Best Electric Generator For Back-Up Power.

[Americano]

Jake,

 

When I moved to the Philippines in November of 2009 I purchased a UPS for my Desk Top Computer. When the power went off it would operate my computer for about 15 minutes which would give me some time to wait for the power to come back on and if it didn't then I could shut down the computer naturally.  Its still operating today but only runs the computer for about 5 minutes so evidently the battery is going bad or needs servicing. I haven't opened the unit to check it yet. Sometimes I would just plug in a fan and it would run for 20 minutes or more. The unit I have is a Panther Model PUP-500, made in the Philippines.

[Americano]

Terry,

 

Thank you for the valuable information you have shared concerning generators and inverters. I look forward to learning more from your experiences.

 

Welcome to the forum,

 

Phillip

[Jake]

Jake,

 

When I moved to the Philippines in November of 2009 I purchased a UPS for my Desk Top Computer. When the power went off it would operate my computer for about 15 minutes which would give me some time to wait for the power to come back on and if it didn't then I could shut down the computer naturally.  Its still operating today but only runs the computer for about 5 minutes so evidently the battery is going bad or needs servicing. I haven't opened the unit to check it yet. Sometimes I would just plug in a fan and it would run for 20 minutes or more. The unit I have is a Panther Model PUP-500, made in the Philippines.

Hey Phillip,

Not too shabby if you ask me.  This company based in Valenzuela City, Metro Manila has many

other products (AVR, connectors, antennas) for those of us DIY (do it yourself).  

 

Have a good one -- Jake

[not so old china hand]

To return to Dave's question of using a small generator, and / or an inverter to run a fridge during an occasional brownout. I did a few "back of a cigarette pack" calculations and came to the conclusion that an inverter/charger system based on a 180 amp hour 12 v battery or on two 150 amp hour 6 v batteries would keep an average fridge running normally for 10 to 12 hours.

 

This is based on occasional use since I have assumed the batteries will be discharged to 20% of nominal capacity. Most manufacturers recommend a maximum DOD (depth of discharge) of 50% for regular use.

 

By "average" I mean a reasonably modern 18-20 cubic foot fridge with a top or bottom freezer and no extra wigets like an ice maker. A fridge like this would draw of the order of 1 to 1.5 kW hours a day with normal careful use (e.g. minimising the number of times the door is opened by taking more than one beer at a time).

 

My battery capacity calculation is as follows.

 

Nominal battery capacity 1.8 kW hours.

 

20% of nominal capacity 0.36 kW hours

 

Actual battery capacity 11.5v x 150 amp hours  = 1.725 kW hours (should be achievable with a smart charger working off a mains supply)

 

Actual capacity - 20% nominal 1.725 - 0.36 = 1.36 kW hours.

 

Available capacity at 220v (using manufacture's estimate of 80% efficiency) 1.36 x 0.8 =  1.088 kWh

 

Fridge at 1.5 KWh / 2 = 0.75 kWh.

 

So there should be enough capacity left over to run essential equipment such as a DSL modem and router for the entire time and appliances such as fans and a TV for part of the time.

 

Please feel free to comment on or query these figures. They are calculations based on the best of my knowledge and not personal experience of running a domestic fridge off of an inverter system. My approach to refrigeration on the junk was completely different (but that's a topic for another thread).

 

Cheers Terry

 

Next episode "Confessions of a Power Junkie"

Edited May 14, 2014 by not so old china hand

[Jake]

Hey Terry,

 

I know very little about generators and types of batteries normally found in an off the grid configuration.  

So please accept my advance apologies for asking you some really basic questions.  After all, in that

part of the world where utility power is unreliable, one must be prepared, especially if you have family.

 

Did some research about depth of discharge and I got totally confused.  You pointed out that going

below the manufacturer's DOD of 50% (you only went down to 80%) you should start worrying about

battery condition and therefore its long term endurance?  In order words, how easily can we abuse

these batteries before they fail?  Do we need to go below a certain level before we charge them again?  

Can overcharging them kill them as well?  

 

And speaking of a certain level, how does one determine depth of discharge?  It can't be simply be like

starting at 12v and now down to 6v, is equivalent to 50% DOD.  Is there a meter or LED readout? 

