how to calculate electricity costs for charging batteries

[ty cohen]

How do you calculate the cost of electricity for charging batteries.

Let's assume the cost of electricity is 6 cents a kilowatt hour and I am using 48v 15 ah batteries and it takes 6 hours to charge.

I know this should be an easy calculation, but I have a brain freeze right now.

 

[pwbset]

Let's assume the cost of electricity is 6 cents a kilowatt hour and I am using 48v 15 ah batteries

I would like to know very precisely also... Here's my math for you, which is likely off because of charger resistance/efficiencies etc. etc...

48v*15ah=720wh
720*.006=4.32

4.32 cents to charge your batts...

 

[swade]

There are energy meters like this one:
http://www.amazon.com/Energy-Meter-LCD-Display-EM100/dp/B000RKVK52

It'll tell you precisely what amount of electricity you are consuming.

 

[Anonymous]

.

 

[dogman dan]

Anybody got a watts up? We pretty much all have the same 2 amp chargers. Let us know how many watthours they use in an hour of run time, and how much they draw if left plugged in after the charge finishes. I'm figuring about a nickel to fully charge a 20ah ping at 11.5 cents a killowatt, but I could be costing a dime for all I know. That would be horrible, instead of paying 5 bucks a year to charge my bike, i could be paying 10. HORRORS!

 

[deardancer3]

How do you calculate the cost of electricity for charging batteries.

Let's assume the cost of electricity is 6 cents a kilowatt hour and I am using 48v 15 ah batteries and it takes 6 hours to charge.

I know this should be an easy calculation, but I have a brain freeze right now.

Using a P3 AC watthour meter, one could just start the charge cycle after a ride and record the AC watt hours when your are finished charging, then multiply by cost per watthour, usually between 5 to 10 cents per thousand watt hours-KWH.

I believe this is the most accurate way to measure the watt hours and the cost, and would be accurate regardless of chemistry or charger brand, efficency losses, etc.

Chargers do have different charge rates, chemistries, charge termination styles etc.

I did this once for a Soneil 24v SLA 2 amp charger, back when electricity was cheaper and it came down to about 1 cent per hour. We were wanting Retailers to know how much it would cost them to let us charge while we shopped there.

For all the instrumentation we all have- DVM's, thermometers, Cycle Analystgs, etc, I think a P3 is very good.

Isnt there a thread about a guy researching why his utility bill went up and was using a P3 to figure it out.

I remember telling the Panera manager "about the same as a laptop", which he did not charge for, and proably less than just one of the 142 halogen bulbs he had on constantly. Got into a very interesting discussion about utility rates, cost of changing burnt out light bulbs, etc.


----- short break--

Darn it; you made me realize I dont know wher my P3 is at. Darn, I was going to have real time data, Fair and balanced, "Breaking News" even.

The P3 is on sale at amazon.com... see seperate posting on retail for sale links

d

 

[ty cohen]

well, I don't think I am going to pay 25 bucks for a kill a watt p3 meter just to find out i am paying 5 cents for a charge. I just wanted to know if it was in the order of magnitude of cents per charge. 5 cents, 10 cents, I doesnt really matter, as long as i get the general idea of how much it costs per charge. (especially when I am going to be paying 500+ bucks for the battery !!)

BUT...... if someone does have one... you could all do us a favor and find out 8)

 

[deardancer3]

well, I don't think I am going to pay 25 bucks for a kill a watt p3 meter just to find out i am paying 5 cents for a charge. I just wanted to know if it was in the order of magnitude of cents per charge. 5 cents, 10 cents, I doesnt really matter, as long as i get the general idea of how much it costs per charge. (especially when I am going to be paying 500+ bucks for the battery !!)

BUT...... if someone does have one... you could all do us a favor and find out 8)

Oh the P3 will pay for itself as you take a look at what your appliances are taking. Many people here are greatful to a P3 for helping get refigerator or computer or air conditioner energy costs under control, self included. Home electric bill now wonderfully low.

This group may specialize on transportation stuff , but its hard to turn off the brain on anther big pocket book issue , wasted home energy.

Best

d

 

[ty cohen]

well, I don't think I am going to pay 25 bucks for a kill a watt p3 meter just to find out i am paying 5 cents for a charge. I just wanted to know if it was in the order of magnitude of cents per charge. 5 cents, 10 cents, I doesnt really matter, as long as i get the general idea of how much it costs per charge. (especially when I am going to be paying 500+ bucks for the battery !!)

