Tell me what I need!

[kyonu]

Okay, so hopefully I will be pulling the trigger on my RV within a few months (hopefully before November, maybe in the middle of that month) and I need to make sure I have a solid list of things I need to get.

First up: Electrical. I've been reading all of the threads cropping up lately, but I need more of a full list of required parts. I've done months of research on different brands, types, etc, and many people have preferences. But I'd rather take if from the people I know who have them working! (hinthintSternWakeyou'reamasteratthis)

So please help me! I know all the terms at this point, so don't try to dumb it down. Just need the best of the best with a price/performance ratio. I do have a budget, but I won't disclose it at this time. I'd rather know what's best beforehand.

A bit of info however: I will be working out of the RV using my computer, an IP phone, two monitor's, a Cisco VPN (required for work at this time), and my T-Mobile equipment to get data (I will be using the VPN to get the unlimited data plan through out my RV since I'll need it.)

Together this would equal about 250 watts, which needs to be run at about 16 hours a day (maybe 250 at 8 hours, 75 at 8 hours). I will be running a dual-induction cooktop with the low and medium surface temps, which will go between 450 and 800 watts for no more than 1 hour a day (30 mins between each meal). If I use two burners at once, assume double that.

I prefer to NOT use Propane at all. It is more dangerous than electric, and I really don't want a mistake (as I am pretty clumsy). As such, I will try to find devious ways to heat my shower, but I will try to minimize my water usage otherwise.

With this in mind, other power items may include a 200 watt LED TV for up to 2 hours a day, another laptop at about 20 watts an hour (overestimating here, should always be plugged in) for about 16 hours a day (max), and other miscellaneous equipment that I will put at around 350 watts an hour for around 3 to 4 hours a day.

A coffee maker will be included which will run about 20 minutes once a day, so assume 350 watts for that.

I will use LED lights throughout the coach, equaling about 20 watts total, for ABOUT 20 watts an hour for 10 hours (combined). Fridge will be the biggest hog at around 350 watts, which I will need to run for a long period of time if not using propane... anyone got ideas for this?

Assuming my math is accurate, I will be using around (without the fridge) just under 7000 watts a day. How much battery power would I need for this? Much of this won't all be running at the same time, and can be separated throughout the day. Lets say 5000 watts at any given time.

I do plan on going solar and wind generation, and possibly other methods, as well as having a backup Honda eu2000i generator (in a quiet box) just in case.

Last note: I am making extremely high estimations for my wattage use to get a more accurate number. Feel free to teach me your ways with that as well.

Have at it!

 

[SternWake]

I think, even if your wattage estimates are overestimated by 50%, you are not going to do this on battery power. You should really get a Kill a watt meter and see how much your computer and accessories are consuming now as you use them.

250 watts at 12.6 volts is nearly a 20 amp load on the batteries.

A pair of GC batteries holds ~220 amp hours, so in 6 hours this pair of GC batteries, discounting peukert effect and inverter inefficiencies, has your battery bank bank well below 50%, just running your computer.

I think you should get a Honda right off the bat and use it all day and just worry about enough battery top get you through the night.

The peukert effect basically says the higher the draw on the battery, the less overall capacity the battery has to give. Your listed loads are huge, requiring a huge battery bank, requiring charging sources which will max out your generator.

It sounds like you are not willing to make any concessions to living on battery power ( no propane and insisting on electrical coffee brewing and cooking) and have little concept of how little energy is actually stored in a battery, and how difficult it is to actually recharge that battery fully so that it can live a respectable cycle life.

It can be done if you have the budget, the space for a huge battery bank, and likely more than one High amp converter/charger and a Generator in the 3kw range which will still need to be run several hours each day.

Be easier to just run the Genny all day long and size a battery bank much smaller just to get you through the night.

 

[PastTense]

Or you can park in places which have a 50 amp or so electrical connection--RV parks or state/local campsites with this available.

 

[kyonu]

@SternWake: Thanks for the stern wake up call! I've been thinking about sizing a battery bank at 500ah... would this still be too soft? At 12.6v, that's 6300 watts, minus a few measurements, that's around 4000 watts... Which I can deal with. Is this not viable? I was thinking LiFPO4 batteries which allow me to take a bit more precaution on the batteries without them frying.

@PastTense: I was indeed going to be staying a lot of RV parks with service, mostly because until T-mobile finishes their network expansion next year, I will need interwebs! I just want options for when I boondock, and if I do boondock, I'd like to be out for around a month at a time... More on that later on I guess.

 

[SternWake]

Really hard to say how big a battery bank you need. Living off battery power is more about using as little of it as possible, rather than carrying enough storage that one does not have to worry about it.

One can carry huge battery banks, that is not really an issue, besides the weight, the Issue is properly recharging the large battery bank, which can be quite complicated.

Far too many people think that if they deplete a battery fully, all you do is put a charger on it and all is hunky dorry again, when in all actuality getting that battery bank back upto its full remaining capacity is quite difficult and time intensive and also requiring the right equipment to complete the task and tools to measure how effective that equipment was. Many just put faith in the charging device, and can still get a respectable lifespan from batteries. Others are not so lucky.

