question

yann avatar image
yann asked

[solved]PAND battery : power and current readings are reversed

Hi all,

I just installed a new system with a multiplus II, 150/60 mppt, cerboGX and 2 PAND Powercube batteries, connected on CAN bus.

Surprisingly, batteries are reconized by the cerbo as "LG Resu". I guess PAND have somehow copied the LG BMS ?

Everything seems to work, but there is a stupid problem : the current/power readings from the PAND BMS is reversed, it's shown negative when battery is charging and positive when discharging, wich cause wrong display on the cerbo screen and on VRM, and I suspect also wrong driving of the multiplus charge levels, because it does strange things sometimes.


Is there a way to change the battery drivers on the cerboGX to correct the readings sign ?

Thanks

Lithium Battery
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4 Answers
yann avatar image
yann answered ·

@Alexandra @mvader (Victron Energy) OK I solved the problem, using the software provided by PAND, it's possible to change the communication protocol in the BMS, there are several inverter brands listed, and when using "GoodWe" it works as expected. Strangely there is a Victron entry in the list, but when using it, battery no more communicates with the cerbo ...


I have the PAND software if someone needs it. You will need USB/serial converter with RJ11 jack, the pinout is in the pand manual.

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klim8skeptic avatar image klim8skeptic ♦ commented ·
@Yann thanks for the update, others might find it useful.
1 Like 1 ·
julien-gaya avatar image julien-gaya commented ·

Hi @Yann

Thanks for this. I would like to have the PAND software, can you tell me how to do ?

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yann avatar image yann julien-gaya commented ·

@Julien_GAYA

2022.2.16 PAND BMS software.zip

Here it is.

On the "firmware" folder you have the latest firmware I have for the powercube battery.

Using this one, and selecting "GoodWe" as communication protocol it works with the cerboGX

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2022216-pand-bms-software.zip (5.4 MiB)
julien-gaya avatar image julien-gaya yann commented ·

@Yann thanks, top !


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kevgermany avatar image
kevgermany answered ·

You might be able to fix it by using the Victron type A or type B cable to connect to the cerbo.

But afik, no way to change it on the Cerbo.

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Alexandra avatar image
Alexandra answered ·

@Yann

It is more likely a battery assembly issues, they have the connection to the shunt in backwards. It happens on some makes. WECO is another one I have seen that on.

So you can either be brave and open it to correct it, or return the battery for an exchange or warranty repair.

It is not uncommon for battery manufacturer use other known brands BMSs, Pylontec lend theirs to alot of others, so there are alot of brands out there that are out the box working with Victrons software that way.

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yann avatar image
yann answered ·

@Alexandra I tried with the two I have, same behaviour...

I already opened the battery because one of the two has a BMS issue and they send me a spare one to replace it. There is no separate shunt for the current measure, the shunt is part of the BMS board and can't be reversed... They measure in the wrong direction by design.

But I'm pretty sure the battery driver on the cerbo can ben hacked to reverse the readings, I just don't know which file it is...

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ commented ·
Hi Yann, its a binary, compiled from closed source C code.


Replacing the canbus cable for a different one wont work.


The best solution that I can think of is for PAND to fix their software.

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Alexandra avatar image Alexandra ♦ mvader (Victron Energy) ♦♦ commented ·
Since it is CAN changing the whole system around to suite one item, then all other items using the bus would be backwards doesn't make sense.

The BMS is not following the correct comms protocol. They should be the ones to adjust.


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yann avatar image yann mvader (Victron Energy) ♦♦ commented ·
Hi @mvader (Victron Energy)

I just wanted to say I would be, as many others I think, really really happy, as a victron installer, user, and a bit geek when I have time, if the full VenusOS was turned opensource :)

I think it would really lead to great improvements in many ways.


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Alexandra avatar image Alexandra ♦ yann commented ·
@Yann

Not sure what exactly you are asking for?

It is fully open source. GUI mods and driver mods are done by enthusiasts all the time..... guys even add python scripts in.

There are plenty posts on the forum under the modifications space from guys who doing that very thing.

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yann avatar image yann Alexandra ♦ commented ·
Well, no, it's not. Most parts of venus os are open source, as it is linux based, but according to what matjis vader answered me, some victron drivers are closed source. I guess he knows what it is spoking about :D :D
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Alexandra avatar image Alexandra ♦ yann commented ·

It's as open source as a person who can read it... lol someone is editing it...

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yann avatar image yann Alexandra ♦ commented ·
??
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