Calculating Power Needed

[mdoverl]

So I have a 2007 Prius that I'll be living out of again and I've been working on figuring out how much power I need to run electronics. I know the best way to determine how much power something takes up is to use a Kill O Watt meter, but I can't by one at the time, because my girlfriend will ask to many questions about it. So I've sat down and written down how many amps everything takes up, based off of the manufacturer notes, though I understand that this can be inaccurate, but it sounds that what is stated is usually higher that what is actually used.

So I did some research and found a couple different types of formulas for converting watts to amps, there is a very complex formula out there, and I was able to find a simplified version of the formula at http://www.rapidtables.com/convert/electric/Watt_to_Amp.htm

So below is a list of some of my electronics I'll be using;

Monitor - Input; 100-240V 1.5A Output; 12V 5A
TV Antenna – Input; 100-240V 50/60Hz 0.4A Output; 12V 1000mA (0.01A)
TV 120VAC 1.6A
Blu-ray Player 120 V 11W 60 Hz 0.1A
Keyboard - 5V 100mA (0.1A)
Laptop - Input; 100-240V 1.5A Output; 19V 3.16A
Mouse - 5V 100mA (0.1A)
Xbox - Input; 100-127V 4A Output; 150W 12V 12.1A
Phone Charger - Input; 100-240V 0.2A Output; 5V 1.2A
TOTAL Amps = 9.4A
 
Amp x Time = Amp hours x 0.5 = Total Amps
9.4A x 8 (hours) = 75.2 Amp Hours x 0.5 = 112.8 Amps
DC watts to amps
Watts / Volts = Amps
AC single phase watts to amps
Watts / Volts = Amps

The total Amps I came up with is 112.8 Amps in an 8 hour period, this doesn't seem correct, can someone point to where I may have left out some math? Not asking someone to do the math for me, just a nudge in the right direction.

 I think this post could be good for people who are not ready to commit money to a electrical system but wish to research and find out of much they need, I'll buy a meter once I move out of the house and begin purchasing the batteries I need for my system, as it'll be critical for troubleshooting purposes.

 

[Van-Tramp]

The numbers you have listed do not really mesh with my knowledge. First, you are taking 120v Amp stats, not 12v and that matters big time. For example, that laptop does not run on 1.5 amps of 12v, more likely 3-5 amps (especially with that 19v power supply). The Xbox at 150 watts is actually 11+ amps on 12v setup (notice it says 12.1 amps for 12v?). With just your laptop, Xbox, and Monitor, you are at 162+ amps of power used on an 8 hour period by my calculations... but that is not your real problem here.

First, to run any or all of that, you need an inverter, which will not be 100% efficient. 90% is more likely (unless you spend more to buy a real good inverter) so your 112.8 already climbs over 125 amp hours used each day, at your math (180ish with my math).

Second, you need a battery bank of AT LEAST 250 amp hours for you to use 125 amp hours in a single day (remember, the batteries cant go below 50% or you kill them for good). That means you need two very good and very expensive batteries or four Walmart batteries (2 years of life at best). Where do you plan to put the 300-350 lbs of batteries in your Prius?

Lastly, you then need a way to regenerate the power you use. I currently have 300 watts of solar, and that brings in enough to cover the power consumption of about 70 amps used during the day... but only on ideal sunny days. On cloudy days our battery bank is depleted within two working days and we are forced to plug in (and we are not running anywhere near what you want too run). For you to run all that, and for that long, you will need 500-600 watts of incoming solar. Where are those panels going to fit?

Or you can get a generator and spend $3-5 per day in gasoline plus the $600+ to purchase the genny.

I don't want to burst your bubble, but there is a reality to this lifestyle that you will need to accept. You will need to live within this reality. Power is not easy to come by, and all your electronics crave too much power. The Xbox is a once-per-month luxury, not a daily use item. A TV in a Prius? I dont see how you are going to make that work. Unless you are willing to spend $10,000+ on lithium batteries and a trailer to hold the 600 watts of solar panels, I don't think you are thinking realistic.

 

[Ballenxj]

  I know the best way to determine how much power something takes up is to use a Kill O Watt meter, but I can't by one at the time, because my girlfriend will ask to many questions about it.

