Power storage in old batteries

[kristopher]

Power storage in old batteries

A group of Swiss and German firms have taken a look at an unusual solution in order to make power storage more affordable – they simply reuse rechargeable batteries at the end of their service lives.

German power provider Wemag of Schwerin plans to roll out a power storage system called Reevolt by the end of the year. Each unit will be able to store up to five kilowatt-hours of electricity, and the firm will be marketing the product to German homeowners with solar arrays.

The storage units contain – new or used – lithium-manganese batteries made by Panasonic for use in Swiss bike firm BikeTec’s electric bicycles. Apparently, a large number of these batteries have been recovered for recycling, according to the power provider's press release (in German). The bike maker rents a fleet of electric bicycles, and the batteries are only used for two years.

At the end of their service lives, the batteries no longer provide the range that bike renters expect, but the batteries themselves still have around 80 percent of their capacity. A company spokesperson says that the storage units come with a guaranteed minimum capacity, and consumers have the option of purchasing new batteries if they prefer. If the batteries used in the storage unit drop below the guaranteed capacity, a new round of used batteries are provided.

The goal, of course, is to make power storage less expensive...

http://www.renewablesinternational.net/power-storage-in-old-batteries/150/510/71520/

[oldhippie]

1. It sounds like a good idea .....

.... but having built several similar size battery packs from used lead-acid batteries, I know how fast they fail due to mis-matched cells and unbalanced strings killing some cells as they charge. That was with flooded lead acid batteries. I haven't ever tried lithium-manganese batteries, so not sure if they have similar problems.

If they do, the company will probably be replacing a lot of cells under their guarantee, so it will be interesting to see what the cost/price structure works out to be for them to be profitable.

Overall, it seems a good idea to squeeze some more useful life out of the batteries in this manner. It would seem to be overall more efficient to use more of their capacity before disposal. I hope we get to see how it works out.

[Fumesucker]

2. I'm using old 18650 cells salvaged from dead laptop batteries for my electric bike

I have about 500 Wh at 50V right now and am headed for about 1 or 1.5 KWh at 50V when I get more cells to add. I have about 2,000 miles on my pack at the moment and it's still working about as well as it did when I put it together. I don't have a BMS on the pack but I balance charge on about every tenth charge cycle and so far haven't had to replace any defective cells.

Those batteries they are using probably have a BMS that will help keep the problems with mismatched cells and unbalanced strings to a minimum.

Used Prius packs are available from junkyards at fairly reasonable prices, that's probably the way I'd go if I was going to shade tree engineer a pack for home use these days. The Prius packs have been quite reliable and there's a bigger supply from wrecked cars than is needed to replace bad packs.

[oldhippie]

3. When you say "balance charge" the pack ....

... is that a controlled overcharge like an "equalization" charge on a flooded lead-acid bank?

That's pretty cool, being able to repurpose dead laptop batteries. Do you have some selection process to determine which, if any, cells are "too dead?" I know when I finally get rid of one of my laptop batteries, it's usually pretty dead, and won't hold a charge for even a few minutes. You must have a way of sorting those guys out.

I have to admit I don't have a lot of hands-on experience with lithium batteries. The ones we used a decade ago in the military scared me with their safety issues. (Try to take one on a submarine and see what they say!) I'll have to do some study on their recycle process.

Do you have any pics of your electric bike? Have you done a thread on it at all? It sounds pretty interesting.

[Fumesucker]

4. Each individual parallel cell group gets charged to 4.1 ~ 4.2 v during a balance charge

In my case I have groups of 5 cells in parallel and 12 of those groups in series so it's a total of around 50 V fully charged.

The charger has a special port for individual measurement/charging/discharging leads for each 4.2v parallel group. Lithium cells don't really take an overcharge, they end up getting damaged if you try and it's also a good way to catch them on fire.

Bulk charging which I do about 80-90% of the time just charges everything in series, if my cells were better matched I could go even longer without balance charging. Balance charging tends to run for several times as long as a bulk charge while the individual parallel groups are brought slowly to the same voltage.

