[huntinghawk]

Plenty of people have generators as backup systems. Really can't be running the generator 24/7. And you want ateast some lights in the evening.
So, some batteries charged during the day from the generator & a battery charger then evenings from batteries threw an inverter & extension cords for some lights. Amount of batteries depends on the amount of power you think you will need to draw which also dictates size of inverter.
This is a good way to add depth to your generator as a backup system for power.

HH

 

[Sweets]

Having been in extended blackouts the odd time, including a really long and bad one in midwinter, I also came to use lead acid batteries for running entertainment items like a dvd player, worldband radio, and so on. Their built in batteries, if they even have them, only run the item for so long, and not nearly as long as a dark winter night. Many of them take almost nothing out of a car-type battery if you use the supplied cigarette lightter adaptor. And, no one wants to run a generator when there's no end in sight, the gas stations can't pump or, even if they can, take card payments, and 12 volts will do.

Nowadays, when so many things (not least of all LED flashlights) run on AA and AAA cells alone, I also have a big stock of Sanyo Eneloops rechargeable NIMH batteries.

 

[jim-analog]

Greetings,

Hi HH! That's an interesting point. We were without power for just about 6 days from the end of October into the 1st week of November. The generator ran 24/7 the entire time BUT consumed somewhere around 70+ gallons of propane doing so. We were heating two buildings with forced air propane furnaces (it was in the low to mid 20s), running the well & sump pumps, power tools and whatever other misc lights, small apps, etc..

I really need to take some time and hook up current monitoring equipment to each of the loads and measure the power each draws. We were fortunate that just as the propane was getting seriously low, the roads got cleared enough that we could get a fill. We have a 1000 gallon tank, but after this event realize that it's not going to go as far as I'd like it to. When planning this, I did not factor in that 80% tank fill is all you actually end up with; that translates into just about 3 full days of no power. Installation of more propane storage is one option, a battery bank and large 220V inverter is another. My current small (1KW5, 120 VAC) inverter set up will not run the 220v well pump. I also have a serious dislike of extension cords running all over, so my preference would be some type of hardwired system. The way I designed the electrical distribution system with multiple panels *may* allow for an inverter switch over set up (but it would require manual load shedding), as I didn't plan for a very extensive DC-AC system. There is no significant sun here in the woods, so a generator would be needed to recharge the battery banks if utility power stayed out.

I really thought we'd be set with the 20KW auto switch over generator; the thought of not being able to be supplied with propane has me concerned now (it's always one more thing). One thing I learned for sure is that it is MUCH less expensive to purchase electricity from the grid than to produce it from any other fuel.

Regards, Jim

 

[CAVman]

Greetings,

Hi HH! That's an interesting point. We were without power for just about 6 days from the end of October into the 1st week of November. The generator ran 24/7 the entire time BUT consumed somewhere around 70+ gallons of propane doing so. We were heating two buildings with forced air propane furnaces (it was in the low to mid 20s), running the well & sump pumps, power tools and whatever other misc lights, small apps, etc..

I really need to take some time and hook up current monitoring equipment to each of the loads and measure the power each draws. We were fortunate that just as the propane was getting seriously low, the roads got cleared enough that we could get a fill. We have a 1000 gallon tank, but after this event realize that it's not going to go as far as I'd like it to. When planning this, I did not factor in that 80% tank fill is all you actually end up with; that translates into just about 3 full days of no power. Installation of more propane storage is one option, a battery bank and large 220V inverter is another. My current small (1KW5, 120 VAC) inverter set up will not run the 220v well pump. I also have a serious dislike of extension cords running all over, so my preference would be some type of hardwired system. The way I designed the electrical distribution system with multiple panels *may* allow for an inverter switch over set up (but it would require manual load shedding), as I didn't plan for a very extensive DC-AC system. There is no significant sun here in the woods, so a generator would be needed to recharge the battery banks if utility power stayed out.

