Best battery cells for DIY projects

ETC LFP206S battery cells

If you want to build your own battery pack to use in an electric vehicle, renewable energy storage system or to replace the much heavier 12 volt lead–acid battery in your car this article might help you choose the right battery cells.

The recommended battery cells depend on the application. If you want a battery to power an electric vehicle, the battery should be compact and light. On the other hand, if you want a battery for an ESS (Energy Storage System) or to replace the 12 volt lead–acid battery in your car, it’s important that the battery has other characteristics.

I’ll divide the recommendations in two types of projects.

Project A

Main applications:

  • ESS (Energy Storage System)
  • 12 V battery

In this project battery cells should be easy to install and replace. The battery also needs to be safe, reliable, durable and with decent power energy. Volume and weight is not very import.

 

Battery cell format

Prismatic cells with screw terminals are perfect for the job. They are like LEGO, super easy to assemble together and also very easy to replace in future upgrades. No soldering required.

 

Battery cell chemistry

As for the best battery chemistry, LFP (LiFePO4) is my choice. It’s reliable, durable, safe and don’t cost a fortune (no cobalt used).

The only downside of LFP battery cells is their low energy density, but even that is being improved.

 

Let’s see the developments made by the Chinese battery cell maker ETC.

ETC battery energy density evolution

 

LFP (LiFePO4) cells have been improved regarding their energy density, while remaining reliable, durable, safe and affordable. Not requiring cobalt is a major quality of this battery chemistry. These sturdy cells are popular for ESS (Energy Storage Systems) and electric buses.

 

The second-generation LFP 206 Ah cells are already available to private buyers. Let’s see the specs of these cells in more detail.

LFP206S battery cell specs

 

With the energy density increase, this second-generation LFP battery cell isn’t much different to the exceptional Samsung SDI 94 Ah battery cell, with the extra benefit of using no cobalt.

 

For DIY projects I wouldn’t recommend battery cells with great specs if they aren’t easy to buy nor affordable. The second-generation 206 Ah LFP battery cells from ETC can be bought for around 190 euros per kWh in here. Moreover, in most countries you’ll avoid import duties and taxes.

 

Summing up, I recommend these battery cells because:

  1. Prismatic with screw terminals (very easy to assemble or replace)
  2. Safe (won’t catch fire even if punctured)
  3. Reliable (work great in most temperatures)
  4. Durable (extremely high cycle life)
  5. Environmentally friendly (no cobalt)
  6. Affordable (around 190 euros per kWh)
  7. Easy to get (Chinese sellers will actually sell and send them to you)

 

 

Project B

Main applications:

  • Electric vehicles
  • Portable power banks

In this project battery cells should be as light and compact as possible. Volume and weight is very import.

 

Battery cell format

Cylindrical cells are small enough that allow to build battery packs in every shape possible. Years ago the 18650 format was dominant and alternatives were almost nonexistent, but now the 26650 format is gaining popularity, especially for electric bicycles.

 

Battery cell chemistry

NCM and NCA are the most energy dense chemistries, therefore are the recommended for this project. These chemistries are very popular in cylindrical cells.

 

In my opinion LiitoKala has the best battery cells for this project. The LiitoKala Lii-50A in the 26650 format is my recommendation. The downside is that you have to solder these cells to assemble the battery pack, unless you buy one already made and ready to use.

LiitoKala Lii-50A

 

For DIY projects I wouldn’t recommend battery cells with great specs if they aren’t easy to buy nor affordable. These battery cells can be bought for around 192 euros per kWh in here.

 

Summing up, I recommend these battery cells because:

  1. Size (small cells give you flexibility to build battery packs in many different shapes)
  2. High energy density (essential for small and light battery packs)
  3. Affordable (around 192 euros per kWh)
  4. Easy to get (Chinese sellers will actually sell and send them to you)

 

Have you ever completed a DIY project involving batteries? Ever thought of building your own customized version of a Tesla Powerwall?