Here's my bike with the previous battery which I got with the bike I stripped for the electric drive system, my current battery is considerably smaller and considerably more powerful but I don't have any pics up online right now.

http://www.democraticunderground.com/1207230

Here's the thread I used to get the info to do my own pack, this is pretty lengthy (long enough it has an index at the beginning) and gets fairly technical with a considerable amount of forum friction and argumentation back and forth over technical points, I found it all illuminating and have read most of it at least twice and some of it more often than that.

http://endless-sphere.com/forums/viewtopic.php?f=14&t=26383

[oldhippie]

5. That's really interesting, thanks!

... with a considerable amount of forum friction and argumentation back and forth over technical points,...

Haha! That's been pretty much the case in every battery group and forum I have been involved with in 40 years! Trying to get battery guys to agree on anything is like herding cats. I still see endless arguments about whether NiCad and NiMH batteries have memory or not.

[lumberjack_jeff]

7. This winter I think I am going to do this.

Do you have any photos of your build? How did you collect the laptop batteries?

[Fumesucker]

9. Computer repair shops tend to stack up dead laptop battteries

You can also find them on ebay for bulk purchase, all it takes is one pair of the six to eight cells in a battery go bad and the whole thing becomes useless for the laptop even though it might still have four or six cells still good. Recyclers are another source for old laptop packs.

Figure long term about a third to a half of cells you dig out of old laptop packs will be good for something.

[lumberjack_jeff]

10. I'd love to know more about how you configured your bike pack...

... and how you charge them.

My goal is 48v 20ah. There's a seller on Ebay who is selling 5ah 18650 cells @ 4 for $8.50. By my math a 12s 4p pack is about $100 and about 5 lbs.

1) is (4) 12s bricks the right way to configure this pack?
2) are pouch cells a better idea? Looking at Hobby king site suggests that the price would be quite a lot higher.
3) what should I do re: bms and charging?

[Fumesucker]

12. I'd be leery of those cells

Genuine Panasonic NCR18650B that are actually good for 3400 mah are going for $10 each or a bit less, I've consistently heard that anything with "fire" in the name is not trustworthy as to specs but actually rebranded factory rejects of pretty much anything. I'm told the equipment to make 18650 cells is nearly turnkey stuff that doesn't cost a lot in finance terms and there are a lot of fly by night operations evidently.

I wouldn't count on more than somewhere around 2000 mah per cell from 18650 long term no matter what their rating, if you were to treat those Panasonic cells like they were only 2000 mah they would last much longer.

The HobbyKing stuff comes with a 10% failure rate I understand, buy 10% more than you actually need and you should have enough after infant mortality, the specs are fairly optimistic and I wouldn't be comfortable storing/charging that many in my house, they are similar to what burned up in the Dreamliner in the recent past except much lower quality. Enough to power an RC plane is one thing, an electric bike is another I think. Others have a different opinion on them but personally I chose to avoid them.

My charger is one made for RC planes which tend to use a much higher output type of cell but it has enough flexibility to charge laptop cells too if you wire it and program it correctly.

Laptop cells can't be discharged very quickly so you need a lot of them in parallel if you need high amps, two hours discharge is about as quick as they are really comfortable with. Size your pack so that your average amp draw will discharge the pack in two hours or more and you should be within the capability of laptop cells.

So for your 40 ah pack you'd discharge it at about 20 amps for two hours (if it was actually a measured 40 ah).

Mine is 12s 5p at the moment and I have a medium box more decent cells to add that will probably bring me to 12s 7p.

What I want is enough pack to only use half the available energy from about the 3/4 charge point to the 1/4 charge point for my longest trip which is about an hour and a half out and back. As it is I use from 1/2 to 7/8 charge most times when I ride now so doubling my pack should get me the range I want.

[lumberjack_jeff]

20. Okay, I found a decent local source of "dead" laptop batteries

Last edited Fri Dec 20, 2013, 11:07 AM - Edit history (1)

$1 each.

That's roughly $1/lb or $0.10 - $0.15 per cell.

I'm going to buy 40 batteries, hoping to obtain 150-ish good cells. I will then dig into that endless sphere thread with a purpose. My goal is a 1200 wh pack (about 40 miles)

I have lots of questions about how to configure and assemble the pack and how to charge it. What charger do you use? Do you think it is better to balance charge each cell? Do you solder the tabs on the cells or spot weld?

Thanks for your help. Everything I read confirms your suspicions about the cheap cells.

[Fumesucker]

21. Good find there

The actual value of the pack you make isn't all that high but the understanding of the concepts is the real payoff.

