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Need help with batteries linking to Inverters

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chriskid

New Member
hi, im trying an experiment and am new to electronics. i was thinking of linking an inverter to a battery to run maybe my lcd tv or something similar. the battery i have is 12v 9ah which i dont think would be able to run the tv for a long time at all? So which AH in a battery would be the best to get in order to run the tv for a few hours at least?

thanks from chris
 

smanches

New Member
60w + ~12w(inverter) / 12v = 6a.

Running it from a 9ah battery will very roughly net you almost 1.5 hours of run time. So much depends on how the battery was rated, as well as how many times, and how deeply, the battery has been cycled in the past.
 
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Sometimes even a 100ah battery is not enough, depending on its state of charge, to 'start' a 13" analog tv. Once going though, several hours of tv is possible. Laptop usually no problem. Not sure on an LCD tv, but the RV.net forum would have the definitive answer. Although the first "expected" answer would be two 6V golf cart batteries:eek:.
 

KMoffett

Well-Known Member
60w + ~12w(inverter) / 12v = 6a.

Running it from a 9ah battery will very roughly net you almost 1.5 hours of run time.
The Amp-Hour rating on batteries is based on drawing only 1/10 to 1/20 of the current of the 1 hour rate. A 9AH battery, when new and fully charged will last ~18 hours when the current draw is 0.5A. Drawing 6A would completely discharge it in much, much less than 1.5 hours. Check the discharge charts for for the particular battery.

Ken
 

smanches

New Member
I've seen so many different ways manufacturers rate batteries that I'm not even going to try and say what's standard. I was more trying to explain the math behind it, not the battery rating system.
 

Sceadwian

Banned
Without knowing how the batteries are rated those amp hour figures are useless.
 

tcmtech

Banned
Most Helpful Member
Before they convince you that you cant do it or need some super battery with a " Super ultra multistage microprossesor monitored battery charger".
I would recommend a standard marine type deep cycle battery. They have good amp capacity and good deep discharge cappability. And a 12 volt 50 Ah rated battery should carry a 100 watt load for at least 4 - 5 hours or more before needing to be recharged.
 

Hero999

Banned
He's said it's a 9Ah battery so the answer is yes, but not for very long.

Assuming you can actually take 9Ah from the battery, it will only last 22½ minutes. In reality I expect it won't even last that long, about 10 miniutes sounds more reasonable.
 
Hello Original Poster,
How did the experiment go? What wattage of inverter did you use? Did your 9ah battery fire up the inverter? How long of tv use did you get?
 

Thunderchild

New Member
Before they convince you that you cant do it or need some super battery with a " Super ultra multistage microprossesor monitored battery charger".
I would recommend a standard marine type deep cycle battery. They have good amp capacity and good deep discharge cappability. And a 12 volt 50 Ah rated battery should carry a 100 watt load for at least 4 - 5 hours or more before needing to be recharged.
oh yes of course the miracle worker is here again with all his expertese in doing the impossible.

the figures are clear, he has a 60 W TV and a 12 V 9 Ah battery and an inverter that is probably 90 % efficient.

now what was it you were saying about anything being possible ?

I use a 12 V 60 Ah battery and can run my computers monitor (19" LCD @ 3 amps) and my moden and router for a couple of evenings when fully charged. my inverter is 90 % efficient so 1 in 10 amps are burnt up in the inverter or rather it as though I had a 54 Ah battery. of course add to that that the minimum draw of the inverter with no load is 150 mA.

your figures for a 50 Ah battery are very very optimistic.
 
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