OK, so its now time to do some monitoring. I bought the RS232 to TTL for my Raspberry Pi3, and then realised that they both have female plugs! So I got the soldering iron out and modified the lead that comes with the PIP4048 Inverter.

I really like the dashboard that Daniel has come up with using Grafana, so he has very kindly taken the time to sort something out for my install by way of an ISO. I am now doing the "Idiot" testing, as my experience of anything other than Windows is extremely limited. The theory is that if I can do it with so little coding knowledge, then a complete beginner should also be able to download an image, put in an SD card and run a program to put the image onto the card. Put it in the Pi, and switch it on, job done!

Just as a footnote, the wiring isn't quite as expected. The TX and RX pins were reversed from the Inverter cable, so pin 1 went to pin 3 on the D type, pin 2 went to pin 2 on the D type, and pin 8 went to pin 5 on the D type plug (ground connection).

Great stuff mate, I'm following with interest.

Bssic stuff have been done and he now gets the data out. I will start a thread about the project itself

I have been tweaking the displays today. I now have exactly as I want it. The logging has also flagged up an issue with the 4048, which is that it was shutting the solar input down every few minutes. This was due to overheat, caused by dust which I have now cleaned out.

Again, many thanks to Daromer for his expertise 



The flat lines on the charge current graph are due to me deciding to put the washing machine on a 2hr26min self clean cycle, so it pulled 1.8KW directly from the solar PV, and the other 1KW from the batteries. Glaring sunshine, so it made perfect sense to really test it!

Well, after a short time away, and whilst trying to get the divorce finalised, it is time for a new project.
This time I will be building clusters of 14S40P, enclosed in a 19" rackmount case to give me 6KWH per unit.
The final aim will be to have 15 of these, as it will run my new home, which is a 70ftx12ft Dutch barge. This is going to be a bit different, as the propulsion will be full electric, coming from a pair of Lynch motors (configured to give 110NM of torque). This will completely replace the old diesel engine, which is 8ft long, 4ft wide and 4ft high. The motor is 2ft long, 1ft high and 1ft wide, and doesn't make any noticeable noise(especially compared to the tractor engine it's replacing.
Heating will be a water source heat pump through a titanium heat exchanger. This way, it will take a small amount of power to make a lot of hot water, and also run the space heating.
The Spec for this is that it is totally renewable powered, so it will have 6.6KW of Solar PV, a 1KW wind turbine and a 500W drag prop (the propulsion motor act as a generator when the tide goes in or out).

Total power calculations went as follows;
System voltage 48V (so from 44V.8 up to 57.4), to give a per cell voltage of 3.2V minimum up to 4.1V maximum. I could go to extremes, but I want this to last. Realistically, when the motor is running and pushing the barge along at 4mph, we only need about 6KWH, which on a sunny day, the solar will keep up with. For domestic use, we only need 10KWH a day, and most of the time, we will be moored at a pub somewhere
With a 40P pack, using Samsung 29E-7, I can unload at 330 amps (8.25A per cell), but, that is bad design, so I designed it and fused it at 5A per cell, to give a 200A maximum per 19" unit. Just one unit could supply the motor, but in the aim for longevity, I will have this well inside the 0.2C discharge characteristic that these cells seem to prefer. 15 units could put out 3000 Amps comfortably, but with the motor peak output at 26KW (@48V is 541 Amps), plus the load of the 8KW PIP4048 twin paralleled inverters (takes it to roughly 800 amps), it is still close enough to the 0.2C. Real world conditions would have the inverter averaging 420 watts per hour in a 24 hour period, so about 10 amps constant. The motor at running speed needs 6KW, which is 125 amps @ 48V.

Looks great! I am trying to understand the fuse idea, as you have one fuse going between each cell from the other strings negative bus bar correct? Yet, the fuses are what is carrying the current, thus if one fuse goes down, the others have to take up the slack, if a second goes down, even more so and that would compound if more then two went down in a string.

Plus, your stacks of three cells are no fused correct?

(11-16-2018, 05:00 PM)keaton85 Wrote: Looks great! I am trying to understand the fuse idea, as you have one fuse going between each cell from the other strings negative bus bar correct? Yet, the fuses are what is carrying the current, thus if one fuse goes down, the others have to take up the slack, if a second goes down, even more so and that would compound if more then two went down in a string.

Plus, your stacks of three cells are no fused correct?

This is true when fuses are used as a load safe guard. Fuses used at the cell level are to protect the pack from a bad cell. The fuses are rated for around 2-3A, usually. The cells generally will only see .5A or less in most builds. So if a fuse does blow, the raise in amps across the rest of the parallel connected cells won't make that big of a difference.

So the pack can only handle between 32-48amp and that is with all fuses on any one string intact. If one, two or three start going down, that will load up the other fuses. If a large enough load is applied, all fuses in one of the strings would blow and take down the whole pack.

I like the idea because of the use of the cell holders, which allows for easy install and replacement on the fly, yet the chance of total pack shutdown goes up with this design.

That's almost where you'd want to have resetable fuses (not ptc, but manual) or little breakers. Hmm, wonder how much tiny breakers would cost. Gotta look them up

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Suppose these could be used
thermal circuit breaker

Altho, they are about $0.75 each

Can't wait to see some pics of this new build !!!