weekend camp

greenheads · August 2015

Hi, we are building a 24'x32' weekend camp that will get used more in the winter than in summer. we have everything in the dry and about to start on the wiring. most times will be for just 2 days max but sometimes a few days longer. we don't have access to pole power so what I would like to do is use a battery bank with inverter to power the house and then use generator (already have a Honda eu2000) and a Iota DLS-55 to keep the batteries up. I have been planning on the samlex 2,000 watt 12v sine wave inverter. I've considered solar but hate to add to the expense when I already have the generator. my plan would be to run the generator during the day and not at night.

for the electrical usage of the house we will have a total of 12 lights ( LED and they won't all be on at the same time), a mini fridge that will only be on while we are there, and a tv and satellite.

I'm just looking for a little help to see if this is feasible and also help with the batteries? Thanks

lkruper · August 2015

greenheads wrote: »

Hi, we are building a 24'x32' weekend camp that will get used more in the winter than in summer. we have everything in the dry and about to start on the wiring. most times will be for just 2 days max but sometimes a few days longer. we don't have access to pole power so what I would like to do is use a battery bank with inverter to power the house and then use generator (already have a Honda eu2000) and a Iota DLS-55 to keep the batteries up. I have been planning on the samlex 2,000 watt 12v sine wave inverter. I've considered solar but hate to add to the expense when I already have the generator. my plan would be to run the generator during the day and not at night.

for the electrical usage of the house we will have a total of 12 lights ( LED and they won't all be on at the same time), a mini fridge that will only be on while we are there, and a tv and satellite.

I'm just looking for a little help to see if this is feasible and also help with the batteries? Thanks

Since you have not yet built the cabin, I would consider running as much directly off of
dc as possible. There are AC/DC fridges, AC/DC TVs and of course lights that are DC.
Of what you have mentioned, perhaps the only thing that will not work from DC is your
satellite TV. My Directv is 20w.

Your loads are as described:
12 lights - 6w each = 72w X 12 hours = 864 wh
Mini Fridge - 3amp * 24 hrs = 72 wh
satellite - 20w X 24 hrs = 480 wh
TV - AC/DC Samsung 28w X 8 hrs = 224 wh

One days worth of power is 1640 wh / 12 volts = 136 ah.
Your batteries will last longer if you discharge them to 50%, so 136 ah X 2 =
272 ah usable capacity at 50% DOD is 544 AH battery bank.

Since you are building your cabin from scratch, you can plan for a place to store
the batteries outside the cabin (utility closet) and use Flooded Lead Acid batteries.

Trojan T 105 6v batteries are 255AH and so four of them will give you the power you need.
The 510 AH battery bank @ 12v can be charged with your 55 amp charger which would be C/10.

You don't need a big inverter, even if you don't decide to power 12v appliances. Your
2000w inverter will take too much power even when powering a small load. If you power
your appliances with 12v, try to anticipate what else you might want for AC power and
multiply by 2X for some headroom. Morningstar makes a 300w UL rated inverter that might
be a good option. I also think Samlex is a very good brand, perhaps better than
Morningstar and believe they have smaller ones as well.

If you power all your appliances with AC, the total I have so far is 156 if you get
a really efficient 32" TV and 228w if you don't. A 300w inverter should work which
means that at 90% efficiency you are adding 30w to your load.

I am new to this, so thanks for allowing me to practice my calc skills. I have been
known to make calculation errors

Also, some of this is subjective, but since you have your generator, you should be
covered.

solar_dave · August 2015

I would still consider at least one solar panel and charge controller to maintain your batteries while away from your camp.

greenheads · August 2015

Thanks for the help, I have considered using either a 6k or 8k btu A/C window unit for the bedroom in the future was the reason for having the 2000 watt inverter. we just don't spend a ton of time down there in the summer but when we do the temps can stay in the 90-102 degree range.

I like the idea of the solar to top off the batteries. what size panel would you recommend? 60 watt?

also is there enough benefit of using 4 Trojan batteries at a cost of $700 vs 4 deep cycle marine for around $400 total?

solar_dave · August 2015

greenheads wrote: »

Thanks for the help, I have considered using either a 6k or 8k btu A/C window unit for the bedroom in the future was the reason for having the 2000 watt inverter. we just don't spend a ton of time down there in the summer but when we do the temps can stay in the 90-102 degree range.

I like the idea of the solar to top off the batteries. what size panel would you recommend? 60 watt?

also is there enough benefit of using 4 Trojan batteries at a cost of $700 vs 4 deep cycle marine for around $400 total?