This Post Has 27 Comments

  1. Nice to read you, as usual.
    This makes me think about electric scooters and mopeds, the affordable ones – Askoll, Vmoto… Most of their batteries suffer from premature degradation that makes them almost unusable after 10k-20k kms. Could these prismatic batteries improve the original packs? Is it easy to make larger packs? Or perhaps it is tricky due to the electronics. I do not have much knowledge on this.

    1. Askoll and Vmoto have some models with VRLA (Valve Regulated Lead Acid) batteries, they aren’t Lithium-ion batteries. Those are very cheap batteries but heavy and with high degradation. Nonetheless, both Askoll and Vmoto also have more expensive models with LFP batteries that last “forever”.

      See here what type of battery each model has.

      https://electricscooters.eu/

      1. I have just moved to Indonesia. There are millions of 2-stroke scooters here, and the air pollution is terrible. I would love to see electric scooter manufacturers move into markets like Indonesia and India, etc.

        Would the LFP cells work in an e-scooter? Or are they too big or heavy? 10 cells would be ~42kg, which is heavy, but I think it might work in a scooter. And 10 cells would mean ~6-7 kwh.

        Would it be better to use the cylindrical cells, or would they degrade too fast in the heat?

      2. Many Asian countries have that air quality problem.
        A lot of e-scooters use LFP batteries, but NCA or NCM is more appropriate, since weight and size of the battery is really important.

        Super SOCO TS is a very popular electric motorcycle that uses a light and compact battery made with Samsung, LG or Panasonic cylindrical 18650 cells.

        http://www.supersoco.eu/en/batteries/

  2. The title is a bit misleading…
    A lot – if not most ! – of DIY project is about micro-mobility, not Tesla Power-wall.

    Like converting to ebike existing bicycle, or to maintain on the road VAE, electric scooter, gyro-wheel, light motorcycle, Hoverboard, etc.. which all require the making of a battery.

    The cell presented here is not then the “Best battery cells for DIY projects”
    What would it be for the micro-mobility application ?

      1. Interesting, I always tough LiitoKala is poor quality Samsung copycat.
        Nkon.nl is usually the way to go to avoid such…

        So LiitoKala is good stuff ?

  3. Oh way too cool! The price seems cool too, I’d love to build my own “Powerwall” and for 2000€ for the batteries it might even be affordable, just a shame I’m no electrician and have no knowledge… darn.. but to be spending 10’000€ on a ready to use Powerwall, just to have a battery, does not justify the expenses, it will never “pay off”..

  4. I guess you can’t use the LFP cells for an off grid ESS in Canada, as the cells might get wrecked if the temperature goes below -20C. Many people in Canada have cottages that are off grid, so there’s a market there for storage systems + solar panels. They all use Lead Acid right now.

    1. LFP batteries are very safe, they can be kept indoors. You can drill a hole in them and they won’t catch fire, just smoke. If you overcharge them they just swell (I actually killed two cells of an electric motorcycle this way).

      https://www.youtube.com/watch?v=EMARDvMz62A

  5. Hi,
    Thanks for this article.
    Why do we have year 2018 quarter 1 (18Q1) in the graph but the batteries are only now being released? Was a Too optimistic timeline plan as Tesla? 🙂
    Also a note that 190€/kWh doesn’t seem cheap as we have already Tesla doing 100$/kWh …

    1. Hello Pedro.

      Battery cells are first made available to companies, then – if lucky – to private buyers like you and me.

      These cells you can actually buy for 190 euros per kWh. How much do you have to pay to get those Tesla/Panasonic cells delivered at home?

  6. This is fascinating. So I can get about 10kwh of decent batteries for about £2k?

    Realistically how hard would it be to turn these into a powerwall? Are there any significant downsides? Why aren’t we seeing lots of cheap competitors to Tesla? I hear they’re charging about £7k?

    1. Tesla Powerwall 2 is very popular because it simplifies things, it’s a 3-in-1 product. It includes a 13,5 kWh battery, 5 kW DC/AC inverter and charge controller in a nice package ready to use.
      Building a DIY alternative isn’t rocket science, it’s fairly easy actually, but it does require some patience and motivation.

      The DIY will require more work but it’ll be cheaper, moreover it’ll be a lot easier to replace/repair any faulty parts.

