# Power Inverter for a Digital Projector not working



## caravelle1 (Aug 24, 2014)

Hello!
Let me start by saying thank you to all the people who contribute to this site, I am newly registered here but this information is invaluable.
I've spent 30 hours over the past week running to various stores trying to get my problem figured out, and buying all sorts of converters and adapters that in some cases I am unable to return.

My problem is this:
I'd like to use a digital projector and power it using a mobile power source.
How I went about doing this was buying a bulky DC battery and a power inverter to switch it over to usable power for my projector.

The specs for the projector say it will use about 245 watts, using a 450 watt inverter it runs for about 5 seconds then a warning within the inverter goes off and the projector turns off.
I then tried to upgrade the wattage to a 800 watt output inverter and had an identical problem.
All inverters I've been able to find in hardware stores output at 115v power - My projector on the cord specifically said "Use only with 120v power"
Every tech I've asked said this wouldn't be a problem and the power is interchangeable between 115v and 120v

My guess is that it is not in fact interchangeable for this projector. I am considering ordering a 120v specific output inverter, but if there is some problem I'm not considering I would simply be investing more wastefully.

This is my projector:
Viewsonic PJD5232 Portable XGA Projector PJD5232 - Micro Center

Here is the 450 watt inverter:
Inverters - Samlex SAM-450-12 12 Volt 450 Watt Modified Sine Wave Inverter

Here is the 800 watt inverter:
Amazon.com: PEAK PKC0BD-02 800 Watt Power Inverter With 2 A/C Outlets (Discontinued by Manufacturer): Patio, Lawn & Garden

Here is the battery:
https://www.1000bulbs.com/product/5...vm9-Xaw_kitI4hagpo7ZS8MpT9jnCRSKw-GgL5nfD_BwE


ty for your help


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## Bill_Bright (Dec 17, 2004)

> All inverters I've been able to find in hardware stores output at 115v power - My projector on the cord specifically said "Use only with 120v power"
> Every tech I've asked said this wouldn't be a problem and the power is interchangeable between 115v and 120v


And each of those techs you asked are 100% correct!!! 120VAC is just an approximation and you will often see other products labeled as 110VAC, 117VAC or even 125VAC. It does not matter AS LONG AS the power is "clean" and relatively stable. 

Typically, anything rated with a 120VAC input rating can use between 90VAC and 135VAC. That is why typical battery backup power supplies (uninterruptible power supplies - UPS) typically "kick-in" when AC input drops below 88VAC or surges above 136VAC.

Your problem [as I see it from here] is obvious!

How many of those "little" batteries are you using? You "should" be using several strapped in parallel as "cells" to make one big battery - probably at least 4 (which, coincidently, is exactly what goes in my 1500VA APC UPS). 

With batteries in parallel, the voltage stays the same and current capability adds. With batteries in series, the voltage adds and the current remains the same. 

With direct current (DC), voltage x current = watts. So 12 x 8 = 48W, not near enough to sustain power to your projector. So you want multiple batteries in parallel to maintain 12VDC and increase current. 

BUT - that inverter is designed to take power from a BIG battery, like a *fully charged car battery*. That's what you should be using, not those little SLA batteries. Not unless you use them in a big and "good" 1500VA UPS with AVR. 

The advantage of a "good" UPS with AVR is everything (batteries, inverter, output voltage regulator, and even surge and spike protection) is in one [heavy] box. The disadvantage of UPS is they use those SLA batteries, like the one you showed, and they tend to have just a 3 year (4 if lucky) life span (but they are easily replaceable by the user). 

The advantage of a car battery and inverter is a good car battery can last 6 years or longer. But car batteries are "vented" not sealed because they are exposed to extreme heat under the hood. And being vented, they do leak a bit of battery acid, thus require extra care during transport, storage and handling.

Edit add: BTW, did you look at the specs for your projector? It obviously has a "universal" power supply as it clearly states it accepts,


> 100 - 240 V 10%, 50/60 Hz AC.


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## caravelle1 (Aug 24, 2014)

You sir are a prince!
I'll upgrade the battery today and let you know if it works


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## caravelle1 (Aug 24, 2014)

I picked up a larger battery:
WKDC12-20NB Werker Battery - 12V - Werker - SLA Sealed Lead Acid Battery - Batteries Plus

this one goes up to 1000 watt output

This inverter is in the mail and will arrive tomorrow:

http://www.amazon.com/Cobra-CPI-880...sr=8-4&keywords=cobra+inverter#cm_cr_dpwidget

hopefully this issue will get resolved, Will post tomorrow!


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## Bill_Bright (Dec 17, 2004)

I don't think that will work either. A large car battery, or better yet, a small generator would be better - or better still, a running car engine. 

And where did you get 1000W? Using the power formula (V x A = W) I included above, 12V x 20A = 240W. 

Your projector is going to pull maximum power when it first powers up (as is typical with most electronics). *IF* this battery can support that initial load, and that is in doubt, it still will not provide much "runtime" before the output voltage drops below the inverter's acceptable input requirements. My "guess" would be 30 minutes maximum, on a good day, and a full charge.


