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Jul 132013
 
This is a wonderful portable generator, costing only $135 and providing both 12V and 110-120V power.

This is a wonderful portable generator, costing only $135 and providing both 12V and 110-120V power.

We previously wrote a detailed four part series about storing electricity which assumed you wanted to live off-grid, long-term, and needed a high-capacity and very long-lived energy storage solution for such a scenario.

That is of course a valid need, and there’s a lot of good information in that series about all aspects of storing electricity – when time allows, you should read it. 🙂

This article, however, is about one special type of energy storage application – a need to have a short-term emergency supply of power when the mains supply fails.  If the failure is a simple short-term thing such as high winds blowing over power lines, then you just need a little bit of electricity ‘to get by’ until the mains power is restored.  These are Level 1 type situations.

If the failure is caused by a major disruption that will escalate to a Level 2 or 3 scenario, you might need some power for a short while to operate radios to communicate and co-ordinate with other members of your group, prior to bugging out to your retreat location.

There are many different ways you can have an emergency power source always on hand, with many different amounts of electrical storage capacity, complexity, and cost. This article considers two approaches.  There are others, but these two are the simplest, and being the simplest is, for our purposes, an essential consideration – simple things are easier to deploy and less likely to fail.

Portable Generators

For almost any non-trivial amount of electrical power, your best solution will always be a generator.

While they are typically heavy, noisy and expensive, you can also get smaller, lightweight, affordable and very quiet generators that would be suitable for use pretty much anywhere – including for apartment dwellers, too.

For example, here’s a portable generator for only $135 on Amazon (pictured above).  This unit is quiet, lightweight, and runs for 8.5 hours on each 1.2 gallon tank of fuel, providing about 400W – 500W of 120V power during that time.  That’s a great value, and with a five gallon container of fuel and running the generator sparingly rather than 24/7, you’ve enough power for maybe three days.

The above generator is a two-stroke generator.  A similar four-stroke generator generates twice as much power using almost the same amount of fuel (four-stroke engines are more efficient than two-stroke), and is similarly quiet, while weighing an extra 10lbs (54lbs instead of 44 lbs) and being slightly bulkier.  It costs just a hair less than $200.

Amazon has plenty of other portable generators, albeit more expensive than these two, as well. Here’s a listing of some of the nicer modelsthat would be excellent as portable, use anywhere, low-sound type generators.

Four quick comments about generators.

First, no matter what generator you might choose, you must operate it outside, due to all the exhaust gases it produces.

Second, you should run your generator once every few months to be sure it is still in good order and condition, and be sure to stabilize your fuel so it doesn’t ‘go off’ while sitting in the generator or fuel can.  There are several types of fuel stabilizer available, the best is PRI.  Don’t settle for any other brand, use only PRI.

Third, these low power generators are very limited in what they can handle (because of their low power output) and you’ll need to be very careful to match the current drains with the generator capacity.  Using a Kill A Watt meter is an easy way to monitor the power being drawn from the generator, and be very careful of peak loads – when motors first start up, they draw a great deal more current than when they are running at normal speed.   These peak loads can fry your generator if you don’t plan carefully for not just average but also peak loads.

Fourth, keep the cords from the generator to the devices using the power as short as possible, and as heavy-duty as possible.  Short heavy-duty cables will waste less power and provide a better voltage level than would be otherwise the case with lighter and/or longer cables.

Lead-Acid Battery and Trickle Charger

The $135 portable generator we linked to at the start of the previous section is probably the least expensive solution for most people, and when you match that with a single five gallon tank of gas, you’ve got the equivalent of about 15 kWhrs of power, and/or about 35 hours of running time.  If that’s not enough, you can simply store as much extra fuel as you need and are legally allowed to have, and/or get a higher capacity generator.

But if you’re in a situation where either you can’t run a generator – maybe you’re in an apartment with no balcony or outside space to operate the generator, or if you’re in a situation where you need a guaranteed, absolutely-must-work source of power for a short but essential period of time, there’s another solution to consider.

