How much Inverter do I need?

[Dray]

I am wanting to install an inverter and am not smart enough to figure out which one I need.  Is it correct that I shouldn't get more than I need because I'll be pulling juice away from my battery than I'm not using?  Help please.

All I want to do is bring my laptop so I can watch movies and maybe surf the net.  

Walmart sells a 200, 400, 800 and a 1200 watt inverter.  I think the 400 watt one is the one is all I need.  Am I right?

Are they hard to install?  

Thanks

[beacher]

All I want to do is bring my laptop so I can watch movies and maybe surf the net.

If that is the ONLY thing you need to power, then an inverter is the least efficient use of your PopUp's deep cycle battery.  A power converter like the iGo everywhere85, or the Targus Mobile 70, will power your laptop, and other DC electronics you might own.

However, if you intend to use other small AC items besides your laptop, then the smallest inverter is the way to go.  Look at your laptop's power supply.  It will list the Amperage input, multiply that by 110Volts, that will tell you how many Watts your power supply needs.

Then simply buy an inverter big enough to power it.


.

[Dray]

If that is the ONLY thing you need to power, then an inverter is the least efficient use of your PopUp's deep cycle battery.  A power converter like the iGo everywhere85, or the Targus Mobile 70, will power your laptop, and other DC electronics you might own.

I have thought about those batter pack products you linked.  But I thought why would I buy another battery when I have one already on the PU.  Tell me why it's not a good idea to use my PU battery.  Thanks.

[AustinBoston]

I have thought about those batter pack products you linked.  But I thought why would I buy another battery when I have one already on the PU.  Tell me why it's not a good idea to use my PU battery.  Thanks.

I think you misunderstood both products.  They do not have their own battery, they are intended to hook to your battery.

Essentially, they eliminate one conversion.  Let me explain.

If you use an inverter, that will convert 12V DC into 120V AC.  Then you plug the laptop adapter into thhe inverter, and that converts 120V AC into 3.3V DC (or, for some older laptops, 5V DC).  In both stages, some energy is lost, which means you are not getting everything possible from your battery.

By using a power converter designed to go straight from your battery to your laptop, one conversion is eliminated.  The 12V DC is converted directly to 3.3V DC, eliminating one conversion stage and preserving a little bit of battery power.

Austin

[Dray]

I see.  I did read and look at the links and then wrote my response at a later time and was thinking of another product called the Duracell powerpack.  

Thanks guys, but I'm gonna go with the inverter just because I think there may be a time where I want to plug something else in other than my laptop.  Plus the price is way cheaper for the inverters at Walmart.com.

[wavery]

I see.  I did read and look at the links and then wrote my response at a later time and was thinking of another product called the Duracell powerpack.  

Thanks guys, but I'm gonna go with the inverter just because I think there may be a time where I want to plug something else in other than my laptop.  Plus the price is way cheaper for the inverters at Walmart.com.

Just remember the way that they rate inverters. Take a 400/800 rating. That means that you can run an item that runs off of 400w. The 800w means that it will give you a "Boost" of up to 800w for starting a motor or heating element. That higher rating is VERY short, maybe 10 seconds or less.

If you decide to go with a larger inverter, say 1500/2500w, you will need to have at least 2 batteries on you PU (wired together). Also, you will need to mount the inverter as close to the batteries as possible and use battery cables from the battery to inverter.

Find the webshots link in my signature line and you can see how I mounted my 2500/3500w inverter. We use it to run our microwave oven while dry camping. It's a 900w microwave and the most that we run it is about 10 minutes. That's about 150w or about 12A from my storage capacity. Not a big deal.

[AustinBoston]

Find the webshots link in my signature line and you can see how I mounted my 2500/3500w inverter. We use it to run our microwave oven while dry camping. It's a 900w microwave and the most that we run it is about 10 minutes. That's about 150w or about 12A from my storage capacity. Not a big deal.

Just a nit to pick...did you mean 150wh?

900 Watts at 120 volts will be about 7.5 amps (not exactly beacuse of the way a/c actually converts watts into volts and amps is a bit more complex than simple multiplication/division).

900 Watts at 12 volts will be about 75 amps.  This is the momentary draw from the battery while the microwave is actually running.

But if you can only run for 10 minutes, that would be 900/6, or 150 Watt Hours.  The average current would be about 12.5 amps, but it breaks down to 10 minutes at 75 amps and 50 minutes at 0 amps.  I'll bet those cables are fairly warm at the end of the ten minutes.

Austin

[wavery]

Just a nit to pick...did you mean 150wh?

900 Watts at 120 volts will be about 7.5 amps (not exactly beacuse of the way a/c actually converts watts into volts and amps is a bit more complex than simple multiplication/division).

900 Watts at 12 volts will be about 75 amps.  This is the momentary draw from the battery while the microwave is actually running.

But if you can only run for 10 minutes, that would be 900/6, or 150 Watt Hours.  The average current would be about 12.5 amps, but it breaks down to 10 minutes at 75 amps and 50 minutes at 0 amps.  I'll bet those cables are fairly warm at the end of the ten minutes.

Austin

Yes, I meant 150wh.

The cables don't get warm at all. I use "00" battery cables that are about 18" long (tightened carefully). I've even run the AC which pulls about 130A@12v (for a very short time) and the cables just get warm.

[AustinBoston]

I use "00" battery cables that are about 18" long (tightened carefully).

Yep, that will do.  

Austin

[Dray]

...Find the webshots link in my signature line and you can see how I mounted my 2500/3500w inverter.

Wavery - I took a look at your pics for how you mounted your inverter.  It looks like you have it attached to the bottom of the bunk end.  How do you slide your bed in with that attached like that?  

Maybe your PU is different than mine, but with mine it wouldn't work.  I think I may just attach my inverter to the battery once I get there and then set it on the tongue somewhere and then run an extension cord from inverter up and into the PU.

[wavery]

Wavery - I took a look at your pics for how you mounted your inverter.  It looks like you have it attached to the bottom of the bunk end.  How do you slide your bed in with that attached like that?  

Maybe your PU is different than mine, but with mine it wouldn't work.  I think I may just attach my inverter to the battery once I get there and then set it on the tongue somewhere and then run an extension cord from inverter up and into the PU.

I placed a 9" long bracket screwed into the bottom of the bunk platform. It only extends down about 1/4" and leaves an open slot between the bracket and the bunk platform. The bottom of the inverter has a 3/16" lip sticking out about 1/2" from the inverter. It is meant for mounting the inverter on a flat surface.

I slide the lip of the inverter on one end of the inverter into the 9" long bracket. On the other end, I have 2 little levers that I twist over the lip on the other end of the inverter. (I hope that all makes sense). It takes me about 3 minutes to install the inverter, each time that we dry-camp.

I did't want the inverter exposed to the weather and I didn't want it inside of a cabinet (it needs air-flow). I find it preferable to remove it and store it after each camp-out.