Start out defining all your loads, a regular energy star fridge is about as efficient as a mini fridge for power usage, there are several good reviews around here.
A window rattler AC is going to use lots of power, do you own it yet? then get a Kilowatt meter and test the number of kWh the unit consumes.

The battery size and thus the maintainer size is all determined by your battery size which will be determined by your loads. An accurate assessment is needed unless you are willing to keep right up on the the battery SOC and hit the generator more often.

lkruper · August 2015

greenheads wrote: »

Thanks for the help, I have considered using either a 6k or 8k btu A/C window unit for the bedroom in the future was the reason for having the 2000 watt inverter. we just don't spend a ton of time down there in the summer but when we do the temps can stay in the 90-102 degree range.

I like the idea of the solar to top off the batteries. what size panel would you recommend? 60 watt?

also is there enough benefit of using 4 Trojan batteries at a cost of $700 vs 4 deep cycle marine for around $400 total?

You would need to look at the specifications of which marine batteries you have in mind.
I would have recommended Trojan's RE series for deep cycle batteries, but the extra
expense might not be a good idea for one's first set of batteries. To compare, look at
things like the:

20 AH rating - Trojan T105 is 255 @ 12v for a pair of 6v batteries
Number of cycles at 50% DOD
Warranty which is an objective gauge of the lifetime you can expect.

In general, marine batteries are dual purpose batteries, used both for
starting and power. It will do both jobs, but will sacrifice deep cycle RE.

Also, if the marine batteries are 12v you will need to run all four in parallel
which can be tricky to get done correctly.

Which marine batteries did you have in mind?

### Edit ###
Some use Costco or Sam's club golf cart 6v batteries successfully.

greenheads · August 2015

Thanks for all of the help so far! The numbers I have been working off are
Lights 8 at a time 10w each 80/hr 10 hours so 800/day
Sat/tv 100w/hr 6hr/day so 600w/ day
Fridge 40w/hr so 960/day
Window a/c 850/hr 12hr/day 10,000 day

These are all guesstimates so feel free to correct them. 1100watts max if everything is on at the same time plus surge. This is where I came up with the 2000 watt inverter. I know while running the a/c I will have to also run the generator and that's not an issue.

I see what your talking about with the batteries and will probably go with the Trojans.

If I only run the a/c with the generator on would I be able to use only 2 batteries or would I need to stay with 4?

lkruper · August 2015

greenheads wrote: »

Thanks for all of the help so far! The numbers I have been working off are
Lights 8 at a time 10w each 80/hr 10 hours so 800/day
Sat/tv 100w/hr 6hr/day so 600w/ day
Fridge 40w/hr so 960/day
Window a/c 850/hr 12hr/day 10,000 day

These are all guesstimates so feel free to correct them. 1100watts max if everything is on at the same time plus surge. This is where I came up with the 2000 watt inverter. I know while running the a/c I will have to also run the generator and that's not an issue.

I see what your talking about with the batteries and will probably go with the Trojans.

If I only run the a/c with the generator on would I be able to use only 2 batteries or would I need to stay with 4?

800w + 600w + 960w = 2360w per day
2360w / 12v = 196 AH
50% DOD with 196 AH = Total per day needed = 393 AH

Lets fine tune this a bit more. Your inverter won't get better than 90% efficiency, so you need 432 AH per day. This is really close to the 450 AH of four 6V golf cart batteries.

Also, you would do well to look at high SEER heat pump type cooling systems. Your $/hr for generator power is going to be pretty high. You may find that the higher cost of the efficient cooling will have a pay back. In fact I would not be surprised if you could run some of those units from battery for at least part of the time and not need to listen to the generator when sleeping. But to do that, you might need to increase your battery capacity.

K4KMG · August 2015

I'm doing about the same thing. I use my camp every weekend. (security sys runs 24/7 all week)
AC is a window unit and it's the only thing I run the EU3000 for, and only at night when needed.
Solar sys cost me about 4200 and I could have done it about 500 cheaper if I'd known better what I was doing.
System is listed in my sig below. it's been running for about a yr and so far, working perfectly.
Pics of camp here: k4kmg.com (site is work in progress)

greenheads · August 2015

K4KMG wrote: »

I'm doing about the same thing. I use my camp every weekend. (security sys runs 24/7 all week)
AC is a window unit and it's the only thing I run the EU3000 for, and only at night when needed.
Solar sys cost me about 4200 and I could have done it about 500 cheaper if I'd known better what I was doing.
System is listed in my sig below. it's been running for about a yr and so far, working perfectly.
Pics of camp here: k4kmg.com (site is work in progress)

Your camp looks good, How do you like that tank for your water? also how do you fill it and what kind of pump did you use to pump water into the camp?