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## gcavan (Aug 13, 2009)

> A large car battery, or better yet, a small generator would be better - or better still, a running car engine.


All very poor options.

A car battery is not going to cut it as those are designed to produce a high starting current and to stay at or near fully charged. A typical car battery will work in this situation however after three or four discharges it will be critically weakened no longer be able to hold a full charge.

A generator will work but you have to deal with fuel and you have to listen to it. I expect it was rejected precisely because of the noise.

What you call the best option, is in fact the poorest. Besides being a very inefficient use of the vehicle (and the fuel) the battery will actually go dead unless you keep the vehicle running at well above idle. It's alternator will only provide a trickle current at idle rpm.

Caravelle has the right idea, but is not thinking large enough. A good deep-cycle (or deep discharge) type battery is the correct choice. The battery chosen should have a capacity of at least 100 A-hr. This will give a 20 amp load a run time of approximately 2 hours. (70% conversion loss at inverter, max 50% discharge).


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## Basementgeek (Feb 7, 2005)

Got to remember, if your inverter puts 110VAC at 4 amps, your are going pull about 40 amps, 12 VDC, from the battery. 

I would look into a lawn/garden tractor battery, about 1/2 the size of most car batteries. They go up to about 300 cold cranking amps. They cost 1/2 the price you paid.

BG


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## Bill_Bright (Dec 17, 2004)

> What you call the best option, is in fact the poorest.


Huh? What did I say was "best"? In fact, where did I say _anything_ was best? Don't think I did. 

If I implied anything was best to use with an inverter, it was a running car. And I stand by that. 

Short of a running car, I said multiple SLA batteries in parallel. 

I do agree that a car battery is probably not the best choice. I should have suggested a marine battery instead as they not only are designed to start the engines, but to provide power for pumps, radios, lights and instrumentations while the engines are off. Plus marine batteries are capable of withstanding more physical abuse. 

A lawn and tractor battery will have the same characteristics of a car battery. And regardless if car, marine or tractor, those batteries not sealed and can vent corrosives and noxious fumes.


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## caravelle1 (Aug 24, 2014)

Interesting information - ty much.

I returned to batteries plus and talked to manager, showed the specs of my projector, the specs of the inverter, and the problem, he highly recommended this battery and said it can output 1000w of energy. The formula he used was simply dividing the amount of amps my projector uses 2.6 by the amount of amp hours on the battery which is 20/ah for around 7 hours of runtime.
As I was checking out I specifically asked him to check the wattage output the battery could produce and was told 1000w. They take returns so if there was some misinformation its no problem.

What I want to do is run this projector at 300 watts and 2.6 amps for at least 3 hours, maybe another 20ah in conjunction?
Obviously if the wattage is 240 this wont be sufficient either


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## caravelle1 (Aug 24, 2014)

They said that the 20ah battery I purchased was what they used in lawn mowers.
Provided it works, ill likely let it run and watch to see the maximum runtime. The 800 watt cobra inverter is arriving today I'll let you guys know


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## caravelle1 (Aug 24, 2014)

Ahhh I see so the 2.6a of the projector is not relevant the real draw is the inverter which will be drawing more?


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## Basementgeek (Feb 7, 2005)

If you are producing/needing 2.6Amps, you inverter will draw about 30 amps from the battery.

Yes, they use this smaller batteries in many smaller lawn machines, but you are only cranking a few seconds. They are capable of 100 amps for a few seconds it takes to start the engine. 20 AH battery is basically 20 amps for one hour.

I would say you need a car type battery. 

BG


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## caravelle1 (Aug 24, 2014)

Basementgeek said:


> If you are producing/needing 2.6Amps, you inverter will draw about 30 amps from the battery.
> 
> Yes, they use this smaller batteries in many smaller lawn machines, but you are only cranking a few seconds. They are capable of 100 amps for a few seconds it takes to start the engine. 20 AH battery is basically 20 amps for one hour.
> 
> ...


Ahhh that is super helpful ty. The employee at batteries plus was clueless to this Im amazed.
looks like I need 100ah in that case to run for 3 hours which as people are saying is a car or marine battery.


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## Bill_Bright (Dec 17, 2004)

> Ahhh I see so the 2.6a of the projector is not relevant the real draw is the inverter which will be drawing more?


Not relevant? Well, not really, kinda - sorta. 

Your inverter is not just converting DC to AC, it is acting as your projector's power supply. As with all power supplies, connected devices draw what they need, not what the power supply is capable of delivering (assuming the PSU is large enough for any "expected" requirement). 

On a computer, for example, if the motherboard (including CPU, RAM, installed cards, attached USB devices) drives and fans need 250W they will draw 250W regardless if the PSU is a 350W or 650W. And the PSU will draw from the wall ~290W (at ~15%), again regardless of the PSU's capability. 

So the projector, as the primary load, is relevant because it determines the load on the inverter, and thus the load on the battery.

I think you need to do some home work for what's available locally in your area. And shipping charges, if nothing. Because batteries are not cheap to ship.

