Need some electrical advice

[plfking]

Well, I've put it off as long as I possibly could......now it's time to s*** or get off the pot.

I'm ready to buy my electrical components. I've read extensively here on the subject, but still don't feel like I've gotten a great handle on it.....so many differing opinions. Could y'all review and advise? Carpentry and plumbing mistakes won't kill me, but electricity's a different story.

Overall usage will be mainly in the boonies, with no desire for spending my time in campgrounds. so I'm foregoing any shore hook-ups. My thoughts are to go with 120V on appliances, so when they crap out I can just swing by a big box store and replace. I've read the arguments for using 12V, and losing efficiency in going from 12V to 120V. Also the higher cost of producing watts from fossil fuels.

My plan is a 4000W generator, charging two 230ah Deka 6V batteries (to start). In about 3 years, I'll want to add solar, so I'd like to take that into account when installing the basic system, as far as adding additional components that will be needed later.

Propane will be used for cooking, heating, and water heating. Electrical needs are a small (4 cu.ft.) fridge, small freezer, water pump, TV, radio, laptop, cell phone chargers, a fan, and a few LED lights.....NO AC. Fridge and freezer will be continuous use, everything else intermittent. I've installed ten 120V outlets throughout the bus, and fridge and freezer will run off seperate outlet boxes.

So.....4000W genny, batteries, 2000W inverter, breaker box, SOC meter, ....? One inverter for all, or seperate smaller inverters for the fridge and freezer?

Any help would be greatly appreciated.

[roach711]

Your 2 6v batteries in series will give you 2760 watts total but for best battery life they shouldn't be drawn down past 50% before recharging so your effective watts available are 1380 minus 10% or so conversion losses in the inverter. Now you're down to about 1240 watts. Whether this is enough power depends on your appliances and how you'll use them so an energy audit is definitely in order. Plugging your stuff into a Kill A Watt Meter will give you a pretty good idea how many watts each one draws.

[kazetsukai]

Originally Posted by plfking

My plan is a 4000W generator, charging two 230ah Deka 6V batteries (to start). In about 3 years, I'll want to add solar, so I'd like to take that into account when installing the basic system, as far as adding additional components that will be needed later.

If you can even put up 100W or 200W of solar now, it will _greatly_ decrease your need to run a generator. Like roach said, with your mentioned setup you'll have about 1240Wh of energy on tap. Whatever you think you can put up, take its rating and triple that- and you'll be close to what you'll actually generate on a good sunny day (so 1x 100W panel mounted flat, will generate ~300Wh - 500Wh during the course of a sunny day, depending where you are). Some days more, some days less, of course.

Panels are very cheap compared to batteries. A single 100W panel is right around $100 these days, and as you can see, it will generate as much as a single battery's total usable capacity during sun. You say you don't want to put stuff off, so don't. Put a couple panels up. Without generation you will be empty more often than not.

[JDOnTheGo]

As Roach says, it's all a guess until you have an energy budget in hand.

You can do it that way. It will work. However; in my opinion, you will end up being surprised that you have to run your generator so many hours per day, and the cost of doing that will also surprise you. I understand having 120V appliances, I have many of them. However; I have the electrical system (and solar charging system) to handle it. I am a noise nazi and I hate generators - ALL generators - even the ones that are half a mile away. So, please forgive me, I cannot fathom how someone could listen to theirs for 8-10 hours/day - especially boondocking (to say nothing of constantly dumping dollar bills into its fuel tank).

Originally Posted by plfking

.. water pump, ... radio, ... cell phone chargers, a fan, and a few LED lights

IMO, it makes zero sense to run these items from 120V. No, they are not huge consumers but all RV water pumps, LED lights, & phone chargers are already DC.

Is the issue that you are uncomfortable running a few DC circuits from your battery bank? Not sure if it helps but DC is far less complicated that AC circuits. A small fuse panel, a couple USB power sockets, maybe a cigarette lighter socket or two, and some wire will have all of the above items operating from DC (instead of DC (battery) inverted to AC and then converted back to DC).