Apples · August 2015

Pics of camp here...

Hey [Edit: Tom] thanks for the pics! I like what you've done with the place. Hahaha... seriously!

You've got a great space to also hang some vintage Coleman lanterns...

I apologize for the threadjack but I did see the word "camp" in the title! Hee!

K4KMG · August 2015

greenheads wrote: »

Your camp looks good, How do you like that tank for your water? also how do you fill it and what kind of pump did you use to pump water into the camp?

Thanks. Have another 250 gal tank I use to bring city water to the camp. Use an Eheim aquarium pump to transfer! Works great.

Have to put fuel in the Coleman's. The colored lights on the deck have 5w led's in them. (10 lights) 50w for a couple of hours in the evening is no big deal.

And... it's 'Tom'. Bob has the camp on the right.

westbranch · August 2015

our neighbour at the lake has this fridge, http://www.canadiantire.ca/en/pdp/cuisinart-4-4-cu-ft-stainless-steel-e-star-compact-refrigerator-0431894p.html#.VcKPPrWlfuc, and runs it off 4 12V marine batteries from same vendor, and keeps the batteries up with 2 x 120W PV 's 1 south facing the other West to lengthen the day, and runs the unit 24/7 in the summer... uses an old C30 PWM CC and a Mastercraft Inverter, which is a rebranded Xantrex

hth

inetdog · August 2015

If you are concerned about either motor starting surge or absolute energy efficiency, to the point of being willing to spend more up front, a mini-split A/C with an inverter driving the motor will let you operate with little starting surge and the minimal power needed to maintain the set temperature instead of wastefully cycling on and off.

mike95490 · August 2015

I'll suggest that if you want to try to run air conditioning off the batteries, you want a 24V system instead of 12V. The higher voltage reduces the current density in the wires and appliances. You could use 2 inverters, one small one for the little loads, and a larger one just for the AC and power it off when not needing the cooler. 4, 6V batteries in series would do it. And keep the generator.

greenheads · August 2015

Thank you for all of the help so far!

I've gotten the rest of everything I need to wire the house minus the inverter, battery, and iota charger. I'm going down this weekend to install the breaker box and all of the outlets and switches in the house.

my next question is on the powering of the breaker box from the inverter.

I am planning on using the samlex pst 2000 watt inverter and 4 6v batteries to start with.

my questions are for the grounding,

1. do I need to ground the battery bank to the earth grounding rod?

2. do I need to ground the iota charger to the earth grounding rod?

3. do I need to ground the inverter to the earth grounding rod?

4. do I need to ground the load panel to earth grounding rod?

5. I believe with this inverter the neutral and ground are bonded so I don't need to bond the neutral and ground in the load panel???

6. the inverter says it has a GFCI, should I put in any GFCI breakers in my load panel? or are they already protected?

7. would you recommend adding AFCI to the load panel?

Thank you for your help.

lkruper · August 2015

greenheads wrote: »

Thank you for all of the help so far!

I've gotten the rest of everything I need to wire the house minus the inverter, battery, and iota charger. I'm going down this weekend to install the breaker box and all of the outlets and switches in the house.

my next question is on the powering of the breaker box from the inverter.

I am planning on using the samlex pst 2000 watt inverter and 4 6v batteries to start with.

my questions are for the grounding,

1. do I need to ground the battery bank to the earth grounding rod?

2. do I need to ground the iota charger to the earth grounding rod?

3. do I need to ground the inverter to the earth grounding rod?

4. do I need to ground the load panel to earth grounding rod?

5. I believe with this inverter the neutral and ground are bonded so I don't need to bond the neutral and ground in the load panel???

6. the inverter says it has a GFCI, should I put in any GFCI breakers in my load panel? or are they already protected?

7. would you recommend adding AFCI to the load panel?

Thank you for your help.

I can't help with wiring and grounding, but are you wiring your four 6v batteries in series to 24v? That would be recommended for a couple reasons, unless you absolutely need to power 12v loads directly. The wire AWG size will be lower which will save you money and the series batteries have less potential for unbalanced parallel to degrade batteries faster. It was recommended to me to place 4 batteries side by side, reversing the orientation every other so that the connections are close to each other and shorter.

There is a chart (on this site I think) that gives you the recommended gauge wire for different voltages and length of run.

