Posted by *ballypinballs* on September 2, 2005, 12:13 pm

Thinking about buying a power inverter for back up power house/camper.

I guess my main question is input amps.Using deep cycle battery/s like

for my trolling motor.How many can I/should I use to run a 2000/4000w

inverter. I guess by putting a couple in parallel or more would hold

12v and multiply amps.But how high can you supply for input and not

damage the inverter?

thanks for any help

Keith

Posted by *Anthony Matonak* on September 2, 2005, 12:29 pm

ballypinballs@yahoo.com wrote:

*> Thinking about buying a power inverter for back up power house/camper.*

*> I guess my main question is input amps.Using deep cycle battery/s like*

*> for my trolling motor.How many can I/should I use to run a 2000/4000w*

*> inverter. I guess by putting a couple in parallel or more would hold*

*> 12v and multiply amps.But how high can you supply for input and not*

*> damage the inverter?*

*> thanks for any help*

The inverter will draw power from the batteries. It's not a question

of how many amps can you pump into it but rather how many amps the

inverter will require from the batteries.

Watts = Volts x Amps

This means that if you have a 4000 watt inverter (and you were to

max it out) that it would need 333 Amps at 12V. Actually, it would

require more because of loss inside the inverter. Generally folks

don't max out their inverters so you'll be using less power and

therefor it would require fewer amps.

The way most folks design backup power systems to is figure the

maximum wattage that would ever be needed at any one moment. This

would be the size of the inverter required. Then they figure out

how many watt-hours would be required over the period of time

they would need to use this before recharging the batteries. This

would determine the size of the batteries, generally by sizing

the batteries with at least 20% more.

Anthony

Posted by *ballypinballs* on September 2, 2005, 1:05 pm

Excellent info, whats the math for watt hours....15 amp draw for 1

hour..I guess the watts would be 1800 but what would it take for

battery/s to maintain that for one hour?....In my mind what I want to

accomplish is run my oil furnance and frig. if we loss power(winter) I

need the formula to do the math :) Most items cycle on and off so the

power need would not be needed 100% of the time. But like a A/C unit

would.

thanks keith

Posted by *Anthony Matonak* on September 2, 2005, 2:43 pm

ballypinballs@yahoo.com wrote:

*> Excellent info, whats the math for watt hours....15 amp draw for 1*

*> hour..I guess the watts would be 1800 but what would it take for*

*> battery/s to maintain that for one hour?....In my mind what I want to*

*> accomplish is run my oil furnance and frig. if we loss power(winter) I*

*> need the formula to do the math :) Most items cycle on and off so the*

*> power need would not be needed 100% of the time. But like a A/C unit*

*> would. *

Watt-hours is exactly what it sounds like, Watts x Hours.

If you have something that takes 100 Watts and you run it

for 1 hour then it consumes 100 Watt-hours. Run it for

1.5 hours and it consumes 150 Watt-hours.

There are also Amp-hours. Amps x Hours. If you know your

batteries need to supply 100 amps for 2 hour then your

batteries need 200 Amp-hours.

You would have to measure, in some fashion, how much your

furnace and fridge consume. They actually sell devices to

do just this but you might be able to rent or borrow one.

You can also use your power companies meter to measure as

well.

Anthony

Posted by *Christian M. Mericle* on September 2, 2005, 4:02 pm

On 2 Sep 2005 05:13:10 -0700, ballypinballs@yahoo.com wrote:

*>Thinking about buying a power inverter for back up power house/camper.*

*>I guess my main question is input amps.Using deep cycle battery/s like*

*>for my trolling motor.How many can I/should I use to run a 2000/4000w*

*>inverter. I guess by putting a couple in parallel or more would hold*

*>12v and multiply amps.But how high can you supply for input and not*

*>damage the inverter?*

*>thanks for any help*

*>Keith*

I think the main thing I learned is, for the longevity of the

battery's power supply, use as much stuff made for 12V DC as possible

and only use the inverter when you have to.

-- Christian

> Thinking about buying a power inverter for back up power house/camper.> I guess my main question is input amps.Using deep cycle battery/s like> for my trolling motor.How many can I/should I use to run a 2000/4000w> inverter. I guess by putting a couple in parallel or more would hold> 12v and multiply amps.But how high can you supply for input and not> damage the inverter?> thanks for any help