[TheArgobus]

Do you have all your appliances yet (or which models you plan on having)? Check their manual and see what their power draw is in watts. That’s a pretty good way to estimate your energy budget when building your system.

[plfking]

Originally Posted by roach711

Your 2 6v batteries in series will give you 2760 watts total but for best battery life they shouldn't be drawn down past 50% before recharging so your effective watts available are 1380 minus 10% or so conversion losses in the inverter. Now you're down to about 1240 watts. Whether this is enough power depends on your appliances and how you'll use them so an energy audit is definitely in order. Plugging your stuff into a Kill A Watt Meter will give you a pretty good idea how many watts each one draws.

Wasn't thinking of the 50% rule.....just my fridge and freezer look to be slightly over that 1240 figure (240kW/yr = .65kW/daily each)

Originally Posted by kazetsukai

If you can even put up 100W or 200W of solar now, it will _greatly_ decrease your need to run a generator. Like roach said, with your mentioned setup you'll have about 1240Wh of energy on tap. Whatever you think you can put up, take its rating and triple that- and you'll be close to what you'll actually generate on a good sunny day (so 1x 100W panel mounted flat, will generate ~300Wh - 500Wh during the course of a sunny day, depending where you are). Some days more, some days less, of course.

Agree, but it's a monetary thing, especially sitting at home for a month. Panels necessitate a MPPT controller also, right? Was wanting to play with my originally-posted components for a few years, then make the entire solar panel/MPPT/new batteries investment right before I hit the road fulltime.

Originally Posted by JDOnTheGo

As Roach says, it's all a guess until you have an energy budget in hand.

You can do it that way. It will work. However; in my opinion, you will end up being surprised that you have to run your generator so many hours per day, and the cost of doing that will also surprise you. I understand having 120V appliances, I have many of them. However; I have the electrical system (and solar charging system) to handle it. I am a noise nazi and I hate generators - ALL generators - even the ones that are half a mile away. So, please forgive me, I cannot fathom how someone could listen to theirs for 8-10 hours/day - especially boondocking (to say nothing of constantly dumping dollar bills into its fuel tank).



IMO, it makes zero sense to run these items from 120V. No, they are not huge consumers but all RV water pumps, LED lights, & phone chargers are already DC.

Is the issue that you are uncomfortable running a few DC circuits from your battery bank? Not sure if it helps but DC is far less complicated that AC circuits. A small fuse panel, a couple USB power sockets, maybe a cigarette lighter socket or two, and some wire will have all of the above items operating from DC (instead of DC (battery) inverted to AC and then converted back to DC).

Been reading your posts for years.....well aware of your noise-Nazi-ism. You are right....I think the 'everything 120V' is because I wanted to learn in stages....but if the DC part is easier than the AC part, then I might as well learn both now.

Originally Posted by TheArgobus

Do you have all your appliances yet (or which models you plan on having)? Check their manual and see what their power draw is in watts. That’s a pretty good way to estimate your energy budget when building your system.

Yeah.....every way i figured it, my budget was well under 2000W/day max (even with everything running continuously), but, as I mentioned, I wasn't taking into account the 'discharge less than 50%' ideal.

Thanks, guys.....you learnt me some things.....

[john61ct]

Originally Posted by plfking

240kW/yr = .65kW/daily

under 2000W/day max

These units do not work.

Ah per 24hours @12V is the best standard.

Wh and kWh if you are comparing systems at different voltages.

Watts are only instantaneous, not stored energy, not usage over time.

[roach711]

You would need a charge controller between your solar panels and the battery bank. The MPPT controllers are the most efficient but also the most expensive.

The 4000 watt generator is likely overkill. We have a 2000 watt Honda that we use during power failures at home and it easily powers a full size fridge, a chest freezer, the furnace, sump pump, TV/sound system and house lights. The Honda is fairly expensive but massively quiet. I hear the small Yamaha gennys are cheaper but still quiet. They both are easy to store and carry and are very easy on the gas.