There's four things you need to know about a cell in order to use it in an EV successfully, leak down rate, internal resistance, current capacity and voltage profile.

Leak down rate is easy, charge all your cells to a consistent voltage, say 4.000V, and let them sit for a while, the ones that lose the minimum voltage over time are easiest to deal with, hopefully very near zero loss. 24 hours would be a minimum for this test, longer is better. If you include cells that leak down in your pack you will have to re balance more frequently.

My charger came from a yard sale, it's an iMax B8. I also have a generic RC wattmeter and a CellLog 8S. I would go with a bit more sophisticated charger if I were doing it over although the unit's not bad.

I solder the cells, spot welders suitable for cells are really expensive to buy and not particularly cheap to kludge even.

[lumberjack_jeff]

22. A $40 education? I can afford that.

I ordered 3 cheap 18650 chargers from DX to help sort the good from bad cells. I'm guessing that there are 200-ish cells in the box, so that process will take awhile.

If I understand your post upthread (and on the E-S thread you linked) "balance charging" only balances the paralleled strings, so with a 6s 12p pack, a 6s charger will balance charge each 12p string to the cutoff value (say 4.15v) Is that adequate? Would one weak cell compromise the energy capacity of the entire parallel string? I had always envisioned that balancing also keeps the cells within a parallel string in synch, but I guess the parallel wiring kind of does that automatically.

I read elsewhere that the goal when using these cells is to create parallel strings that match one another in energy capacity, so where parallel string 1 might have 11 cells, parallel string 2 might have 13. True?

I'm thinking that a reasonable goal is (2) 6s 12p (24v, 25ah) packs. I'd like to convert my wife's bike too, and 600 wh seems like an adequate range for casual recreational use for the two of us.

Most of the time, I'll be riding by myself. In those cases, I'd like to install both packs on my bike in series. Do controllers care what voltage (within an acceptable range) is input? Can I run 24v to a "48v" controller?

[Fumesucker]

23. I'm using a ten cell (36V) controller on twelve cells (44V),

Doubling the voltage isn't really going to be practical on the average controller, a couple of extra cells is one thing, going from six to twelve is another.

Plus if you are using the same motor at double the voltage the gearing has to change considerably since the motor will draw way too much current otherwise, all this stuff is a rather delicate balance to get decent performance and range from minimal equipment, change any parameter beyond a fairly narrow band and you end up having to change other parameters to make it all work together.

Yeah, I think the "capacity bank" is a good idea, don't worry so much about exactly how many parallel cells, consider instead how much total capacity they have. The closer you have all the banks matching in capacity the closer they will track each other while charging and discharging and the less balancing you'll need to do.

I would say 10s 8p would be a better idea for around that number of cells, at 24V you start drawing a lot of current to make much power and things tend to get hot. So much depends on the motor, wheel size, weight, terrain, prevailing winds, tire type and inflation, phase of the moon.

What I would like now I've ridden for a while is a motor that is totally silent and not at all obtrusive to the ride, there's two systems just coming on the market that would probably make that happen or get very close, the Falco hub motor and Bafang crank drive.

[lumberjack_jeff]

24. That makes sense.

I've been looking at 48v systems, but now I'm thinking that a 36v system would work well, and I have easy access to enough cells to convert two bikes.

How much range do you get from your 36v setup?

[Fumesucker]

25. I've actually been twenty five miles and had some but not a lot of battery left at the end

Each cell holds roughly around seven watt hours or maybe a bit more, at fifteen watt hours per mile that means about a half mile of range per cell, so a sixty cell 12s 5p pack with some pedaling should carry you around thirty miles at around eighteen mph which is not far off what I'm seeing in reality.

[lumberjack_jeff]

26. Here's my version 1.0

Last edited Thu May 22, 2014, 06:51 PM - Edit history (2)

I get 20-ish MPH on 12s 12p cells. Total weight: 65 lbs.

I built the battery pack into the frame triangle because I wanted to preserve use of the luggage rack (not shown).

[kristopher]

27. I love it.

Hope the battery management system doesn't let you down; it could give real meaning to the term 'being in the hot seat'.

But seriously; that is a both a labor of love and a work of art.

