Battery bank and charging questions. Help please

[MJR1133]

Okay, so I'm going to cut to the chase and keep a long story short.

My friend and I are going to be converting 2 short busses and each building the same battery bank/electrical charge set up. Once we convert our buses we will travel the country in them.

However, we don't really know crud about wattage/watt hours/a power/dc power plus probably some others I'm not thinking of.

This is what we want. (Some of this info may be vague or redundant, I'm not a pro at this.)

1. A battery bank of 10, 12v deep cycle batteries. Maybe smaller battery banks instead and split thr power usage amung needed appliances and luxaries.
We want this battery bank to be our main source of power. Lights, fridge, water tank, small tv, plug ins, all the works you need for day to day electricity. Lots of camping so have to be able to run a good stereo system at times.

2. We want our solar panals to charge our battery bank and just our battery bank. The sun shall charge us when there is sun.

3. When we run our generator, we want it to not only run our necessary appliances and outlets, but we also want it to charge our battery bank. However we have no idea how to wire it to do that.

4. We want our shore power to do the same as the generator. Power everything in the bus, (because shore power is endless lol) whIle also charging our battery bank. But we have the same issue as we don't know how to wire it.

So basically, we don't know how to make our battery bank send out power, while also being able to receive power. I don't want to make a surge and have the two colide. Don't feel like blowing up.

One final question. We are unsure how to determine how much power we to distribute vs how much power we are using. Without knowing how to figure that out we are really just waisting our time.

Thanks for reading. Any and all help would be amazing!

[superdave]

for solar you will need the panels, charge controller, batteries and breakers. 6-6 volt golf batteries would do it, 12 volt batteries are not true deep cycle batteries. they make whats called inverter/chargers, it inverts the dc into ac until you plug in to shore power then the ac loads switch over to shore power and the inverter becomes a converter and charges the battery bank. do some reading on R E systems, good luck

[turf]

use an online calculator to figure your electrical need. then head to a solar equipment supplier, tell them your needs and have a pro design your system. there are so many variables in electric solar systems that no one can answer except you. the 2 big questions are 1) how much money is in your pocket? and 2) are you willing to part with it?

how much is your daily use going to be?
what kind of battery chemistry do you want?
how many days do you want to go between charging?
do you want to expand it in the future?
are going to run 30A wiring or 50A?
why 10 - 12volt batteries?
what voltage are going to use for the panels?

and a ton of more questions.

there is another thread about a 2 weeks ago maybe you should read, called "solar blue print". check it out.

[Iceni John]

A Kill-A-Watt meter will tell you exactly how much power is used by each AC appliance. Knowing this, you can then calculate how much battery capacity is needed for two or three days' autonomy, then how much solar power is needed to correctly charge those batteries. Don't forget standard deratings for PV, charge controller and inverter.

It would be well worth your time to read some of the postings on the Northern Arizona Wind & Sun forum - the folk there know solar.

John

[MJR1133]

how much is your daily use going to be? - we are unsure. We are trying to determine the best way to figure that out. Probably taking a meter like John said and make a list of all our appliences we want to use and message how much energy they use and just add it up. I feel like that's sort of lazy though.

what kind of battery chemistry do you want? - I'm assuming the answer to that is 12v deep cycle batteries.

how many days do you want to go between charging? - I would like to be able to schedule 1 day a week to charge my system. So I would like to last 5-6 days without direct charging.

do you want to expand it in the future? - no.

are going to run 30A wiring or 50A? - 30A

why 10 - 12volt batteries? - because why not? We don't want to run out of power. But we also don't want to have to baby our power either.

what voltage are going to use for the panels? - we are unsure. We don't know much about electrical work.

[MJR1133]

One of our biggest concerns is the proper wire.... pathways. As in.. how do we make our shore power charge our battery bank while supplying power to the rest of the system? Same for the generator.

We just need a basic explenation of the path.

Example. A wired to B then wired to C produces D. Something like that. How to charge your batteries with a generator while also supplying power to the rest of the system for dummies haha.

[GreyCoyote]

Disclaimer: there are a million ways to do this. This is MY way.