I really thought we'd be set with the 20KW auto switch over generator; the thought of not being able to be supplied with propane has me concerned now (it's always one more thing). One thing I learned for sure is that it is MUCH less expensive to purchase electricity from the grid than to produce it from any other fuel.

Regards, Jim

Good thought-provoking post!
I like to read about other folk's thought processes and try to apply it to our issues at our cabin...
Question: Did You Mean 70 Gallon of Propane A DAY?
OR 700 Gallons During The Outage?

Thanks,

CAVman in WYoming

 

[jim-analog]

Greetings,

Hi Cavman!

Yes, propane consumption was right around 70 gallons a day! The generator (20KW) was running 24/7, the heating systems in both buildings (barn where we are living and house that is under construction) were also running and consuming propane. It took me a while to figure out (just last week actually), but I found and corrected a major problem with the barn heating system. This was causing it to run constantly, but not really warm the building up very much at all (FYI, during the outage, it didn't get above the mid to high 20s in the day and it was in the low 20s at night).

I'm very concerned about the high fuel consumption and am trying to figure out what I can do about it. Yesterday the tank got filled (last fill was just after the outage in early Nov), 560 gallons to get it up around 80%. Not looking forward to that bill when it comes. One big issue is the generator itself (Generac). It seems that anywhere up to 50% load, it consumes pretty much the same; so at idle up to half load it's eating up about 1.5 gal/hr (IIRC). The consumption goes up at over 50% load to just under 3 gal/hr (though I don't think we ever pulled even 50% power out of it).

If anyone is looking to purchase a generator, consider the newer inverter types that sip fuel at low power loads. I don't know how large you can get these and they were not readily available back when I got the one I have. Otherwise, I have no complaints about it; it ran without problem 24/7 for just about 6 days, starts itself every week for a self test and has an automatic transfer switch. It just eats a lot of propane!

Though the power and comms outage, ice, blocked roads and everything else that week kind of sucked on several levels, it gave my "systems" a good work out and an opportunity to see what worked, what didn't and what I need to dedicate time and effort towards. I too am very interested in learning what others have experienced.

Regards, Jim

 

[huntinghawk]

Jim, not sure if what I'm going to suggest is a viable option for you but something to consider.
Some wood heaters & fans to circulate the air. Small battery bank & inverter will take care of lights, fans, etc. My guess is it would cut your need for running the generator in half. Refrigerators, freezers, etc only need run a few a hours a day.

HH

 

[jim-analog]

Greetings,

Hi HuntingHawk!

Thanks for the great suggestion; I'm working on it. The house chimney had already been installed when I was doing the rough framing, but the wood stove itself did't actually get delivered and hooked in till about two weeks ago. We have a pretty large (huge actually) stack of hard wood logs from the lot and driveway clearing that I still need to cut and split.

You're 100% right that we can drastically reduce energy consumption by burning wood for heat and using the generator much more judiciously as mentioned (augmented by a battery bank/inverter for some loads). The wood stove in the barn was already hooked up and had been in use last winter when I burned just about all the wood that was already cut, but I just haven't had the time to cut and split the vast majority of the wood pile yet.

It is one of those tasks that I figured I'd have plenty of time to "get around to"............not the case of course and now winter is upon us. This is my first winter here with a partially completed house (was hoping it would be done by now, but we went through the wettest year in history, which drastically slowed down construction). Doing the best I can, but there are only so many hours in a day.

Regards, Jim

 

[huntinghawk]

OK, here's some money thoughts.

$600 roughly for four Trojan T-105 batteries which are 225AH each.

$440 for Samlex 1500watt pure sine wave inverter. Advantage is a pure sine wave is just better for electronics & motors but much more expensive.

$320 for a 1500watt generator

$50 for a battery charger.

So about $1500 you have a good standby system.

Now, with that in place, you can then add solar to charge the batteries.