I'm wondering what the problem would be with just telling her you need it to calculate your power usage? Are you spending her money?

 

[SternWake]

The amperage numbers you list are the absolute maximum the device can pull. their average amperage will likely be much less.

Like the Tv antenna amplifier, no way is that thing pulling 1 amp the whole time it is on.

Also my Tv on average pulls about half of the maximum listed on the AC adapter it came with. When the dvd player worked it rose upto 3/4 of max.

My laptop needs a 90 watt adapter, yet with fully charged battery, streaming video it draws 35 to 40 watts, just typing on forums is about 28 to 30 watts. the only time it pulls 90 watts is when the laptop battery is well depleted, and I am spinning a DVD with another window open in background.

It is not instant death for a lead acid battery to be drawn below 50%. 50% is a fuzzy goal/ rule to attempt to not go under. Going under 50% it is not great for them, but assuming a prompt full recharge it is not the end of their world. I have 500+ deep cycles on my AGM, and several dozen of those are are well under 50%, with many as low as 20%. When I do bring it that low I do what I have to to get as full as possible that day. if I can't I use less electrocity that night hoping the next day i can.

Chronically keeping lead acid batteries in the 50% range is very hard on them.

Also, I am not sure if you are using the Prius battery or not for house loads. If so that changes everything, but having no experience with using a Hybrid car battery for house loads, I will offer no input.

So unless you are using the Xbox for 8 hours each day, I do not think you will exceed 100Ah consumed in those 8 hours. But that is a guess.

It is easier to consume less electricity, than it is to generate enough that one can keep all their stick and brick domecile habits.

 

[mdoverl]

I'm wondering what the problem would be with just telling her you need it to calculate your power usage? Are you spending her money?

Not spending her money, I'm worried that this will give off the fact that I'm leaving, which I'm trying to keep under the radar with her.

Sent from my LG-H631 using Tapatalk

 

[Ballenxj]

Not spending her money, I'm worried that this will give off the fact that I'm leaving, which I'm trying to keep under the radar with her.

OK, time for me to zip it.

 

[deadwood]

The first thing I thought of is... How are you going to get all that stuff in a prius? How do you watch tv and play xbox in that car.

 

[mdoverl]

The numbers you have listed do not really mesh with my knowledge. First, you are taking 120v Amp stats, not 12v and that matters big time. For example, that laptop does not run on 1.5 amps of 12v, more likely 3-5 amps (especially with that 19v power supply). The Xbox at 150 watts is actually 11+ amps on 12v setup (notice it says 12.1 amps for 12v?). With just your laptop, Xbox, and Monitor, you are at 162+ amps of power used on an 8 hour period by my calculations... but that is not your real problem here.  

First, to run any or all of that, you need an inverter, which will not be 100% efficient. 90% is more likely (unless you spend more to buy a real good inverter) so your 112.8 already climbs  over 125 amp hours  used each day, at your math (180ish with my math).

Second, you need a battery bank of AT LEAST 250 amp hours for you to use 125 amp hours in a single day (remember, the batteries cant go below 50% or you kill them for good). That means you need two very good and very expensive batteries or four Walmart batteries (2 years of life at best). Where do you plan to put the 300-350 lbs of batteries in your Prius?

Lastly, you then need a way to regenerate the power you use. I currently have 300 watts of solar, and that brings in enough to cover the power consumption of about 70 amps used during the day... but only on ideal sunny days. On cloudy days our battery bank is depleted within two working days and we are forced to plug in (and we are not running anywhere near what you want too run). For you to run all that, and for that long, you will need 500-600 watts of incoming solar. Where are those panels going to fit?

Or you can get a generator and spend $3-5 per day in gasoline plus the $600+ to purchase the genny.

I don't want to burst your bubble, but there is a reality to this lifestyle that you will need to accept. You will need to live within this reality. Power is not easy to come by, and all your electronics crave too much power. The Xbox is a once-per-month luxury, not a daily use item. A TV in a Prius? I dont see how you are going to make that work. Unless you are willing to spend $10,000+ on lithium batteries and a trailer to hold the 600 watts of solar panels, I don't think you are thinking realistic.

Sorry I haven't been able to respond to your post  in awhile.

