mppt still run, power off

Announcement - Help us fight the BOTS! Please report all spam including stuff in your inbox!

Patalhetas

New member
Joined
Oct 24, 2019
Messages
21
hi to all,
Today I find some estrange,
I shutdown my system for testing the protection, i cut the power supply to multiplus II, battery charger (simpbms bms) Cerbo Gx, but the mppt connected via ve.direct to GX in absorption mode .... still send energy to the batterys .... is dangerous because this energy goes without control.
Is possible fix this fault ? my config ? ...
 

OffGridInTheCity

Active member
Joined
Dec 15, 2018
Messages
1,746
Not sure of your setup - but yes, an MPPT charge controller that has input and an output connection to the battery will continue to charge the battery as long you have (PV) input coming in. I handle this by having circuit breakers between the charge controller and the battery bank - and turning them off is one of my checklist items before working on the battery.
 

italianuser

Member
Joined
Feb 25, 2020
Messages
361
I bought two mechanical switches (horrible big black blocks!) and DC MCBs to interrupt both lines (PV-Controller and Controller-Battery). At the end I mounted DC MCBs because they fit nice on DIN rail while mechanicals switches don't.
 

Korishan

Moderator
Joined
Jan 7, 2017
Messages
6,552
Could always put something like this on the lines:
1621463757111.png

Looks really neat on the wall, and serves a practical application. When the handle is up, system is off, handle is down, system is live (or vice versa). Very easy to see from a distance w/o the need for power to light up an LED

btw, that's called a "Throw Switch" or a "Knife Switch" if you're curious ;)
 

Korishan

Moderator
Joined
Jan 7, 2017
Messages
6,552
The great thing about a Throw Switch is, they won't wear out from repeated use and you won't degrade the auto-disconnecting ability of the breaker.
MCB's might not suffer from this, but using a breaker as a 'switch' can actually weaken it and keep it from tripping, or tripping early. So something to keep in mind when putting switches of any kind in the system. If it's a rare time the disconnect needs to occur, then a breaker would be fine. But if you find that you will need to disconnect often, use a different switch in line with the breaker and let the breaker do its own thing.
 

Patalhetas

New member
Joined
Oct 24, 2019
Messages
21
Hehehe bigs breaks ... but if U don’t there to open it ....
The dangerous still there !!!
 

floydR

Member
Joined
Aug 23, 2017
Messages
1,312
Put a 2 pole contactor/shunt trip on the line that is powered on by the Victron system and opens when it doesn't have power?
Later floyd
 

Redpacket

Member
Joined
Feb 28, 2018
Messages
1,307
We all know the knife switch above is a joke :) Safety of those things certainly is! LoL Sparks & arcs would add to the entertainment!
Like said above you need some DC breakers:
Solar panels > breaker > MPPT(s) > breaker > shunt > batteries.
 

Patalhetas

New member
Joined
Oct 24, 2019
Messages
21
We all know the knife switch above is a joke :) Safety of those things certainly is! LoL Sparks & arcs would add to the entertainment!
Like said above you need some DC breakers:
Solar panels > breaker > MPPT(s) > breaker > shunt > batteries.
I think U don´t understand my point. (experience)

the only "problem" is the mppt don´t stop working when cerbo/bms/inverter stops working for some fault !!
 

Korishan

Moderator
Joined
Jan 7, 2017
Messages
6,552
The MPPT will continue to try to output power as long as their is a place to deliver it to. The only way to turn it off is to disconnect it's power source, ie, the solar panels.
That is, if the MPPT controller is separate from the inverter, which appears to be what you have.

So, as mentioned several times by different ppl, you would disconnect the solar panel from the MPPT via a switch of some sort, whether it be a break, an MCB, or other switch.
Redpacket went as far as to give a word diagram of the layout, Solar Panel -> Breaker -> MPPT -> breaker -> .....
 

Patalhetas

New member
Joined
Oct 24, 2019
Messages
21
So, as mentioned several times by different ppl, you would disconnect the solar panel from the MPPT via a switch of some sort, whether it be a break, an MCB, or other switch.
The only way I see is, when the shunt trip is off, in the same time a contactor cut the power from the panels !
 

Korishan

Moderator
Joined
Jan 7, 2017
Messages
6,552
The only way I see is, when the shunt trip is off, in the same time a contactor cut the power from the panels !
Yup, you can do that too.
If you use a shunt trip contactor, you can have several contactors connected to one shunt trip connection. So you'd have 2 shunt trips that are wired in parallel to each other. When one pops, the other pops.
 

slimf

Member
Joined
Sep 26, 2017
Messages
179
I noticed this behavior with my setup, and honestly, with the size of some of their MPPTs, it doesn’t seem right to me. The MPPT is supposed to be controlled - and you’d think when it looses communication with the GX device that it would have some fall back behaviour..
 
Top