While battery chargers are said to recharge batteries fully, they are actually designed to NOT overcharge batteries. All batteries are different in their requirements to reach full recharge and this will change as the battery ages, so no one charger, despite all the genius, confidence inspiring marketing and claims, is going to do the job the consumer expects of it. The blinking green light indicating full charge is wrong 95% of the time.

Yet the person aware of this can spend way too much time and effort to get that extra year of lifespan from the batteries, and this time and effort might not be worth it, compared to just replacing the batteries earlier.

Lifpo4 batteries give a good indication of the budget you are working with. I am not familiar with them and will give no advice in their regard.

Get a Kill a watt p3, plug your computer power strip into it and see how many watts it consumes in actual use, as you will use it.

Get over your fear of propane, at least for the absorption/propane fridge your rv will likely come with. If you have the option, get a DC or an AC/DC compressor fridge rather than a 120vac only residential fridge.

Cooking with electricity via battery power is, IMO, foolish. Same with making coffee. Fire up the generator for such tasks, or use a fossil fuel and some common sense regarding its safety

 

[SoulRaven]

It sounds like your needs/desires are totally unreasonable for anything other than a generator.

Get an RV with a BIG generator, put a quiet muffler on it, and you' good to go.

 

[kyonu]

Okay, so I've made a few budget changes. I've decided that I will not be running the coffee maker and cooktop without the generator, and will use LP with the fridge. It's been done for decades, so I think I could give it a shot.

So, with that in mind, that racks off the biggest loads, which is more than half the wattage necessary. So now, from there, what would you recommend?

Also, I will try to get a 3000w generator, but definitely want the quiet box around it so I can use it whenever I need it in a populated camp site. The cost of that should be easily made up from the cost of batteries I don't need to buy.

I just need to get a real list going so I can make sure I stay on track.

 

[SternWake]

I still can't make a capacity recommendation as I have no Idea how much your computer/ internet system is actually going to consume.

The power ratings listed on the power supplies is the maxumum the PS can provide tol meet the maximum demands of the appliance they are designed to feed, but actual consumption can be much less, and it all depends on what the computer system is doing and how cpu intensive it is and how efficient the appliance is.

Get one of these:
http://www.amazon.com/P3-P4400-Elec...id=1404953558&sr=8-1&keywords=kill+watt+meter

Get this device, use it, take records over a few days, post the results and I'd feel fairly confident making a recommendation of minimum battery capacity you should strive for to meet the demands of your maximum electrical draw.

Anything else would just be a wild guess and a possibly huge overestimation.

 

[LeeRevell]

So, the OP's first post assumes 7,000 watts. Since Watts = Volts X Amps, Amps should be Watts divided by Volts...? 7,000W / 12V = 583.33 Amps of battery power needed for one day. Whoowee! Gonna need a trailer load of batteries and solar. My math may be off though.
I agree with using the meter to learn what the true power usage of each device is, and whittle this guess down some.

 

[kyonu]

I already have one on the way, Stern. Also, I am not using a desktop, only a laptop for me and for my lady friend. Well, I have my own two laptops, so make that three... Regardless, much less than a desktop hog. I think my biggest power draw will be my monitor's when they are on (looking at upgrading them to LED as well) and the large cisco VPN needed for work... But I will test with the kilowatt.

 

[SternWake]

Cool. It will ultimately cost less, to get more efficient appliances, and use less electricity, than it would be to act like you are in a stick and brick housing.

As far as Lee revells Calculations go, one would need to add 15% for inverter inefficiency, and then double that number, so as to not use more than 50% of the Lead acid batteries capacity.

For the laptops, get DC to DC "car adapters" for each laptop. These will use at least 15% less electricity to power and recharge the laptops than using an inverter to power the original power brick would use.

Look for LED backlit monitors which have power bricks that take 120vac and convert it to 12 to 13.5vdc. These you can bypass the power adapter entirely and save another 15% or more battery power.

Always easier and cheaper to use less than to accommodate stick and brick luxuries. One just needs to realize they are luxuries.

 

[kyonu]

Understood! I have plans on getting thin LED monitors (possibly OLED for even more power savings), and will find the least power hungry adapters of them all. Our laptops use 90w adapters, but they are charged to full almost all day long, so that won't use too much power. I think the biggest power draw will be the work equipment (which I also use my laptop for.)

That and the TV, but we rarely use the TV, it's just a "we're bored during dinner" thing. But it's also LED and doesn't draw much.

 

[SternWake]

My Laptop also has an adapter capable of providing 90 watts, but the laptop is using less than 25 to type this, as the battery is already full.

Some people will use the laptop battery up, then plug the laptop in to charge, but this actually uses more battery power as Li-ion batteries still require more electricity be put into them to recharge, than was used during discharge, so overall, it uses less lead acid battery to keep the laptop battery fully charged than it is to cycle the laptop battery.

