Hi Ya'll !

System

Hello everybody !

My name is Susan and I'm a noobie what it comes to
solar stuff and ye, kinda sorta handy and usually a fast learner.

We got an off-grid cabin up in the Green Mtns region and have
been running a Honda eu2000 for the two fridges, a ceiling fan
and a few dim lights.

Can't really complain about fuel consumption, been getting 14-15hrs
on a full tank without running any power tools etc.

Would like to figure how to add a battery bank to run the same load
overnight and give the poor little kennyrator a break even thou it's been
basically only idling thru the night kicking up for a few seconds only
when one of the fridges crank up.

Thanks for any and all suggestions,

Sue

PS> Edit: Also would like to add panels on the rooftop later....

Cariboocoot

Re: Hi Ya'll !

Welcome to the forum.

Many fans of the Honda generators here, that's for sure!
But we can well understand the desire for quite power at night. Or should I say even quieter power?

What you really want to do here is get a Kill-A-Watt meter (or similar) and see just how many Watt hours you use. Since we know the maximum output of the EU2000i is 1800 Watts, we know you can't be peaking over that. Must be good refrigerators to not knock that off-line on start up.

So you'd want around a 2 kW inverter. For preference that would be a 24 Volt one as well. This lessens the DC Amperage and makes wiring a bit easier. Then it's just a matter of applying the Watt hours total to the magic battery formula: Watt hours / system Voltage = Amp hours * 2 (or 4) = battery bank capacity. Gets you in the ball park at least.

As a rough guess you'd want about 450 Amp hours @ 24 Volts (based on my own system performance - extrapolated to your equipment needs).

In all likelihood you'll want to start with an inverter/charger and use the gen to recharge during the day. Then perhaps add solar charging as fits the budget.

Yeah, I know: WHAT budget?

icarus

Re: Hi Ya'll !

Even though the horse is out of the barn, if a cabin is only used on the weekends and the occasional week, you could consider a propane fridge. Expensive to buy ( although getting them out of wrecked RVs is firly common) but cheap to run, and silent. We use two Dometic 10 cu ft fridges. With weed insulation they use 1500 btu/hour, and have a duty cycle of ~ 30% with an ambient in the 70s. FYI, a gallon of propane has ~ 79,000 BTUs so it users about 1 gallon of propane a week.

Tony

PS the equation between conventional fridge and a propane begins to favor a conventional ( with PV) the closer to full time it gets used.

BB.

Re: Hi Ya'll !

One of the big things to do is get as much energy from the genset into the battery back as fast and efficiently as you can.

There are some very interesting combination Inverter/Chargers (Xantrex, Magnum, and a few others).

And, there are (fewer) technically superior AC to DC battery chargers.

If you want to see what one person ("Stevek")went through trying to find the "optimum" AC battery Charger for his eu2000i--Take a look at this thread:

Question about battery charger selection with EU2000 generator.

If you are OK with a combination Inverter/Charger--there are a few nice programmable units from Xantrex (and Magnum?) that are worth a look at too.

Otherwise, use a separate battery charger and if one fails, your are not out both devices--As you would be if your Inverter/Charger fails.

-Bill

System2

Re: Hi Ya'll !

Thank You All for all the answers, unfortunately one fool can ask more questions than ten wise men can answer, so please bear with me...

What are the upsides/downsides in having 12/24/48v system, I do understand that the higer the voltage the lower the amps and transfer losses, so should I look into 24v or 48v system keeping in mind the future (hope so) addition of panels.

Is it better/simpler to have a inverter/charger or two separate units, the cost actually seems to be almost the same that I can find. Also there doesn't seem to be much selection in 24/48v choices.

How about sizing the inverter/charger, should I look into a 2kW unit or something smaller, I do have two Eu2000i's and gonna get the parallel cables one of these days anyway... Now on the issue of economy, I've been getting ~14hrs per tank
with current load, lets call it 2 gallons per day. If the kenny will be running on heavier load and sucking more fuel is there really much point in investing on the battery bank etc instead of letting it quietly chug thru the night.