8 ea GC-2 "golf cart" batteries in series-parallel for two 24 volt banks
4 ea 330 watt/72-cell solar panels wired in series-parallel. (Sun Electronics - Lowest Prices in Solar Panels, Kits, Inverters)
1 ea 90-amp charge controller (ie, Midnight Classic 150, MidNite Solar Classic 150 MPPT Charge Controller - Wholesale Solar)
1 ea Magnum Hybrid inverter, 4000 watt (Magnum Energy MSH4024RE Inverter - Wholesale Solar)

The battery bank stores about 9.6 kwh of energy, about half of which shouldnt really be used for best battery life, so lets use 4.5 kwh as our safe number. The batteries obtain this performance level at the 20-hour rate which means you can draw 225 watts for 20 hours before you hit the self-imposed 50% depth of discharge. But much more than 225 watts is available. These batteries will surge to HUNDREDS of amps for a few seconds easily, 75 amps for more than an hour, and the inverter is capable of 4000 watts non-stop (if you had the batteries to do it). So basically you have a bunch of power to ride-out a rainy day or two and still watch Caddyshack with microwaved popcorn and your electric blanket.

The neat part of this system is the inverter. It has three inputs. If grid is available, it will use grid power and recharge the batteries. If generator power is available, it will use that and also charge your batteries. If nothing but battery is available, it will happily use them. There is no "switching" needed. Give it power, any power, and it will sort it out for you.

The neat thing about the hybrid inverter is its ability to use multiple power sources under heavy load. Example: you have a little Honda EU2000 capable of 1600 watts continuous. While your demand is less than 1600 watts, the ijverter will use whatever power your loads are not using to charge batteries. But if you plug-in the microwave and suddenly suck 2000 watts, the inverter gets those extra 400 watts from the batteries instead of overloading the genny.

This type of system just begs to be run hard dry-camping in the boonies. With more than a kilowatt of solar, you shouldnt really need the genny much. And if you do, it will likely just be to get you through a dark couple of days.

Anyway... One mans opinion. This is basically the system that I'm putting in my bus this spring.

Final shot: I used Wholesale Solar for the links, but you can do much better price-wise elsewhere. Check out SunElec.com for some SCREAMING deals on panels. Nobody can touch this guy. He has 300-watt panels for as low as 38 cents per watt, or about 2.5 times cheaper than most of the solar bandits out there. Heck, the guy is giving away FREE used panels by the crate! Read his blog on the SunElec website for details.

[MJR1133]

Originally Posted by GreyCoyote

Disclaimer: there are a million ways to do this. This is MY way.

8 ea GC-2 "golf cart" batteries in series-parallel for two 24 volt banks
4 ea 330 watt/72-cell solar panels wired in series-parallel. (Sun Electronics - Lowest Prices in Solar Panels, Kits, Inverters)
1 ea 90-amp charge controller (ie, Midnight Classic 150, MidNite Solar Classic 150 MPPT Charge Controller - Wholesale Solar)
1 ea Magnum Hybrid inverter, 4000 watt (Magnum Energy MSH4024RE Inverter - Wholesale Solar)

The battery bank stores about 9.6 kwh of energy, about half of which shouldnt really be used for best battery life, so lets use 4.5 kwh as our safe number. The batteries obtain this performance level at the 20-hour rate which means you can draw 225 watts for 20 hours before you hit the self-imposed 50% depth of discharge. But much more than 225 watts is available. These batteries will surge to HUNDREDS of amps for a few seconds easily, 75 amps for more than an hour, and the inverter is capable of 4000 watts non-stop (if you had the batteries to do it). So basically you have a bunch of power to ride-out a rainy day or two and still watch Caddyshack with microwaved popcorn and your electric blanket.

The neat part of this system is the inverter. It has three inputs. If grid is available, it will use grid power and recharge the batteries. If generator power is available, it will use that and also charge your batteries. If nothing but battery is available, it will happily use them. There is no "switching" needed. Give it power, any power, and it will sort it out for you.

