 to 220 inverter that will run my well pump as well
let me know if you find something suitable i tried ordering a cheap inverter out
of australia but it did not work not sure if it was a frequency or mod sine
wave problem.i also looked into parralel xantrex inverters but have not tried
that yet.

Re: Don't buy a cheap power inverter
 

That's because the "4000 surge" is only for 1/2 second, not long enough to start a heavy induction load.

The surge ratings on the cheap MSW (power amplifier look-a-likes) type inverters is misleading !

Re: Don't buy a cheap power inverter
 

most likely you are right but for the most part i have been happy.for 150 odd dollars i think they of all the crap i have purchsed from harbor freight have been a decent deal. they do have a 4000 watt continuous model i think
which would be better.

they run a lot of stuff better than the generator as long as the bats are
well charged.

so my 2cents is at least try a cheaper inverter you may be surprised at what they can acomplish.the same ratings in xantrex or other comparable inverters
are 3 times the price why not give the cheaper a go

Re: Don't buy a cheap power inverter
 

pat i am looking for a larger inverter to run the well pump are you actually running one of these yet?

do you have a very large fridge?

the fridge i have is rated at almost 600 watts run and it is fairly large im guessing that the startup is maybee
close to 2000 watt either way my cheapy inverters have never had a problem with the fridge.

also during power outages before i went of grid i used to run it on a 700 watt continuous inverter and
the fridge worked fine.

700 watt inverter was even cheaper

Re: Don't buy a cheap power inverter
 

I think these are 48v, so we will have to wire in series and in parallel.

for full price inverter to 220v, this is the best one I have seen (on specs only, have not used)

http://www.partsonsale.com/magnum.html

Re: Don't buy a cheap power inverter
 

Agreed, but it also serves to lessen the surge current required to start the pump.

Re: Don't buy a cheap power inverter
 

posting for link.
I am looking for the RV but need it for the pc.

Re: Don't buy a cheap power inverter
 

Start up load for a 600 watt compressor can be up to five times RLA (running load Amps). Start load is given as LRA (locked rotor Amps).

If you ran a 600 watt refrigerator on a 700 watt "cheap" inverter I can't see how it even started. Unless it was an RV fridge and its running a heating element instead of a compressor.

Add the defrost heaters (if the fridge has them) and your "cheap" 700 watt inverter must be using nuclear fuel instead of batteries ...

Re: Don't buy a cheap power inverter
 

I have a Magnum inverter/charger on my RV system, I actually bought one of the solar kits from the company in your link...Solartron. Good companies, good support, good products.

Re: Don't buy a cheap power inverter
 

Do your own due diligence - the current state of consumer service from Tripp-Lite is the absolute worst, and apparently so are their current production models. Tripp-Lite may have been a great company years ago, but it appears that is no longer the case. I was going to buy some Tripp-Lite equipment until I started reading online reviews.

Re: Don't buy a cheap power inverter
 

Stay away from xantrex and anything under its umbrella as well including trace. Trace was in Arlington, WA before xantrex bought it up and sent everything overseas. Outback Power is in Arlington, WA about 3 or 4 blocks from where Trace was. I'll let you put 2 and 2 together.

Re: Don't buy a cheap power inverter
 

high starting torque.

Re: Don't buy a cheap power inverter
 

i was surprised the little inverter ran it as well it is a full size fridge/freezer
using a compressor not an rv unit.

Re: Don't buy a cheap power inverter
 

I run my whole house from an outback 2000 watt (rated) inveretr.
In continuous service since 2003. Outback FX2024, will run freezer, refrigerator, microwave oven, a couple computers, deep well pump, clothe washer, coffee maker, etc.
The well pump is run through a real heavy 4KVA step up transformer, which feeds it a rock steady 244 volts ac, ( zero sag)
Although the inverter is only rated at 2000 watts, I have seen it pull 6 kilowatts, running engine block heaters, it doesnt seem to mind a bit.
If you plan to make 6000 watts with an inverter, bring LOTS of batteries. and use BIG copper cable to connect all your DC stuff.

Re: Don't buy a cheap power inverter
 

Not to disrupt your thread, because there is always a need for electricity to run things, but why not generate your own methane gas from biomass and rig the propane fridge to run off that?

Re: Don't buy a cheap power inverter
 

There are cheap Modified Sine Wave inverters made in Japan / China, these units are imported and the old American Company names are printed on them. The intention of this thread is to help others understand the difference between the cheap units and the heavy duty MSW inverters.

BTW - it was Tripp-Lite's web page that actually tells the customer the difference between their imported units and what is true surge current.

