Power inverter considerations

First posted
Friday March 1, 2013 07:42
Tuesday May 28, 2013 15:54

Solar Charging Harbor Freight 12 V 35AH AGM battery. Audio captions.

Core i3, 5, 7 power.

The PNM Prosperity Energy Storage Project features one of the largest combinations of battery storage and photovoltaic energy, commonly referred to as solar energy, in the nation.

Field trip to Affordable Solar Monday March 4, 2013. :)

Harbor Freight Portable Household Battery Solar Charger Item #68690 oscilloscope and meters tests.

Unadvertised software features.

Lenovo Z580 core i5 or 7 Windows 8 to XP?

Tuesday May 28, 2013 15:54

Recently notice tech@harborfreight.com

Tuesday May 28, 2013 15:33

Hello Harbor Freight,

80W, 200W, and 400W modified since wave inverters purchased from Harbor freight caused me to investigate

Google 'modified sine wave inverter damage'.

Question: Will any of these inverters damage any equipment sold by Harbor Freight?

If so, which devices.

Please ack if you receive this email.


Wednesday March 20, 2013 10:50

Solar charging the 12V 35Ah is the eventual goal. Grid charge to be used for second charge however.

5 Hours discharge at between about 4.2 to 4.4A at between 13.3 to 11.8V.

Roughly 4.3 * 5 = 21.5Ah.

Discharge to half the Ah battery rating, or 17.7Ah advised in instruction manual.



Exchanged Wednesday March 20,2013.

Generic problems 66814 or just our first unit?

Wednesday March 20, 2013 08:53

Hello Harbor Freight,

400W Inverter model 66814 purchased on Monday 3/18/13 may not be operating correctly.

1 No audible beep when start switch depressed.

2 Voltage rose from about 120V to 127V over a 5 hour period driving a nominal 40W load powered by a Harbor Freight 12V 35Ah AGM battery.

3 Battery voltage fell from about 13.3V to 11.88V at time of disconnect.

4 66814 reconnected. Green LED lighted continuously but red LED blinked. No power output.

Instruction manual does not address this scenario.

5 Within a fell hour start switch depressed again and 66816 started but without beep.

6 66814 appears to have failed under warranty and is being returned for replacement.

7 Records of test is found at

prosefights.org. http://www.prosefights.org/lenovog580/inverter.htm


Tuesday March 19, 2013 17:59

Video taken on field trip to CFV solar test laboratory Monday March 18, 2013.

Redo of the 40W light bulb 80W inverter experiment using the 400W inverter.

Harbor Freight Digital Electricity Usage Tester Chicago Electric - item#65731 is seen plugged into inverter. Appears to work fine. And it surely contains a microcontroller.

Kill-a-watt had a problem with modified sine wave inverters.

Video 1.
Video 2.
Video 3.
Video 4.
Video 5.
Video 6.
Video 7.

Efficiency of about 84% is computed from DC Amps, Volts adn AC power from values in the videos.

From 66814 manual
4. Attach the red Cable’s Alligator Clip to the Positive (red) terminal on the battery, then attach the black Cable’s Alligator Clip to a clean unpainted metal part of the chassis. (Note: If connecting to a battery not installed in a vehile, connect to the Negative (black) terminal.)

Rio Rancho Autozone employee reported that they were taught to connect battery negative terminal first, then the positive.

May be less 'shock' to electronics if ground [return] connected last?

National Security Agency Orange hardware/software design specification mandated audio and visual indication in event of failure.
5. The red Fault LED will light up momentarily and the alarm will sound as the Inverter draws power. Then the alarm and red LED will turn off and the green Power LED of the Inverter will light up.

400 Watt Continuous/800 Watt Peak Power Inverter

400w pOwER iNVERTER. 66814. SET up aNd OpERaTiNg iNSTRucTiONS.

Attention getters.
Deep cycle (marine and RV) batteries can be charged more times than a car battery, and are a better choice for repeated use of the Power Inverter.

Do not discharge your car battery more than 10% of its total capacity, and deep cycle batteries more than a 50% discharged state.

[Battery it totally discharged at 10.5V, we read.

Harbor Freight 35Ah AGM battery shows about 13.3V fully charged.

Does this mean (13.3 - 10.5)/2 =1.4V drop to be 50% discharged or 11.9V?]

