Power Inverters, etc

tlbaker78

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Mar 24, 2008
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Hi, I have question about Power inverters.. I was told in a previous post I would need a 1.5k inverter and 4 batt. I am sorry for my ignorance on such things, but I am not sure I know what it is.. An overter to me is one that just changes the current of power.... Is that what also charges the batteries?? I was thinking of like APC battery backups, but i see they really dont give you any time at all... Can someone explain a little more, PLEASE, maybe send me a link to an example on ebay (I found some mitsubishi 1.5k power inverters, but i see nothing about batteries)
Thanks
 

Rocky

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Here's a link to our favorite brand.
Xantrex Technology Inc.
The problem is that it's enough to confuse even a fairly knowledgeable person, so let's just run over a few details here.
An inverter should do both, change AC to DC and DC to AC, so the unit would be capable of charging batteries (AC to DC) and also provide 110 volt AC during power failures, from the batteries. (DC to AC)
Some companies mislead by calling converters, inverters, so beware.
It has to do both functions to be a true inverter.
So the net result is the following, assuming you have the adequate equipment.
Power goes off, inverter changes mode in milliseconds and supplies power to your house, then when the power returns, it changes modes once more, allowing the AC to flow through and supply the house, all while it also recharges your batteries.
 

anitaemma

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1,5 k inverter and 4 batteries sounds a bit small. Which kind of equipments you have plant to use ? A/C , TV , pump etc
 

Rocky

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1,5 k inverter and 4 batteries sounds a bit small. Which kind of equipments you have plant to use ? A/C , TV , pump etc
This fellow is planning on living a very simple existence here in the DR, and if anything, it may be more than what he needs.
If someone is only powering 1 economy bulb, a fan, a TV and a laptop, you'd be surprised as to how far he could go with a 1K unit and only 2 batteries.
 

Chip

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This fellow is planning on living a very simple existence here in the DR, and if anything, it may be more than what he needs.
If someone is only powering 1 economy bulb, a fan, a TV and a laptop, you'd be surprised as to how far he could go with a 1K unit and only 2 batteries.
Boy, that is roughing it! For that reason I sugggested a 1.5 with 4 batteries, to make sure the house/apt can be lighted relativley easily. If the guy bathes quickly, he might even be able to use the head mounted water heater thing - real quickly though, but a must here in Santiago in winter.
 

Ringo

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Everyone is going to have different needs and give different advise. Best that you do your research and determine your own needs. Follow Rockys' advise and gain real information that is more intuned to your needs at the Xantrex web site that he posted, they have an amazing amount of information that will inform and teach IF you take the time. After you have gained some knowledge, then it is the time to ask questions based on some understanding rather then several individuals with different requirements, budgets and use.

Regards, Ringo
 

tlbaker78

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Also, I was wondering, if I could buy it here in Mexico, or USA and bring the Inverter, and / Batteries on the plane to DR... I am sure they would be cheaper, But what aqbout import taxes, or duties? I am not sure I can bring the batteries on the plane.... I am sure I can get the inverter for less than $100 USD, But I am not sure what the Customs Guy will say.. Any ideas???
 

rubio_higuey

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Certainly do not bring batteries.

New, quite quaility deep cycle 6V batteries can be bought here starting at US$ 100 per piece.

Have you ever weighted the battery? It weights a lot!! Your airline baggage allowance would be eaten up by 1 or maybe 2 batteries.
 

Chip

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Certainly do not bring batteries.

New, quite quaility deep cycle 6V batteries can be bought here starting at US$ 100 per piece.

Have you ever weighted the battery? It weights a lot!! Your airline baggage allowance would be eaten up by 1 or maybe 2 batteries.
I concurr, the airline fees will eat you up. As far as the inverter goes, if you can fit it in the luggage, all the better, just remember tourists are treated like king in the airports here and therefore rarely bothered, so just remember to not speak any Spanish, especially in the customs area(ok for negotiating a good cab fee, though). Also, points are given for loud flower shirts with cowboy hats, shorts, fish belly white legs with black socks and dress shoes, seriously!
 

rubio_higuey

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Here is the rough estimate of battery capacity you will need:

Add all kwh usage of all applicances you intend to use. Divide by 12. You will get number of amperhours you will need. Each battery has its amperhours, e.g. 200 amperhours. Battery discharging equally would theoretically give you 100%. Battery discharged at let's say double the equal discharge mode would give you about 80%.

