question

alan avatar image

MPPT RS remote on off and pylontech

After some clarification of the behaviour of the RS when connected to pylontech batteries.

Lithium pre-set is selected which in turn changes the remote mode to BMS, which would be logical.

DVCC is on on the venus device, pylontech detected over the can bus etc...

The MPPT RS shows networked operation as external control and BMS,

1619236528994.png

yet the RS stays in BMS off mode and will not charge.

Switching the remote mode to remote on/off with the stock jumper installed in the I/O plug enables charging?


I can't seem to find any information anywhere detailing the behaviour of these modes apart from the mention of the VEBus BMS, shouldn't the setting relate to all BMS's?


BMSmppt rs
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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Alan

I am curious where you saw the instruction to set the MPPT RS to the Lithium battery setting?

That enables the allow to charge, allow to discharge contacts. This is not necessary for the Pylontech which uses the DVCC controls instead. So in this case the MPPT should NOT be set to lithium.

I can see why that is confusing of course, but also, I don't think there is anywhere in the Pylontech instructions that directs you to do that, so please let me know if there is, or if you decided to add that step yourself.

There is a somewhat obscure note of this behaviour in the MPPT RS manual - I will consider how to make the documentation clearer in this regard.

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alan avatar image
alan answered ·

this doesn't make a lot of sense, as in its not very logical.

I can now see how choosing that pre-set selects this, however as there’s a BMS and the mppt reports BMS controlled under network operation it would be more logical that BMS would be the valid option to be selected under remote mode.

I chose lithium to set a fixed charge curve when setting these fail safe settings as per manual

The settings below can be set as a precautionary measure.

1619263704039.png


I assume this is In the case comms are lost from the venus/pylontech etc.

While I understand the pylontech will protect itself, I would rather not have the BMS shutting down on high voltage etc. Some sites can't be accessed for over a week if the venus fails.


If you select Li-ion as a built in preset you cannot change the voltages

If you select user defined after you select li, then remote mode enables again.

If you select lifepo4 under select preset, then remote mode enables and selects BMS and doesn't charge. With the screen on the RS starting BMS off.

If you don’t change anything the voltages can’t be adjusted.

So what is the correct settings to select?


apart from this small issue, the RS is a complete game changer. Easy to install, electrically flexible works well and has the same victron reliability that we have enjoyed for decades.


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