      This would be my DIY choice:

      17x LFP206S battery cells (11,28 kWh): 2.000 euros
      1x 5 kVA Hybrid inverter: 800 euros

      Why 17 LFP cells instead of the standard 16 for a 48 V system? Because this way the battery would never pass a SoC (State of Charge) of 80 %, increasing the lifespan.

      https://pushevs.com/2018/04/27/battery-charging-full-versus-partial/

      https://www.powerstream.com/z/lfp-la.jpg

      1. Thanks Pedro,

        What do you recommend for the part of deciding+allowing the system to charge or discharge the battery?
        (I Imagine the basic option is to charge the difference “producing – consuming” (when house is producing more than consumes) and discharge the amount “consuming – producing” (when consumption>production);
        (We also can go further and make smart algorithms to only discharge if we are in a expensive hour to buy electricity… and even charge during the night for cheaper electricity : this would allow a lower kWh battery solution for the house)

  7. hello pedro, next month I install 19.8 kW photovoltaic system on my flat roof, on my order is written ‘inverter fronius from September ready to install solarwatt or byd storage battery’, I know that byd batteries are lifepo4, do you think that i can buy these LFP206S cells with an appropriate bms (I hope the inverter fronius handles the charge/discharge properly) ? can you recommend a bms suitable for about 40 kWh of these cells ? i think the current fronius symo hybrid three-phase inverter use fronius battery modules with nominal voltage 51.2 volts, my inverter is 20 kW

    https://www.fronius.com/~/downloads/Solar%20Energy/Datasheets/SE_DS_Fronius_Energy_Package_EN.pdf
    http://www.europe-solarshop.com/fronius-battery-module-1-5-rf.html

    1. Hello Luca.

      That’s a massive project. I recommend a BMS with bluetooth, this way you can check the voltage of each cell and adjust parameters with your Android phone.

      https://pushevs.com/product/bms-for-lib/

      I strongly recommend you to join one or more renewable energy forums to advice you regarding the inverter’s connection with a DIY battery.

  8. Hello Pedro. Another great article has always.You recommend this store based on your personal experience or based on your research?

    1. Hello Nuno. I didn’t buy anything from that store yet, but the seller seemed to know well the product he’s selling. He sent me PDFs with a lot of interesting information about the battery cells, including the specs, charts and roadmap in this article. Moreover that store assures duty and import tax free to most countries, which is nice.

  9. Agree. Good for energy storage and larger vehicles. One drawback is energy density though. 18650 has about 270 wh/kg while these have 160 wh/kg. So for everything on two wheels I’d say 18650 or the 28650 are still the best.

  10. Service life only 5 years?!

    1. That parameter isn’t very clear. My guess is that ETC considers that the battery cell will remain for at least 5 years with a capacity above 80 % that corresponds to EOL (End-of-life).

      More detailed specs here: https://www.sendspace.com/file/g6ty7t

    2. Yes, I also have this question: Regarding the 206 Ah LFP case we see a 3000 cycles lifespan (the LiitoKala is even worse: 500). If we consider a cycle per day we get 8,22 years (3000/365). Doesn’t seem much if we compare e.g. with this 10000 cycles’ LG Lithium technology: https://www.efimarket.pt/bateria-de-litio-de-isolada-9-8kwh-48v (although 4X more expensive we don’t need to redo installation work as often and is more eco-friendly, reducing disposables) By the other hand, Tesla powerwall just give us 10 years warranty (https://www.tesla.com/pt_PT/powerwall)

      1. Hello Pedro, you can easily increase the cycle life by reducing the depth of discharge, see the chart below for LFP battery cells.

        https://pushevs.com/wp-content/uploads/2019/08/LFP-cycle-life-based-on-depth-of-discharge.gif

        The LG Chem RESU 10 has a total battery capacity of 9,8 kWh of which 8,8 kWh are usable.

        https://www.europe-solarstore.com/lg-chem-resu-10-48v-lithium-ion-storage-battery.html

        The best thing about a DIY project is that you can decide the depth of discharge you want.

Leave a Reply

×

Cart