 

Let's talk about configuration, starting with a basic generator (gas, propane, diesel) to provide 220VAC.

One of the characteristics of selecting a genny is watts per hour capacity.  I guess in most cases, that

could average around 2K-5KW for most applications during emergency.  The other type of configuration

requires additional items if you want to live more off the grid.  I won't get into solar panels, another topic

perhaps.

 

Anyway for that configuration, you can have a generator providing all the loads, including maintaining a

charge on a heavy duty 12v battery, so it can be used later when you turn off the generator because you

ran out of gas or it got fouled.  That battery can now be the main source to a power converter (12 to 220)

to provide power to a more limited load.  In your particular case, you're really off the grid.....on a Chinese

junk!  

 

I really like the idea of having two 6v batteries connected in series, more flexibility for emergency connections

and less weight.  In the harbor or anchored off shore, you're not running the main diesel (for propulsion, H2O

pumps, utilities), so you need to crank up those genny's to keep your beers cold and other essentials.  

 

I am really fascinated about emergency power when the chit hits the fan.  Of course the chit just sits there

because the power is off....he, he.  I'm becoming more interested in renewable power these days.  In southern

California, I need to maintain power and security, especially when those zombies come staggering in....he, he.

(The Walking Dead TV series)

 

Respectfully -- Jake 

Edited May 14, 2014 by Jake
spil chek

[Thomas]

You pointed out that going below the manufacturer's DOD of 50% (you only went down to 80%) you should start worrying about battery condition and therefore its long term endurance?

(For some types of rechargable batteries it's recomended to "empty" them before recharging to make them have good condition as long as possible, but I don't know which type is which.)

[robert k]

Thomas, those are probably NiCad batteries as many cordless tools used.

[Americano]

 

You pointed out that going below the manufacturer's DOD of 50% (you only went down to 80%) you should start worrying about battery condition and therefore its long term endurance?

(For some types of rechargable batteries it's recomended to "empty" them before recharging to make them have good condition as long as possible, but I don't know which type is which.)

 

 

Lead Acid batteries which are in most cars. motorcycles, and boats should never be run completely down. Running them completely down will greatly shorten the battery's life.  Batteries which are in most cell phones and in many other devices ( I don't remember the full name right now) last longer if the battery is run completely down before recharging. Instruction that came with the battery or device will give you the correct time to recharge the battery.

[robert k]

Lets explore lead acid batteries for a moment, what makes them fail totally? A broken plate or other broken part. mineral build up between plates shorting them out, acid completely depleted so they will not charge, build up of particles in the bottom of the battery shorting out the plates again. Only the part of the plates immersed in the acid are doing any work, so keep them full. Take a dead lead acid battery with nothing wrong physically and dump it out and refill it with acid and you have a functional charged battery again. Nothing mysterious about it. If I were the manufacturer I would recommend you not discharge the battery more than 50% also, so I can sell twice as many batteries. The battery will last longer, because you are only using it half as much. Many things will last longer if you only use them half as much. I know, crazy talk, I do that sometimes. :thumbsup:

[Jake]

Many things will last longer if you only use them half as much. I know, crazy talk, I do that sometimes. :thumbsup:

So, let me get this straight soldier.....if I only use my little Herman half as much (2.5 min vs 5 min), I should be fully

recharged the following morning?  

 

Seriously, I really don't know when to pull the plug from my power converter or in a smaller load condition, from a

UPS setup?  There's got to be a meter or some sort of alarm telling me the battery is at 50% threshold?

I took the opportunity to shop around for a no maintenance, sealed type batteries in Amazon....they are not cheap:

 

So this guy gets charged in your vehicle and then placed inside your home to connect to a power converter

(12vdc to 220vac with multiple outlets) for awhile.  Gas generator was not needed.

http://www.amazon.com/Vmaxtanks-VMAXSLR125-battery-electric-generator/dp/B00B79GEOO/ref=sr_1_3?ie=UTF8&qid=1400098322&sr=8-3&keywords=deep+cycle+battery+for+off+the+grid