Fridge/freezer appliance manuals usually list the full load amps (FLA) drawn which is the starting amps drawn when the compressor motor starts up. FLA is the highest draw the appliance will draw but the running amps will be much lower. Your inverter needs to be able to handle the higher FLA plus some of the other loads without tripping the breaker. The FLA draw is only momentary so don't use it to estimate your daily power usage. A Kill A Watt meter will give you accurate daily power use.

Watts = amps x volts.

[plfking]

Originally Posted by roach711

You would need a charge controller between your solar panels and the battery bank. The MPPT controllers are the most efficient but also the most expensive.

I was under the impression that the MPPT controllers were like $500, but I see them online for well under $100.......same animal? Or cheaper for a reason that will quickly become obvious?

The 4000 watt generator is likely overkill. We have a 2000 watt Honda that we use during power failures at home and it easily powers a full size fridge, a chest freezer, the furnace, sump pump, TV/sound system and house lights.

Maybe my thinking is flawed.......I was only going to run the genny to charge the battery bank, not have it running while using appliances or accessories? I assumed the 4000W genny would charge a battery bank faster than a 2000W version?

In any case, I see I'll need 4 batteries instead of 2. I'd rather have more than I need, than not enough.

[kazetsukai]

Originally Posted by john61ct

These units do not work.

Right, you can't measure energy without Time.

Originally Posted by john61ct

Ah per 24hours @12V is the best standard.

We have kind of been over this before, but I just don't see why this is preferable over Wh.

Ah per 24h is not a measurement of Energy. It is a measurement of Current over time, and its usage is most common in battery ratings. It can't be divorced from voltage, so you might as well use Watts/Watt-Hours.

Not everyone is on a 12V system, and once you involve inverter loads, you're talking about mixed voltage systems already, so it is more convenient to say "My pump draws 100W and uses about 35Wh per day" and "my fridge draws 150W and uses 600Wh per day" to measure your energy needs than scale the fridge for 12V in A/Ah. In reality this is how appliances are tracked, for good reasons. Some dryers are 220V, some are 110V. The derived unit makes more sense when comparing the two.

System/appliance voltage is more of an "implementation detail" for the lack of a better term. If I have a 48V system, you have a 12V system, and we both have the same fridge, we both have roughly the same energy requirements for it, perhaps with efficiency differences.

Again I'd agree that you can't ignore A/Ah, but using it as a vehicle for Energy I just don't see the utility over Wh. Then again, I'm scratching my head trying to figure out Capacitance (Farads)....


EDIT: Perhaps a good retort of the above would be (I think you mentioned) https://en.wikipedia.org/wiki/Peukert%27s_law ? Because then you can scale your usable capacity based on draw? More trying to understand than anything.

[JDOnTheGo]

Originally Posted by plfking

I was under the impression that the MPPT controllers were like $500, but I see them online for well under $100.......same animal? Or cheaper for a reason that will quickly become obvious?

I smaller (less capacity) MPPT controller is not expensive. However; you do get what you pay for and, IMO, the name brand equipment is better. Victron has a wide variety of very good products (one possible example here). As pointed out, you can install a few hundred watt solar array and charger quite inexpensively. Given your scenario, I would bet that you would pay it off in a very short period of time (few months) when compared to the amount of generator fuel you will consume.

Originally Posted by plfking

Maybe my thinking is flawed.......I was only going to run the genny to charge the battery bank, not have it running while using appliances or accessories? I assumed the 4000W genny would charge a battery bank faster than a 2000W version?

