Inverter selection

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johanz asked Jul 10, '23

Inverter selection

Morning I am in process of changing my inverter in my offroad motorhome from the existing Dometic combi 2500 inverter (have change to Li-Ion batteries) and want to go for the Victron but need your recommendations, my existing equipment:

4 x 300 watt solar panels
Morningstar TS MPPT-45 regulator
Victron Orion Smart DC-DC charger isolated 24/24-17
Victron BMV 712
3 x Pylontech UP2500 (new model) Lithium-Ion Phosphate batteries
Truck Starter batteries Victron 24V battery balancer

Requirements:

24 Volts Inverter +-3000VA
Inverter must communicate directly with batteries
Remote panel for on/off & information if possible (not remote switch) Information can also be via Blue tooth
Blue tooth connection
All other standard functions

The confusing selection is which is the best way to go, I do not require all the functions of the Cerbo GX & the Multipluss 11 does not have blue tooth which I find great to use on the BMV, where we travel there is most of the time no internet so this function would be limited & blue tooth far more usefull, also in all reality all the functions are hardly used & I do not need to connect fuel levels etc. to the unit

I do require a panel whereby the inverter can be swtiched on & off but blue tooth must still operate, I understand that theColor control GX does not have blue tooth

Can you advise the best cost effective way to go

Thanks Johan

inverter rs

2 |3000

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Modifications Space

Node Red Space

Answer 1 · 2023-07-10T11:41:34Z

I would go with 3000va multiplus ii and colour GX. For your requirements you'll need a gx device of some kind. If you've got generator and shore hookup then go quattro for the double AC inputs.

You could use a cheap tablet and a raspberry pi running venus os instead of colour gx. The tablet would access gx device via internal LAN (internet) connection. You dont need external internet for this to work, ie on the same wifi with no external access to internet but the tablet and gx can communicate as they're on the same local network.

Another option is to just use a screen on the raspi. Much cheaper but more work involved installing of course.

You mention the requirement for communication with batteries I believe you also need GX device of some kind and supported battery (Pylontech are).

Personally though I don't really like using battery/BMS communication with solar equipment and I personally prefer to have a separate Smart shunt installed and use that instead. (it's long but I've explained why i think this below)

My logic for preferring smart shunt and not using BMS communication:

The main benefit in my opinion of BMS communication is that the battery can tell solar system to reduce charge rate when almost full to protect the battery/extend battery life. However if you set sensible absorption voltages and use a separate smart shunt for battery monitoring then this reduced charging happens anyway without communication as voltage is set constant in absorption phase so current reduces overtime.

Then with a smart shunt you've essentially got 2 safety systems, the solar equipment should cut-off based on smart shunt settings (which I set as more conservative). Then the BMS would have more extreme cut off settings but in theory these should only ever be hit if there's an error with the smart shunt/solar equipment.

If you just have BMS and no shunt, then you just have one safety device and if that breaks for whatever reason the battery could get damaged.

Answer 2 · 2023-07-10T11:46:46Z

nickdb answered · Jul 10, 2023 at 11:46 AM

Pylontech require the battery to be managed for their warranty, so you're tossing that away if it isn't used. They also have one of the best/most mature BMS's around, it works well. Choosing to rather use a shunt is trying to fix something that isn't broken.

If any BMS stops working or is disconnected, the system will shut down regardless with an error 67. Zero chance of breaking the battery. Good batteries have good protection.

4

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matt1309 commented · Jul 10, 2023 at 01:00 PM

Is that true?

I was under the impression that if the inverter settings were confirmed by Plyontech or Authorised seller then lack of communication does not void warranty.

At least that's what's noted in the documentation I received with US3000: (number 7 is what I based my understanding on) Maybe this is UK only?

I see your point but to me the benefit of BMS communication is outweighed by having the two systems separate.

I prefer BMS to purely manage the battery and not manage the wider solar system/charge rates etc.

Good protection can still fail... Arguably overkill but makes me sleep easier

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nickdb ♦♦ matt1309 commented · Jul 10, 2023 at 01:11 PM

#7 seems to be a newer addition, as long as you are authorised to do it and it is noted and accepted when you register your batteries then you should be fine.

Without proper management, if the battery has an issue and requests low to no CCL, your system will keep charging it until it has to intervene by itself. It doesn't take much to turn cells into balloons. Considering the expense, not letting the battery do what it is designed to do, is just unnecessarily complicating things.

Not all batteries are equal, and if the BMS was hopeless, I would agree a shunt could be a better way to go, but I wouldn't do that to Pylons myself.

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matt1309 nickdb ♦♦ commented · Jul 10, 2023 at 02:17 PM

Fair enough, I suppose I just don't trust BMS manufacturers enough then.

I think I'm stuck in the mentality that BMS is a safety device, rather than a solar management device.

So in my head all scenarios where I need BMS to act i dont want/need it to communicate. Like you said doesnt take much to swell a cell so you dont want to wait for coms to tell solar to slow down/turn off. You want it off.

But i suppose it's more added benefit of having coms after the fact rather than relying on them for the safety element.

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nickdb ♦♦ matt1309 commented · Jul 10, 2023 at 01:32 PM

Seems to vary by the battery:

The warranties in respect of the Product only apply if the Product:

is purchased from Pylontech or an Authorized Reseller in the Territory;
has the official Pylontech serial number;
is installed in the Territory and indoor environment;
is installed, operated and maintained in accordance with the Product Manual; and
be used on a daily cycle basis and only for energy storage system,

No #7.

Authorised is also specifically defined as a regional distributor or a reseller approved by pylon themselves.

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Answer 3 · 2023-07-10T13:41:14Z

johanz answered · Jul 10, 2023 at 01:41 PM

Thanks for all the info

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