12V 100Ah is more than enough but those batteries are not cheap. After doing some more homework on this, I note there are 12V SLA marine batteries too. If you live near the water, marine batteries may be the cheaper option in your area. 

Do remember that a battery is made up of one or more cells. And the cell can be in the same case as other cells or separate or both. So you can buy 2, 3, or 4 or more smaller 12VDC batteries, strap them in parallel and be good to go. The advantage to separate cells is they can be replaced separately when they fail - without having to replace the entire battery at once. And if you find you need a little more run time, you can strap on more cells. 

Do note a current 55 inch LED TV consumes less than 100W. Even Plasma 50" is less than 150W.


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## caravelle1 (Aug 24, 2014)

great information, thank you so much. Im pretty keen to figuring stuff out with a little help, I was honestly amazed at the lack of knowledge at menards, batteries plus, guitar center, microcenter, and radio shack. Everyone said electrical wasn't their thing, and the guy at batteries plus just gave me flatout wrong info.

I think I've got a good understanding with the amp usage being about 10 times more because im upping from 12v to 120v and the wattage output being 12v times the amp per hour.

Makes it very easy to see why I would need a larger battery.

It is about $200 for a 100ah marine battery here. My only concern with that is would i have output or charge issues as opposed to a deep cycle battery? There is a 35ah enclosed they sell for $90 I could do 2 or 3 of those.

Unsure on the best option


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## Basementgeek (Feb 7, 2005)

100ah battery will not be big enough, IMO, for what you are trying to do. Once the voltage drops off to maybe 11V, your inverter will stop working. As you draw the amps the voltage drops off.

I don't see any conversation chart from CCA (Cold cranking amps) to amp hours.

BG


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## caravelle1 (Aug 24, 2014)

Gotcha, so as the battery gets low percentage of max power it lowers voltage output? Or is that more indicative of long term wear on the battery? Longer is definitely better and if there is any chance of premature failure I'd rather have the more powerful battery. Tomorrow I'll hit up batteries plus and some auto stores and compare


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## caravelle1 (Aug 24, 2014)

My inverter arrived,

You guys are spot on, the image was solid with the occasional flicker,
It lasted 20 minutes before the low battery warning went off on the inverter.

going to hit up batteries plus and hopefully I can get a 150+ sealed AH


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## Panther063 (Jul 13, 2009)

Just as an example, I have a remote block of land with a caravan for weekends, it has two old solar panels charging one very heavy and quite large 100Ah Gel type battery for storage, that lasts up 3.5 hours at night running a 12V 21.5" LED TV only, which may draw up to 20A.
To run that Projector for any number of hours you may need at least 2 or more of this type of Battery.
Even better, as suggested, a generator.


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## Basementgeek (Feb 7, 2005)

Panther063- No 21 inch LED TV draws 20A. Check the label.

BG


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## Panther063 (Jul 13, 2009)

Yep you're right, it's 12V 6A and 72W
and I meant LCD not LED :angel:


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## Bill_Bright (Dec 17, 2004)

> I don't see any conversation chart from CCA (Cold cranking amps) to amp hours.


I don't find that surprising. You don't crank an engine for hours - typically just seconds and that's the capability CCA indicates. 



> Panther063- No 21 inch LED TV draws 20A. Check the label.


Agreed. 20A is more than a toaster oven or large microwave! 



> and I meant LCD not LED


 I think you are still confused. "LCD" monitors and TVs require backlighting and that is done with 2 different technologies. The first and oldest is with an inverter and CCFL (cold-cathode florescent light). Newer LCD monitors and TVs use LED backlighting. Either way, they are still "LCD".


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## caravelle1 (Aug 24, 2014)

After considering all the options presented I bought a Honda EU2000i inverter generator and its running flawlessly. It should net me at least 4 hours per gallon of gas.

Thanks for all the help, learned a ton. Issue is solved


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## Bill_Bright (Dec 17, 2004)

I think you made a wise choice - even though you ended up spending a bit more than you originally planned, I suspect. Do get a high quality heavy duty extension cord. Don't try to save pennies there. You will want a long cord to move the generator noise as far away as possible. But the longer the cord (conductor) the more resistance and power loss in the wires. So the bigger the conductors (smaller the gauge #) the better. A quality cable will have quality connectors attached with quality assembly and manufacturing techniques for minimum resistance, maximum grounding, and suppressed "electrical noise" too.


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## Panther063 (Jul 13, 2009)

Bill_Bright said:


> I think you are still confused. "LCD" monitors and TVs require backlighting and that is done with 2 different technologies. The first and oldest is with an inverter and CCFL (cold-cathode florescent light). Newer LCD monitors and TVs use LED backlighting. Either way, they are still "LCD".


Thanks professor, but I am aware of that, and I'm not confused, hence my clarification as to which version I have


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## Bill_Bright (Dec 17, 2004)

Except your "clarification" was not clear! And considering the confusion with current draw, and the fact inverter/CCFL backlighting consumes more power than LED backlighting (which affects runtime while on battery) it is important for "all" reading, not just you, that the facts are clear.


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## Basementgeek (Feb 7, 2005)

This topic appears to be done. This post is closed.

BG


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