Recent content by FrankB

The cells show very different self-discharges. In particular, there seems to be negative self-discharges, so the cell produces current. There seems to be a chemical process here that leads to a residual voltage of the cell. This intrinsic voltage seems to be above 3.0V. Channels date...

Measurement First, the cells are discharged to approx. 2.9V with an electronic load. Then they are connected to the measuring device, which recharges the cells. The measurement takes about one week. The measurement data are recorded with an ESP32 and two INA3221s.

Interim status: Unfortunately, I still don't have the Z-diodes. So I have now changed the circuit a little. I now use a 3V constant voltage regulator as a voltage reference. The circuit is powered by a 5V USB power supply. I use two prototype boards of the INA32321 for measuring. On the INA3221...

The self-discharge should be measured by adjusting the working point of the cell. Since LiFePO4 cells have a very flat characteristic curve over a wide range, the measurement is best carried out in a completely full or completely empty state. The self-discharge of the cell itself is also...

I already bought cells of them. The cells are realky cheap. But there had only 80% capacity. For me it is ok. So price per value fits.

Can you pls test one ore to cells to check the capacity?

I connected an balancer with 5A (chinese) balancer current. That means, it works perfect for 1A. So I charged tho whole 16S Battery to 3.35Vx16=54V with 5A. Then I changed the charging current to 1A/56V and the cell gets balanced in about 4hours...

In normal Situation nothing happen. But the short circuit protection wouldnt work. In that case, you get some arcs in the BMS: in the MOSFET and the tvs diode. For an 48V system you need the 75V tvs diode!

I own 5kW Solar panels. My plan is to use 8 of this boxes to store the Energy. This is the first prototyp.

my main point are: 48V System for better efficiency and less cable cross section each block shall be moveable -> max 30kg per battery 30kg / Battery -> each cell about 2kg (2kgx16 = 32kg) Best cell fit for that is 105Ah (130mmx37mmx200mm) Then I searched for an enclosure and I found the...

I opened for that reason an 8S BMS. I found a tvs diode with 75V breaking voltage. The Diodeis from "littlefuse.com". So from protection point of view it should be possible ( in my case!!). To be shure, you need to oben your BMS :p But netherless i decided to use an 16S BMS for the 48V system...

How big is your difference? The main reasons are the different loop resistance of your battery packs. There are more possible details to be checked: - same cable length? - same cross section of cables? - same bms sytem? - same temperature?

:cool:

No. The form factor is not a problem. My problem is the weight. Id like to build, setup and test the complete package before carring to the final position. So the battery should not heavier than 40kg. This is 2.5kg per Cell for an 16S configuration.

Hallo sshibly, for me your deal looks different. For 16x105Ah it is about 666EUR with free shipping. You had a good deal with 592$. -> Is there a tax difference? Thx