Also, a caution. When you say "to start with" for your battery bank. It is not recommended to add new batteries to an old bank. The difference in capacity of the old batteries will affect the new ones. And as you are probably aware, if you use a larger inverter than necessary for your application, it will draw more power internally (not used for powering) than one that is matched to your load. A 2000 watt inverter at 90% efficiency will use 200w to operate.

BB. · August 2015

greenheads wrote: »

my next question is on the powering of the breaker box from the inverter.

I am planning on using the samlex pst 2000 watt inverter and 4 6v batteries to start with.

As Ikruper asks... Is this a 12 or 24 volt system? And if you are using Golf Cart batteries (6 volts @ ~220 Amps)--The largest "practical" inverter you can use is around 1kWatts. A 2 kWatt inverter pulling 2,000 Watts from the battery bank will only only work for a few seconds/minutes (reliably--Surge current).

my questions are for the grounding,

1. do I need to ground the battery bank to the earth grounding rod?

Functionally, the system will work correctly with the bank floating or grounded. Safety wise, tying the DC negative battery bus to the common ground road (for AC side of system, cold water pipe, etc.)--Is traditional.

If you have a good chance of lightning in the area, I would certainly recommend ground bonding the battery bank (following good wiring practices for grounding).

2. do I need to ground the iota charger to the earth grounding rod?

Just through the AC power cord should be OK.

3. do I need to ground the inverter to the earth grounding rod?

The ground wire can go from the inverter chassis to the AC power panel grounding. Or it can go directly to the DC negative bus...

Remember what the primary reason for grounding is... It is to prevent the metal chassis of the AC inverter (and the AC neutral) from becoming energized. The DC breaker/fuse feeding the AC inverter DC input will be at least 100 amps DC (for a 12 volt inverter, it would be 300 amps). If the + of the DC bus touches the chassis, you need to carry enough current to trip the DC fuse/breaker. So, the DC ground wire back to the DC battery ground/negative bus should be the same size as the DC power cables.

Table 8.2 recommends 2/0 AWG for 12 volt 2kWatt inverter or 4 AWG minimum for 24 volt inverter for power leads--It would be best to use that same AWG for the ground cable too (for example, 6 AWG cable fuses around 600 Amps... To trip a 300 amp fuse with 6 AWG is too close to the fusing current of the 6 AWG).

4. do I need to ground the load panel to earth grounding rod?

Wire up the AC system of the cabin just like you would for a normal home. Tie all metal boxes/panels together with green wire grounding. Run the ground block of the main AC panel to the earth ground rod.

Note that the AC ground rod is not there to "trip" an AC fuse or breaker--It is there for lightning surge current (and for an utility connected home, to protect against crossing a 12 kVolt distribution line to your 120/240 VAC AC main drop). The green wire/conduit/etc. grounding around your AC panels/boxes/outlets is there to provide a return path to the AC main panel (and your neutral to ground bus bonding) to trip fuses/breakers.

5. I believe with this inverter the neutral and ground are bonded so I don't need to bond the neutral and ground in the load panel???

http://www.samlexamerica.com/documents/manuals/11001-PST-1500-2000-12-24-0513.pdf

Neutral “N” (16) is bonded to the metal chassis of the inverter through a loop of wire
connecting the “N” terminal on the Line side of the GFCI to the chassis of the inverter.

Ground bonding in the AC main panel is traditional. If you ground bond in both the AC main panel and the AC inverter (with GFI outlet/breaker)--You will trip the GFI in the AC inverter (more discussion below about GFI).

6. the inverter says it has a GFCI, should I put in any GFCI breakers in my load panel? or are they already protected?

7. would you recommend adding AFCI to the load panel?

If you were plugging in an extension cord to the AC inverter directly--The GFI outlet and the internal ground bonding to neutral is just fine...

HOWEVER, since you are wiring a cabin up as "traditional" ac wiring--I would suggest:

Do not use the GFI outlet in the inverter--Remove it
Lift/remove AC Neutral to Ground bond inside inverter. Use the AC Neutral Bonding in the AC main panel (standard location, if you have a genset/etc... Less confusing)
Remove/don't use the GFI outlet on the AC inverter.

I like GFI outlets at point of use (near sink, outside, etc.). If you have a GFI trip, only that outlet (or string of outlets) is turned off.

If you have a single GFI in the inverter--A trip at the sink outlet will plunge the entire cabin into darkness. A GFI per outlet is nicer. If you have a trip, you pretty much know where that trip occurred (vs a GFI breaker--It can be in any outlet on that circuit).