The PV-xxx-FC series Tripp-Lite heavy inverters are (dollar for watt) the best buy on the market.

Re: Don't buy a cheap power inverter
 

I bought one of those cheap Chinese msw inverters last fall when things were looking real scary. Got it on eBay for $335. It is rated at 6000 watts continuously . I'm guessing that it will handle at least 4000 watts, which is how much the biggest aftermarket car alternators put out. I also bought a 2Kw 120v-240v transformer to run the well pump from it. But... I have never actually tried to the thing yet. I've read accounts from people who claim their msw inverters have been running almost everything in their house flawlessly for years. And others who say that half of their stuff just won't run on a msw inverter. It IS a fact that motors will run 20% hotter with a msw inverter, but I'd like some real-world info from anyone who has actually run their well on one for years. I'm a bit reluctant to connect it up to my well for fear of burning the motor up, although I'd think the 50F temp of the ground would help protect it. So, can anyone personally confirm having used a msw inverter to run their well for several years?

Re: Don't buy a cheap power inverter
 

I'm guessing that you intend to use the inverter from a 12 volt source from a car alternator charger.

At 6000 watts you will need battery cables that will handle 500 Amps !

That's two and a half times the size of the main feeders that service a normal home.

That's the problem with 12 volt power inverters, getting cables large enough to stop the inverter from tripping out on a voltage droop.


For portable emergency power a 1200 watt continuous inverter requires 100 amp cables, I use welding cables.


For home use in that power range you'll be hard pressed to come up with cables and connectors big enough to handle the amp draw.

Re: Don't buy a cheap power inverter
 

I played around once using a cheap 800watt inverter to power a full sized fridge. The thing was $30, so certainly not a quality heavy-duty piece of equipment. That being said, it worked fine. The fridge started up and ran several hours before the inverter started beeping at me about low voltage. The compressor kicked in and shut off many times during that period. I think the fridge was rated at 650watts.

However, the same inverter won't handle my 1/2 hp garage door opener for more than 4 seconds.

I have some really heavy booster cables that will handle this (and more). They weren't that expensive (maybe $60).

Re: Don't buy a cheap power inverter
 

500 Amps ?

Yeah, right ... for about two seconds.


I don't think you have a clue what 6000 watts will do to those "really heavy booster cables" ...

Here's a formula to help you out - I = P/V



.

Re: Don't buy a cheap power inverter
 

They're just over an inch thick so I'm assuming at least 3/4" copper inside even with heavy insulation. They'll handle it.

Re: Don't buy a cheap power inverter
 

Someone (besides their jumper cables) is blowing smoke.

Re: Don't buy a cheap power inverter
 

How do you think people boost trucks that require a huge amount of cranking amps? You get a pair of heavy duty booster cables. They're thick and they're not very long and they handle a lot of amps.

http://www.generalcable.com/NR/rdonl...gSpecSheet.pdf
That sheet suggests that 000 gauge copper (about 3/8" diameter) should handle 500 amps over 100 feet for welding applications.

Re: Don't buy a cheap power inverter
 

Booster cable are nothing but jumper wires to allow one running engines alternator to put enough of a charge into the other vehicle battery to allow it to start. You don't need large wire to do that.

Welding cable is high frequency current, you're comparing apples to oranges.

You would need OOOO size cable to handle 500 Amps of DC battery current for any length of time. This is why larger off grid homes use 24 and 48 volt battery banks instead of 12 volt, it allows them to use a reasonable wire size to handle the amps required.

I = P / V

500 = 6000 / 12

but if,

250 = 6000 / 24

or,

125 = 6000 / 48

Notice how the wattage never changed but magically the amp draw goes down when we use higher voltage ?

This would be the input current to the inverter.

Re: Don't buy a cheap power inverter
 

These ratings are for lengths starting at 100 foot lengths.


The wire size can go down and amps go up,,,,as the wire length becomes shorter


Note 100 foot of 3/0 wire will handle 500 amps'
The o/d of 3/0 is 0.670 inches ,,

That is about 5/8 inches in dia.
and these ratings are for 500 amps , continuous current.

You can us a smaller wire size for shorter runs.

http:///www.generalcable.com/NR/rdonlyres/7EBE5634-7C22-4077-B5B2-FFFha5291871F1/0/CAR_0121_0509CarolpreneWeldngSpecSheet.pdf


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• FOR ALL BRANDS OF INVERTERS UP TO 9000 WATTS

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Re: Don't buy a cheap power inverter
 

If the dead battery is incapable of taking any charge then your boost simplifies to just starting one truck with a second battery hooked to booster cables. Yes it should only take 10-15 seconds at most but the cable still has to be able to pass enough current through to get it done. The kind of voltage drop that would lead to the cables smoking would also mean not enough power at the other end to turn over the engine. I have my large cables because regular ones were not up to the task when starting bigger engines this way.

