electricity usage question

[#101]

How much would it cost per month to run a 12 volt battery charger with a 2 amp input and a 2/10 amp output? Its always ran on 2 for the output.

[Tommy Warren]

pocket change...just get a battery tender

[wilkin250r]

Energy is sold in units of kilowatts per hour. 2 amps times 12 volts is 24 watts, which is 0.024 kilowatts. The average price around the Unites States is about 12 cents, so you would be spending 12*0.024 = 0.288 cents per hour. (that's a little less than one third of one cent per hour) or $0.00288 dollars per hour.

24hrs per day, 365 days per year is 8760 hours, multiplied by $0.00288 is $25.23 dollars per year. Go ahead and call it a hair over two dollars a month.

Now, this gives you a rough guess, but it can be really inaccurate. For example, energy prices in New England seem to be significantly higher, (some as high as 19 cents) while the Midwest seems to be lower (9 cents), so that could possibly push you up to $40 per year, or $3.33 per month. Plus the energy conversion from the 120V wall outlet to your 12V battery isn't 100% efficient, so add 20% for the energy conversion, which could push your bill up to $48 per year, or $4 per month.

But more significant is that if you're leaving it on all the time, it means you have an automatic charger, which also means you're not pushing the full 2 amps all the time. (if you DON'T have an automatic charger, you better not be leaving it on all the time, you'll overcharge your battery and ruin it). Your charger will push the full 2 amps for a little while, then back off into monitor mode. When the voltage drops a little, the battery charger will kick back on to the 2 amp charge, and then back off into monitor mode again. Because you're not pushing the full 2 amps all the time, you're not pulling that full amount from the wall outlet. If I was going to take a guess, I would bet you're pushing an average of about $1.50 a month in electricity.

[ben300]

Originally posted by wilkin250r
Energy is sold in units of kilowatts per hour. 2 amps times 12 volts is 24 watts, which is 0.024 kilowatts. The average price around the Unites States is about 12 cents, so you would be spending 12*0.024 = 0.288 cents per hour. (that's a little less than one third of one cent per hour) or $0.00288 dollars per hour.

24hrs per day, 365 days per year is 8760 hours, multiplied by $0.00288 is $25.23 dollars per year. Go ahead and call it a hair over two dollars a month.

Now, this gives you a rough guess, but it can be really inaccurate. For example, energy prices in New England seem to be significantly higher, (some as high as 19 cents) while the Midwest seems to be lower (9 cents), so that could possibly push you up to $40 per year, or $3.33 per month. Plus the energy conversion from the 120V wall outlet to your 12V battery isn't 100% efficient, so add 20% for the energy conversion, which could push your bill up to $48 per year, or $4 per month.

But more significant is that if you're leaving it on all the time, it means you have an automatic charger, which also means you're not pushing the full 2 amps all the time. (if you DON'T have an automatic charger, you better not be leaving it on all the time, you'll overcharge your battery and ruin it). Your charger will push the full 2 amps for a little while, then back off into monitor mode. When the voltage drops a little, the battery charger will kick back on to the 2 amp charge, and then back off into monitor mode again. Because you're not pushing the full 2 amps all the time, you're not pulling that full amount from the wall outlet. If I was going to take a guess, I would bet you're pushing an average of about $1.50 a month in electricity.

dont forget that power prices change daily depending on the previous days forecast demand, how much power is being produced, how much power is being put into the grid, of peak/on peak hours, and other variables...when i worked as a process engineer at a power plant near pittsburgh, i saw electricity as low as 8 cents per kwh and as high as 90 cents per kwh on a 95 degree wednesday after noon..

but you are right...it wont cost that much and a battery tender would probably work better

[#101]

Awesome thanks guys! I used the electricity usage calculator online but it didnt seem right because the price was so low.