Hi, is it possible that upgrading smart bluetooth fimrware from V2.5 to V2.52 leads to MPPT absorption voltage régulation unstability because battery voltage, current and temperature are shared through V.E. smart netword ? Upgrade was performed on both devices: BMV 712 and MPPT 150/70. Batteries are supplying a 48/5000/70 MultiPlus inverter. When consumption is low (about 150 W) absorption voltage is stable and MPPT current is shared as following 4 Amps to absorption and 4 Amps for the Multiplus load. As load increase to 1000 W (water pump running) additional 20 Amps current is supplied by the MPPT. Battery absorption voltage is stable at 58 V. But when pump stops, the MPPT voltage starts to oscillate which leads to battery current between max charging current -30 A) to 0 every 5 seconds. To stop theses oscillations, i’ve to stop the charging mode of the MPPT and start it again a few seconds later.
How high is the voltage drop ( round trip) between mppt and battery at 20-30 amps.
If the battery differs too far from mppt the sense function is probably disabled, that could lead to bad vibes.
This works for analog sensing, i guess its also included in the smart network.
HI Ludo,
Voltage drop is about 1,76 V before MPPT compensates with the current to come back to the absorption voltage of 58,16 V.
May be some delay due to the V.E. smart communication time makes the stabilization impossible when current consumption suddenly stops.
Your wiring is too thin, or you are losing voltage over connections or circuit breaker.
You should bring your loss down to under 0.5v then it should get better.
But only gut feeling…
What wiring size do you have installed now ?
Pls check correct size in your mppt manual
Ludo,
thanks for your advice.
Copper wire size between MPPT and 48 V Battery bank is 25 mm² with 3 m total length.
Copper size of wires between battery bank and Multiplus is 70 mm² with about 4 m total length.
I’ve measured each 12V 220 Ah Victron Gel battery internal resistance of about 0,016 ohms with SM8124A device. Which gives a battery bank total internal resistance of 0,064 ohms.
1,76 V voltage drop for 20 A gives a 0,088 ohms resistance (depending on how accurate is the voltage drop measurement…)
MPPT bulk charging current is set to 30 A.
Should be 35 !
For my feeling the 220 gel batteries don’t habe enough power for the 48/5000 multi.
AGM or lithium in 200 should be ok
OK, but maximum power delivered by Multiplus is about 3 kW.
Things i’d like to try is to downgrade to previous blutooth firmware, because i feel that issue came with this upgrade from V2.5 to V2.52.
Do you know if its easy to get the previous firmware back ?
I have no idea.
OK.Hope someone reading the post will know how to do it.
Regards.
My advice: don’t update the Bluetooth interface to version 2.52 on any device without a compelling reason.
If the system is running well with BT interface V 2.50, don’t touch it!
I have 5 units running on v2.52, absolutely no problems. I think you’re barking up the wrong tree.
@ Ludo,
I’ve disconnected the MPPT from the V.E. smart network and nothing changed. From time to time, always the same voltage oscillations and issues to regulate the current when in absorption mode without inverter consumption.
I’ve to try something else.
By the way, MPPT to battery wire section is 35 mm² and voltage drop @ 39,7 A is 56 mV for negative wire and 91 mV @ 36.6 A for the positive wire including, 300A fuse and Victron 275 A switch.
Regards.
Ok, at least it proves the bt network is innocent.
In your previous posts the voltage drop was 1.7v, the wiring 25 sqmm..
Hi Ludo,
I was wrong about wiring size (real size is 35 mm²) and measurement came from victron connect graph reading. Last measurement was made in steady conditions with multimeter @ 39,7 A and 36.6 A.