Low Budget Lifepo4 Experiences anyone?

[kenbo]

As to heating water with excess PV I'd recommend changing your heating element from 220VAC to 12VDC, it would more efficient and less costly. I'm also not aware of any MPPT controllers that have the load diversion utility. They may exist, I'm just not aware of them.

In my experience, the best way to make hot water with solar is direct heating not PV panels. If you are interested https://heliatos-solar.myshopify.com/

[Franziska]

Thanks for your input. We are actually using something similar to the Heliatos panels on the "engine cooling loop" of the calorfier (we do not have inboard engines).

The thought with the diversion load is just to give the panels some use when the batteries are fully charged. Not sure if that is really necessary.

As we do have the 800w/220v heater cartridge already and simple 1000w inverters are not so expensive we thought it might be easier that way, especially as we also keep the ability to use shore or genset power alternatively.

So, basically we would need to plug the diversion load in manually when we see that the batteries have reached a certain voltage?

Are there no relays for this which we could install right behind the MPPT's to do the switch over?

@noelex & newhaul

Thanks for pointing that out with the amps from the MPPT's.
Does one need to leave a margin or is is ok to get a 35A controller for a panel with say 34A?
I see there are several different watt panels models so we could perhaps choose one which is just under the 40A or 35A MPPT rating.

Last not least, is a load balancing option which is built into the BMS essential? What if we do not have that.
We are not really into making electric powering a new hobby of ours :-)

Originally Posted by kenbo

As to heating water with excess PV I'd recommend changing your heating element from 220VAC to 12VDC, it would more efficient and less costly. I'm also not aware of any MPPT controllers that have the load diversion utility. They may exist, I'm just not aware of them.

In my experience, the best way to make hot water with solar is direct heating not PV panels. If you are interested https://heliatos-solar.myshopify.com/

[kenbo]

Depending on how deeply you charge and discharge a balancing function may not be essential. In any event, if you find that cell balancing is a utility you want/need there are several inexpensive active balancers that you could add to your system. But most of them require adding a conformal coating.

[Franziska]

Thx again. Can that be retrofitted later without to much hassle?
Do we need one of those for each cell pack?
Can you point me to one?

Regarding the diversion load from solar, is that necessary, will we damage something in the system if we do not have that?

Originally Posted by kenbo

Depending on how deeply you charge and discharge a balancing function may not be essential. In any event, if you find that cell balancing is a utility you want/need there are several inexpensive active balancers that you could add to your system. But most of them require adding a conformal coating.

[newhaul]

Originally Posted by Franziska

Thx again. Can that be retrofitted later without to much hassle?
Do we need one of those for each cell pack?
Can you point me to one?

Regarding the diversion load from solar, is that necessary, will we damage something in the system if we do not have that?

No you will not damage anything . The charge controllers will just stop allowing power to go into the batteriesmonce the set voltage has been reached.

After a short time you will have an idea as to the charging needs of the bank then just use your 1000 watt inverter to heat the water and draw some power out of the bank .

Most important is to forget everything you know about lead based batteries.

[kenbo]

Originally Posted by Franziska

Thx again. Can that be retrofitted later without to much hassle?
Do we need one of those for each cell pack?
Can you point me to one?

Regarding the diversion load from solar, is that necessary, will we damage something in the system if we do not have that?

Yes, it can be retrofitted easily as long as you have long enough terminal studs.
Yes, one for each pack.
As an example but there are others https://www.aliexpress.com/item/4001...archweb201603_

[Franziska]

So this should work like attached, correct?

Changed from previously:
1)
3x Epever 40A MPPT instead of 3x 20Amp MPPT (Could someone please double check this, I attached the Solar Panel Data Sheet as well. Red marked in there the panels of which we intend to get 3 if the price is not too crazy.)
2)
Additionally 3x Active Balancer (How is that actually tied into the circuit with the BMS?)
3)
Removed additional 1000w inverter for solar load diversion.
We will use our existing inverter with our existing 220V 800w water heating element if the batteries are quite full and we want to use the extra solar power available. Still, this CAN be done, but if I understand it correct, there is no formal need to do so.

