I would like to know how long I can expect a new auto battery to last if using a power inverter to run 300wats/1.5amps continuously?

Asked by May 03, 2013 at 03:56 PM

Question type: Maintenance & Repair

I want to an AC device that uses 300watts/1.5amps in an area where there is no
electericity so I thought I could use a battery with an inverter

9 Answers


A lead acid battery will last around three hundred full cycles. A full cycle is from zero volts to full volts to zero volts. Every time a battery is discharged and recharged, it is a percentage of a full cycle. Look for the battery with the longest warranty to find the one that will last the longest. - -- Since you are using it as a continuous power supply, you might want to consider smaller lawn tractor and motorcycle batteries that are more easily moved for recharging in a vehicle.

Tenspeed, Thanks for your answer. I do not care about the weight of the battery, I need to be able to run the AC device continuously for 8 hours, I just want to know if it will last that long?


If your battery has a reserve capacity of 120, it should run for 25 hours. A reserve capacity of 60 should be good for 12 hours. You don't want to drain the battery. You don't want to run it down lower than 9-10 volts, it throws all the formulas off and the amperage increases to maintain the same power output.

Thank you very much Tenspeed

of course Mr Tenspeed is THE authority one Deep-cycle batteries, like the kind golf carts and electric submarines use, but an automotive application has different concerns, the largest of which is to be able to withstand a three second dead-short, then be able to BE charged up with a load tester...the amount of time that it takes to charge up from this three second dead short is the indicator of the life of this automotive battery...Auto batteries degrade by ten percent per year, that is the ability to recharge gets impaired ten percent per year (according to Battery Engineer (electrochemical doing car batteries for 35 years)....my dad Mr. Nawaz M Qureshi a battery will be dead in ten years and will no longer accept a charge~....also they are no longer made from lead, they are made from an antimony/tin alloy....FYI

Bottom line, you don't want to use an automotive battery for a deep-cycle application...you should be using a bank of golf-cart batteries~...designed for the three hundred cycles that tenspeed spoke of.~

Can't tell you the number of batteries I put on the load tester---dead short for three seconds...to never come back...never accept a charge no matter how long the charger was on there....that bad boy is dead~...lot of 'em running around with weak sisters under the hood~

What's remarkable is some are unphased by a three second dead short--- -I want THAT brand in the middle of winter!

Interstate Batteries, Mr. N.M. Qureshi is the Electro-chemical Engineer on Duty there...you could call him to bug him with annoying questions...that's all he does all day~

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