How to calculate how long a car battery will last as backup

[Chin_Lee]

I've been looking for a system to use as a backup power supply for my tank in the event of a power out. I was considering a UPS but most of them won't last long enough (and expensive) or provide enough power for heaters if needed. I've been looking at the Motomaster Eliminator PowerBoxes that come in 300A, 500A, 600A and 1200A.
http://www.canadiantire.ca/assortmen...romSearch=true
There was a trend regarding these powerboxes and Chad indicated he was going to test his 300A powerbox out. I've PMed him and he said he was going to test it. Looking forward to those results Chad

The 1200A box comes with a 60amp-hour battery and a 1200w inverter. Is there a generic formula to calculate how long a certain wattage appliance will last with the different batteries alone before having to use the plug in the inverter and start up the car?

[AndyL]

You might want to do some more testing - often the UPS and other battery backup systems use a Square wave output (AC power is sine wave) which results in pumps not working - so definitely test these out on your pumps before you go and blow large sums of money making sure you have enough run time - because you might end up with a LOT more than you expected...

Andy

[StirCrazy]

you want to look for the reserve rating of the battery, CCA doesn't really tell you anything.

so look for a reserve or a amp hour rating.

Steve

[Rus]

steve , the one that chin-lee mentions has a 60amp hour rating do you know what the formula is to figure out how long this will last ? is the 60 based on one amp per hour ?


thanks -Russ

[Willow]

Originally Posted by AndyL

You might want to do some more testing - often the UPS and other battery backup systems use a Square wave output (AC power is sine wave) which results in pumps not working - so definitely test these out on your pumps before you go and blow large sums of money making sure you have enough run time - because you might end up with a LOT more than you expected...

Andy

doesn’t the inverter convert the power to a/c? i have one for my truck and it powers everything ive plugged into it.

[Veng68]

Motomaster Eliminator 1,200A PowerBox

Product# 11-1815-0
Price $249.99

The Motomaster Eliminator 1,200 A PowerBox is a portable power system that can supply up to 1,200 watts of household electricity - enough to run almost any electronic product or appliance you might connect to your wall outlet at home.

An excellent alternative to a generator - no noise, no fumes, no fuel, and no moving parts

Provides 120V AC household power, 12V DC power
Built-in 1,200W inverter
Easy-to-monitor, dual-outlet AC panel
Sealed, 60 amp-hour AGM battery withstands long periods of inactivity with minimal self-discharge
Recharge PowerBox from a standard wall outlet or from your car, truck or RV
Jump starts vehicles (cables sold separately)
Ideal for power emergencies - run essential appliances like refrigerators, cordless/mobile phones, radios, fireplace fans, table lamps, microwaves, etc., when the power goes out
Operate power drills, belt sanders, circular saws, hedge trimmers, leaf blowers, vacuums, computers, large monitors, fax machines, and inkjet printers
Run blenders, video games, TV and VCRs, satellite equipment, coffee makers, portable coolers and more
With a rugged cart that can be wheeled from room-to-room or outdoors over rough terrain

Cheers,
Vic [veng68]

[Veng68]

I am taking a guess because I know little about electronics except:

watts= volts * amps

so

watts = 110 * 60

6600 total watts power would be my guess.

Cheers,
Vic [veng68]

[Willow]

yeah but if your running say 300 watts how long will that last?

[StirCrazy]

Originally Posted by Veng68

I am taking a guess because I know little about electronics except:

watts= volts * amps

so

watts = 110 * 60

6600 total watts power would be my guess.

Cheers,
Vic [veng68]

Should be 120 for your Voltage.

I was looking at thoes but I figure it would be useless to run a tank for any amount of time. now if you go to larger batteries and modify it with say two 120 amp hour batteries now were cookin. is there anywhere that you can get more info on thoes? I am interested in the amount of time it will last with say a 5 amp 120V load on it.

Steve

[r_wellwood]

5 amps, seems like a lot of equipment could run on that. Wouldn't the idea behind the backup be to maintain temperature, water flow (PH or two, return pump from sump if heater is there), and areation? Maybe some minor lighting could be powered, but why bother with keeping MH, VHO, all PowerHeads, etc going?

Strange things happen randomly in nature, and a power outage for a Fish/Reef tank for even a day should be tolerable for the system (with temperature, basic flow, and aereation maintained).

I could see something heavy-duty being necessary on a larger/complex system if say a chiller was also involved (closed loop pump and compressor).

RW