But, I was surprised how little I use up ON INVERTER.

4 bulbs, big TV, small TV, DVD, 2 x cable box, cellphone charges, computer, 12ft fridge, etc.

it gets to use about 3 amps, which is 360 watt (0.36 kwh consumption) (not charging the inverter).

So my use 360 watt / 12 = 30 amps.

If your battery has 225 ampshours, and you have 4 batteries, it is 1000 amps hours
your consumption would last you, technically, 33.3 hours.

1000 ampshours discharged equally over 20 hours, it's 50 ampshours every hour, so calculated above your 22ampshours every hour would be better than recommended discharge, you would not put a strain on batteries using higher discharge than recommended 20-hr equal discharge.

Scenario 2:
Now, suppose you have a load of 200 amps on your inverter, with the same battery capacity of 1000 ampshours.

In theory, that whould provide you 5 hours of service (1000 ampshours / 10)
but the bigger the battery discharge rate, the more strain you put on battery and the fewer power it gives out.
Recommended discharge is 20 hours, but here you discharges it in only 5 hours. 5 Hour theoretical discharge would give you only 80% of capacity, so you would only have 800 ampshours to use out of 1000. Discharging at 200 amps would give you, in reality only 4 hours of service.

Now, here you can learn more http://www.majorpower.com/inverters/battery_sizing_faq.pdf
 

Rocky

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Ok, I know i am ignorant, and should know more... But is this what you are talking about when you say a 1k inverter....? Will this work?

Amazon.com: Duracell DC to AC Power Source Inverter 1500 Watt #813-1500-07: Automotive
Nope,
That's just what we call a converter.
You can tell by the price.
A 1.5k inverter in a decent brand will be in the area of $500 US.

The inverters we are talking about are automated back up power systems.
The small unit that you linked to would be way over rated and would fry to a crisp if you ran it constantly near it's rated power, and it would require a battery charger and a lot of dicking around, according to whether there is or isn't city power.
So each time it comes or goes, you would hook up, unhook wires, plug in, unplug things.
Do you know what I mean?
In short, that thing is a toy.
 

Ringo

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Rocky gave you the site to learn. Should take about a day before you come back with real questions that are applicable. Happy learning.

Ringo
 

Skippy1

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Feb 21, 2008
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Another thing to take into account is the recharge time, it takes longer to put the power back into the battery than it takes to discharge.

After a long discharge it will take several hours to reach the same capacity. Should you get another blackout you will not have full capacity available this could eventually lead to (if the interuptions to the power supply are frequent) a situation where your 1000amphr battery source is as little as 200amphr.
Temperature aso plays a big factor is both discharge and recharge.
Due to efficiency loss you can reach a point where you are only getting 80% of what you put in.
When the supply company charge you they are will recover more than you use.

Skippy
 

Skippy1

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Feb 21, 2008
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One other thing to remember lead acid batteries give off hydrogen gas while charging so never put the batteries in an unvent area the fumes are not good to breath and can cause serious problems to health......

Skippy
 

reese_in_va

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Feb 22, 2007
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I think everyone gave very good advice here. Inverter and batteries MUST be completely secured i.e. locked up. These systems are extremely popular on the "black market", they will be quickly stolen and re-sold for pennies on the dollar. Ever see the trucks that drive around with the loud speakers buying old batteries? These trucks/ people buy batteries and inverters (stolen and new) from the thieves. Unfortunately they encourage door to door service for this type of crime.
Also, any kind of resistance type power eats up the energy very fast. This includes irons, toasters, hot water heaters, coffee makers, ect. Motors too eat up the power including clothes washers. I have read a post here that you can use a refrigerator. From my experience this too eats up the power fast. I don't run any kitchen appliances on the inverter, especially my fridge. Our system is solely used for limited power during these outages that occur DAILY for us up here in the campo. We have four batteries 24V and only get on average 8 hours of consumable energy. Once a month I check the water level of the battery cells. Since our batteries have been replaced recently, they have been fine but after a while they will get low and need to be kept at a consistent level, otherwise they will burn out.
Batteries must be stored in an area where there is airflow. First of all the inverter will have a small fan that cools it down and second the batteries do emit fumes, that could be dangerous if not explosive.