Very interesting thank you
Ok I’ve decided to go with a single shunt initially as it will allow me to see how useful I find it. I can add more later if required. I will make a short copper busbar to connect the three battery banks’ negative cables together and connect the smart shunt between that and the existing negative busbar. Does anyone know what the maximum thickness of the connection terminal can be on the 300A smart shunt M8 bolts? It’s not shown in the manual and I’m wondering if I can attach the 10mm thick copper busbar directly to it, or if I’ll need to make a short length of cable with copper tube crimp terminals?
This is my DC distribution board. At the bottom, you can see the three SmartChunts for battery measurement. Originally, I wanted to build the distribution board with some reserve capacity, which is why the fuses for the solar chargers are at the top and the two large fuses at the bottom were originally intended for the two batteries. But then a third battery was added and I had to improvise (bottom left). The three fuses in the middle are for the three Mp5000/48. I think it’s always better to have one or two slots in reserve. I just about managed to ‘conjure up’ the third SmartChunt. Mechanically, the disadvantage is that the SmartChunts are too small for this design and require a 2 mm copper sheet so that the electronics are not mechanically stressed. The power machines are made of 10 x 400 mm copper, as they are weakened by the screws in the corresponding places. I mounted the size 00 NH fuse holders on 3D-printed spacers so that they are at the same mounting height as the larger ones.
My SmartShunt has arrived. The copper/brass blocks that form the high current terminals are tapped for M8 bolts so I can use a couple of longer bolts to attach my copper 10mm thick busbars directly to the shunt. Only snag is the electronics module projects slightly above the brass block so I’ll have to put a thick wide copper washer between the busbar and the shunt to provide some clearance.
I’ll post a photo when I’ve assembled it.
[picture deleted]
hopefully this shows the gap between the busbar and the terminal on the smart shunt. I need to mount the smart shunt at 90 degrees to the busbar (which is 300mm long) so I have no choice but to insert a copper spacer washer. Shame the smart shunt black plastic electronics enclosure isn’t slightly lower down…
Short busbar made and two M8 holes tapped plus an 8.5mm untapped through hole in the centre to attach it to the smart shunt.
3x 95mm2 crimp terminals (one for each battery) now able to be connected to the smart shunt.
That is a nice piece of copper, but shouldn’t you be using DIN cable lugs for cat 5/6 cables?
I don’t know. Should I? Any advice or explanation gratefully received.
Do you plan on maxing out any elements of your system? Are any elements of your setup close to max spec?
I have deliberately gone conservative on the cables. I am joining 3x70mm2 flexible cables (not 95mm2 as I said in the photo caption - my mistake, that’s a different circuit) each of which is protected by a 160A NH 00 fuse link. The maximum power draw of the circuits fed from the batteries is 10kW @ 48V DC nominal (2x 25.6V LiFePO4 batteries in series per bank, x3 banks in parallel). I used a hydraulic hex die crimping tool for the non-DIN tin plated copper lugs . I have checked the temperature of the crimps and busbars and cables under load and they are all below 30 degrees. It’s a static installation in an outbuilding. I believe the risk of non DIN lugs is acceptable in this case (to me) but appreciate any observations or thoughts.
I can scan your smartshunt and use the serial and puk number… not clever on a open forum
oops didn’t think of that. I will delete the pic. Thanks for pointing this out.
Absolutely.
Klauke has good information about the differences, theres two links in this post, but the whole thread is a good read
If at all affordable, use three BMV 712 Smartshunts ánd use the midpoint function as well. Then investigate VenusOS large to create a single aggregated virtual lithium battery and add as many ‘bells and whistles’ protections to it based on the 3x individual current and midpoint Voltage measurements. Add 3x relais and if it all possible 3x individual HF chargers, look at Huawei R4875G1 to gather some ideas.
And whatever you do, double all wiring (cross section) and make absolutely sure all wiring within the ‘composite single battery system’ is OCD grade electrically symmetrical.
Thanks, all interesting advice. I believe I’m generally pretty conservative on all electrical loading aspects. I’ve read all about the Klauke crimping system before when deciding which tools to buy. I’m curious to know how many domestic installations use DIN standard crimping. Especially seeing the quality of electrical work done previously by supposedly qualified professionals in domestic settings!
Oh and I measured all the cables to the nearest millimetre when cutting them…
what will you do with that number in the end? what benefit could you take out of it?
Sorry, very strange posting and thinking
If your device is connected via bluetooth or vrm, anyone with the serial number and PIN can access your settings.
Hardly anybody seems to care about such down to earth things as basic security so it seems. If I go boating in Amsterdam I can pretty much log into yet another Smartshunt still using the 000000 pin for Bluetooth every 10 minutes or so. That has only recently been changed to per device different pin numbers.
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Maybe we should write a logger, like the Chinese do for Bluetooth and SSID scraping and see how many devices actually show up.