Note--The next question will be do you need to install Arc Fault breakers in some of your breaker slots? The theory that arc faults in bedroom ac appliances/cords are more common and dangerous... Not all people like arc fault breakers--They are not cheap and can trip when you plug a vacuum into them (the universal/brushed motor in vacuums, hand drills, kitchen appliances can cause false trips).

Code may require Arc Fault breakers in some circuits (if you have to meet code for your place).

-Bill

greenheads · August 2015

Thanks for the help, while I would rather deal with 12v I will probably go with 24 just to cut down on wire size and the ability to add solar later.

greenheads · August 2015

Thank you BB again for the wiring help! I have a question about loads now. If I run with 24 volts I will have 220ah. .5 discharge is the max I want? So 110ah/5 hours is 22 amps at 24volts max load I need to run?

22amps x 24volts x.9 eff loss = 475 watts in the house?

BB. · August 2015

To be clear... If you have 4x 6 volt @ 220 AH flooded cell lead acid golf cart batteries in series, that is a 24 volt @ 220 AH battery bank.

More or less, this is how I would suggest using the battery bank:

C₂₀ Battery 20 Hour Capacity (20 hour to discharge the battery to dead--The standard value we use to define the battery capacity for our rules of thumbs--The faster you discharge the battery, the less apparent capacity it will have... I.e., discharging at C/5 rate, the battery bank may appear to have a 180 AH capacity).
C/20 discharge rate... The average discharge where you discharge for 5 hours per per night for two nights to 50% capacity (5+5 use, +10 ours "reserve" = 20 hour discharge rate)
C/8 discharge rate... The typical maximum recommend discharge rate a flooded cell battery can be discharged and provide reliable power.
C/5 discharge rate... The maximum you should draw from a battery bank for an hour or so
C/2.5 discharge rate... The maximum surge current (seconds to minutes) that you should draw from a flooded cell battery. More than that, you you will eventually collapse the battery bus voltage.

So--Your loads out of an AC inverter would look like:

220 AH * 24 volts * 0.85 typical inverter eff * 1/20 hour discharge rate = 224 Watt suggested load for 5 hour per night, for two nights.
220 AH * 24 volts * 0.85 typical inverter eff * 1/8 hour discharge rate = 526 Watt max continuous discharge
220 AH * 24 volts * 0.85 typical inverter eff * 1/5 hour discharge rate = 898 Watt short term max continuous discharge
220 AH * 24 volts * 0.85 typical inverter eff * 1/2.5 hour discharge rate = 1,795 Watt max surge power

That would suggest that a 600 Watt inverter minimum would take good use of this battery bank. And since the "typical" inverter can supply about 2x rated output for starting surge, that:

1,795 Watt max surge / 2 surge rating = 898 Watt max inverter "useful" rating

So, for this bank, more than a 1,000 Watt inverter is not really useful--And since the larger the inverter, the more "tare"/wasted energy usage (inverter turned on wastes something like 6 watts for a small inverter, 10-20 watts for a moderate size inverter and over 40 Watts for a large inverter)--That keeping the inverter small saves on energy waste.

The above are not exact numbers--And are intended to reflect what you should (roughly) expect from an older battery bank... You don't want to design your system to support your needs for a year, then have to replace the batteries because they get a little age on them. I suggest you design your system (and set your expectations) on the conservative side (and that includes picking loads that are very efficient and are as small as practicable for your needs). Of grid solar power is not cheap and costs something like 10x what utility power costs--So extreme conservation will generally save you money over the long therm.

-Bill

greenheads · August 2015

Thank you for your help BB. That makes sense now. I picked up a kill-o-watt and am now working to determine some of my actual loads. I assume if I switch to 8 batteries all those figures double. I already have the Honda eu2000 and I believe the biggest IOTA charger I can run is the DLS 27-25 which has 25amp output. would this be to small for a 8 battery bank? Thanks?

BB. · August 2015

Yes, 2x larger battery bank, 2x the ratings.

Don't pick hardware yet. Study your loads first. There are other options to the Iota, but you need size the system first.

-Bill

greenheads · August 2015

BB. wrote: »

Yes, 2x larger battery bank, 2x the ratings.

Don't pick hardware yet. Study your loads first. There are other options to the Iota, but you need size the system first.

-Bill

I haven't bought anything so far, I checked a couple loads tonight and my tv (42") pulls 120w and my sat box pulls 36w. I will be getting a new tv for down there though.

weekend camp

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