[lumberjack_jeff]

28. My BMS is: watch the voltages carefully.

There are enough WH (about 1500) in the pack that I shouldn't get caught with "an empty tank".

And 18650 are pretty tolerant little devices.

I do have a couple of low voltage alarms on order though.

[Fumesucker]

29. That's very nice, congratulations I'm impressed

What did you make your battery box out of?

That looks like a Nine Continents motor or a clone thereof, I just got one like that last week and I'm planning my next build around it. I have someone who wants to buy my current ebike but I can't let it go until I have another one finished.

[lumberjack_jeff]

30. Thanks! I'm told it's a 9C clone

http://www.ebay.com/itm/370934929537

the battery box is made of scraps of 6mm marine ply with 9mm framing.

Motor, controller, controls, batteries and charger cost $330.

I suspect that the controller is not providing the advertised 20a to the motor, but until I get a cycle analyst I won't really be able to do much diagnosis.

I learned a lot. Thanks for your advice and in particular for that endless sphere thread.

My wife now calls me Pee-Wee.

La-la-la.

[lumberjack_jeff]

31. Sorry to resurrect an old thread, but I just converted my wife's bike

It's pretty awesome. The motor kit came from xiongda - a two speed front wheel geared hubmotor. It has far more hillclimbing torque than my motor and pulls only 250w peak while doing so.

https://www.electricbike.com/2-speed-e-matic-xiongda/

The battery pack in my bike is 13p 13s, which is a lot of cells (and a lot of weight) to enable the 20a (1000w) peak loads - and cell voltages drop quite low when I hit the throttle.

Her bike on the other hand has 10p 13s, which reduces the weight about 5 lbs. The controller is set up pedelec, so no throttle. I expect she will have about the same 40 mile range as my bike, but much lighter and better hill climbing torque.



I love this motor. I wouldn't consider a direct drive hubmotor now unless top speed was my only concern.

[Fumesucker]

32. I looked hard at the Xiongda a year or so ago, they just didn't seem to have the reliability then

After a number of emails back and forth I couldn't get a straight answer from them as to how many rpm each motor turned at what voltages. I already had a bike that would go 18-19 mph and wasn't about to spend hundreds and get another one that would only go 19-20 mph. My riding is almost all on 45+ mph speed limit two lane roads and the faster I go the lower the closing speed of traffic coming from my rear and the fewer times I get passed, anything much under 20 mph and I spend too much time and energy looking at the rear view mirror.

From reading the long long thread about the Xiongda I think it might now fill my requirements, I'm glad it worked out for you.

I'm still using the 12s 12p pack I made up over a year ago, it sat through the entire winter at outside ambient temps and didn't seem to lose anything at all capacity or voltage wise.

[lumberjack_jeff]

33. In fairness, I can't attest to long term reliability at all. I have only a couple of miles on it.

For my wife's riding, the lower top speed will probably be preferred... if the tradeoff is better torque and a lighter battery pack.

[eridani]

14. I'm impressed as hell

However, this subthread is useless without pictures!

[Fumesucker]

18. The battery doesn't look like much but it can give me about 30 miles of light to moderate assist

Here it is without the cardboard and duct tape wrapper. Each vertical row of cells is a parallel bank of five, there are twelve banks in series, the skinny black and red wires on the multipin plugs are for monitoring each bank of parallel cells separately, the two gray wires at upper left and right are the main power leads and the short, thick black wire in the middle jumps 2 24V sub packs to make the 48V.

Still thinking about and trying different things to find the best way to go about this, I've managed to find quite a few ways not to do it.

[eridani]

19. Very inventive. You should write that up in detail with illustrations

Cooking and Baking sometimes has recipe posts with pictures of the process step by step, and they are very enjoyable. You could probably publish in Mother Earth Journal and the like.

[progressoid]

6. Hasn't this idea been around for a while?

I remember reading about a guy doing this on his own a couple decades ago.

[oldhippie]

8. Anybody have an update on this story?

German power provider Wemag of Schwerin plans to roll out a power storage system called Reevolt by the end of the year

.

That would seem to be about now. Did they do anything, or was it just wishful thinking?

