2 source to charge 1 battery bank

[MihaiPet]

It's possible to put 1 hibrid inverter mpp solar 3024gk(4kwp of panels)+lifepo4 battery bank(Eve 280ah) and another mppt solar  charger with 6 panels(1440wp) on the same battery bank(Eve 280ah) ???

[willie_b]

Hi @MihaiPet

This is exactly the same question that I wanted to come find out on this forum.. I'm hoping that someone has some experience with this. There's basically 2 things that makes me a bit worried to do this.

1. The BMS Comms from the battery can only go to 1 inverter as far as I know. And in my case the BMS control the Charge Amps via the interface
2. How would you split the battery connection at the Keto Breaker to ensure that the voltage being charged from 1 inverter doesn't influence the reading on the second one.

FYI: I have a Growatt SPF5000 that is completely maxed out from a panel perspective. In order to increase my ability to store energy, I need to be able to charge more before adding more batteries to my system. I have an existing Pylontech US3000.

 

Not trying to hijack your post - hopefully someone can help.

[WannabeSolarSparky]

23 hours ago, MihaiPet said:

It's possible to put 1 hibrid inverter mpp solar 3024gk(4kwp of panels)+lifepo4 battery bank(Eve 280ah) and another mppt solar  charger with 6 panels(1440wp) on the same battery bank(Eve 280ah) ???

Yes, you can use multiple mppts chargers on same battery, you just need to make 100% sure you do all the settings correctly.

[willie_b]

On 2023/11/21 at 8:40 AM, WannabeSolarSparky said:

Yes, you can use multiple mppts chargers on same battery, you just need to make 100% sure you do all the settings correctly.

Thanks for the response on this. At this point, I'm really looking for some sort of a wiring diagram of some sorts that would indicate what this could look like.

For arguments sake, 

1 X Growatt Inverter with own array of panels

1 X Victron 75/15 Charger with own array of panels

Connected via a KETO breaker to 

2 X Pylontech 3000C batteries.

 

The BMS is linked from the Pylontech to the Growatt to regulate charging. The question then becomes, how will the victron know when to charge at 16A and when it can push a bit harder to charge... Without the direct BMS interface, the Victron won't know anything and keep pushing to hard. This would ultimately result in a BUS error on the BMS.

Or do I have it completely wrong?

[WannabeSolarSparky]

59 minutes ago, willie_b said:

The BMS is linked from the Pylontech to the Growatt to regulate charging. The question then becomes, how will the victron know when to charge at 16A and when it can push a bit harder to charge... Without the direct BMS interface, the Victron won't know anything and keep pushing to hard. This would ultimately result in a BUS error on the BMS.

Since you mention/indicate you already have good comms then best is to leave that as is and treat it as the "main controller" to determine sett5ings from.

Now adding extra chargers should be pretty simple, make sure you set the separate chargers to about 100mv below the settings of the bms.
And maybe keep all voltages the same i.e. if the float voltage is 3.45V then on the extra chargers set their bulk/absorb/float all to 3.35V that way they will not interfere with the "main controller" controlling bms.

Note: I used single cell example on lifepo4 chemistry, multiply as required for your battery number of cells and adjust voltages according to the chemistry.

The batteries will only take whatever amps they need, just make sure all the possible combined amps do not exceed the batteries specified max charge amps..

Also find out how this setup will affect your warranties, battery suppliers have become weird with the rules of what you can or cannot do.

Edited November 27, 2023 by WannabeSolarSparky

[Chris Louw]

On 2023/11/20 at 9:31 AM, MihaiPet said:

It's possible to put 1 hibrid inverter mpp solar 3024gk(4kwp of panels)+lifepo4 battery bank(Eve 280ah) and another mppt solar  charger with 6 panels(1440wp) on the same battery bank(Eve 280ah) ???

I have a Axpert 5kW inverter running with  2 Epever 30A mppt on 10.5kWh Pylontech battery bank. Charge control done by Epever mppt.Axpert charging set lower to allow Epever to control the charging. Monitor with Solarassistant.

Axpert 4500 Watts panels , No 1 Epever 1500 Watts ,No 2 Epever 1880 Watts. Running for 2 years with good results.

[willie_b]

14 hours ago, Chris Louw said:

I have a Axpert 5kW inverter running with  2 Epever 30A mppt on 10.5kWh Pylontech battery bank. Charge control done by Epever mppt.Axpert charging set lower to allow Epever to control the charging. Monitor with Solarassistant.

Axpert 4500 Watts panels , No 1 Epever 1500 Watts ,No 2 Epever 1880 Watts. Running for 2 years with good results.

Thanks for joining the conversation Chris,

So based on description of your system - the BMS cable from the Pylontech battery bank is connected to your Epever MPPT?

 

The reason why I'm harping on about the BMS and the comms is primarily due to the fact that the BMS determines how much charge could be fed into the battery by virtue of the Comms cable into CAN or RS485 Port. So, once you charge the battery with anything that doesn't have the BMS comms linked - it will just go full tilt with 30A X 2 (Excluding Axpert) in your case, and charge the battery faster than what it's expecting based on the internal controlling measures. 

[Chris Louw]

7 hours ago, willie_b said:

Thanks for joining the conversation Chris,

So based on description of your system - the BMS cable from the Pylontech battery bank is connected to your Epever MPPT?

 

The reason why I'm harping on about the BMS and the comms is primarily due to the fact that the BMS determines how much charge could be fed into the battery by virtue of the Comms cable into CAN or RS485 Port. So, once you charge the battery with anything that doesn't have the BMS comms linked - it will just go full tilt with 30A X 2 (Excluding Axpert) in your case, and charge the battery faster than what it's expecting based on the internal controlling measures. 

No the cable from the Pylontech goes to the Axpert. The Epever is set up to charge the battery to programed settings.There is a lot of parrameters in the program and controls beter than the Axpert.That is why I use the Epever as the master and the Axpert is running at 0.2v les than the Epever. The Epever  does have a over voltage notification and switch of the mppt should that occur. I set the Axpert to 50A max so that the battery max Amp is not exceeded.The system  is monitored  by Solarassistant and running for more  than  2 years without  any  problems. 

The benefits of this is that Axpert is running at a lower temperature. Power is avialable for more time during the day. Better flow of power when high loads is switched on.As we are running offgrid this is a great benefit.