Need help with power inverters

diesel lover · Feb 9, 2014

My last power inverter was a Stanley 100 watt. When It burned out I went and bought one from battery's plus store and it failed first use while trying to charge a digital camera battery. Many things are made low quality now days.

At menards they have a Stanley 500 amp, and a peak 400 amp for 39$!! What a good dead. Which should I buy and not think twice about it? I am looking to stay around 400 to 500 watt range and around 40$. Thank you

Industrial Toys · Feb 9, 2014

I have a friend that sells thousands of these a year to utilities mostly. I get all kinds from take outs, give many away and throw many out. I have absolutely no love nor confidence in any of these! And they are some of the supposedly highest quality manufacturers.

I am an electronics technician. I see the biggest issue is that they don't use large semiconductors for the final high power switching, but instead banks of smaller cheaper basically transistors. One blows for whatever reason and then they ALL blow in cascading fashion! The OLDER models used heavy transformers on the outputs and this probably offered some kind of protection as those units were more robust. Buy hey, copper and steel cost money, so that technlogy has gone by the wayside!

I have an old inverter here. Basically a 12 volt DC motor coupled to an alternator. Probably not very efficient but I would have confidence in that. The idea was for some contractor to be able to use a skill saw away from power, with his truck left running of course. I have been meaning to play with it.

Back to the electronic ones, I might use them for FUN or experimentation, but would never rely on them for anything! When they fail, you just use them for target practice. Quite satisfying actually!

Just my opinion of course!

diesel lover · Feb 9, 2014

My use for power inverters is minimal. While away from home I will use a 400 or 500 watt to power my cell phone charger, battery charger for my drill/ and my cordless impact, 17 watt automotive work light etc. my last 100 watt power inverter last 2 years completing these task. It did not have a fan to keep it cool.

I understand the use of portable generators but for the small task I will not need one.

Thank you industrial toys!! I have a great knowledge of basic electronics and understand your explanation of why the newer power inverters may not last very long.

With the power inverter I will get the protection plan to make my purchase last longer in case it does burn out. As right now I have nothing, and I see no reason what so ever to purchase a cell phone charger for 20$ when it only fits my phone. I will purchase a power inverter for my needs.

For most house hold brands are they very similar quality ?

bullbreaker · Feb 9, 2014

I don't mess with em much but have bought some of these Cobra models (even way larger) in past and had no problems ,from this company : DonRowe.com: Cobra CPI-880, 800 Watt Modified Sine Wave Power Inverter On occasion they run special deals gotta catch-em.
Haven't researched it but you might want to look them up on Amazon (power inverter).

grsthegreat · Feb 9, 2014

I have a 1,000 watt power inverter in my work van. Have used it for years. The biggest issue with getting mine to run properly was determining the size of wire to feed from the battery. The ones that plug into cigarette lighters are junk IMO.

a 500 watt inverter using 12 volts is needing 41 amps of current draw from battery to operate. Alot of the cheap units have small wires to attach to the battery. You would need a #8 copper wire to run this unit....as short as possible.

I run a 2/0 copper wire for mine and mounted the unit right below the firewall so my battery runs are about 3' long. The voltage drop in these units is amazing. too long of a cord and its useless.

The best way to operate an inverter is to use 12" wires and place the inverter right next to the battery. This isnt usually possible.

I spent over $500 on my inverter, but i bought a good one as my 1st unit caught fire. That was a cheap ebay inverter. fuses never blew, but unit actually caught on fire. luckily i have a fire extinguisher on van.

ya get what you pay fore in life.

Industrial Toys · Feb 9, 2014

Too bad. If you lived close, I would just give you one.

The utilities use them mostly for the same reasons as you. Lap tops, cell phones (which a simple USB charger would do) and to charge cordess battery packs. Actually, all these applications are quite stupid and backwards, but I could tell you stories about the utilities! Anyway, to convert 12 VDC to AC and back to DC is just DUMB! But it's when they try and power AC inductive loads (like drills) that they start to have problems!

I gave my Dad a small 1000 watt Zantrex inverter, and installed it in his Dodge Sprinter to run a small fridge. So far so good, but he has not used it much and the fridge uses bugger all power, even though it is an inductive load.

Possibly one user error is not having suitable DC cables to the batteries to account for current and voltage drop. You draw 10 amps on the AC side and you are sucking 100 amps (or so) out of your batteries.

timswi · Feb 9, 2014

My mom bought me a Sears 400w inverter..Have had it for at least 5 years. Used it mostly to run the flatscreen TV and DVD player in the motorhome while in route...Still works perfectly.

3930dave · Feb 9, 2014

I like the Xantrex I've used, but I don't know their pricing these days at the low end.

I also have a 300w Philips that has been doing fine for a few years, other than a whiney cooling fan.

If you mostly are charging portable electronics,what about a 12v to USB adapter ? Just thinking about staying low cost... it's easier to make a USB adapter low cost and reliable, than an inverter.

Rgds, D.

Stimw · Feb 9, 2014

Industrial Toys said:
I have an old inverter here. Basically a 12 volt DC motor coupled to an alternator. Probably not very efficient but I would have confidence in that. The idea was for some contractor to be able to use a skill saw away from power, with his truck left running of course. I have been meaning to play with it.

Running the motor first was the long way around.

I have a 35 year old portable welder that used a 16 hp Briggs turning a truck alternator.
It was rated at 200 amp DC with a 120 V DC outlet on it.
They ran the alt at about 9000 rpms with pulley drive. It has a bank of diodes converting the 3ph AC to DC and controlled the exciter voltage to
change the amp output. And a smaller diode bridge for the 120 v.
The thing worked great BUT the vibration shook the electronics apart and it was hard to keep the belts tight. Plus the DC 120 V was a pain.
I used to jump start Semi's with it! I connected the welder leads to the battery and brought the rpms up until I heard the unit loading up.
I seem to remember they were selling car type alternators wired to put out 120 V.