The chart I referenced for welding cables is for the secondary voltage. This is DC and usually 12-24V. I don't know what you are saying about "high frequency current."

Yes it starts at 100' but it was the only chart I could find on short notice.

Anyway my point was that it's not *that* difficult or overly expensive to find cables that handle the amperage (I don't know any household that uses 6000watts continuously anyway). 100' I think is more than enough for 99% of people's setups - I'd imagine most just need 5 - 15 feet.

Re: Don't buy a cheap power inverter
 

The reason I used the above chart, is some do not believe that heavy jumper cables can handle the load of 500 amps .

They can.

You do not need 0000 size cable to carry 500 amps

The chart shows 100' of welding cable 3/0 size , can carry the load.

If 3/0 can do it at 100' ,,a smaller cable can do it at a shorter length.

The shorter the run, the smaller the wire size needed to carry the load full time.

Re: Don't buy a cheap power inverter
 

to get the most out of any inverter cheap or expensive running of 12 or 24
volts keep the distance between inverter and bank as short as possible
and use heavy cables.

when your bank gets low say down to 12 volts and you get a heavy load
even just 40 or 80 amps its all to easy with lighter cables and longer runs
to get .5 volt drop which will trip out most inverters as it should.

Re: Don't buy a cheap power inverter
 

At 100 amps with my 1/0 cables feeding my 1200 watt inverter 6 feet away I loose 3% of the voltage to the inverter. (That's full load)


At 12 VDC drawing 500 amps using monster 4/0 cable only 6 feet will cause a voltage drop of over 5%.

Now you only get 11.395 volts to the inverter.

Re: Don't buy a cheap power inverter
 

fortunately there is not very many single uses which draw 6000 watts
only thing i can think of is the water heater or maybee electric range

and both of these things are not good to be running from batteries and inverters especially 12 and 24 volt systems.

sure with big enough inverters and cables and batteries it can be done
but you still need to have adequate charging facilties
better to find other ways to acomplish these tasks
ie solar hot water,wood stove with hot water jacket, gas range
on demand gas heater etc etc

i think 6000 watts for a alternate energy preparedness use is
not realistic.
my biggest energy draw is water pumping from a deep well 350 feet
while its pumping its sucking about 3000 watts this is probably
about the max for a 12volt system and for the most part i will continue
to use generator into a storage tank but i do want the backup of being able to run the well pump from the batteries if i can not get fuel.

Re: Don't buy a cheap power inverter
 

Couldn't one use a "soft-start" device to lower the momentary high amp draw from a well pump? At work, on our bigger motors like air compressors, blowers, etc we have the star-delta device on them to reduce the amp draw.

Re: Don't buy a cheap power inverter
 

This is cheap

Re: Don't buy a cheap power inverter
 

I agree with you 100% damoc !

If we're going to buy the cheaper HF (high Frequency) type inverters its best to be oversized to handle the surge currents.

My point was that the advertised surge wattage is BS. You made up for the difference in choosing the big rig. Smart move on your part.

Everyone showed have an inverter and batteries for emergency power. The car/truck can be employed to do the charging in an emergency.

Re: Don't buy a cheap power inverter
 

most everything i have already has a start capacitor on it dont know about the well pump but i have less trouble with the well pump anyway because it is
220-240 volt it seems to start much easier of the generator than for example the washing machine.

Re: Don't buy a cheap power inverter
 

I just got the tripp lite inverter and it seems to really be a nice unit for the price.
I replaced a fried aims 2500 peak power with the tripp 1250 continuous/2500peak. The weight difference speaks volumes.

Unfortunately the tripp will not start my clothes dryer, the aims did.
I figure it is because of the inrush current from the motor, and I have been looking into an off-the-shelf soft start device without much luck, at least not in the under $100 range.

Seems like a plug-in soft starter would make an inverter much more useful since it is the startup amps that keep small inverters from running large inductive loads.

Re: Don't buy a cheap power inverter
 

Went ahead and got this for power outages. Hooked it up with 4 awg copper. Runs a big screen,home theater, xbox at the same time with juice to spare. The microwave made it beep...but it still worked. My DC cables are about a foot and a half too long, I used a small gauge AC ext cord cuz it was close by (handy, convenient) and that microwave draws a lot. Microwave was only for a test, propane or wood will heat my food if I need it.