The neat thing about the hybrid inverter is its ability to use multiple power sources under heavy load. Example: you have a little Honda EU2000 capable of 1600 watts continuous. While your demand is less than 1600 watts, the ijverter will use whatever power your loads are not using to charge batteries. But if you plug-in the microwave and suddenly suck 2000 watts, the inverter gets those extra 400 watts from the batteries instead of overloading the genny.

This type of system just begs to be run hard dry-camping in the boonies. With more than a kilowatt of solar, you shouldnt really need the genny much. And if you do, it will likely just be to get you through a dark couple of days.

Anyway... One mans opinion. This is basically the system that I'm putting in my bus this spring.

Final shot: I used Wholesale Solar for the links, but you can do much better price-wise elsewhere. Check out SunElec.com for some SCREAMING deals on panels. Nobody can touch this guy. He has 300-watt panels for as low as 38 cents per watt, or about 2.5 times cheaper than most of the solar bandits out there. Heck, the guy is giving away FREE used panels by the crate! Read his blog on the SunElec website for details.

That's all fabulous information and is a tally very informative.

However we are 22 years old and do not have quite the piggy bank for bad ass inverters as such. Which is kind of why we want such a big battery bank.

So, we need to know how to manually switch between generator/shore power/and just batteries. And again, we want shore and genny to charge our batteries while powering our system.

So how do we do that? Set up toggle switches and just turn off the electrical pathways for the sources of power we don't want to use? How do we wire the correctly? Do we need multiple inverters? Or can we use 1 inverter for the genny, shore, and bank? Again, we have to do things manually.

[superdave]

Originally Posted by MJR1133

That's all fabulous information and is a tally very informative.

However we are 22 years old and do not have quite the piggy bank for bad ass inverters as such. Which is kind of why we want such a big battery bank.

So, we need to know how to manually switch between generator/shore power/and just batteries. And again, we want shore and genny to charge our batteries while powering our system.

So how do we do that? Set up toggle switches and just turn off the electrical pathways for the sources of power we don't want to use? How do we wire the correctly? Do we need multiple inverters? Or can we use 1 inverter for the genny, shore, and bank? Again, we have to do things manually.

deep cycle batteries require multi stage charging, you need a good charger or your batteries will fail after a few months to a year. inverter/chargers will work ok as long as its a good one. my l-16's need to be brought to 15.4 volts for 2 hours then floated at 14.4 volts the rest of the day. a car charger is not the answer. my zantrex inverter/charger charges at a 100 amp rate but stops in the 14 .6 range, i only use the charger in emergency's. lots to learn in renewable energy. read up, its not cheap

[GreyCoyote]

Ok. I hear ya. But SuperDave pretty much nails it. You cant do solar halfway. This isnt just about wiring and switches. Its about understanding the core theory and making a system work safely.

Cheap chargers are designed to charge a battery (not multiple batteries) that are not connected to a load. They generally lack the intelligence to understand that sudden dip in charging voltage does not mean the battery is bad, but that someone simply turned on a light. Smart chargers specifically built for the solar industry dont react this way. And they are expensive. And they can handle multiple batteries with ease.

Cheap inverters are designed for intermittant use. The waveform is generally a square wave or modified sine wave, and the components used are not high quality. If all you want are lights, they work, but connect a good stereo to one and you'll often find a buzzy, distorted mess coming from the speakers. They fault at the slightest surge, require the battery to be disconnected to reset, etc.

As you can see, are no easy or cheap answers for the solar project you propose. You cant just wire up some batteries to an inexpensive inverter and charger and call it good, switching cords and plugs to make it go. Solar is going to be expensive but if you scrounge you can find second hand stuff at fair prices with a lot of life left. Thats why I gave you the SunElec link.

Suggestion: call some of the solar vendors and give them an opportunity to design the system. Tell them you are price conscious but not poor. They can do it quickly and its free. You will get back a parts list. Research that list. See if you can find specials, open box deals, refurbs, or used gear.

