Power inverter

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ditsjets7

Well-known member
Joined
Oct 5, 2017
Posts
196
Location
Woodstock, NY
Hi all, As we are planning a big trip out west I?m thinking about purchasing an Extertal DC power inverter. I have a very basic one I Purchased mini years ago and it works great. The problem is it doesn?t have a lot of capacity and if I even tried to charge your laptop while the kids are watching a movie it will not work.  I know people that have motorhomes with built-in inverters and they are not cheap but I am looking at something that will charge my laptop so the kids can watch a movie and maybe An outlet. I found this on line but I have no idea  if this is too much or too little. Thanks in advance for anything you might share.

Mike
https://shop.gpelectric.com/products/700-watt-pure-sine-wave-inverter-12v?gclid=EAIaIQobChMIoMDotpqQ4wIVCcDICh0lPQxtEAAYASAAEgJ1-PD_BwE
 
That is likely overkill, assuming the kids are using a modern flat panel tv, and maybe a blue ray player.  The problem is many of the low end cheap inverters out there are way too optimistically rated, so that 300 watt inverter, may be really only good for 80 watts, or it may be an actual 300 watt inverter.

Nearly any modern flat panel TV under 40 inches in size built in the last 3-4 years will draw less than 80 watts (smart tv models), some much (I just bought a 55 inch smart TV that is rated under 50 watts) less a blue ray player or satellite receiver will draw another 15-30 watts.  Most laptop computers built in the last 2-3 years draw under 50 watts, a handful of power hog models can draw as much as 90-100 watts.  If the kids have a Play Station 4 or Xbox One, then these will add another 100-125 watts in their latest version or up to 350 watts in their earliest release models.

Regardless of how you cut it, charging a notebook computer, plus handling the kids tv entertainment should not draw more than 250 watts if all the equipment has been bought in the last year or two.

So if you pick an pure sine wave inverter made by a reputable company, then something in the 300-500 watt range should be plenty.  On the upper end perhaps something like this Xantrex (note you will need to mount it near your battery and use large battery wires, the larger the inverter the more this is important) https://smile.amazon.com/Xantrex-806-1206-PROwatt-600-Inverter/dp/B002O5P8BA  or perhaps something a bit smaller like https://smile.amazon.com/dp/B01N0W4H34/ or https://smile.amazon.com/Samlex-Solar-PST-300-12-Pure-Inverter/dp/B00H8N97E2

p.s. changed the last link to show the newer, less expensive updated model
 
My First inverter was a Xantrex prosine 2.0  Pure sine wave. 2000 watts. lasted about 12 years (I still hope to get it fixed)

New one is also 2KW (2000 watt) Xantrex 2000 XC. way less expensive.

They also make a 1500 Cheeper still. also pure sine wave

I found it here on the web. not where I bought mine from though

My one complaint is the 120 volt connections are a bit... hard to connect to.
 
You didn't say what happens using your existing inverter.  If your inverter shuts itself off trying to charge the laptop, odds are it's a low battery voltage fault. Please describe in more detail what you have (inverter & battery) and what happens when you try to charge the laptop.

Most likely the problem with your existing inverter is lack of battery capacity, not the inverter itself. As Issac explained, the power draw to charge a laptop is modest in terms of watts, usually 50-100, so even a 200W inverter is plenty for what you described.  However, getting 100W from your battery(s) means getting a steady 10A (roughly) from the battery and that's a lot for an older or smaller battery.

 
Anytime I attempt to use anything electrical that has a decent load it kicks off on the inverter. Goes from green light to red light.
 
Is the wiring on the DC side large enough and a short enough path to the battery, this is a classic symptom of undersized DC wire feeding an inverter.
 
ditsjets7 said:
Anytime I attempt to use anything electrical that has a decent load it kicks off on the inverter. Goes from green light to red light.

Couild be bad or dirty battery connections or other connections  as the load goes up so does the draw on the batteries.. a fraction of an ohm resistance translates into several volts drop. the Inverter says BEEP "LOW BATTERY" and turns off.
 
When the inverter tries to draw amps from the battery faster than the battery can provide, the voltage falls.  Most inverters will shut down if the voltage falls to 10.5v because they cannot produce usable power without at least that much input voltage.

Undersized battery, weak battery, undersized wires or poor wire connections are all possible causes.
 
ditsjets7 said:
This just puts into the cigarette lighter
And there's the problem.  You can't get more than  about 125 watts that way. Your inverter could be 400 or so watts, but you'll never get that from a cigarette lighter plug.  You will need to wire it to a better source with larger wire.
 
Depending on the size of the laptop and how discharged its battery is, something like 100-200 watts.

Get yourself a heavy duty 12v utility outlet and hook direct to the battery.  Should work somewhat better if the battery is in decent condition. Something like this:

https://www.amazon.com/NOCO-GC017-Adapter-Socket-Battery/dp/B00G8WLX78/
 
Wow Gary! My wife says thank you! You guys here have all been so incredibly helpful!

We leave on Thursday Very excited. A little nervous. Can?t wait! Thanks again!

Mike
 
Gary RV_Wizard said:
Depending on the size of the laptop and how discharged its battery is, something like 100-200 watts.

Get yourself a heavy duty 12v utility outlet and hook direct to the battery.  Should work somewhat better if the battery is in decent condition. Something like this:

https://www.amazon.com/NOCO-GC017-Adapter-Socket-Battery/dp/B00G8WLX78/


Gary, I can hook this to the battery under the steps right? Maybe my current inverter will actually work on the lap top with this.
 
It's guesswork, but plugging an inverter to the outlet on the dash or similar location is rarely successful. Those outlets are typically not wired for any significant amp draw, even though they may be fused for 10A or 15A.  Hopefully direct to the battery (under the steps) will help by elimintaing all the intervening wires and connections. If can't help a weak battery, though.  Best of luck!!!
 
That's a pretty small inverter.  I doubt it'll charge your laptop and operate a dvd player at the same time. I'd get a 300 to 400 watt hooked directly to the battery as recommended by Gary. It doesn't need to be true sine wave, modified sine wave will be just fine. I have 2 msw inverters I bought at Northern Tool for $50 each. They work just fine for charging battery operated devices. They wouldn't do well with devices with clocks built in that rely on a good accurate sine wave as a timing source.
 
If your current inverter is only 140 watts then you do need something a bit bigger,  See the ones in my link above, they will also need to be wired directly to the battery with the shortest possible length of wire.  You can run AC extension cords from it if needed, DC does not like long wires though.

Pure sine wave is not absolutely necessary, a $25-$35 modified sine wave 250 watt inverter would probably work fine for what you are doing.

Something like this perhaps https://smile.amazon.com/VOLTCUBE-Inverter-Adapter-Independent-Outlets/dp/B07F13X9SN  though I would hard wire it to a battery and not use the clips or the cigarette lighter plug,  Note the listing says cigarette lighter plug only good up to 150 watt level.
 
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