BUT...... if someone does have one... you could all do us a favor and find out 8)

Oh the P3 will pay for itself as you take a look at what your appliances are taking. Many people here are greatful to a P3 for helping get refigerator or computer or air conditioner energy costs under control, self included. Home electric bill now wonderfully low.

This group may specialize on transportation stuff , but its hard to turn off the brain on anther big pocket book issue , wasted home energy.

Best

d

yeah, I thought of that too, but my appliances are the least draining load I have. I heat with electricity, so during the winter time, I can be using 70+ kilowatt hours of electricity a day. My electric bill for the winter is about $300 a month.

I try to heat as much with firewood as possible, but still, I use up a heck of a lot of electricity.

 

[nasukaren]

I have a Watt's up, but all I have for right now are little 7Ah SLAs from my Razor toy bikes.

I also have a Killawatt which is a much more accurate way of testing how many 120 VAC watts are being used:

If you're willing to extrapolate from a 24VDC 7Ah SLA to your own packs, I'm willing to give it a go.

Karen

 

[dogman dan]

Yes please, Karen. Just tell us what kind of charger you have, like 36v 2 amp, or whatever, and how many watthours used in one hour, and also how many watthours per hour when the green light is on after the charge is finished. I'm dying to know if that is the same number.

I can relate on the electric heat I have it too, but really, if you are using at least 75 bucks in the spring or fall, then 225 a month for heat is not so bad, unless you live in a warm place. I do, and propane users are spending a lot more than 225. I am blessed with a south facing house with a big window but this summer I'm scoring some sliding glass door panels to freebie a trombe wall. Since my rate is the same whether it comes out of the furnace or the wall plug, I also save some by using little oil radiators to heat rooms individually.

 

[johnrobholmes]

About 4 cents is a good estimate, but the only way to really know is to get a wattmeter on the charger. Battery side works, but the charger will have inefficiencies. You could figure out the inefficiency by comparing wall drain vs watts into the battery.

 

[Dalecv]

Turn off all electric consuming items in your house and verify this by checking your electric meter. (use electric breaker panel and leave one plug circuit on) When the meter is no longer moving note the readings. Plug in charger and charge your battery. When the battery is charged check the meter and the change is what you consumed. Simple and cheap as long as you don't ruin anything during the process.

 

[dallasfoto]

Turn off all electric consuming items in your house and verify this by checking your electric meter. (use electric breaker panel and leave one plug circuit on) When the meter is no longer moving note the readings. Plug in charger and charge your battery. When the battery is charged check the meter and the change is what you consumed. Simple and cheap as long as you don't ruin anything during the process.

I thought of doing just that....but in Dallas in July the median temperature is 103 this week and I don't wish to roast the cats and the dog. :lol:

 

[dogman dan]

Yeah, even for one hour, that would be harsh for me too. Especially the no tv or computer! maybe while I'm out of the house in the subaru. In any case, we're talking about finding the difference between a nickel or a dime. The cost of ebikes is in the battery purchase, after that, big woo. But still, I am the curious type.

 

[sandmanhi]

You are paying less than 10 cents a kw? Feel lucky, as back in 2006 our rates were about 23 cents and I know our rates have gone up drastically since the price of oil shot up as this island is pretty much reliant for something like 95% of power from oil. Oh, they have the garbage to energy plant too and a small bit of solar, but mostly just oil. Talking about electric bills, I have worked so hard to keep my usage down that I am using a third of the electricity that I used in 2006, yet my bill is almost double.

 

[nomad85]

If you charge at work/school it's free

 

[dallasfoto]

If you charge at work/school it's free

Yes I would be allowed to charge every day at school. But I would feel funny about it ethically. Plus my vendor at home is Green Mountain so, although i pay 12 cents per KWH, I do know that it is green because GM feeds the grid with wind and solar.

I just want bragging rights!!!!! Like 1250 miles per gallon energy equivalence!!!! I am getting the middle school science teacher to do the math on this with her kids this term.

 

[nasukaren]

I was going to calculate how much it costed using my Doc Wattson + Wattameter, but I managed to break my Doc Wattson within a week of buying it. Without it, I won't know how much juice is going into the batteries.....

So, I know I promised to post some results, but it'll take some time before my (drum roll).... cycle analyst .... arrives. I'll be sure to put a 1/2" lexan barrier around it so I don't bust it!

Karen