48v 16 s

[Dunndeal]

I’ve been advised to put 2 of my solar panels in series and 2 in parallel to reduce the voltage and increase the amps, which I’ve done. Panels are 4 305 watts. 36.8 volts and 8.3 amps

A little different situation I’d like answered.
I’ve got 16, 90 ah lifepo4 cells wired in series. Very high voltage Low amperage. Should I put 8 of the 16 cells in series and the other 8 in parallel to reduce overall voltage and increase amperage. I bought a Growatt 3000 48 volt. What do you pros say?

 

[Tooth Fairy]

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[time2roll]

no no no. If the Growatt is 48v the battery must be 48 volt.

Amps x Volts = Watts
Either way it is the same energy in total. However the battery and inverter need to be at the same voltage.

 

[HRTKD]

If you have a 48 volt inverter then there isn't much you can do - with the existing cells - unless you buy a different inverter.

Another set of the same 16 cells will double your Ah. Or, ditch the cells you have now altogether and buy 16 280 Ah cells.

 

[mandrews44]

I'd say you might want to contact the manufacturer of the batteries and make sure the BMS in each of them will handle 48 volts. They also need to be the same general age and even better they should be tested to be closely matched. The problem with this is you won't have balancing between the batteries that will be basically operating as 'Cells'. Unless you want to pull them apart and use a 48V BMS, you might need an external balancer to insure the batteries themselves remain balanced across the entire bank that is now a battery in itself.

Your solar panel configuration as 2p2s, your total voltage coming from the panels has to be greater than the battery you are charging. 36.8v * 2 is open circuit but might work. However, the two limiting factors here are the BMS capability to handle 48v and keeping the batteries balanced.

 

[time2roll]

I’ve been advised to put 2 of my solar panels in series and 2 in parallel to reduce the voltage and increase the amps, which I’ve done. Panels are 4 305 watts. 36.8 volts and 8.3 amps

I assume the controller will not like all in series as the voltage may exceed the design limit. The energy is the same.
This is a different situation compared to matching battery and inverter voltage.

 

[sunshine_eggo]

I’ve been advised to put 2 of my solar panels in series and 2 in parallel to reduce the voltage and increase the amps, which I’ve done. Panels are 4 305 watts. 36.8 volts and 8.3 amps

I would likely choose the same config as most MPPT can't handle the 4S Voc.

A little different situation I’d like answered.
I’ve got 16, 90 ah lifepo4 cells wired in series. Very high voltage Low amperage. Should I put 8 of the 16 cells in series and the other 8 in parallel to reduce overall voltage and increase amperage. I bought a Growatt 3000 48 volt. What do you pros say?

Borderline insane proposal. 48V requires 16S. Period. Trying to build a battery with series components of different capacity is like building a battery of hand grenades with the pins pulled.

8S + 1S8P = 9S battery with the 9th cell 8X larger than the others.

Hi
Wire the batteries in series to get the 48v, you can have as many 48v batteries as you want, then wire the 48v batteries in parallel.

Not good advice.

Each one of my batteries is 48v made up of 320 x 3.7 volt cells or 16s20p.

Why would you do that? 3.7V nominal need 14S for optimal 48V system config. 15S is do-able. 16S is silly UNLESS you intend to keep your peak V/cell notably lower than typical. If you're calling LFP cells, 3.7V, they're 3.2V, and 16S 3.2V cells is what you want.

 

[mandrews44]

I assume the controller will not like all in series as the voltage may exceed the design limit. The energy is the same.
This is a different situation compared to matching battery and inverter voltage.

16.6 amps would require a hefty cable to the panels for the energy is not the same through wire loss. I have not seen many controllers that will handle > 100v input and I have seen higher than rated voltages coming from my panels during the winter. I normally run ~70v from the panels and I've seen nearly 100v (my Victron limit) during the winter.

 

[Tooth Fairy]

I would likely choose the same config as most MPPT can't handle the 4S Voc.



Borderline insane proposal. 48V requires 16S. Period. Trying to build a battery with series components of different capacity is like building a battery of hand grenades with the pins pulled.

8S + 1S8P = 9S battery with the 9th cell 8X larger than the others.




Not good advice.



Why would you do that? 3.7V nominal need 14S for optimal 48V system config. 15S is do-able. 16S is silly UNLESS you intend to keep your peak V/cell notably lower than typical. If you're calling LFP cells, 3.7V, they're 3.2V, and 16S 3.2V cells is what you want.

The growatt 3000 charges to 58v as does my Deye 5K.

 

[MisterSandals]

The growatt 3000 charges to 58v as does my Deye 5K.

58V / 16 cell = 3.625Vpc

I would hope (expect?) that every lithium aware charger has the ability to charge at least to 58V.

 

[sunshine_eggo]

The growatt 3000 charges to 58v as does my Deye 5K.

Okay. For 16S 3.7V cell chemistry, that's insane. 3.7V chemistry charges to 4.20V. 3.625V is almost useless for 3.7V chemistry.

The issue appears that you don't understand LFP cells are 3.2V cells not 3.7V cells.

 

[time2roll]

16.6 amps would require a hefty cable to the panels for the energy is not the same through wire loss. I have not seen many controllers that will handle > 100v input and I have seen higher than rated voltages coming from my panels during the winter. I normally run ~70v from the panels and I've seen nearly 100v (my Victron limit) during the winter.

OK and the OP was advised to REDUCE voltage so the alternative with all series is Voc 147+. Unless the OP gives more details there is not much to debate. My point was that it seemed the OP was crossing the thoughts over to the battery-inverter connection and I wanted to express that it is not the same issue.

My Morningstar goes 150v and 147 would be too close for me. Morningstar also makes a nice 600 volt if needed.

 

[Tooth Fairy]

Okay. For 16S 3.7V cell chemistry, that's insane. 3.7V chemistry charges to 4.20V. 3.625V is almost useless for 3.7V chemistry.

The issue appears that you don't understand LFP cells are 3.2V cells not 3.7V cells.

So educate me rather coming across as some superior know all being!!

 

[sunshine_eggo]

So educate me rather coming across as some superior know all being!!

I've tried to for two posts now. I'll try to make the 3rd time the charm.

If you have LFP (Lithium Iron Phosphate, LiFePO4), you do not have 3.7V cells. You have 3.2V cells.

If you have 3.7V cells (not LFP - some other Lithium like NCA, NMC, LMO, etc.), 16S is too many, and you will only be able to access a very small portion of the battery capacity only charging to 58V.

 

[Tooth Fairy]

Thats the problem with some forums, one or two take on the superior high and mighty ground, newbies look then leave and the forum stagnates.

 

[sunshine_eggo]

Thats the problem with some forums, one or two take on the superior high and mighty ground, newbies look then leave and the forum stagnates.

But do you understand now?