Isolating battery bank from Classic

[asdex]

Hi, I noticed this comment while reading questions and answers on the forum:
"the classic wont like having the battery removed with the pv still connected. If you do this you'll need to remove the pv first."

So is it correct that is isn't good to isolate the batteries from the Classic while the PV panels are still connected?
If so what problems will it cause? I have a circuit breaker between my battery bank and the Classic.
Thanks,

[Resthome]

Hi, I noticed this comment while reading questions and answers on the forum:
"the classic wont like having the battery removed with the pv still connected. If you do this you'll need to remove the pv first."

So is it correct that is isn't good to isolate the batteries from the Classic while the PV panels are still connected?
If so what problems will it cause? I have a circuit breaker between my battery bank and the Classic.
Thanks,

You should also have a Breaker on the PV at the controller so the PV can be disconnected from the controller.

[asdex]

Yes, I have that as well. But should I always turn off the PV first?

[Vic]

    "So is it correct that is isn't good to isolate the batteries from the Classic while the PV panels are still connected?
If so what problems will it cause? I have a circuit breaker between my battery bank and the Classic.
Thanks   ..."

Hi asdex,

As noted by Resthome,  it is good practice to always shut OFF the PV input breaker to the CC first,  then open the battery breaker.  AND  when re-powering the CC,  do the reverse  --  battery breaker ON first,  PV input breaker second.

The result in not doing things the proper way are essentially unpredictable.   You might get away doing things backward,  but  the results may result in  improper behavior of the CC.

The battery voltage operates the CC,   not the PV input,  at least for most MPPT CCs.

Also,  it is a very good idea to place both the PV in,  and battery breakers for the CC close to the CC,  within arm's-reach.

The above is good practice for any CC

[asdex]

Thanks for that. Yes I have them close (as per picture attached.

[Vic]

asdex,

Thanks for the pic,  nice clean installation,  using some creativity.

Vic

[boB]

Well, I suppose the answer depends on what you are planning on doing with
the  Classic's battery terminals  while it is still running off of
only the PV input.  I disconnect the battery from the Classic quite a bit
without any problems.

If you turn off the battery and the Classic stays running and then reconnect
that same battery a moment later, it should also be OK.

If you were planning on reconnecting a DC load like an inverter to the Classic's battery terminals
with the battery disconnected, then there would be very little filtering on the
battery side and if the load is very large, the 120 Hz ripple current might not be so good
for the Classic's battery side capacitors...  But usually, in say, Solar tracking mode,
turning off the battery breaker will just make the Classic shut off from the PV input
because it sees a large-ish change in power and thinks it's time to sweep.

boB

[asdex]

Thanks for your replies. I'll make sure I isolate the PV panels first from now on. Its generally when I have wanted to work on the batteries I haven't taken note of which one I turn off first. I will now.
Cheers,

[boB]

Yes, just working on the system, it doesn't matter which one you turn off first.

PV first I suppose but shouldn't really matter.

boB