Call me baffled....

icarus

Re: Hi Ya'll !

Size the inverter to the expected loads. An inverter that is too big will waste a lot of power to supply loads that aren't the. That said, you need a big enough inverter to provide the starting current required for the fridge.

What about tweaking the fridge t-stat such that the fridge runs just above freezing through out the day, shut it off at night completely, insulate the cabinet better, and let the temp rise over night? Adding 2" of foam insulation on the cabinet will reduce heat gain dramatically. Or consider a blanket over night. The biggest heat loss (gain) is through the door gasket. Covering the entire fridge with a good blanket will m ake a significant difference.

Most fridges run with maybe a 50% duty cycle, so 10 hours over night, is reall only 5 hours of run time. A well inulated, well stocked fridge will hold it's cold a long time. You could also consider rotating frozen water bottles through out the day. Freeze them during the day when the fridge is on the genny, then putting them in the fridge cabinet over night, repeat the next morning.

We routiney travel with a travel cooler, with two two litre bottles frozen when we start. They are still somewhat frozen after several days.

Just random thoughts.

Tony

Cariboocoot

Re: Hi Ya'll !

Okay, Baffled.

First the issue of running then generator all night. Uses gasoline, makes noise, needs maintenance, and eventually wears out the generator(s). The batteries for the solar will have to be replaced in 5 or so years, but in the meantime they are silent and just need a bit of distilled water now and then. So on the whole, the more power you need in terms of Watt hours the more viable the solar electric becomes.

Should you have an inverter/charge or two separate units? You'll find that if you get in to the larger capacity good quality inverters the charger is built-in anyway, so why not use it? This is a case of picking the right inverter for the job, as there's no option of with/without charger on something like a VFX 3524.

So what one should you get? That depends on several factors. Meeting power needs now is primary. Considering future expansion is secondary. Is it likely you'll have loads totaling 6 kW? If not, why buy a 6 kW inverter? Your two gens together add up to 3600 Watts. If they've done the duty separately so far, then it's likely your needs will remain under 4 kW. That's really quite a lot of power for off-grid applications. Trust me! My 3.6 kW OB puts out under 500 Watts most of the time. But then there's always that one time when everything comes on at once ...

The whole system Voltage thing is a matter of keeping DC Amps down and manageable. There's a sort of rule-of-thumb regarding it that's something like up to 1 kW = 12 V, 2 kW = 24, 4 kW or more = 48. That's for consistent use. An occasional 2 kW load can be run from 12 Volts, so you really have to get a kind of "feel" for that aspect.

Another consideration in system Voltage is the total Watt hours. If they're higher, it is better to up the system Voltage and keep batteries wired in series rather than in parallel. This ensures even current flow through all batteries. Many a time we've seen 1000 Amp hour 12 Volt battery banks - lots of parallel wiring and plenty of potential for problems. Better to have 500 Amp hours @ 24 Volts or 250 @ 48 if that's the kind of power you need.

You don't go up in system Voltage if you don't need to. Double the Voltage means double the expense for batteries and panels, so why spend the money on power you won't use? Okay, I'm a cheapskate; it's not my money, spend it as you will.

And again we find the answers to all the questions are based on loads: total Watts at any one time (determines size of inverter) and total Watt hours daily (determines size of battery bank and needed recharging capacity).

Photowhit

Re: Hi Ya'll !

icarus wrote: »

"... insulate the cabinet better, and let the temp rise over night? Adding 2" of foam insulation on the cabinet will reduce heat gain dramatically. Or consider a blanket over night. "

This use to be common practice, but there are rarely/never cooling tubes in the back of the fridge anymore, they are now built into the walls of the fridges, hence the warning to keep 2" of space around the outside walls of the fridge.