Ok, I'm starting to understand your original post. This is a bit 'overstated' but for the sake of learning.... The generator does not charge your battery bank (ignoring the tiny 12V circuits that some generators have). It only produces 120VAC power. You will need a battery charger (commonly referred to as a "charger/converter"). It is this device that charges the battery (from 120VAC power). The rate at which the batteries charge is dependent on their chemistry, state of charge, and the charger. The output of the generator has nearly nothing to do with the rate at which the battery will charge (assuming some minimum amount of power is available). You are planning to use batteries that are fairly slow to charge. The details are complicated but generally speaking power can only come out and go into a battery so fast (before it becomes very inefficient or damaging). So, even if you have a 4000 watt generator and a 50 amp charger, your batteries may only be accepting a few amps (especially from 80% to 100%). That means you are running a generator for hours and hours and it is doing very little. This is why it is best to use a generator for the "bulk" charging (50%-80% roughly) and then let solar take over and slowly bring the batteries to 100% over many hours.

Originally Posted by plfking

In any case, I see I'll need 4 batteries instead of 2. I'd rather have more than I need, than not enough.

I've never heard of anyone having "more than they need" when it comes to battery capacity.

[john61ct]

When you are actually on shore power, who cares about efficiency?

Certainly not the average USian of such appliances.

Once you are off-grid, then the inverter overheads, even-worse consumption levels, must be taken into account.

Ah are the most relevant actual unit of energy in that context, reflect most accurately how stored energy is produced and used.

Solar panel watts rating is meaningless, as are watts into the SC. Actual Ah entering the bank much more useful, but of course the energy you put into the bank is greater than what you can get back out.

Watts and watt hours Wh kWh those are the derived values, vary much more than Ah, depending on current rate, bank SoC etc.

Yes when you want to compare usage across different voltage systems, convert your canonical Ah@12V to Wh. But only when that is required.

[kazetsukai]

Originally Posted by JDOnTheGo

I've never heard of anyone having "more than they need" when it comes to battery capacity.

What do think about my proposition, though? Do you think he's better off with more capacity, or some modest solar? What will get him more for the buck in this case?

An even cheaper Victron:
https://www.amazon.com/dp/B00U3MK0CI/

[JDOnTheGo]

Originally Posted by kazetsukai

What do think about my proposition, though? Do you think he's better off with more capacity, or some modest solar? What will get him more for the buck in this case?

A useful response is very difficult for me until an energy budget and goals are known. However; mention of a 2000 watt inverter and two FLA batteries usually makes me raise my eyebrows.

My opinions are too 'strong' to be of much value. I think solar is magical and I recommend it for nearly all situations (recognizing that there are a few where it has very limited value). I think generators are evil and should be used only occasionally (as in a couple times per year - recognizing that there are some situations that require their use (e.g. camping in 100 degrees and 100% humidity)). So, I will nearly always fall on the side of larger battery bank and more solar.

[john61ct]

A lead bank takes 7+ hours to charge no matter what.

Increasing current rate, say 180A from 60A, might only save 20min.

[JDOnTheGo]

Originally Posted by john61ct

A lead bank takes 7+ hours to charge no matter what.

Assuming that info, a generator burning .5 gal/hr, and fuel price in the $3/gallon range. The plan stated in the original post will cost something like $300/month in fuel plus oil/maintenance. At roughly 2500/hours per year, may require a new generator every year or so as well (I am unsure what quality generator we are talking about or what its lifespan might be).

A VERY crude bit of math tells me that this will cost something around $5,000/year. If nearly all of this could be replaced with a 500 watt solar system (I don't have the info to say that it can) and that system cost $750-$1,000 - that strikes me as a very good deal.

Don - I am the first to admit that I do not know what your energy budget is or if solar charging is even possible for you (where you plan to spend time). Just trying to share some info that might be worth considering.

[kazetsukai]

Originally Posted by JDOnTheGo

Don - I am the first to admit that I do not know what your energy budget is or if solar charging is even possible for you (where you plan to spend time). Just trying to share some info that might be worth considering.

No matter what the source, without some kind of active generation to at least offset usage, any battery bank is going to feel quite small.