[Iterate]

11. Richtfest für Schweriner Batteriepark (Topping out ceremony)

Richtfest für Schweriner Batteriepark
11.12.2013
Errichtung läuft nach Plan - Inbetriebnahme am 17.09.2014
http://www.wemag.com/ueber_die_wemag/presse/pressemeldungen/2013/12_11_Richtfest_Batteriespeicher.html

I'm assuming this is the same project, but another, much earlier, article mentioned an April 2014 opening. This press release says the construction is topped out, and will be online in Sept. 2014.

from pv mag:
Commercial 5 MW battery park to be developed in Germany

Berlin startup Younicos and renewable power utility company Wemag AG are setting up a 5 MW lithium-ion battery park in West Mecklenburg, Germany. Samsung SDI will be supplying the batteries with a 20-year guarantee.
...
http://www.pv-magazine.com/news/details/beitrag/commercial-5-mw-battery-park-to-be-developed-in-germany_100011100/

OK, this isn't the same story, it's a completely different project, but you can see what the company is up to. But there isn't anything in their current press release about the mentioned product.

Every once in a while I need a reminder of why I shouldn't try to do too many things at once.

[kristopher]

15. It's called Reevolt - Your power will be needed. Make him happy!

They might want to try a different handle if they bring it over here, but I can see the Reevolt wordplay works nicely there. The association of "revolting" with disgust is "empörung" according to google, leaving the name to connote revolution, reuse and electricity all at the same time.


http://www.reevolt.de/

Via google translate:
http://www.reevolt.de/produkte/photovoltaik/

The first step to independence:
The ReeVOLT! Photovoltaic package
The current prices for consumers have risen by almost 60% over the last 10 years. According to experts, it will go up to 2025 so on. We really want that? Is not it time for your very own energy revolution?

Your entry to exit:
The photovoltaic package with a small system size at an affordable price is the first step on the way to your energy independence. With tailored to your needs system, you can reduce your electricity from the grid by up to 25 percent. That's worth it because the feed-in tariffs under the EEG with about 17 cents per kWh is well below that already today, you have to pay for a kWh from the grid.

The 10 most important reasons for our Photovoltaic package - these are the benefits!
1 Small, high-performance system at an affordable price
2 Cutting the plant size to your needs and possibilities
3 Lowering your electricity discount from the first day of use
4 Savings of up to 25 percent of the electricity purchases
5 No feed of EEG, since power consumption compared to feeding is much more affordable today
6 System with our innovative power storage combined
7 Each time installing additional components is possible
8 Low-maintenance system
9 Extensive product and performance guarantees
10 Smooth operation, since all services from a single stem




Each ReeVolutionär his right system!
Your personal energy revolution begins with the lighting of your energy needs. Then we advise and plan the optimum system size. Our ReeVOLT! Photovoltaic package we offer you in six different sizes from 0,980 kWp. From a consumption of 2,500 kWh, you can save up to 20% of your electricity consumption!

No ReeVolution without reliable technology
All components of your system are delivered by an experienced photovoltaic specialist, assembled and put into operation. Fast, reliable and uncomplicated. The system can be installed on the roof, the carport and on open spaces.

Powerful component
1 Modules from the manufacturer "Astronergy" (depending on system size 4-9 modules)
- Catching the sunlight and convert it into solar power (DC) to
- TÜV certified
- Guarantee of performance by reinsurers "Munich Re" hedged
- Manufacturer agrees after use for recycling (a member of the PV Cycle)
2 Inverter manufacturer's "SMA"
- Converts the direct current into alternating current produced by
- German manufacturer
- World leader in solar inverter
3 Accessories
- Systems for different mounting locations (including roof, carport)
- Solar Cable
- Components for installation and mounting of components

Manageable costs - so the energy change becomes affordable
- Attractive prices starting from 4,199 €
- Subsequent extension gradually possible
- Saving in power consumption compared to feeding the generated electricity into the grid
- Financing by the Sparkasse Mecklenburg-Schwerin possible
- Little follow-up costs because maintenance plant

An unbeatable duo - The photovoltaic package and the ReeVOLT! Current memory
So much independence has never been! The combination of our photovoltaic system with the developed by us based on recycled, Germany unique in storage for solar energy allows you to even more effective use of your current self-generated. So that you are and we on the right track!