Thanks for pointing out the math, I guess I should have been using Output Volts instead of Input Volts. SO I re-did my math, and updated the formula (remove x 0.5 (my brain knew this meant 50%, but I figured other people would get confused by it) with x 2) and came up with following;

12 V Amp x Time = Amp hours x 2 = Total Bank
21.67A x 8 = 173.36 Amp Hours x 2 = 346.72 Amps

Wow, that is a lot of Amps, now the batteries can be hooked up to Prius and be charged that way. I believe a member of the site has done this, he is an electrical engineer If I remember correctly, "Oberneldon", sorry if I spelt that wrong, completely going off of memory.

I had research Iowa state law for storing objects on top of vehicles, and determined that a 310 watt Renogy solar panel would exceed legal limits by 6 or 5 inches on the side of the vehicle. Yes I have thought of adding a solar panel to the top of the Prius, but this would completely destroy stealth factor, and I spend most of my time in the city anyways. So I'm thinking of ditching the solar panel idea, but it's still creeping in the back of my mind due to my inquisitive nature of curiosity and wonder. So legally I could fit a smaller renogy solar panel on my Prius, but once again, STEALTH. So for now, ignore that please. (Sorry I must confusing to  people, I sound like I'm not for something, and then am for it in the same sentence)

Then I started to think, well I don't really play Xbox anymore, I could easily sell that and the 50 plus games I own. Then after realizing in your post that the Xbox takes up 12.1 Amps, ooch, I don't need that, really. So I re-did the math with the following;

12 V (Without Xbox) Amp x Time = Amp hours x 2 = Total Bank
9.57A x 8 hours = 76.56 Amp Hours x 2 = 153.12 Amps

Now 153.12 Amps seems much more manageable, but, I don't plan on using everything for 8 hours a day, that was just overkill to enure I had extra power for days that I don't charge the battery (or overcast, IF I go that route), and decided to see what the math looks like for 4 hours;

12 V (Without Xbox) Amp x Time = Amp hours x 2 = Total Bank
9.57A x 4 hours = 38.28 Amp Hours x 2 = 76.56 Amps

76.56 Amps looks better, but I still need to research batteries (Amp loads and what not, so much fun stuff to learn and math to play with), that will come later, I have such limited time.

Oh yes, storing batteries, I have two ideas.

1. A trailer, but this would destroy stealth in the city (I'm starting to wonder if I really care about stealth though, I don't really cover the windows much, never been bothered, sure I've been noticed though)

2. Inside the Prius, I have room to store them, but it would come at a sacrifice of storage for everything else. Plus I would have to sleep right next to them (not sure if I want to wake up in the middle of the night with my face melting off or choking on the gasses), I'm pretty sure I could easily store one battery depending on it's size, more research.

Thanks for the replies everyone!

 

[mdoverl]

The first thing I thought of is... How are you going to get all that stuff in a prius? How do you watch tv and play xbox in that car.

I'm going to remove the passenger seat and build a desk/entertainment/storage area there and use the rear right seat as a desk chair! When it's time for bed, I lower the rear right seat and make my bed there, essentially a Multi functional area!!!

 

[mdoverl]

OK, time for me to zip it.

Keep it quiet, Keep it secret

 

[Van-Tramp]

The bit of advice I have it to sell all the unnecessary stuffs; TV, Blueray, Xbox and games, and monitor (unless you need it for WORK) which sounds to be worth a fair amount of cash...

Then take all that money and place it directly in the hands of your Ex, because you are going to financially screw her by leaving without any notice at all. Really... you should man up, and live up to your 30-day notice at the very least. Get out with some moral high ground, or at least some maturity. If you have money to buy a battery bank to play games in your car, then you have money to live up to your 30-day notice. Move out right away, but leave her the correct amount of money (getting a receipt is fair).

Now, once you have done all that, you have only a single laptop. They are great movie watching machines, mini-game platform, and you can even work on it. Then you only need to keep it charged, and that can be done off a $20 100 watt inverter, or guy buy a cup of coffee and hang out at the nearest Starbucks... or better yet, free Internet and power at the local library.

 

[mdoverl]

The bit of advice I have it to sell all the unnecessary stuffs; TV, Blueray, Xbox and games, and monitor (unless you need it for WORK) which sounds to be worth a fair amount of cash...

