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crisis
Suicide drones regularly attack critical infrastructure in Ukraine.
Some disruptions are caused directly by attacks – power plants, substations, transformers, power lines were destroyed, some are premeditated – the power grid was not designed to work, while some of its power plants and transformers have been destroyed and are under repair.
Cold weather also does not help with power cuts, the load increases a lot as people stay home for longer periods of time, use electric heating which is just pure energy → heat transformer and it is very consuming.
There was even an official program to replace your old lightbulbs with new LEDs for free which is a win-win. clean.
Solution
Common necessities like water pumps, elevators, and corridor lights in apartment buildings are sometimes supported if people vote to spend money on local generators in the building.
Nowadays, in the fourth year of the shutdown, almost every Internet provider has implemented some kind of solution, either battery for RJ45/copper connections (~12 hours uptime) or FTTH (Fiber to the Home) which can work even for 1-2 days, because with this technology a central node can serve thousands of apartments over passive fiber without the need for intermediate switches.
Small businesses often use generators to stay open during power outages, so they get a lot of noise during shutdowns.
Fun Fact: Large grocery stores and apartment buildings use large generators, they are the size of a car and are quieter than smaller generators.
Just like a motorcycle engine is much faster than a car engine.
(Below is a photo made by me)
People back up needs with power stations inside their apartments (Bluetooth and Ecoflow are the most popular).
During shutdown, prices at power stations increase by 20-60% which is the market norm.
The router can be powered with just a power bank + USB C → DC12 cable which has become very popular in recent years.
our case
We need to power the X1 HP ProLiant dl380p g8; x1 hp proliant dl360p g8; x20 google pixel 6.
We measured this entire setup to be around 500 watts.
Given that the average scheduled shutdown lasts 5 hours, we calculated that we would need about 2.5kWh of battery capacity.
Next came the question of which battery/solution to buy.
There is a DELTA 2 Max from Ecoflow brand which is priced at ~$1500 and has a capacity of 2kWh, which is not enough for us, and the next one is DELTA Pro of 3.6kWh which is priced at an astonishing ~$2300.
Everything seems extremely expensive in the ready-to-go market.
So we decided to create our own battery solution. Spoiler – it cost us $600 and has better features than the $2300 EcoFlow.
At this point making your own battery systems has become almost a national folk craft for tech-savvy Ukrainians who want to save or get more value for their money.
To make your own gear you will need to purchase individual components such as battery cells, protection boards for them, inverter for 220V AC, charger etc. and assemble/connect it yourself.
This is challenging because if you do something wrong you can destroy the equipment, burn down your dwelling or harm yourself or your neighbors.
First, there is the choice of battery cell chemistry. The most common are lithium-based family chemicals: Li-Ion, Li-NCA, Li-NMC, LiFePO4. I chose LiFePO4, as most Ukrainians do, because it is the most optimal option for price, performance and safety.
Safety is an important factor because if something goes wrong, such as when the battery is overcharged, other types of batteries can explode or burn like thermite, whereas LiFePO4 simply swells and/or vents excessive gases through special safety valves.
These gases aren’t healthy but at least you won’t burn down your apartment.
The voltage of each cell is 3.45V so you need to connect several in series (4 in my case, for 12-13V).
The first thing I bought was 4 Envision LiFePO4 315Ah cells, giving me a total capacity of 4.3kWh.
I found a local seller who bought several pallets of them (several hundred cells) directly from a Chinese factory.
I was also lucky that he had a spare BMS board (Battery Management System) which he had purchased for his own use and did not plan to sell, but sold to me, still saving me some time in purchasing it separately. And I paid for it with USDT which felt like the future 😊
The role of the BMS is to live between the battery cells and the load, and to control that the battery is not overcharged/overdischarged, protect it from overcurrent/short-circuit and also to balance the voltage between the individual cells during the charging process.
Different cells, even from one batch, are not completely identical, they may vary slightly in internal resistance which will lead to uneven charging and some capacity loss, so the BMS will transfer some power from one cell to the other to equalize the charge.
The next thing you need is some way to convert the 12V DC battery voltage to 230V AC mains voltage to power common devices like servers.
You can buy an inverter to independently generate AC mains voltage and a high-current battery charger to charge the battery while the power is on, but this is a jerry-rigged setup.
Fun fact: Most of the battery chargers sold on Aliexpress and Ukrainian markets are made from power supplies from old servers.
So people who want to make it more reliable buy so-called solar-inverters.
It is a device designed to work with solar panels, converting their electricity into AC, mixing it with mains electricity or funneling it to the battery when consumption is not enough.
Importantly, it can operate without being connected to solar panels and has a built-in battery charger using AC power.
Therefore, many such hand-made constructions use them as simple UPS.
You can connect the entire apartment to such a battery system using cables with plugs at both ends, although it is important to remember to turn off the main breaker beforehand, otherwise the inverter will malfunction when the power is turned back on.
The proper way to do this is with a device called an “automatic transfer switch” which, as the name suggests, will automatically switch inputs depending on who has power.
Automatic transfer switch gear for one of our other forms:
At this point there are only a few items left to purchase, such as the power cable for the battery and various consumables, and we can begin assembly of the entire setup.
Assembly of the battery is very straightforward, you put the battery cells together, changing the polarity as the negative terminal of one cell must be connected to the positive terminal of the next one, placing a fiberglass sheet in between as an insulator. Then you fix them well with duct tape.
The BMS board is then strategically duct-taped near the negative terminal of the last cell and attached to it, along with all the balancing wires (this is the top of the red wires), they are connected individually to the positive and negative terminals of the battery and the positive terminal of each cell.
As it happens, I was assembling it when the power went off 🙂
Now the battery is assembled and the BMS board needs to be configured. There is an Android app for this, it connects to the BMS via Bluetooth and allows you to configure many battery intensive parameters.
It has a nice default preset for LiFePO4 batteries, I only needed to adjust several parameters.
I then slammed it together on the table to check that everything worked before final installation, as well as stress-testing it under maximum load to check that the connections weren’t overheating.
Found out that the short circuit protection of the BMS was triggered incorrectly under medium-high load, adjusted it in the settings. And I forgot to tighten one connection, it was overheating.
Finally I brought everything to the site and installed it in place.
Since our main activity is running a phone farm, we have a few spare phones, so one of them was sacrificed as a bluetooth terminal to show battery stats 🙂
And just like that, the fire test of the backup battery was completed in just four hours.
our startup
We will now continue to operate as before, garnering social media engagement for us and our clients, applying to YC 2026 and other VCs.
We have a total of 60 Google Pixels across 3 locations in Kiev.
It’s a very strange feeling that your business is under constant threat of physical destruction and you have to fight the consequences of war to serve your customers.
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Author: Nicolas and my co-founder Ihor
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