question

simonc avatar image

bmv 712 wiring for 48v with mid point

hi everyone,

my first post looking for some help , i have a 72v battery pack (forklift) 36 x 2volt 400amp, i want to use my multiplus 3000 48v inverter and phoenix 2000 24v inverter at the same time, splitting the battery pack into a 48v and 24v battery packs how would i wire the bmv 712 with mid point on both battery packs? can i use my gx venus on both batteries? the 48v is using 2x 150/35mppt and one 150/35 mppt on the 24v.

thanks

BMV Battery MonitorVenus GX - VGX
2 |3000

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3 Answers
markus avatar image
markus answered ·

Hi Simonc,

yes this is correct.

My answer was related to "how would i wire the bmv 712 with mid point on both battery packs?"

So i thought you would like to use one BMV and monitor 2 Banks with midpoint voltage with it. That is not going to work.

If your Battery Banks share the same minus, then its possible to configure one BMV to measure voltage and current from the first Bank, and only voltage from the second Bank.

The second wire for midpoint measure can then no longer be used for midpoint measurements as you have to connect it to the second Bank.

Markus

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hi,

Darn it !!! yes that was the idea, and was assured by the sales guys that it would work for both banks after and after reading The BMV-712 features an additional input which can be programmed to measure the voltage (of a second battery), battery temperature or midpoint voltage. ..looks like the bmv 712 is going to be used only on the 48v bank.

wkirby avatar image
wkirby answered ·

I would really not recommend split wiring the battery bank that way. It's not a good idea to have two different chargers (and two different loads) on one bank of batteries. This is because the loads on the 48V MultiPlus might be more or maybe less than the loads on the 24V inverter. This will cause your whole battery bank to go out of balance.
If you did connect the BMV at the mid point of the 72V bank (36V) it would work, but it would be giving balancing alerts very quickly for the reasons I said before.

The best way for your situation is to completely separate the two systems one 48V system and one 24V system. Then have a BMV to monitor each separate battery bank.

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hi, sorry about that , didnt explain it very well, i will be using 24 x 2v batteries for the 48v bank and the remaining 12 x2 batteries to make the other 24v bank. so basically two separate batteries banks.

all the diagrams i can find on the bmv712 are using 12v batteries not 2v linked in series, i see the bmv 712 is for two battery banks

markus avatar image
markus answered ·

You will need 2 BMVs to monitor 2 separate Battery Banks with midpoint Voltage.

There are 2 Red wires to connect to the BMV. You have to connect the first one to the full series of the Bank and the second red wire to the half of the series.

Markus

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hi Markus,

i was under the impression that the The BMV-712 features an additional input which can be programmed to measure the voltage (of a second battery), battery temperature or midpoint voltage.