Efficiency 16s, 17s, 18s

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question

dirk-s asked Oct 21, '22

Efficiency 16s, 17s, 18s

Hello,

Currently I'm using pylontech US3000C batteries with a Multiplus II GX 5000. The cells are 15s inside Pylontech. Nominal Voltage 48V.

I plan do make a DIY Batterie with at least 16s. But could also make the battery with 17s or 18s. I will never charge more than 3,55V per Cell.

Will the Multiplus be more efficient with the higher voltages or is there no effect?

Thanks so far.

Bye Dirk

Multiplus-II 48v battery

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apple047 commented · Oct 05, 2023 at 07:40 PM

Hi @Dirk_S

Just checking if you went ahead with your project? Any complications:advice you may have?

I’m contemplating of going all in with 18s, checked the MPPT and it goes up to 65V, inverter the same, shunt it ok, no other components connected to the DC lines, Cerbo is on a separate 24V supply

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dirk-s apple047 commented · Oct 05, 2023 at 07:55 PM

No, because of a big health issue I stopped it. I still use my 6 US3000C.

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Answer 1 · 2022-10-21T08:03:27Z

Paul B answered · Oct 21, 2022 at 08:03 AM

there would be no measurable effect I would think.

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Answer 2 · 2022-10-21T08:11:03Z

pedaaa answered · Oct 21, 2022 at 08:11 AM

you will definitly have more power available. As you have same Amps, but more Volts

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dirk-s commented · Oct 22, 2022 at 03:59 AM

Current will reduce and power remains the same as far as I know.

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pedaaa dirk-s commented · Oct 22, 2022 at 07:01 AM

why should current be reduced? You have any source or manual that says so?

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dirk-s pedaaa commented · Oct 22, 2022 at 07:59 PM

I have read it here or in an other forum from a user, who observed it on his installation.

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Answer 3 · 2022-10-21T08:55:52Z

jeanmarie answered · Oct 21, 2022 at 08:55 AM

not more power but more energy, yes

just keep in mind that

- choosing a 16S or 17S architecture will make it incompatible with any existing pylontech (15S)

- 17S means voltage can goes as high as 62V (3,65x17) all your hardware must be able to accept such a voltage

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pedaaa commented · Oct 21, 2022 at 01:49 PM

also more power.

say a multi 5000 does 70A max.

with a typical 15S voltage of 50V thats 3500W Power.

With a 17S system at same charge level, you would have 56,7V, which will provide 3967W

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dirk-s commented · Oct 22, 2022 at 03:58 AM

Pylontech will be replaced. Other hardware accept higher voltage.

Do you know something about efficiency?

Power will not increase. Multiplus is controlled by power and heat development as far as I know.

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Answer 4 · 2022-10-21T13:42:00Z

dirk-s answered · Oct 21, 2022 at 01:42 PM

I will replace my Pylontech. So no issue at all. I will never charge up to 3.65 Volt. Max Voltage per Cell ist 3.45 Volt. I never use more. It is not necessary for Lifepo4.

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Answer 5 · 2022-10-21T20:43:50Z

Stan answered · Oct 21, 2022 at 08:43 PM

First limitation is BMS. Not all can handle 18S.

Second limitation is mppt. Victron I think can charge to 64V, but I have never tried it.

Third limitation is inverter. MP2 has input voltage 38-66V, so it is ok, but better to check other inverters, just to be sure.

Forth is the law. Voltage above 60V is not considered as "safe" voltage.

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dirk-s commented · Oct 22, 2022 at 03:56 AM

Thanks, but first I will use a JK BMS which is flexible up to 24 cells.

Second, I will not use MPPTs.

Third point: I want to use Multiplus. No other inverters. In case in future is there an issue, I will remove one cell. It is DIY and very flexible.

Do you know something about efficiency increase?

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Answer 6 · 2022-10-21T21:31:50Z

hardy-tuner answered · Oct 21, 2022 at 09:31 PM

All mppt delivering more power with higher voltage, limiting factor is the Ah from mppt.For example:

Pylontech @52V with 20A =1040W

Selfmade 17s @58.9V with 20A = 1178W

So around 13% more power delivery with one mppt is possible…

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