Hello, thank you, we are glad that the work helps others with their projects. Of course, we do not know what the fireproof box can withstand in an emergency. But in the case of a strong chain reaction, we suspect that the box quickly reaches its limits. But exactly, it gives you valuable minutes...
I was allowed to film a friend's solar system. For plant is quite exciting, so I have added extra English subtitles for you. He uses 5600 18650 cells with the diy BMS from my channel and a mpi 5k (mppsolar).
does one of you know if the MPI 10k from MPPSolar can feed only the current load into the house grid (withthe EnergyMeter)?
So just feed your actual load andwithout feeding into the public grid?
(I hope you understand what I mean)
I got new China-LiFePo4 cells and after charging the voltage drops relatively fast by 0.1V.
Is the behaviour normal for LiFePo4? It seems quite strange to me.
All other values are ok, IR=6mOhm and the capactiyis ok.
I'll admit that's a possibility. To be honest, it's just too expensive for me.
I also think that if you can't see a change in capacity and resistance, then the probability of a change after a few months is relatively low. But maybe there is one.
Another possibility would be to take 4 new and...
That would actually be very interesting, unfortunately these specialcellsare my servants for everything ;) I'm afraid but these cells won't live for a few months.
In addition, there would be no comparison cells, how is that possible with used ones? So I would have no statement after a few...
I did a test to find out if soldering 18650 cells leads to a loss of capacity or not.
I tested 4 cells and used the following procedure:
1. Each cell measured 4x (capacity). So 16 tests overall
2. 2x soldered, (one solder point)and then again soldereda piece of virtual wire.
3. let it...
Thanks for the answers, that was very helpful. I think I understood the off grid solution now.
Just one question to off-grid: The most off-grid inverter (i'm intersted in mppsolar devices, or maybe there are better) have a bypass mode, so just connect the grid to the output if th battery goes...
we are about to build a house and of course I am already thinking about the PV system with a DIY Battery Bank.
At the moment I have a 2x7s60p 9kWh 24V battery and would like to use it with a MPPSolar Inverter.
A few things I do not understand however yet.
In the Offgrid case:
Adding new cells and a hybrid system is simply not the same. From the amount of work and also from the behavior. 10kWh are enough for me and I just don't want to see notebook batteries any more ^^
So why not use and protect my 10kWh with a relatively small high-quality buffer.
With a small...
I asked myself, if it would be possible to add a lto battery Bank before (parallel but physacl. before the 18650 Bank) my 18650 Bank.
The idea is to increase the lifespan of my 18650 bank with few lto batteries. Just like using capacitors to get rid of the voltage spikes.
So i currently use a...
Hey Wolf, sorry I'm currently working on a cheap Raspi based battery monitoring system. So I forgot to post the new data, here it is. I think the results are good enuough to be helpfull:
However, the most interesting resultwere these guys here (Cell Name, Nominal mAh, pre Voltage, pre...
This looks very promising, 5% is not to much. I thought it would be more.
In the Surrogate Model I builded, wolfs data gets an own correlation function and is used as low-fidelity data. So I can answer the question how accurate the measurement are in a more "surrogate model" way...
This sounds like a very interesting project, which kind of battery do you plan to use?
In my experience the "explosion" of genuine 18650 is not really powerfull and in most cases there is no explosion. Maybe generic "china" cells are more dangerous if the overpressure valve is not designed...
Which results do you exactly mean?
There are now some cells with low capacity and itseems to work quite well also.
But there is one cell, which was predicted quite bad in my opinion (in the probability plot ~30% prob and 2500mAh). It's aSanyo UR18650NSX with 12.5 mOhm.
This diagram showsrather what we are interested in:
On the X-Axis is the measured Capacity and on the Y-Axis the predicted probability that the cell will have more than 2000mAh. So this looks quite good, most of the cells which have a probability>50% are actually over 2000mAh.
Of course you can...
I like the new ideas that started in this thread.
But using some kind of Metamodel and put some data in it and hope that it will create good results doesn't work in reallife.
The development of such models is my dayly work and the models I show here are also complete developed by myself over...