[warewolff]

Wah wah wah. You're being told how to do things the right way by some very experienced board members. We are all ignorant before we learn. Before you buy anything (and more importantly, touch any of your new equipment), read this blog in it's entirety:

HandyBob's Solar Blog

Bob likes to ramble, but he knows his ****. If you still have questions after reading all of that, come back to the forum and ask. We can't educate you on designing a system if you don't understand the fundamentals.

I can educate you on the following: You will not design the type of system you're talking about without breaking the 'piggy bank'.

Going for a week in between charges, any quality 10 x 12v battery bank is going to put you well into the thousands. Additionally, you need a large solar panel array to adequately charge a bank that large. I assume you're talking about over 1000aH. You should have close to a kW or more on your roof if that's your plan. The batteries you're most likely sourcing are going to be junk if you buy the cheap ones. They are cheap because they don't last long enough for you to get an adequate ROI. Crown and Trojan batteries, (two rows of 6v to pair into a 12v system, or your standard 12v) regardless of what you're doing, are going to be the way to go as they may last you a decade. As far as I'm concerned, and this is also Bob's opinion by the way, the Morningstar charger is the only superior and quality solar charger to keep your expensive battery bank charged properly, at least on a smaller system. If you are going to use anything but 12v solar panels you'll likely need an MPPT charger, but really you should use an MPPT charger regardless.

All this talk about matching voltage between panels and batteries is generally hogwash as a 12v panel will actually output 18v. A PWM charger chops that 18v to 12v, then delivers it to the 12v battery bank. Am I missing something here? An MPPT charger is marginally more efficient (~15% more, but don't quote me on that) and you will not lose any power (excluding efficiency) between the solar panels and the charger this way. Additionally, MPPT chargers are 20-25% more efficient in cold weather. So realistically, if you want to stay out boondocking for a week and conserve as much of your precious harnessed solar power as possible, you'll need to go MPPT. But the Morningstar TS-60 amp MPPT is selling for ~$525 on Amazon right now. Trust me, I know, because I just bought it.

With an MPPT charger you can buy 24v (really 36v) panels online, maybe even at 30 or 40 cents a watt, but you'll have to pay for freight shipping which is anywhere from $300-400. And most of the ones in your price range are rebranded without warranty, so good luck with that if you have any issues. I make my living on solar and can tell you that the average 24v residential panel is around 3'x5'. You need to think about space on your roof and how they'll mount. Will a 5' long panel fit on the width of your curved roof? Maybe. Due to the length, you most likely won't be able to angle them in the winter to harness those last sun hours. I ended up going with 6 x Renogy 12v 100w panels. They are $140 a piece, free shipping on Amazon Prime. More importantly, at 47" by 21" each, they are SMALL. I will need no more than a 600w system, and even that might be overkill. If I get 5 sun hours a day, at 66% efficiency (average with an MPPT charger) I'm harnessing a bare minimum of 1.9kW hours daily. I can run a residential fridge (~1.2kW daily), media center computer (~20w/hr), 32" LED tv (~25w/hr) with headspace on this setup.

Then you need an inverter. Depending on your needs you can use a modified or pure sine inverter. Read up on it. You are looking at anywhere from a few hundred for a cheap modified sine to a few thousand for a fancy pure sine with auto capabilities.

Do yourself a favor and buy a Kill-a-Watt meter to find out your energy needs. You may be really surprised. But even then expect to spend over two grand on a quality setup. That's on the cheap.

Please read up on everything and then come back. We are happy to answer your questions but without an understanding of the very basics you are shooting in the dark.

/rant

[ Okay, I'm a softy, click here for a detailed explanation on how you're going to accomplish auto charging the batteries and auto switching between inverter/120v/genny ]. You should start pricing inverter/chargers.

[SDR76]

@ Grey Coyote--- That inverter cost more than my bus!!! Great info though!!

[roach711]

And remember, with solar charging you have to park in full sun and that can really heat up the interior of a bus.

[pepepito]

Originally Posted by SDR76

@ Grey Coyote--- That inverter cost more than my bus!!! Great info though!!

I bought a Magnum Energy ( not sine wave) 4000W peak at 600 US on ebay, if you wait you can find some good deals.