If the alarm sounds, this means that the input voltage is at or below 10.8V. The 1. battery needs recharging. You should stop using the Power Inverter and recharge the battery. If this is not done, the Inverter will shut off automatically at 10.5V.

If your television will not start, it is important to keep in mind that some appliances 3. (including many televisions) may require two to six times their wattage to start up.
Favorable evaluation of the 80 W inverter prompted

Another free DVM. :)

Solar generated electricty will, not can, produce over/under voltage conditions. That's why the HQPR solar panel reguator was purchased.

Saturday March 9, 2013 07:56

AGM battery charge about 40-50 mA, AARP Bulletin Harbor Freight ad video.

7 W float charger power consumption.

7 * 24 * 365.25 = 61326 or 61.326 kWh.

$.1071/ kWh in New Mexico.

$6.57 to run the float charger continuously for one year.

Friday March 8, 2013 20:42

Inactivity can be extremely harmful to a battery. It is a VERY poor idea to buy new batteries and "save" them for later. Either buy them when you need them, or keep them on a continual trickle charge.

Solar cycle won't work?


Float charger is drawing 6 W. Voltage out is 13.03.

AGM battery is 13.30 V.

DVM set on 20 A scale.

Which way is the current going to flow?

Will there be smoke?

Float charge AGM battery test video.

Float charger impressive performance video.

Statement of 80 mA is incorrect.

Minimum is 80 mA. Maximum is .08999999999 A or 9 mA.

AGM battery was fully charged on March 5, 2013. But then let stand with only a free Harbor Freight voltmeter connected to it.

90 day Harbor Freight warranty. :)

Battery Float Charger, Automatic Cen-Tech - item#42292 output voltage measured 12.99 V.

AGM battery measuring 12.32 Thursday March 7, 2013. Hmm?

Friday March 8, 2013.

Transformer output is 15 V @ 500 mA.



Battery dropping about 2-3 V/day.

Wednesday March 6, 2013 13:20

Deep Cycle Battery FAQ.

Tuesday March 5, 2013

Full battery green light on.

0 A out of charger. Battery at 13.48 V which what the voltages was when purchased. But

continue to flow into charger.

Tommy Trujillo was phoned an message left.

Trujillo rerturned call on our land line to confirm. And asked my last name.

Over and undervoltage is a concern which must be studied.

The 66944 apparently checks for both. And has the capability of running and 120 V AC pump? Problem solved?

Grid charging experiment.

No load.

80 W iverter and power meter loads.

Not low voltage out of inverter with 380 mA load.

40 W incandescent load.

Automotive charger set to 12 A deep cycle video.

Monday March 4, 2013 13:13

80 W inverter connected to AGM battery.

Note voltage.

Inverter draws about 220 mA with no load.

AC power meter reports 107 V output with only the power meter which draws about 200 mA.

AGM connected to 80W inverter through autoranging digital multimeter set on Amps.

Output of inverter connect AC power meter which now reports 117 V output.

Experiment comenses
Note time.

Note time again.

Start of experiment video part 1.

Start of experiment video part 2.

Friday March 1, 2013 07:45

What has to go in at nominal 12V DC for what at max comes out at 120 V AC?

How long does battery last until inverter shuts off?

10.5 V for 66944.

Harbor Freight March flyer.

Focus is on power in required to supply max power out.

Then battery life.

90 W out of 66944 @ 155 V.

Power in Watts = I*V.

80/115 = .696 A.

Second law of thermodynamics. More has to go in than comes out..

12 nominal out of automotive power socket. At Max about 14.2 V from alternator.

80/12 = 6.67 A in to achieve 80 Watts out? But 66944 is peak 85% efficient.

X * .85 = 6.67 or X = 7.84 A in at least.
66944 use not planned for 2006 Honda CR-V use for reason that expensive alternator damage is possible.

Battery input to the 66944 is under investigation.

Lenovo G580 initial observation is about 40 W power consumption while charging battery with laptop running. And about max of 20 W and 13 W idle when battery is full.

40/12 = 3.33 A.

X * .85 = 3.33 or X = 3.92 A.

About 9 hours under 3.92 A load?

Slected on basis of Amazon reviews, not lowest cost.

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