r/diybattery

ebike battery pack i bought is 48v 20ah. this is what i got.

attached pics:
- battery specs

- closer battery specs.

- length of the battery case 38cm

- length of actual battery inside the case. 26cm

- showing 4p config.

i'm posting here cuz i need some help.

1. it is clear that it is 4p right?
2. it is clear that the battery spec is 3.7v and 2000mah?
3. i included the length as it is a 48v battery pack with 4p (which is why i was asking it in 1).
4. i'm makingthis post in case i am missing something cuz the seller said it is 48v 20ah which i can't see how it would be given that it is 4p with 2ah per cell. based on 4p, it is only 8ah. i'm not concerned with the voltage but i did count the s and it is 13s making it 13s4p but i want that to be seen in the pic cuz i am going to submit these pics as evidence and dispute the purchase.

assuming that you agree it is 4p and that the lenght 26cm is 13s cells deep. is there any way that the battery pack can be 20ah?

any suggestions in terms of pics and explanation so that i can explain it properly in my dispute?

thanks in advance to those who will answer. i apologize if this is not the place for this.

Upgrading from 18 kWh to 27 kWh storage completely changed how much of our own solar we actually use

We’re in the San Francisco Bay Area, California.

When we first installed our system, we started with 10 kW rooftop solar and 18 kWh of Sigenergy SigenStor battery storage. On paper, it looked like more than enough.

After running the system for a little over a month, the energy data told a different story.

During the day, our 10 kW solar array easily covered the entire household load. It also fully charged the 18 kWh battery by the afternoon. After that, we were still exporting around 10 kWh back to the grid almost every sunny day.

The problem didn’t show up until the evening.

Once our EV came home and started charging, the same 18 kWh battery had to power both the house and the car. That extra demand drained the battery much faster than we expected, and we ended up importing electricity from the grid during peak hours.

Instead of adding more solar panels, we decided to expand the battery.

We simply added one Sigen BAT 9.0 module, increasing total storage from 18 kWh to 27 kWh.

The difference has been surprisingly noticeable:

* Much higher self-consumption of our own solar energy

* Less electricity exported to the grid during the day

* More stored solar available for EV charging at night

* Lower peak-hour grid imports

* Better overall energy independence

One thing I really like about the Sigenergy SigenStor platform is its modular design. Expanding the system was straightforward—we didn’t have to replace the original battery or redesign the system.

Looking ahead, if we add more high-power appliances (or even another EV), we’ll probably add another BAT 9.0 (9 kWh) or BAT 6.0 (6 kWh) module.

With AI workloads, electric vehicles, heat pumps, and increasing household electricity demand, I honestly think home battery storage is becoming less of a luxury and more of a necessity.

Has anyone else here found that adding battery capacity delivered a bigger improvement than adding more solar panels?

Hello I am in the process of soldering the sense wires to the parallel groups. But I can't get the wires to stick to the copper plates? I have tried soldering with flux, and I have tried to scratch the copper surface nothing works it won't stick.

I received notification that my bus bars have shipped!

I still need some assorted hardware (M4 threaded rod and lock nuts and M6 screws and lock washers)

I modeled the bracket for the BMS, I’ll probably add some cable management to the BMS bracket and an Anderson Powerpole connector for the main power connector

Once I have all the hardware in a couple of weeks I’ll top off each cell and connect everything and program the BMS.

I still need to fabricate a cable to connect UART to an ESP32.

Still functions, didn't notice it at first and used it for a few rides. Is it fine? Or fixable?