question

Juraj Nikolov avatar image
Juraj Nikolov asked

(parallel) connection of different battery types

Technical question :)

At home I have, unplugged - unused (in good condition) two battery packs (2x 16x280Ah JKBMS from one project),
whose capacity I would like to use in the system that already runs at home from 4x pylontech U3000C (ESS mode, not offgrid).

Would using the following involvement be safe enough? :

1) MP + GX = Master smartshunt (as main battery managment)
2) 1secondary smartshunt + pylontech pack (charge and discharge 148A) + solo raspberryPi Ven-OS (only for monitoring battery healt)
3) 2secondary smartshunt + 15x280A JKMBS (set on BMS charge and discharge 148A) + solo raspberryPi Ven-OS (only for monitoring battery healt)
4) 3secondary smartshunt + 15x280A JKMBS (set on BMS charge and discharge 148A) + solo raspberryPi Ven-OS (only for monitoring battery healt)
5) dva clanky by ostali ako spare, alebo dokupit dalsich 13clankov na dalsi battery pack.

Charging control would be a solution through the voltage of the MPPT regulators and Master SmartShunt, not through the BMS.

In this way, safe balancing between battery storages will be ensured ??
Will it be possible to operate such a connection via ESS?


Thanks for inspiration.

battery charging
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Alexandra avatar image
Alexandra answered ·

Pylontec is 15s. Your others are 16s.

Charged voltages are different i would imagine, unless you have programmed/set up the JK bms otherwise?

So on face value not compatible.

One set will either be overcharged (pylon) if you match the vomtage of the 16s.

Or

The other (jk bms) will be undercharged (and maybe not balance again depending on set up).

Otherwise ESS works quite fine with non gx connected dvcc controlling batteries and a bmv. I have quite a few systems in the field running like that.

Balance of storage sort of self manages with a good bus bar current sharing system

So you would have to address the charge voltage difference before continuing.

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Juraj Nikolov avatar image Juraj Nikolov commented ·

I wrote that I have 2x16 cells, but I also wrote that I would use 2x 15 cells of 280Ah, exactly the number of cells that pylontech has :)

In t, all three batteries should be set to the same voltage of 52.5~53V max. With the fact that 4xU3000C can charge and discharge 148A. I would set the same discharge and charge current of 148A for both JKBMS batteries.


I just want to check my theory if the battery blocks {as a whole 15 cells} (packs) will balance themselves if one block(of 15cells) is initially charged eg. Another 90% to 80% and another to 70%, I assume that they will balance themselves and the current from the accumulator will not exceed 148A, ked to bude mat tak nastavene v BMS. Before I connect it I need to make battery case.


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Juraj Nikolov avatar image Juraj Nikolov commented ·

@Alexandra

Can I ask ? :)
Why VenusOS ignore settings in ESS and DVCC? This is basically the reason why I want to connect the 2 battery packs to eliminate the problem.

In DVCC, I have set the maximum charging current to 100A ... but it charges more and ignores the 100A limitation, can you advise why? I assume that pylontech's BMS is superior (master) to that setting, and if Pylontech has the option to charge 148A, the system will charge 148A if it has that option...
In ESS, I have set the limit for inverter power to 4000W, VenusOS is ignoring this setting...
I also set the Feed In to 3500W and it simply ignores it, sending 4000-4500W + plus idle consumption of the object until the converter overheats...
Have you encountered something similar?
Thank you |:)

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Alexandra avatar image Alexandra ♦ Juraj Nikolov commented ·

Do you still have the Pylontecs reporting to and controlling the system?

Are you following your set up in the main post?

You will need to remove that and use the victron shunt now one of them set as the master for the bank.

If there are still problems simplify and remove any monitoring that is not the most basic needed for thr system. So all extra shunts dont connect to the main GX.

And i dont feedback to grid so cant comment on the not following the set amount, other than to say update the system so they are all on the latest firmware.

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Juraj Nikolov avatar image Juraj Nikolov Alexandra ♦ commented ·

@Alexandra

I don't have the other batteries connected yet, I'm still only using 4xU3000C pylontech battery and BMS control of the pylontech solution...Just to be sure, JKBMS and the batteries I wrote about are not connected. :) Also no Shunt connected or some else.. used the last released Firmware for all devices, for GX also beta versions :)

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Alexandra avatar image Alexandra ♦ Juraj Nikolov commented ·
On the battery charging no. I have not seen the over amp charge when limited in DVCC

Have you tried just limiting the input current limit a bit?


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Juraj Nikolov avatar image Juraj Nikolov Alexandra ♦ commented ·

@Alexandra

You mean MPPT as input ? Or ACin as input ? Because it is charging from MPPT not from ACin. I was expand my PV field on 4.9kwp. I used before only 6 kwp PV field and this limitation in DVCC was working, after expanding PVfield (for cloudy days) start to do this "ailments" .
One way how to solve it is add Battery, another is fix software bug... I see it as SW bug :) And I set 100A becouse one par of pylontech cable hold 125A... I orded next par but, if it start to charge with 220A the pylontech battery they start to burn on 100% if is SW bugged...
For me it is incomprehensible why it is working on 6wkp and why it is not working on 11wkp on DVCC ...
As for the inputs, I thought that the system is regulated by self via the MPPTs , that if the mppt 150/85 would offer 4kwp and the charge limit would be set to 100A, then other Mppts would be cut in performance, so that the charging would not exceed the set 100A... by 3x 150/45 mppt it works so, after adding 150/85... not . Magic things :D

By another offgrid instalations I use 16kwp and works it fine... this is hapen only in ESS mode. As I say "Magic things :D"


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Alexandra avatar image Alexandra ♦ Juraj Nikolov commented ·
Sorry for the feedback i was thinking of the input current limit.

For the PV control connected to Grid, with battery charge. I have not seen an issue, but then we don't feedback. It does obey charge limits.

If you read the ESS manual though you will see for grud feedback, the DVCC limit from the battery is ignored. It is possible it also affects the user input value as well. It is dif6to work out why your system is behaving unexpected over the internet.



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