I think the way fridges are currently made this would be counter productive.

icarus

Re: Hi Ya'll !

Yea, but is am talking about covering the fridge while it is shut off, not while it ie running. I know specifically that some small chest freezers use the side of the case to disperse the heat, so you ae correct, covering it then would be counter productive.

Tony

Photowhit

Re: Hi Ya'll !

Got ya, add insulation, just for the over night hours...

icarus

Re: Hi Ya'll !

Or, add it over night, and 24/7 where you can, depending on the fridge condenser design.

T

System2

Re: Hi Ya'll !

Hmmm...

Any thoughts on using a Xantrex Freedom HF 1800 with
4 deep cycle wet batteries as a starter setup ?

I know its not 24v, but the price looks a lot better...

BTW, how do you guys ground your off-grid circuits and kennyrators,
common or separate grounds ??

Cariboocoot

Re: Hi Ya'll !

Roadkill wrote: »

Hmmm...

Any thoughts on using a Xantrex Freedom HF 1800 with
4 deep cycle wet batteries as a starter setup ?

I know its not 24v, but the price looks a lot better...

BTW, how do you guys ground your off-grid circuits and kennyrators,
common or separate grounds ??

One big ground rod driven 10' into the Earth. Generator left "floating" 'cause when it's hooked to the system the neutral-ground bond is in the breaker box and the ground is connected. Do NOT do this with a MSW type inverter; they don't want the neutral-ground bond at all.

What about the Freedom HF 1800? Well, will it meet your needs? That's the question and it's one only you can answer. On the whole MSW inverters aren't good with motors. If you read the spec sheet http://www.xantrex.com/power-products/inverter-chargers/freedom-hf.aspx you'll see they very carefully avoid mention of things like refrigerators.

System2

Re: Hi Ya'll !

Gee, thanks - now my head went 'POOF!' again....


How do you separate the neutral from eatrh ground,
ain't the neutral busbar supposed to be grounded at
the service panel or is there just a jumper to disco ?

I'd like the idea of all-in-one unit with pass-thru instead of trying to grok up
how to hook up a xfer switch, charger and inverter all separately...

Also, the cost is an issue, $$ are tight nowadays...

Cariboocoot

Re: Hi Ya'll !

Roadkill wrote: »

Gee, thanks - now my head went 'POOF!' again....


How do you separate the neutral from eatrh ground,
ain't the neutral busbar supposed to be grounded at
the service panel or is there just a jumper to disco ?

I'd like the idea of all-in-one unit with pass-thru instead of trying to grok up
how to hook up a xfer switch, charger and inverter all separately...

Also, the cost is an issue, $$ are tight nowadays...

Ooh, now that gets problematic. Without seeing your install there's no way of knowing where or even if there's a neutral-ground bond. It should be a jumper in the breaker box but ... And I'm sure I'm not alone with stories of multiple junctions, rods, wires and other grounding messes.

But take heart! One of those plug-in outlet testers with the 3 LED's can tell you if you've got neutral-ground bond. If so, and you find a connection in the box and disconnect it, it can tell you when you don't have it too (have successfully disconnected the bond).

NOTE: I got interrupted writing this so it may not be clear.

waynefromnscanada

Re: Hi Ya'll !

Cariboocoot wrote: »

One of those plug-in outlet testers with the 3 LED's can tell you if you've got neutral-ground bond.

Just be sure to do this test with your generator, BEFORE you connect your MSW inverter. Neighbor of mine got an electrician to wire her MSW inverter to her panel. They then turned it on and instantly there was a loud POP, a brief puff of smoke, then stunned silence, followed by her electrician explaining that obviously her inverter had been defective. Yeah. Right.

TheBackRoads

Re: Hi Ya'll !

Lots of great info above no question. However you seem confused Roadkill... Buy yourself one or 2 of these Meters to see what your overnight usage is. Do that, and then come back with your info and the family here can help ya get setup!