Which components should we apply conformal coating to?
I'd think the load balancers and the BMS. Anything else?

Last not least, when sizing the main fuse between the batteries and the switchboards, what load governs the size of this fuse/breaker?
Total max Amp possible ever drawn at the same moment?

[kenbo]

The active balancers are independent of the BMS. The Heltec works anytime it is connected to the 4 cells and the lowest cell voltage is >3vdc and any cell voltage is +/- 5mv from the others. It takes the power from the higher voltage cells and directs it to the lower voltage cells. It does have a parasitic draw of 15mv so if you are leaving the boat for a long period you may want to remove it.

Yes, the BMS and balancer seem to be the only components that need the conformal coating.

[more]

Originally Posted by noelex 77

Unfortunately not. You will need 3x controllers capable of handling 35A+.

why 3 controller for 1 solar panell 500w..
She needs 1 controller 40-50A

[Franziska]

Three 500w panels. Each with a dedicated controller.

[more]

Originally Posted by Franziska

So this should work like attached, correct?


Additionally 3x Active Balancer (How is that actually tied into the circuit with the BMS?)
3)
Removed additional 1000w inverter for solar load diversion.
We will use our existing inverter with our existing 220V 800w water heating element if the batteries are quite full and we want to use the extra solar power available. Still, this CAN be done, but if I understand it correct, there is no formal need to do so.

Which components should we apply conformal coating to?
I'd think the load balancers and the BMS. Anything else?

Last not least, when sizing the main fuse between the batteries and the switchboards, what load governs the size of this fuse/breaker?
Total max Amp possible ever drawn at the same moment?

you don't need extra LCD for tracer, you have a shunt battery monitor. you bay connection cable Bluetooth for pc.

and your BMS choice is not for sea condition. and you dont need 3 BMS. connect 2-3 cell in parallel and now this is 1 cell 840??? ah affter this conect 4 this cell in serial and 1 Dally BMS waterproof 200-250 A.
BMS must be plug and play.

[Franziska]

4cells in serial @ 3.2v make 12.8V together they make 280Ah.
Take three of these cell blocks and you have 840Ah at 12.8V.

You need 3 BMS because you have 3 blocks of 4cells each.
The BMS will get a conformal coating and be mounted in a dry location.
Conformal coating=coating for circuit boards to reduce corrosion and humidity issues.

We prefer displays over apps/pc, sometimes we can't avoid apps but we prefer the hard wired displays.

The displays for the MPPT show the incoming current of the 3 solar panels.
The MPPT are not mounted in plain sight, therefore the displays.
Similar to the one from the wind gen.

As explained earlier one dedicated MPPT for each panel. Better redundancy and slightly better efficiency.

The overall monitor displays the charge status of all three 3 cell blocks combined=total power status.

Originally Posted by more

you don't need extra LCD for tracer, you have a shunt battery monitor. you bay connection cable Bluetooth for pc.

and your BMS choice is not for sea condition. and you dont need 3 BMS. connect 2-3 cell in parallel and now this is 1 cell 840??? ah affter this conect 4 this cell in serial and 1 Dally BMS waterproof 200-250 A.
BMS must be plug and play.

[kenbo]

If I understood more, I believe he was suggesting a 3P4S format for your bank instead of the 3 x 4S format. There are pros and cons to both formats.

[newhaul]

Originally Posted by kenbo

If I understood more, I believe he was suggesting a 3P4S format for your bank instead of the 3 x 4S format. There are pros and cons to both formats.

Personally I would go 3p4s for a single big battery and one Daly 200amp bms for bulletproof simplicity

[kenbo]

Originally Posted by newhaul

Personally I would go 3p4s for a single big battery and one Daly 200amp bms for bulletproof simplicity

True it is simpler but in Franziska's 3 x 4S format there is redundancy. As I said pros and cons to both format.