Also, you can use less battery power by using the laptop batteries up right before firing up the generator to cook or make coffee, or run the converter/charger to feed the 12v lead acid batteries. Laptop batteries also consume more current at lower states of charge, which increases the Peukert factor.

Reducing the brightness settings on monitors/tvs can significantly reduce the power consumed. My laptop uses .45 amps less on the lowest brightness setting compared to the highest. Volume on speakers can make pretty big difference too depending on their wattage. Turn down the Bass levels.

My 12v TV with DVD player is rated at 27 watts, but right now is using about 12. The 27 watt rating is for when watching a DVD, and perhaps spinning it upto speed is the only time it will consume 27 watts.

These are but a few examples where the max rating of the power brick is not really indicative of the actual consumption of the appliance.


My van's stereo will use nearly 0 .5 amps more listening to a CD than it does when I am using an mp3 player, at the same volume.

Lots of TV's also run off 12v DC but come with a power adapter, sometimes this is internal to the tv, to convert 120vac to 12vdc, so this is another area where bypassing the inverter and power brick can reduce battery consumption by a good percentage.

All sorts of little strategies can add up to lower the demands on the batteries, and the less the batteries are discharged, the longer they will last and the less time required to bring them back above 80%.

When using a generator, one should use a battery charger which can quickly get the batteries back above 80%. batteries really slow down how much they can accept above this level, but a bigger converter/charger that gets them to 80%+ the fastest, will use less gasoline, and noise.

 

[kyonu]

Sounds good! I will report back once I have tested the kill-a-watt meter. Should be in Friday, so that gives me a weekend!

 

[SoulRaven]

I'd probably go with a 6.5k generator so you will also be able to power the RV's air conditioning if you need it, then make sure you have a good battery charging system, which not all of the stock ones are.

I'm not sure how a quiet box works, but on most RV's just putting an upgraded muffler on the generator can make them almost silent. No more noisy than a really quiet car. I think most of the generators are air cooled, so if air can get to it to cool it, noise can get out.

I've also seen where some people have added a 12v alternator to their on board generator to make a more efficient battery charging system.

 

[Patrick46]

I will try to get a 3000w generator, but definitely want the quiet box around it so I can use it whenever I need it in a populated camp site.

You'll need to learn to run it with great discretion, and absolutely during the daytime only,

...otherwise, be prepared to be very unpopular with the neighbors.

Even relatively quiet generators drive people ballistic after awhile.

 

[Optimistic Paranoid]

Are you familiar with the technomadia site?

They are a high tech couple who live in a converted bus. They put in a huge lithium battery bank, and blogged extensively about the options, why they chose what they chose, and how it all worked out.

http://www.technomadia.com/lithium/

Good read, and sounds exactly like what you are trying to do.

Regards
John

 

[kyonu]

@Patrick: Yeah, that's why I wanted the Honda series. They have a very low decibel, and a quiet box knocks half off. A buddy of mine did this to his, and he was reading about 39 to 42 dB right at the box. 10 feet away you couldn't even hear it. Of course, he had to make an intricate cooling pipe to let the air in and out, but I can copy his design.

@Optimistic: I have read technomadia's stuff. They're popular and know their stuff, I just don't really follow them. They are tech guru's but can't even get their live stream video's above 240p... that confuses me. Anyways, their article is also 3 years old. I was looking for the new lithium batteries (which unfortunately are more pricey...) But I decided I think I will do AGM for now, and then upgrade as I go so I understand my power requirements more.

 

[akrvbob]

I'm assuming you have the money to spend and want to buy the best. 1000 watts and 8 golf carts should easily do all you ask since you are guessing high. I'm also suggesting two smaller distinct systems rather than one huge one. If anything ever fails you won't be powerless. I'll make it very simple:

4 Kyocera 250 watt panels
2 Morningstar Trimetric 40 amp controllers
8 golf cart batteries

2000 watt pure sine inverter
1000 watt msw inverter.

Honda 2000 if you're sure you will never want to have air condiioning or Honda 3000 if you think you will. Or you can buy a single 2000 and add a second one in parallel (4000 total) later for air conditioning. The 3000 will have electric start, which can be nice.

Bob

 

[kyonu]

Well I got my Kill-a-watt in this afternoon. Gonna plug it up in the morning and test it out!

@Bob: Thanks for the information! Couple of questions... I do in fact plan on having two separate systems, one that I will maintain as my primary, and one for a secondary/"load too big" setup. I may just break it into certain appliances/devices go on one, the rest on the other. Might be easier to choose battery sizing that way.

But my main question was... Why would I need a modified inverter? I thought pure sine was 100% the way to go? I plan on having 1000 watts of panels, but I plan on getting the kind that I can rotate. If I can ever find a system like THIS ONE, that would be perfect. I just don't think Zolargus is currently accepting orders... which sucks.

I plan on either getting two 2000 watts in parallel or a 3000 watt for the remote start. I would REALLY enjoy remote start since I will be sitting in one spot most of the time (for work) and would need a quick way to get it running. I think a 3000 remote start should be enough, and would be cheaper than two 2000's. I also plan on getting the extended gas tank.