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Old 01-07-2022, 16:51   #1
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Do I still need a battery monitor if my MPPT and BMS already give same infos?

Hi,


I am planing to get a lifepo4 battery that has a bluetooth daly bms inside. Plus I'll use a victron smartsolar MPPT.
Both of these devices give a bunch of informations through bluetooth via their smartphone app.
So I was wondering if a battery monitor was still needed?
I am not talking about the expensive victron BMV ones, but cheap monitors you can find on amzn or ali. What informations do the BMS and the MPPT lack? To me they seem very complete...
Thanks
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Old 01-07-2022, 17:00   #2
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Re: Do I still need a battery monitor if my MPPT and BMS already give same infos?

I'd get one. I did actually. An expensive one too. Cheaped on the lifepo4 batteries though. Go figure.
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Old 01-07-2022, 17:32   #3
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Re: Do I still need a battery monitor if my MPPT and BMS already give same infos?

if the battery bms gives voltage, current, and state of charge. then you don't need a 2nd one. we have no idea what your BMS gives...

if it does not give current or SOC, then you should buy one. get a victron they are not expensive
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Old 02-07-2022, 03:55   #4
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Re: Do I still need a battery monitor if my MPPT and BMS already give same infos?

The advantage of having a Bluetooth bmv is it will relay tail current to the mppt controller
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Old 07-08-2022, 08:56   #5
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Re: Do I still need a battery monitor if my MPPT and BMS already give same infos?

Quote:
Originally Posted by goboatingnow View Post
The advantage of having a Bluetooth bmv is it will relay tail current to the mppt controller
I have a smart bmv712. Just to be clear, When I get my new victron solar controllers, I can connect the BMV to them and it will relay tail current? Can't the solar mppt sense tail current current anyway?
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Old 07-08-2022, 09:05   #6
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Re: Do I still need a battery monitor if my MPPT and BMS already give same infos?

It also depends if you have 1 or 2 banks, the monitor can be connected to both.
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Old 07-08-2022, 09:11   #7
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Do I still need a battery monitor if my MPPT and BMS already give same infos?

Quote:
Originally Posted by Jerry Woodward View Post
I have a smart bmv712. Just to be clear, When I get my new victron solar controllers, I can connect the BMV to them and it will relay tail current? Can't the solar mppt sense tail current current anyway?


To sense tail current you have to be able to differentiate what’s going into the battery as opposed to coming out of it.

So no a mppt device can only sense charge current and only charge current that it’s producing.

Yes if you add a BMV712, it will relay total battery current. So the Victron mppt can therefore assume that the difference between its current output and the BMV712 is in effect tail current ( that can be confused where’s there is multiple chargers but Victron Ve.smart network handles that too )

I use this approach on my mppt , Victron mains charger and bmv 712 to correctly deduce tail current and also to synchronise the chargers.
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