my modified balancer is working good
@Chris87 made it for me
its a 60w 1A x16 cookingplate now and it does cook well

that knee balancer is only conected for first top balance

have made rj45 connectors to easy daisy chain more banks

its not finished, there must be a cover above the seplos bms.
i make one soon for safety

if the fan (12V 50mA) is on it stays cool at 37C° so no temperature problems if all cells go to bypass
screenshot with test bypass start

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Hello anyone,

I have never connected a shunt, so is there a picture/schematic how to connect the 4.61 board? The board shows +VOLT BUS, Shunt Batt+, Shunt CHG/LOAD.
I think, +BOLT BUS = 48v Battery positive,
Shunt Batt+ = same side of shunt as 48v Battery positive , and
Shunt CHG/LOAD = Positive to inverter?

This is HIGH side? I see lots of other post about shunts using LOW side or negative to inverter. I’m confused and will not connect till I understand.

initial top balancing with dynamic charging algorithm works very well

@stuart 99% :wink: i have reported this in the shunt issues

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Very nice - great work!

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The system is designed for high side monitoring (the shunt is in the positive cable).

“+ VOLT BUS” = 48V positive cable (connect directly to the battery positive via a fuse if possible)
“SHUNT BATT +” = The shunt terminal nearest the positive battery terminal
“SHUNT CHG/LOAD” = Connect to the other shunt terminal towards the charger/inverter.

The “+ VOLT BUS” provides a single voltage source for monitoring the whole battery. The other 2 terminals measure the “current across the shunt” by measuring the voltage drop.


A picture might help (from Stuart Pittaway youtube video)

Yes, I had seen the picture, thanks.

Okay, I have shunt going, but battery voltage tile is only 0.10v. I suspect no ground? My controller v4.61 is powered from dc to dc converter using pack voltage.


For the Battery Voltage it is important to connect the Controller GND to Battery Negative

Are you using an isolated DC to DC converter? That would remove the ground connection and likely to cause the mis-read.

If you are using an isolated DC converter, I don’t know if you are likely to damage it if you connect the battery negative (ground) to the controller board.

I was thinking same, didn’t want to go there. I have had this converter long time, was going to use it on my esp32 tracker, but turned out not to need it.

SM-PLG06A Specifications
1.The product is easy to install and can be used directly on the motherboard
2.Fixed installing holes in four corners to prevent product power outages resulting in movement / vibration . fixed hole diameter each :3.2mm 3.85-264VAC 或 110-370V DC。Globally used input voltage : 85-264VAC OR 110-370VDC
4.High efficiency, high power density, low output ripple noise and high output voltage accuracy
5.High input and output isolation
6.With full protections of over-current ,short-circuit and the temperature
7.Output built-in LC π filtering, without external filter circuit.
8.Guarantee period : 3 years

P.S: Powered with USB, shunt tile shows 1.02v
Also, don’t think it matters but this 18650 bank is in parallel via bus bars with LFP 16s 280ah bank. The LFP bank is on XiaoXiang BMS.
P.S. I’m okay without shunt battery voltage (already have that reading with BMS) and the current is correct!


please help, I have 4.61 board, powered by MeanWell power supply 230V AC/5V DC It works fine till…
I connected GND battery to GND power supply, connected shunt, enabled internal shunt in web application, set numbers, all was OK, exept current it was 0,25A less then DC A-meter showed. All looks fine.
Then I started to play with CAN bus setting Pylontech emulation. From this time it lost comm to modules, ESP is restarting…
What did I destroy, mainboard, ESP, did I misstake use this power supply…

DONT DO THIS - Power the controller board directly from the battery - you are linking the mains AC with the negative of the battery.

could he use the same buck converter im using? meanwell DDR 15L 5
its an isolated one
i cant test this because i have the external isolated shunt

maybe you should do an detail video how to connect the internal shunt and what hardware is needed

I use the DC-DC converter DDR 15L 5 with the internal shunt. The battery minus is connected to the 5V GND. The DC-DC converter does not cause any problems

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Thank you, I will use non isolated stepdown DC converter powered directly from the battery terminals (and a suitable fuse)



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I also don’t understand Stuart’s formulation:
“Power the controller board directly from the battery”
Battery can be, for example, 48 V and on the controller board it says that it must have 5 V.
I’m not the right person to answer this question, but I found this picture on this forum - I hope the picture is right!

Yes, you would need a DC to DC converter to drop the 48V to 5V. As people build different voltage batteries I can’t provide a single answer/solution for every possible combination.

So adding details, I understand a step-down d.c. converter powered by the battery (with a negative rail common to both input and output) is what is required.

MeanWell power supply 230V AC/5V DC

you are linking the mains AC with the negative of the battery.

Umm … how could an AC-to-DC power supply possibly accomplish that? These things are isolated.