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How much should you pay for batteries ?
Finding battery packs is totally dependent on where you are located as I have found.  And of course buying in large quantities should reduce the price.  But as I have indicated in previous posts I have found that within 100 miles of two locations the price can vary a lot.  For some it makes sense to buy from someone that has gone to effort, made the investment of $$ and time to acquire them for resale.  As long as it makes sense economically ....which includes what you value your time at, it should be a win win for both parties.
i mean considering the cost of electricity in germany i could buy new and still be borderline
and i´d like to think that Im not doing solar/powerwall stuff just for cost. I think there is something very appealing to being off grid even if its only partial.
In my area shopkeepers always tell Me that "unfortunately, another Guy was here just the other Day, so sorry, no battery packs". Or, they look at You as if You were a Nut, and should be sectioned.
Local Recycling stations states that Lithium Cells are dangerous, and all laptop batteries must be individually wrapped in plastic before being stored in sealed containers Sad .
To top it off, the Municipality has ruled that scavenging is prohibited and will be reported as theft.
Just a couple of Months ago I spotted a cage with at least 40 discarded laptops, all with batteries still in. Regretably there was no way of getting the battery packs out, the cage was 3 levels up. After a Month or two out in the Rain, I figure all is destroyed.

I am now left with buying cells on the net. However, prices has risen to ridiculously high levels.

More than 1€ ea. for cells with unknown history. Are You Lucky, cells can be next to new, due to controller failure, but they can also be battered, worn out cells with countless cycles under their belt.

Some sellers even want money for laptop/e-bike cells with only 0 - 500 mAh left ...

Then there is new, branded cells, but they are out of reach for a pensioner.

(04-20-2018, 11:48 AM)completelycharged Wrote: The economics for a powerwall with $0.06/kWh electricity cost would only make sense if it is to cover blackouts/loss of power and you value the lost power highly.

This is SPOT ON !

Where I live we are currently experiencing 8 hours of load shedding per day (up from 4 hours per day last month) and it is expected to hit 8 hours twice per day in the next month and possibly only 4 hours of supply per day by years end. This is due to drought as most energy here is hydro produced. Can't produce much hydro without water......

So if you value your lifestyle and have gotten used to having lights on at night, or your fridge keeping your food good etc.....much less the nice things like your computer powered up, your TV and/or Hifi running.....then the cost of the batteries and PV is largely irrelevant (within reason, but then again PV prices have crashed compared to just 5 or 6 years ago).

A good way to think of it is like your car. How much cheaper is it to use public transport? But a lot of us use our own private cars anyway. Why ? Because it's much nicer and far more convenient. Power is the same thing. You can use the public grid - it is much cheaper. But your own private power supply is much nicer and far more convenient but it costs......just like your car.
Ibiza likes this post
Having a home ess, is not really cost effective yet.
If it was, there would be a lot of extra "rules".
Its pretty cost efficient in a ev yes, if you transfer the sun into your tank.
But try in the Netherlands to buy a ev without or with a worn out battery...
You must have a ess in your home anyway to fill up your car.

Even if you buy a new ev, they really want you to have a seperate connection, cous they won't sell you a regular 230 or 380v charger.

To replay at bicycle dealers: Sounds very familiar and yes even one was aggressive, some dealer in Diemen, the Netherlands.
I would like to add: They know exactly what to "give" or sell you, if they give or sell, just saying.
I have been to a lot of "dealers", you can keep them, the same applies for powertool bats and laptop bats.

I pay around 71 cent for a cell (minimum 2600mah 90%SoH), looking back i think its doable.
Without price increase in power, i pay ~130 euro a month for my electricity.
That would be ~1500 euro a year, 7500 euro for the next 5 years.
I think, in that amount of money, it can be done, if we look at the lifespan of solar panel and our much beloved and much hated cells.

