Hey!
I have been discharging and recharging arround 500 18650’s and want to know howmuch KWh I spend doing so.
I used 3 nitecore D4 to charge and 6 of these to discharge.
Mostly I want to know howmuch KWh the recharging is gonna be, added up I charged 500.000mAh in total using 220v.
Any help would be awesome!
Most accurate way would be to measure the current draw of the charger X hours charging X 220V. That will include power used by the charger as well as that which gets stored. Oh, and divide by 1000 to get kWhrs.
Or just turn off everything but the charger and watch your meter for awhile.
500,000mAh (500Ah) in total multiplied by the average voltage during charge, which is around 3.9V or so, gives 1950Wh. Factoring in around 80% efficiency for the charging circuit gives 2438Wh. Just an estimate.
So 2.4 KWh?
If so that would mean it only cost be about 60 cents???
Edit: I pay arround 25 cents per KWh
Yep. From the numbers you gave it seems your cells only have about 1000mAh? Is that right?
A more useful and interesting question would be “how much does the electricity cost to charge up a single 2000mAh cell?”
Questions like these do NOT generally require and exact answer. An estimate will do.
Lets assume a total of 50% efficiency in the charging process. Also I will assume that electricity costs 20 cents per kWh.
A 2000mAh (2Ah) cell will hold 3.6V x 2A or 7.2Wh. (V x A = W)
So the cost to charge 1 cell, in dollars, would be (0.50 x 7.2 x .20)/1000
0.00072 dollars, or .072 cents
Seems like a pretty good deal, no?
Nah I did what I should have done from the start but never …. wanted to, but! finally did!
Been harvesting 18650’s for 2 years had about 600 of them and 4 weeks ago I wanted to know what they were really worth.
So I bought 6 of those discharge mAh meter thingies and started ( yes took me 4 weeks )
All the cells below 500mAh I threw out which were arround 120 of them :cry:
The others ranged from 500mAh upto 2200mAh, all added up they came to 500.000mAh’s
Seems like a super deal!! I’m really happy about it!
Also I can recharge my Idol 4 90 times with those 18650’s all for 60 cents.
Just incase the power goes out like it does ever more often in the Netherlands lately.
In Amsterdam 2 days ago for 4 hours or so, 3 people died….
The 18650’s were free…. salvaged
Not sure if I’d hang onto cells so far under capacity. 500 mAhrs seems pretty worn out. If you have that many I’d suggest bumping to 1000mAhr and recycle the rest.
While I was typing my estimate, EasyB posted his.
According to his assumptions and the OP’s guess as to his cost of electricity, I would cost him 60 cents to charge those 500 cells.
According to my assumptions and guess as to his cost for electricity, I came up with 0.072 cents per cell. Multiply by 500 and it comes to 36 cents.
Now here is the most important point I want to make
Which answer is right?
For this question, I don’t think it really matters. What does matter, is that it doesn’t cost very much. In fact so little, that it is almost free. It is something that one needn’t even be concerned with.
What ever the correct answer is, in this case it is enough to know that it isn’t $100, even $10.
Even a very crude estimate can be VERY useful!
I don’t use them, I have new 3400 Panasonics and 30Q samsung’s for daily use.
The salvaged cells are there for just in case the power goes * poof * This way I can stay entertained for weeks :money_mouth_face:
I also checked which cells got hot when charging and I tossed them out also, for your information all the cells that got hot were Sanyo’s.
To be honest while I can charge my phone with 500 mAh cells ( it would take 10 of them 
) I want to use them for lighting.
With these and these tested them and on the highest setting it can run 1 hour per 100 mAh.
Glued magnets on the backs of the powerbanks so I can stick them where I want, the light is warm white so bloody cosy too.
Small electronics use negligible power!
I drive/charge my car everyday and I only pay a few dollars a month in electricity to charge my car, and it’s battery is over 15kWh (!!!).