Without the batteries one would have to run the genny 100% of the time energy was required. How much reduction in genny runtime are you hoping for? Do you want to run it X hours per day or every other day? What's the goal there?

[roach711]

The time to full charge in a deep cycle battery bank is longer than that of a starting battery because the deep cycle bank is designed to be slowly discharged/charged and the starting battery is designed to put out a big slug of power to start the engine then be quickly recharged.

A good deep cycle charger will do a three stage charge: bulk, absorption and float. The bulk stage goes pretty quickly but the absorption phase takes hours. So for charging purposes all you need is a generator large enough to power the charger/converter plus your appliance draws. That's a pretty small genny.

As with any equipment you buy, a higher price generally gets you better equipment. Here's a good link on types of charge controllers.


https://www.morningstarcorp.com/sola...ge-controllers

[john61ct]

Originally Posted by JDOnTheGo

Assuming that info, a generator burning .5 gal/hr, and fuel price in the $3/gallon range.

LOL

No no no. It would be **insane** to try to get you lead bank back to 100% Full, just using a genset.

Depending on the genny + charger amps capacity, you could be at 80% after say 90min, 90% at three hour.

Only 10% left five hours to go!

Obviously that is what solar is for.

Really should shoot for solar covering almost all your needs.

Then a few times a year maybe, you run the genny early in the morning before insolation starts, just long enough until you're sure the solar day will get you to 100%.

And you don't need to get to that every cycle for decent longevity, couple/3 times a week is good enough.

Firefly Oasis AGMs are special, just a few times a month, but pricey.

And if you can't avoid PSOC abuse, just means buying a replacement bank more often, that has to be cheaper than runny the genny so much!

Whole issue goes away completely with LFP.

[Chef Santa]

Originally Posted by plfking

Well, I've put it off as long as I possibly could......now it's time to s*** or get off the pot.

I'm ready to buy my electrical components. I've read extensively here on the subject, but still don't feel like I've gotten a great handle on it.....so many differing opinions. Could y'all review and advise? Carpentry and plumbing mistakes won't kill me, but electricity's a different story.

Overall usage will be mainly in the boonies, with no desire for spending my time in campgrounds. so I'm foregoing any shore hook-ups. My thoughts are to go with 120V on appliances, so when they crap out I can just swing by a big box store and replace. I've read the arguments for using 12V, and losing efficiency in going from 12V to 120V. Also the higher cost of producing watts from fossil fuels.

My plan is a 4000W generator, charging two 230ah Deka 6V batteries (to start). In about 3 years, I'll want to add solar, so I'd like to take that into account when installing the basic system, as far as adding additional components that will be needed later.

Propane will be used for cooking, heating, and water heating. Electrical needs are a small (4 cu.ft.) fridge, small freezer, water pump, TV, radio, laptop, cell phone chargers, a fan, and a few LED lights.....NO AC. Fridge and freezer will be continuous use, everything else intermittent. I've installed ten 120V outlets throughout the bus, and fridge and freezer will run off seperate outlet boxes.

So.....4000W genny, batteries, 2000W inverter, breaker box, SOC meter, ....? One inverter for all, or seperate smaller inverters for the fridge and freezer?

Any help would be greatly appreciated.

Wow and I thought I was the only one thinking the same thing I'm looking to do the same the only changes that I'm going to do is first I'm running the house batteries connected to the bus battery to keep them all charged using a doctor battery device when I'm driving and other is I bought a portable 100 Watt solar system for now from harbor freight audium $150 can't beat it I'm hoping to be able to go out West to Arizona in November for the annual bus built in quartzite and have the solar panels mounted on the side of my bus because I'm disabled and can't get on the roof I've seen some mounted there but I'm gonna put them on hinges to be able to lift them out for the Sun to get them at the right angle. But all my other items are the same as yours. stay safe and stay strong stay healthy god bless and enjoy life keep in touch. ps I forgot to tell you I also have a 4000 W predator generator on the back of my bus for emergency use it came with my bus it's brand new never been used.