question

cookiedude avatar image
cookiedude asked

What is the correct order to power up a MP2

Hi,

I have a fairly simple system (not quite yet completed) Of A MP2 (10000) with 4 x pylontech US5000. Where the whole house feed first goes through the AC IN, then it goes from the AC OUT to the consumer unit.

I am unsure of the best way to start turning switches on to start the system.

My guess is to turn things on in this order:

  1. AC IN has an isolator switch (so first give the MP2 grid power)
  2. MP2 has its own switch (I-0-II) rocker. (turn on the MP2 to I-normal)
  3. I have a DC isolator between batteries and MP2 (on the positive cable)
  4. Each pylontech battery has its own rocker switch (so slowly enable each battery)

Does this sound sensible?

TIA Ross

viktron mp2
1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

dognose avatar image dognose commented ·

Given in "unforseen situations" any order could occur, none should really hurt / cause any damage.

Personally, I would switch on Batteries, first, just to avoid the MP / cerbo is starting to generate Battery Warnings after startup.

Iirc, documentation states that the MPs should be turned off, before disconnecting the batteries, hence for Power Up, I would also assume reversed order here.


Grid doesnt really matter, the MPs are able to handle a grid loss / restore at any time. (At least, That's part of their job description ;-) )

2 Likes 2 ·
3 Answers
Craig Chamberlain avatar image
Craig Chamberlain answered ·

I have an MP2 5kVA with 4 US5000 batteries and without any doubt the correct sequence is DC first then setup then AC.

However, it’s really important to use the built in soft start feature of the Pylontech batteries to avoid damaging your DC isolator due to start up surge. There is no need for a pre-charge circuit with US5000s.

So, starting with everything off including the US5000 rocker switches and DC & AC isolators, and the MP2 at the 0 position on the switch:

  1. DC isolator switch to ON
  2. Pylontech rockers turned on starting from master battery. This is usually the top one or more particularly the one without the Link In port occupied.
  3. Press Start button on master US5000. This will turn on each module in turn and initiate soft start to avoid surge.
  4. Wait for any separate Cerbo GX or other GX device to boot up.
  5. You would do any initial configuration at this point including using VE Configure to set up battery charge profile (very important) but can continue if that’s done.
  6. AC isolator to ON
  7. Switch MP2 rocker switch to ON (or charge only if desired)

Conversely to power down, you would do:

  1. MP2 rocker switch to OFF
  2. AC isolator to OFF
  3. Pylontech start switch held for (IIRC 0.5 sec) to initiate shut down.
  4. Pylontech rocker switches to OFF once shutdown is complete ( a few seconds )
  5. DC isolator to OFF
  6. For safety if working on DC system I normally disconnect the Pylontech positive cables from the batteries at this stage too since I have only fuses in the battery circuit with my DC isolator in the inverter circuit.

HTH.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Exactly the other way around.

4 (read the manual) -> 3 -> 2 -> programming everything -> test AC Out -> 1

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

dc-marine avatar image
dc-marine answered ·

One thing to remember is turning the batteries on before the multi may lead to a peak current from the multi pre-charging its capacitors. Using a pre charge circuit and first turning on the multi, then turning on the batteries helps prevent wear on your BMS.


AC IN would be the first input to activate.

2 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

nickdb avatar image nickdb ♦♦ commented ·

Do not precharge via AC IN. You will cause significant wear to the relays, this is not a supported method.

1 Like 1 ·
dc-marine avatar image dc-marine nickdb ♦♦ commented ·

I wasn't suggesting using AC to pre-charge. However are you saying that everytime you turn on a multi with only AC power, you're damaging it's relays ?

0 Likes 0 ·

Related Resources

Additional resources still need to be added for this topic