$80 for 30amp solar controller regulator

$1,000 roughly for seven 80watt panels which would be 560watts. And that would almost elimate the need for the generator.

HH

 

[deadfoot]

Jim,

Some quick thoughts about designing in lead-acid batteries in your system. The first is that the battery storage capacity will degrade over time so there is a balance between life of the battery and the number of batteries. This is complicated by the fact that the life of the battery is directly related to the number of charge/discharge cycles and how fast the battery is charged. End result is you will need more batteries than is readily apparent from the simple numbers.

If it was me I would be looking at a combination of batteries with ultracapacitors used to reduce the number of cycles and charge rate on the batteries.

 

[jim-analog]

Greetings,

Hi Deadfoot and thank you for the info!

What can you tell me about UtraCaps in this type of application? I could figure it out, but how many total Farads would be required to come up with any reasonable deduction from the battery bank? I'd had a brief discussion with a friend regarding caps in addition to batteries and I really didn't think they would be all that useful. At the time, I was looking at a "Joule to Joule" comparison, but perhaps I wasn't thinking it out correctly?

What I'd experienced before was that all of the wet cell lead acid batteries I'd used before behaved exactly as you state. The small/experimental systems I'm working with now use AGM (Absorbed Glass Mat) battery construction. It's way too soon to tell how long they will last, but I'd done a good bit of research before paying that kind of $ for batteries. From what I could find it seemed the AGM battery is pretty well optimized for this type of use. One of my systems is dedicated for use on the back up sump pump (the battery alone weighted over 70 pounds; I need to go look at it to find the A/Hr and other details. At my previous house, the lead acid batteries (and they were the specified type for the same sump system) lasted just about exactly one year. The system here has only been hooked in since early summer, so we'll have to wait and see what the battery life ends up like.

I have another small, (portable, build onto a hand cart) (1KW5) inverter system that I'm pretty much using as a UPS for the computers, electronics and such or to move around where needed. I had to change out the inverter that came with it to a true sine type as the factory modified sine unit must have been putting out square waves; not much at all would function with it (other than purely resistive loads), and it destroyed a relatively new sump pump motor. It started out as an older version of one of these:

http://www.xantrex.com/power-products/backup-power/xpower-powerpack-1500.aspx

I don't have a handy link to the pure sine inverter I upgraded to, but I'll find it if you're interested. I'm still looking into my options to run the really important house loads; particularly the 220v well pump, reefers, freezer, etc..

I found what seems to be a good 2 pole AC, 24 (or 48) VDC inverter/charger unit (Magnum), but it is very pricey.

http://www.thesolar.biz/magnum_energy_msae_120240_volt.htm

Then add a compatible AGM battery bank, connecting gear, etc. and we're likely up well over $5K. I could probably get an inverter generator that would take care of those loads for that price. Ahh, back and forth and no easy solution!

Regards, Jim

 

[deadfoot]

Hi Jim,

The primary use I see for ultracaps in an application like this is between the gas generator and batteries. The physics that work against the system is the gas generator is inefficient at low power levels and batteries should not be charged quickly. End result is a lot of power is wasted while charging the batteries. With an ultracap in between, the generator can run a short period of time and quickly charge the ultracap. The generator can then shutoff and batteries recharged by a trickle current from the ultracap. Check out:

http://www.maxwell.com/products/ultracapacitors/applications/application.aspx?sid=QUICK-CHARGE

Ultracaps don't have anywhere near the energy density of a lead acid battery so they are not much use as a prime energy source. The best example I have seen for their use is a scenario for battery operated carts with charging stations along the route such as a golf course. Pull up to the tee and plug in the cart. A quick burst of current charges the ultracap and then as the cart is driven off the battery is slowly charged.

The best way to estimate the size of ultracap is to profile the energy usage over time. Once this is done then the combination of ultracap and battery usage will determine the cycle rate of the generator. If the rate is greater than an hour then the system should be very efficient compared to battery alone and the battery life should be extended considerably.