For us: the diy ers, we have one big advantage, we grow with the new technology, so get on board and stay.
We payed a lot of learning money and time. (had fun?)
Technology is not standing still, but we have already paid for our installation, testing stuff, unnecessary purchase and such.
There will be always enterprising hobbyist, people that bend the rules, and the diy community.
In five years from now, probably my first 30-50kw needs replacement, i don't think i will buy 18650, i think lto or lifepo will be much more advanced, for sure cheaper.
In the meantime i will keep on learning and adding.

But oke, my salary is going up and the prices of 18650's also, i have to only replace my cell packs, but now i know how and what.
It will probably costs 3 - 5000e for the next five years(five years from now), how much will a kwh cost in about five years.
Maybe my point of view is very wrong, but this is how i look at it now.

I'm nearing 7,000 18650 cells now over the last 2 years. I mostly purchase from Alarm Hookup and Power2Spare rather than try to do 'raw' laptop cells or 'raw' sources and have been able to avg 90-95% of original specs in the 5-8yr old age range with capacities from 1800mah (low) to 3100mah (high). My average to date is $1.57/cell for a 53kwh battery bank.
At offgid,
How long do you have your pack running.
At 50% DoD?
at 100% DoD?
You had to start somewhere, or did you run from the first start 50%?

Thanks in advance
(09-04-2019, 05:12 AM)100kwh-hunter Wrote: At offgid,
How long do you have your pack running.
At 50% DoD?
at 100% DoD?
You had to start somewhere, or did you run from the first start 50%?

Thanks in advance

I have 3 parallel 'batteries' online and a 4th in progress.   Each battery is 14s120p (aprox 1680 cells) / 260ah@48v.   Total of 780ah@48v / 40kwh.  

1st Battery -  15 months, 403 charge/discharge cycles, avg 41% DOD.     First 103 cycles was avg 56% DOD.  
2nd + 3rd Battery -  8 months,  225 charge/discharge cycles, avg 33% DOD

Started with 1st battery with no concept of DOD but have gotten focused on battery life / consumption patterns with eye toward the lowest DOD that is 'easy' to achieve with the setup.
100kwh-hunter and completelycharged like this post
@ OffGridInTheCity,

How are you compiling all these stats? What sort of systems/computer's/single board computers etc are you running and what software?

You have very detailed information on your setup and its very very interesting.
(09-04-2019, 10:11 AM)Jack Daniels Wrote: @ OffGridInTheCity,

How are you compiling all these stats? What sort of systems/computer's/single board computers etc are you running and what software?

You have very detailed information on your setup and its very very interesting.

Data Collection Level:
1) Query the Midnite Classic controllers and store in a database.    (Midnite temp & shunt)
2) Parse the Batrium auto-dump snapshot files and store in a database.    (Batrium shunt) *I admire @Daromer with live Batrium queries - but its beyond my abilities at the moment
3) Record Inverter output - amps delivered to distribution subpanel          (meters and dataloggers)

This lets me pull and display live/raw info like this - oriented 6am (beginning of a day/cycle) to 5:59am next day:

Top is live info (every 10secs)
Middle is Batrium measured pack info - lowest, difference between hi/low, and highest packs.
Bottom is things like Inverter on(voltage) and off(voltage), kwh for last cycle, peek charge voltage for the day, ahs/voltage after PV input stops, ....

This let's me build a spreadsheet with lots of 'junk' to try to make sense of things:

Things like column E "L Meter" and F "R Meter" are the kwh consumed on each 120v leg of the 240v inverter output.    Column X "DOD %" is based on peak charge voltage for the day vs the inverter off voltage.     Column AF is hours of Inverter ON with AG as the average power consumption by the house during those hours. 

The goal is to build overall queries to produce the spreadsheet type output/recaps once I figure out all the things I want to know, but for now, I type in the values to the spreadsheet from the raw data as I try to make sense of things.

One goal that has emerged is that I want to minimize DOD % to prolong battery life... and from the data I can think about future such as whole house heat pump and see how many more panels, how much more battery etc - to balance the whole system to low DOD in the 'normal case' - e.g. lowering my power bill as much as I can but using grid to make up shortfall in power needs.
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