BMV for 2 batteries and a 3 way switch

Question

question

muth asked Dec 11, '22

BMV for 2 batteries and a 3 way switch

Hi,

I've got 2 lifepo4 160ah battery:
- one old (non smart)
- one new (with smart option

Both are managed with an external BMS ve.bus.

I don't want to put the battery in parallel because one is more than 3 year old and the other is brand new. So I decided to put a 3 way switch for choosing between the first or the second battery.

Can I monitor my state of charge of the both battery with a BMV 712 ?

I make a scheme for better understanding:

Is my wiring good ?

BMV Battery Monitor Lithium Battery BMS SmartShunt smart lithium

capture-decran-2022-12-11-a-171534.png (95.4 KiB)

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Modifications Space

Node Red Space

Answer 1 · 2022-12-11T16:47:11Z

muth answered · Dec 11, 2022 at 04:47 PM

Ok, I'm answering my own question, I was pretty sure that the BMV can get the % of charge of a second battery. But he can only get the voltage of the second one.

So it is impossible with 1 BMV and 1 shunt, I need 2...

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 2 · 2022-12-11T16:53:44Z

kevgermany answered · Dec 11, 2022 at 04:53 PM

Yes, for SOC you need two.

Your diagram above wouldn't work, either, Ancienne batterie would bypass the shunt. So no current monitoring either.

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

question