Buy a 12V ‘golf cart’ or other ‘deep cycle’ battery (or two 6V batteries that you’d connect in series).  Note that these are very different to auto starting batteries – do not get a regular car battery.

You also will need a trickle charger to maintain it (them) at full charge.  If the mains power fails, the fully charged battery becomes a source of 12V DC power, and if you connect an inverter, you can get 120V AC power from it too.

This is a clean, totally silent and reasonably compact form of electricity generation and storage.  There is almost no maintenance you need to do – you can just set it up and then forget about it for several years before then testing the battery, perhaps once every six months after that, until you note its capacity has diminished to an unacceptable level.

There might be restrictions on how much fuel you can store in an apartment (either from the landlord or the fire department) and there might be restrictions on running a generator, and you might not want to attract attention to yourself and your generator, either; but none of these constraints apply to batteries and battery power.  They don’t need to be stored outside, and modern non-gassing batteries are perfectly fine indoors to store, to charge, and to use as a power source, especially when connected to an intelligent charger.

If you need a lot of standby power, we’d suggest batteries such as these or these.  Other highly respected battery suppliers include Concorde/Lifeline and Rolls/Surrette.

If you don’t need such an expensive high-capacity battery, then a Trojan U1-AGM is a good entry-level battery, probably costing about $125 or thereabouts.  Trojan make other batteries with successively greater capacities, too.

You then need some sort of trickle charger to keep the battery charged.  We consider the NOCO Genius products to be the very best, and you’ll probably find either the G750 or G1100 to be adequate for your needs.  Neither is very expensive, and because your need is more to maintain a charge rather than to recharge the battery, you don’t need a higher current capacity unit.

If you want your battery to run 110-120V appliances, you’ll need an inverter as well.  Get the lowest powered inverter you need, and use it with caution, because any/all 120V appliances will use up your 12V battery very quickly.  We’d suggest you consider getting whatever emergency appliances you need that are designed to operate off 12V DC (and which are designed to be ultra-efficient, too).  That way you don’t ‘waste’ some of your energy by converting it to 120V and then using it in a device that does not have energy efficiency as its main design criteria.  Many appliances designed for sail boats are high-efficiency 12V units, and you can get many different sorts of 12V LED lighting that provide the most energy efficient source of emergency light.

You could also consider getting a set of solar panels to recharge your battery if you were planning for an extended period of needing the battery, but this would likely only give you a very little bit of top up charge each day, unless you had large panels, and then you’re moving beyond the scope of this article (and should read our full four-part series on storing electricity).  Here’s a single panel system that claims to provide 100W of power, and complete with the necessary charge controller unit too; this is about as good a simple choice as possible before needing to move into complicated bulky and fixed installations.  In reality, we expect you’re more likely to get 50W rather than 100W of charging power from the cells, but if you’ve no other way of recharging your battery, this could give you up to as much as 500 W hrs of extra power each day during the period of your power outage.

If you do get a solar panel system like this, you should trial it to understand how it works and how much power to realistically expect, then carefully put it away and not touch it again until you need to start recharging your battery during your power outage.

One more thing to add to your setup.  A 12V to USB charger/connector – a device that will enable you to recharge all your electronic things that can be charged from a USB port.  These devices typically come in the form of a cigarette lighter type adapter for a motor vehicle – they are perfectly good in that form; although you will then either need to solder leads to the adapter or else get a matching socket to connect to your battery.

Make sure that any such USB power supplies are high current (ie more than 2 Amps) so as to be able to recharge tablets as well as phones and other low current devices.

Summary

Many of us have our homes wired up with heavy-duty generators and transfer switches, and many of us have extensive other power storage facilities of various sorts too.

But sometimes these requirements are overkill.  Sometimes we just need a small amount of power, for a short term solution.  Perhaps it is a relatively benign brief power outage, or perhaps it is such a severe event that we’re forced to get out of Dodge just as quickly as we can rendezvous with the other members of our group.

In such cases, a simple small portable generator, or a fully charged golf cart type battery can give us everything we need, and for under $200.

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David Spero[suffusion-the-author display='description']

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