- Independence of the legal framework
- Independence of electricity price fluctuations
- Independence from the daily whims of the sun

The storage unit itself
http://www.reevolt.de/produkte/energiespeicher/

Because we want you to use your own generated electricity as efficiently as possible, we have developed a novel power storage for you. It stores excess solar energy and allows you to benefit with little sun hours of the photovoltaic energy. At the same time reducing your electricity purchases to other precious kilowatt hours.

The ReeVOLT! Current memory for your solar power
Imagine: Throughout the day, the sun shines and can produce your photovoltaic plant lots of happy power. That you are shame at work and do not need it!

Your power will be needed. Make him happy!

Effective, flexible and independent.
Our current memory for your energy revolution.

Household storage with modular design
Expandable up to 16 batteries
Increase your energy independence
possible capacity between 0.26 and 5 kWh kWh
less than other memory that were previously on the market
several options such as buying or renting
Price advantage in the package with photovoltaic system
Storage of recycled
Available on request with new batteries
Storage of recycled.
Good for all.
Our aim was to be as resource-efficient as possible in the development of the current memory. Therefore, it is based on the secondary use of used lithium-ion manganese batteries from our pedelec. This sustainability also gives us a good feeling.

Properly what is on the box!
Technical data of the pedelec batteries:
Manufacturer: Panasonic
Battery Type: Lithium-ion manganese
Work: 260 Wh
Voltage: 26 V
Capacity: 10 Ah
Number of Cells: 14 cells

[Iterate]

16. Shown at the Schwerin Handwerk fair in October, also available in a package deal

Somehow in the other post I'd conflated it with two other things I was looking at -but thought I'd leave leave the mistake as note about another 5MW storage project by Wemag in Schwerin.

The completed product was shown at Messe „Handwerk 2013“ in Schwerin in October.
http://www.reevolt.de/reevolt-zeigt-stromspeicher-und-elektroauto-auf-der-handwerksmesse-schwerin/

It's now available in a complete array/storage package starting at 4,199 €, with financing arranged and a performance guarantee. "Schwimmen Sie mit uns gegen den Strom." They just couldn't resist.
http://www.reevolt.de/produkte/photovoltaik/

Or the unit by itself. I see they stuck with the repurposed batteries and added the option for new ones. Buy or lease. Still looking for the starting price, but if the package deal is 4k...it should be less than half of that. I'll edit when I see it. Or fake an order.

Oh what the hell, here's what a polished Reevolt ad looks like; let the cynics frolic as they will:

[quadrature]

13. the value to society of time-shifted electricity

in my area.
the grid buys electricity at peak at 80 USD per Mwh.
at the low part of the day. USD 30 per Mwh.

diff is 5 cents per Kwh.

this device stores 2.5 kwh.
12.5 cents per day.

makes no sense.

[Iterate]

17. Essentially, 91,32€ net per month until the cabinet is paid for, 23,10€ afterwards.

This is the unit with the panasonic batteries:
Preis: 5.042,- EUR
Preis monatlich ab 91,32 EUR (Energiespeicherschrank: 68,22 €/Monat + 16 Akkus: 23,10 €/Monat) All prices include the 19% VAT. Financing of the net amount over KfW program 275.

That would be with 16 batteries, performance guaranteed. Elsewhere they had mentioned a 50% estimated savings, so essentially this would be attractive to any residential customer with over half the average 60-80 euro monthly electricity bill who wished to "pay ahead" for a system, then just rent the batteries later.

Or for a residence with an electric car, where the initial cost would be offset by gas savings.

It's an better idea for the right kind of small business. They have the room, they have the roof, they can invest.

Karabag appears to be a partner company that does auto conversions and also offers a reevolt packages. Looks like they also have an arrangement with a network of 800 service centers. Insurance too.

German original, with video:
http://www.elektroauto-karabag.de/reevolt/

En translate (scroll down for the storage units):
http://translate.google.com/translate?hl=en&sl=de&tl=en&u=http%3A%2F%2Fwww.elektroauto-karabag.de%2Freevolt%2F

In case anyone thinks these are only for the "rich Germans&quot whatever that is), a couple of weeks ago I noticed an old whiskery guy driving around the neighborhood. He has a one-man shop, mostly picking up binned but repairable electronics and appliances, fixing them, then reselling. He also does service calls. He was driving a rather colorful e-car. That in itself isn't unusual.

I didn't put it together until today that this is the car and system he was using and promoting. Jeez, I'd just looked away and nearly missed something.