Pylontech stack - additional charger?

[resybaby]

Evening all, after a bit of assistance again from you kind and knowledgable guys.

Quick recap.
I have an existing 4kw FIT system, and has a new 5.45kw Sunsynk Ecco 3.6 hydrid system with 4xus5000's added as a separate system. All AC coupled.
Sunsynk invertor has taken some getting used to, lots of complicated settings to operate it, but a typically appaling manual that explains nothing whatsoever, together with an overly enthusiastic company CEO who, although well clued up, struggles to explain things clearly for an amateur like me to understand also.

System works fine now i have fathomed it out, but i have noted that the power provided by the FIT system doesnt get fed back to the Pylontechs to be stored as i thought it would. So im wondering if there is a way around this to help during the winter with battery charging (the summer wont be a problem im certain).

What ive noted on the Pylontech stack os that there is a spare positive and neutral connection across the stack, one connection on the top battery and one connection at the bottom.

So what im thinking is is it possible to use my existing Marlec iboost to connect up a separate battery charger (as per below) directly to these 'spare' connections to utilise the power that my uncontrolled FIT system is kindly sending back down the Grid currently?

In effect, charge my pylontechs from both my new solar, and via the separate charger at the same time.
Im assuming that the pylontech BMS will control the charge from the Sunsynk as currently, and that the battery charger will have its own controls to also sense when the batteries are full also, so neither will 'cook' the battery.

Hope that makes sense and im not just making myself sound more of a dummy than i usually manage.

Have attached schematic and details of charger.

Have also attached a 'teaser' photo of a split A2A heatpump that ive installed, thanks to the excellent writeups on here from a few of you. Managed to hide my pipework in boxing in the garage, and knocked up a housing to try and keep the salty sea rain off the condensor. Will do a write up and post the piccies when i get chance. a thousand thanks for the inspiration.

Thanks guys

[robl]

I’m in a similar position! 4kW fit, recent sunsynk + 15kWh battery that doesn’t charge from the fit system. But we get Seg export instead of deemed fit export (still fit generation), so I don’t sweat it - we get paid slightly more to let the pv go out than we pay for ‘go’ electric, and it’s probably greener to use the night low CO2 electric and donate out daytime stuff. My longer term strategy is to get more PV on those sunsynk inputs

That Iboost is almost certainly a simple triac based phase controller - think old school incandescent lamp dimmer - it’s fine for old school motor speed control and heating elements, but not for anything clever like a power supply. It might work a little initially, but you’ll bust the charger eventually. Will the sunsynk know the charge level of the batteries if you do this (maybe yes if you have the batt comms working).
As an interesting thought experiment, a kW or so power supply charging the batteries all the time sort of does what you want, as the sunsynk will just pull the power from the batts to power it if there isn’t enough sun(!). Don’t do it though, it’s a waste of power going through two inverters. I feel there should be a sunsynk based solution somehow!

[nowty]

Sounds like your hybrid inverter are DC coupled to the batteries so the excess from the FIT systems wont charge the batteries. Thats why I prefer an AC coupled battery inverter which will take the excess from the FIT system.

[pudding]

The Sunsynk should and can charge from your existing fit system. It's exactly what mine does. Must be a settings problem or CT clamp issue.

[Tinbum]

Show where the CT is on your diagram.

[Stinsy]

The Sunsynk should charge from the FiT system. Sounds like the CT isn’t fitted correctly. Does the FiT system have its own mini-CU?

[Tinbum]

The Sunsynk should charge from the FiT system. Sounds like the CT isn’t fitted correctly. Does the FiT system have its own mini-CU?

See his diagram in the first post.

[richbee]

Evening all, after a bit of assistance again from you kind and knowledgable guys.

Quick recap.
I have an existing 4kw FIT system, and has a new 5.45kw Sunsynk Ecco 3.6 hydrid system with 4xus5000's added as a separate system. All AC coupled.
Sunsynk invertor has taken some getting used to, lots of complicated settings to operate it, but a typically appaling manual that explains nothing whatsoever, together with an overly enthusiastic company CEO who, although well clued up, struggles to explain things clearly for an amateur like me to understand also.

System works fine now i have fathomed it out, but i have noted that the power provided by the FIT system doesnt get fed back to the Pylontechs to be stored as i thought it would. So im wondering if there is a way around this to help during the winter with battery charging (the summer wont be a problem im certain).

What ive noted on the Pylontech stack os that there is a spare positive and neutral connection across the stack, one connection on the top battery and one connection at the bottom.

So what im thinking is is it possible to use my existing Marlec iboost to connect up a separate battery charger (as per below) directly to these 'spare' connections to utilise the power that my uncontrolled FIT system is kindly sending back down the Grid currently?

In effect, charge my pylontechs from both my new solar, and via the separate charger at the same time.
Im assuming that the pylontech BMS will control the charge from the Sunsynk as currently, and that the battery charger will have its own controls to also sense when the batteries are full also, so neither will 'cook' the battery.

Hope that makes sense and im not just making myself sound more of a dummy than i usually manage.

Have attached schematic and details of charger.

Have also attached a 'teaser' photo of a split A2A heatpump that ive installed, thanks to the excellent writeups on here from a few of you. Managed to hide my pipework in boxing in the garage, and knocked up a housing to try and keep the salty sea rain off the condensor. Will do a write up and post the piccies when i get chance. a thousand thanks for the inspiration.

Thanks guys

Keith, over enthusiastic - no!!

Not sure if it possible but someone on the Sunsynk FB group was suggesting connecting extra PV - in this case the FIT system, to the 'generator' input on the inverter, as it can be used by wind turbine etc or diesel generator

[richbee]

The Sunsynk should charge from the FiT system. Sounds like the CT isn’t fitted correctly. Does the FiT system have its own mini-CU?

Would be interested to know how it should be set up to achieve this - as I'm planning extra 'balcony' solar panels with microinverters and no CT coil etc - would be ideal if it can also charge the batteries, but I was guessing it probably wouldn't.

[robl]

The Sunsynk should and can charge from your existing fit system. It's exactly what mine does. Must be a settings problem or CT clamp issue.

Ooohh that's interesting! Care to post your images from the two rather cryptic System mode pages? Pretty much every time I mess with those I b**ger something up. Tried watch a Keith Goth video, and he told me it was simple, that's all I learnt..