Then take all that money and place it directly in the hands of your Ex, because you are going to financially screw her by leaving without any notice at all. Really... you should man up, and live up to your 30-day notice at the very least. Get out with some moral high ground, or at least some maturity. If you have money to buy a battery bank to play games in your car, then you have money to live up to your 30-day notice. Move out right away, but leave her the correct amount of money (getting a receipt is fair).

Now, once you have done all that, you have only a single laptop. They are great movie watching machines, mini-game platform, and you can even work on it. Then you only need to keep it charged, and that can be done off a $20 100 watt inverter, or guy buy a cup of coffee and hang out at the nearest Starbucks... or better yet, free Internet and power at the local library.

Well...

Man up, wow. You make it sound like she does not have access to my bank account already. But thanks for assuming i have money for a battery bank. Didn't realize that if i talk about mathematics that means i unlimited resources and income at my disposal. Guess i should have read about the forum rules regarding starting a thread about something i don't money for, So I apologize to you Van-Tramp, and the rest of the community.

Well...

This was suppose to be a simple thread about mathematics, theory, and problem solving. Maybe I'll take my money and buy morals and maturity. Because mentioning an Xbox must mean I'm low life scum who is wasting previous oxygen on this planet, maybe I'm obligated to pay for the oxygen to?

Well..,

I'm sure my girlfriend can make a down payment for the oxygen with the money she had drawn from my account.

I came to this site because i needed help and had questions. But clearly you do not like me, and maybe you'll rally the people behind you because of how much of a horrible person i am, get me banned from the site, and have this thread deleted.

There was a previous thread where i was irresponsible, i didn't like what someone said, and said something. I don't remember what It was i said, but it wasn't disrespectful, i kind of stopped responding after that. Recently i thought to apologize to that person, but couldn't find the thread, which lead me to believe it was deleted. The thread was about rebuilding vintage campers, if your that person, i would like to give a sincere public apology before I'm banned from this site. Good day.

Maybe I'm too sensitive, a worthless scum who served his country for 9 years

Sent from my LG-H631 using Tapatalk

 

[Ballenxj]

Well...

Man up, wow. You make it sound like she does not have access to my bank account already. But thanks for assuming i have money for a battery bank. Didn't realize that if i talk about mathematics that means i unlimited resources and income at my disposal.
<-------->
Maybe I'm too sensitive, a worthless scum who served his country for 9 years

Oh PLEASE! Don't be so thin skinned! That's my job.
The main concern here was that you didn't leave her high & dry? So much miscommunication on the net.
There are always at least two sides to every story, and that's not my concern at the moment.
PS, Thank you for your service. Now let's all take a deep breath and get back to the subject?

 

[mdoverl]

Oh PLEASE! Don't be so thin skinned! That's my job. [emoji14]
The main concern here was that you didn't leave her high & dry? So much miscommunication on the net.
There are always at least two sides to every story, and that's not my concern at the moment.
PS, Thank you for your service. Now let's all take a deep breath and get back to the subject?

Sorry, but that reply i made wasn't even directed at you, i thought i had quoted someone else, at least it shows that on tapatalk on my phone. Sorry if you thought that was directed at you, my apologies.

Sent from my LG-H631 using Tapatalk

 

[Ballenxj]

Sorry, but that reply i made wasn't even directed at you, i thought i had quoted someone else, at least it shows that on tapatalk on my phone. Sorry if you thought that was directed at you, my apologies.

Nope, I didn't think it was directed towards me, I'm just trying to say there is no reason to get worked up and leave over this.
See what I mean about misunderstandings on the net?

 

[highdesertranger]

come on people, let's stay on topic and be respectful. highdesertranger

 

[akrvbob]

It's extraordinarily rare for anyone to get banned and no one here is at any risk of that.

The most wonderful thing about this forum is we become like family--it's great!

The most terrible thing about this forum is we become like family--it's a pain!

Like all families sometimes we stick our nose a little too much in others business than we should--but like family, deep down we mostly mean well, even if it doesn't look or feel that way.

So like all families, tolerance and patience are required to smooth out the rough spots. I hope you can bear with us, we will not be perfect. However, I honestly believe that nearly everyone here wants to be helpful to you and make your life better, even if we are a little butt-in-ski.